Use of the film grain characteristics frame packing arrangement, region-wise packing, and colour transform information SEI messages in a bitstream

Abstract

A mechanism for processing video data is disclosed. The mechanism includes determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain. A conversion is performed between a visual media data and a bitstream based on the processing chain.

Description

Use Of The Film Grain Characteristics Frame Packing Arrangement, Region-Wise Packing, and Colour Transform Information SEI Messages In A Bitstream CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority to and benefits of U.S. Provisional Patent Application No.63 / 701,806, filed on October 1, 2024 and U.S. Provisional Patent Application No.63 / 702,376, filed on October 2, 2024. All the aforementioned patent applications are hereby incorporated by reference in their entireties. TECHNICAL FIELD

[0002] This patent document relates to generation, storage, and consumption of digital audio video media information in a file format. BACKGROUND

[0003] Digital video accounts for the largest bandwidth used on the Internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, the bandwidth demand for digital video usage is likely to continue to grow. SUMMARY

[0004] A first aspect relates to a method for processing video data comprising: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain; and performing a conversion between a visual media data and a bitstream based on the processing chain.

[0005] A second aspect relates to an apparatus for processing video data comprising: a processor; and a non- transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform any of the preceding aspects.

[0006] A third aspect relates to non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of the preceding aspects.

[0007] A fourth aspect relates to a non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain; and generating a bitstream based on the determining.

[0008] A fifth aspect relates to a method for storing bitstream of a video comprising: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within aprocessing chain; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

[0009] For the purpose of clarity, any one of the foregoing embodiments may be combined with any one or more of the other foregoing embodiments to create a new embodiment within the scope of the present disclosure.

[0010] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0012] FIG.1 is a flowchart for an example rearrangement and upconversion of side-by-side packing arrangement with fp_arrangement_type equal to 3, fp_quincunx_sampling_flag equal to 0 and ( x, y ) equal to ( 0, 0 ) or ( 4, 8 ) for both constituent frames.

[0013] FIG.2 is a flowchart for an example rearrangement and upconversion of side-by-side packing arrangement with fp_arrangement_type equal to 3, fp_quincunx_sampling_flag equal to 0, ( x, y ) equal to ( 12, 8 ) for constituent frame 0 and ( x, y ) equal to ( 0, 0 ) or ( 4, 8 ) for constituent frame 1.

[0014] FIG.3 is a flowchart for an example rearrangement and upconversion of top-bottom packing arrangement with fp_arrangement_type equal to 4, fp_quincunx_sampling_flag equal to 0 and ( x, y ) equal to ( 0, 0 ) or ( 8, 4 ) for both constituent frames.

[0015] FIG.4 is a flowchart for an example rearrangement and upconversion of top-bottom packing arrangement with fp_arrangement_type equal to 4, fp_quincunx_sampling_flag equal to 0, ( x, y ) equal to ( 8, 12 ) for constituent frame 0 and ( x, y ) equal to ( 0, 0 ) or ( 8, 4 ) for constituent frame 1.

[0016] FIG. 5 is a flowchart for an example for rearrangement and upconversion of side-by-side packing arrangement with quincunx sampling (fp_arrangement_type equal to 3 with fp_quincunx_sampling_flag equal to 1).

[0017] FIG. 6 is a flowchart for an example for rearrangement of a temporal interleaving frame arrangement (fp_arrangement_type equal to 5).

[0018] FIG.7 is a block diagram showing an example video processing system.

[0019] FIG.8 is a block diagram of an example video processing apparatus.

[0020] FIG.9 is a flowchart for an example method of video processing.

[0021] FIG.10 is a block diagram that illustrates an example video coding system.

[0022] FIG.11 is a block diagram that illustrates an example encoder.

[0023] FIG.12 is a block diagram that illustrates an example decoder.

[0024] FIG.13 is a schematic diagram of an example encoder. DETAILED DESCRIPTION

[0025] It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and / or methods may be implemented using any number oftechniques, whether currently known or yet to be developed. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

[0026] Section headings are used in the present document for ease of understanding and do not limit the applicability of techniques and embodiments disclosed in each section only to that section. Furthermore, H.266 terminology is used in some description only for ease of understanding and not for limiting scope of the disclosed techniques. As such, the techniques described herein are applicable to other video codec protocols and designs also. In the present document, editing changes are shown to text by bold italics indicating cancelled text and bold indicating added text, with respect to the Versatile Video Coding (VVC) specification and / or the SEI messages for coded video bitstreams (VSEI) standard. 1. Initial discussion

[0027] This document is related to image / video coding technologies. Specifically, this disclosure is related to specifying the use of the film grain characteristics (FGC) SEI message, the frame packing arrangement (FPA) SEI message, the region-wise packing (RWP) SEI message, and the colour transform information (CTI) SEI message in a coded video bitstream, e.g., a bitstream of the versatile video coding (VVC) standard, the high efficiency video coding (HEVC) standard, or the advance video coding (AVC) standard. The ideas may be applied individually or in various combinations, for video bitstreams coded by any codec, e.g., the VVC standard, the HEVC standard, the AVC standard, and / or the versatile SEI messages for coded video bitstreams (VSEI) standard. 2. Further discussion 2.1 Video coding standards

[0028] Video coding standards have evolved primarily through the development of International Telecommunication Union (ITU) telecommunication standardization sector (ITU-T) and International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC) standards. The ITU-T produced H.261 and H.263, ISO / IEC produced motion picture experts group (MPEG)-1 and MPEG-4 Visual, and the two organizations jointly produced the H.262 / MPEG-2 Video and H.264 / MPEG-4 Advanced Video Coding (AVC) and H.265 / high efficiency video coding (HEVC) [1] standards. Since H.262, the video coding standards are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized. The Versatile Video Coding (VVC) standard (ITU-T H.266 | ISO / IEC 23090-3) [2] and the associated Versatile Supplemental Enhancement Information for coded video bitstreams (VSEI) standard (ITU-T H.274 | ISO / IEC 23002-7) [3] are designed for use in a maximally broad range of applications, including both the simple uses such as television broadcast, video conferencing, or playback from storage media, and also more advanced use cases such as adaptive bit rate streaming, video region extraction, composition and merging of content from multiple coded video bitstreams, multiview video, scalable layered coding, and viewport-adaptive 360° immersive media. 2.2 SEI messages in general and in VVC and VSEI

[0029] SEI messages assist in processes related to decoding, display or other purposes. However, SEI messages are not required for constructing the luma or chroma samples by the decoding process. Conforming decoders are notrequired to process this information for output order conformance. Some SEI messages are required for checking bitstream conformance and for output timing decoder conformance. Other SEI messages are not required for check bitstream conformance.

[0030] Annex D of VVC specifies syntax and semantics for SEI message payloads for some SEI messages, and specifies the use of the SEI messages and video usability information (VUI) parameters for which the syntax and semantics are specified in ITU-T H.SEI | ISO / IEC 23002-7. 2.3 The film grain characteristics, frame packing arrangement, region-wise packing, and colour transform information SEI messages

[0031] JVET-AI2006 [4] and version 3 of the VSEI standard [3] include the specifications of the film grain characteristics (FGC) SEI message, the frame packing arrangement (FPA) SEI message, the region-wise packing (RWP) SEI message, and the colour transform information (CTI) SEI message.

[0032] An improved version of the specifications of the FGC, FPA, RWP, and CTI SEI messages is as follows. 8.5 Film grain characteristics SEI message 8.5.1 Film grain characteristics SEI message syntax film_grain_characteristics( payloadSize ) { Descriptor f characteristics cancel fla u(1)fg_intensity_interval_lower_bound[ c ][ i ] u(8) fg_intensity_interval_upper_bound[ c ][ i ] u(8) 8.5

[0033] Use of this SEI message requires the definition of the following variables: – The variable SeiProcStgIdx, indicating the processing stage index associated with the film grain characteristics (FGC) SEI message within a chosen processing chain. – The list CandInputPicList[ SeiProcStgIdx ], containing a list of pictures in output order from which the input picture for the process implied by the FGC SEI mesage is selected. When SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ SeiProcStgIdx ] are decoded pictures. NOTE 1 – When SeiProcStgIdx is greater than 0, the list CandInputPicList[ SeiProcStgIdx ] contains pictures after the application of the process(es) implied by the SEI message(s) associated with processing stage index values less than SeiProcStgIdx. – A picture width and picture height in units of luma samples, denoted herein by PicWidthInLumaSamples and PicHeightInLumaSamples, respectively. – When the syntax element fg_separate_colour_description_present_flag of the film grain characteristics SEI message is equal to 0, the following additional variables: – A chroma format indicator, denoted herein by ChromaFormatIdc, as described in clause 7.3. – A bit depth for the samples of the luma component, denoted herein by BitDepthY, and when ChromaFormatIdc is not equal to 0, a bit depth for the samples of the two associated chroma components, denoted herein by BitDepthC.

[0034] This SEI message provides the decoder with a parameterized model for a film grain synthesis process. The film grain synthesis process should be applied to the input pictures from CandInputPicList[ SeiProcStgIdx ] prior to their display.

[0035] NOTE 2 – For example, an encoder could use the film grain characteristics SEI message to characterize film grain that was present in the original source video material and was removed by pre-processing filtering techniques. Synthesis of simulated film grain on the input images, which could be the input pictures or converted from the input pictures, for the display process is optional and does not necessarily exactly follow the specified semantics of the film grain characteristics SEI message. When synthesis of simulated film grain on the input images for the display processis performed, there is no requirement that the method by which the synthesis is performed be the same as the parameterized model for the film grain as provided in the film grain characteristics SEI message.

[0036] NOTE 3 – The display process is not specified in this Specification.

[0037] NOTE 4 – Society of Motion Picture and Television Engineers (SMPTE) Registered Disclosure Document (RDD) 5 (2006) specifies a film grain simulator based on the information provided in the film grain characteristics SEI message.

[0038] The film grain models specified in the film grain characteristics SEI message are expressed for application to the input pictures from CandInputPicList[ SeiProcStgIdx ] that have 4:4:4 colour format with luma and chroma bit depths corresponding to the luma and chroma bit depths of the film grain model and use the same colour representation domain as the identified film grain model. When the colour format of the input pictures is not 4:4:4 or the input pictures use a different luma or chroma bit depth from that of the film grain model or use a different colour representation domain from that of the identified film grain model, an unspecified conversion process is expected to be applied to convert the input pictures to the form that is expressed for application of the film grain model.

[0039] NOTE 5 – Because the use of a specific method is not required for performing the film grain generation function used by the display process, a decoder could, if desired, down-convert the model information for chroma in order to simulate film grain for other chroma formats (4:2:0 or 4:2:2) rather than up-converting the decoded video (using a method not specified in this Specification) before performing film grain generation.

[0040] The process implied by the FGC SEI message should be applied to each picture in CandInputPicList[ SeiProcStgIdx ] that is the corresponding picture or an associated inserted picture of a picture for which the FGC SEI message persists. When the process implied by the FGC SEI message is applied to such a picture, that picture is considered as the input picture.

[0041] fg_characteristics_cancel_flag equal to 1 indicates that the SEI message cancels the persistence of any previous film grain characteristics SEI message in output order that applies to the current layer. fg_characteristics_cancel_flag equal to 0 indicates that film grain modelling information follows.

[0042] fg_model_id identifies the film grain simulation model as specified in Table 1. The value of fg_model_id shall be in the range of 0 to 1, inclusive. The values of 2 and 3 for fg_model_id are reserved for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this Specification. Decoders shall ignore film grain characteristic SEI messages with fg_model_id equal to 2 or 3. Table 1 – fg_model_id values Value Description

[0043] fg_separate_colour_description_present_flag equal to 1 indicates that a distinct combination of luma bit depth, chroma bit depth, video full range flag, colour primaries, transfer characteristics, and matrix coefficients for the film grain characteristics specified in the SEI message is present in the film grain characteristics SEI message syntax. fg_separate_colour_description_present_flag equal to 0 indicates that the combination of luma bit depth, chroma bitdepth, video full range flag, colour primaries, transfer characteristics, and matrix coefficients for the film grain characteristics specified in the SEI message are the same as indicated in VUI parameters for the CLVS.

[0044] NOTE 5 – When fg_separate_colour_description_present_flag is equal to 1, any of the luma bit depth, chroma bit depth, video full range flag, colour primaries, transfer characteristics, and matrix coefficients specified for the film grain characteristics specified in the SEI message could differ from that for the pictures in the CLVS.

[0045] When VUI parameters are not present for the CLVS or the value of vui_colour_description_present_flag is equal to 0, and equivalent information to that conveyed when vui_colour_description_present_flag is equal to 1 is not conveyed by external means, fg_separate_colour_description_present_flag shall be equal to 1.

[0046] The input image Î, which may be the decoded picture or converted from the decoded picture, used in the equations in this clause is in the same colour representation domain as the simulated film grain signal. Therefore, when any of these parameters does differ from that for the pictures in CLVS, the input image Î used in the equations in this clause would be in a different colour representation domain than that for the pictures in the CLVS. For example, when the value of fg_bit_depth_luma_minus8 + 8 is greater than BitDepthY (i.e., the bit depth of the luma component of the pictures in the CLVS), the bit depth of the input image Î used in the equations in this clause is also greater than BitDepthY. In such a case, the input image Î would be generated by converting the actual decoded picture to be in the same colour representation domain as the simulated film grain signal. The process for converting an actual decoded picture to the 4:4:4 colour format with same colour representation domain as the simulated film grain signal is not specified in this Specification.

[0047] fg_bit_depth_luma_minus8 plus 8 specifies the bit depth used for the luma component of the film grain characteristics specified in the SEI message. When fg_bit_depth_luma_minus8 is not present in the film grain characteristics SEI message, the value of fg_bit_depth_luma_minus8 is inferred to be equal to BitDepthY − 8.

[0048] The value of fgBitDepth

[0000] is derived as follows: fgBitDepth

[0000] = fg_bit_depth_luma_minus8 + 8 (19)

[0049] fg_bit_depth_chroma_minus8 plus 8 specifies the bit depth used for the Cb and Cr components of the film grain characteristics specified in the SEI message. When fg_bit_depth_chroma_minus8 is not present in the film grain characteristics SEI message, the value of fg_bit_depth_chroma_minus8 is inferred to be equal to BitDepthC − 8.

[0050] The value of fgBitDepth[ c ] for c = 1 and 2 is derived as follows: fgBitDepth[ c ] = fg_bit_depth_chroma_minus8 + 8, with c = 1, 2 (20)

[0051] fg_full_range_flag has the same semantics as specified in clause 7.3 for the vui_full_range_flag syntax element, except as follows: – fg_full_range_flag specifies the video full range flag of the film grain characteristics specified in the SEI message, rather than the video full range flag used for the CLVS. – When fg_full_range_flag is not present in the film grain characteristics SEI message, the value of fg_full_range_flag is inferred to be equal to vui_full_range_flag.

[0052] fg_colour_primaries has the same semantics as specified in clause 7.3 for the vui_colour_primaries syntax element, except as follows:– fg_colour_primaries specifies the colour primaries of the film grain characteristics specified in the SEI message, rather than the colour primaries used for the CLVS. – When fg_colour_primaries is not present in the film grain characteristics SEI message, the value of fg_colour_primaries is inferred to be equal to vui_colour_primaries.

[0053] fg_transfer_characteristics has the same semantics as specified in clause 7.3 for the vui_transfer_characteristics syntax element, except as follows: – fg_transfer_characteristics specifies the transfer characteristics of the film grain characteristics specified in the SEI message, rather than the transfer characteristics used for the CLVS. – When fg_transfer_characteristics is not present in the film grain characteristics SEI message, the value of fg_transfer_characteristics is inferred to be equal to vui_transfer_characteristics.

[0054] fg_matrix_coeffs has the same semantics as specified in clause 7.3 for the vui_matrix_coeffs syntax element, except as follows: – fg_matrix_coeffs specifies the matrix coefficients of the film grain characteristics specified in the SEI message, rather than the matrix coefficients used for the CLVS. – When fg_matrix_coeffs is not present in the film grain characteristics SEI message, the value of fg_matrix_coeffs is inferred to be equal to vui_matrix_coeffs. – The values allowed for fg_matrix_coeffs are not constrained by the chroma format of the decoded video pictures that is indicated by the value of ChromaFormatIdc for the semantics of the VUI parameters.

[0055] fg_matrix_coeffs shall not be equal to 0 unless fg_bit_depth_luma_minus8 is equal to fg_bit_depth_chroma_minus8.

[0056] fg_matrix_coeffs shall not be equal to 8 unless one of the following conditions is true: – fg_bit_depth_luma_minus8 is equal to fg_bit_depth_chroma_minus8. – fg_bit_depth_chroma_minus8 is equal to fg_bit_depth_luma_minus8 + 1.

[0057] fg_blending_mode_id identifies the blending mode used to blend the simulated film grain with the input images as specified in Table 2. fg_blending_mode_id shall be in the range of 0 to 1, inclusive. The values of 2 and 3 for fg_blending_mode_id are reserved for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this Specification. Decoders shall ignore film grain characteristic SEI messages with fg_blending_mode_id equal to 2 or 3. Table 2 – fg_blending_mode_id values Value Description

[0058] Depending on the value of fg_blending_mode_id, the blending mode is specified as follows: – If fg_blending_mode_id is equal to 0, the blending mode is additive as specified by: Igrain[ c ][ x ][ y ] = Clip3( 0, ( 1 << fgBitDepth[ c ] ) − 1, Î[ c ][ x ][ y ] + G[ c ][ x ][ y ] ) (21) – Otherwise (fg_blending_mode_id is equal to 1), the blending mode is multiplicative as specified by:Igrain[ c ][ x ][ y ] = Clip3( 0, ( 1 << fgBitDepth[ c ] ) − 1, Î[ c ][ x ][ y ] + (22) Round( ( Î[ c ][ x ][ y ] * G[ c ][ x ][ y ] ) ÷ ( ( 1 << fgBitDepth[ c ] ) − 1 ) ) ) where Î[ c ][ x ][ y ] represents the sample value at coordinates x, y of the colour component c of the input image Î, G[ c ][ x ][ y ] is the simulated film grain value at the same position and colour component, and fgBitDepth[ c ] is the number of bits used for each sample in a fixed-length unsigned binary representation of the arrays Igrain[ c ][ x ][ y ], Î[ c ][ x ][ y ], and G[ c ][ x ][ y ], where c = 0..2, x = 0..PicWidthInLumaSamples − 1, and y = 0..PicHeightInLumaSamples − 1.

[0059] fg_log2_scale_factor specifies a scale factor used in the film grain characterization equations.

[0060] fg_comp_model_present_flag[ c ] equal to 0 indicates that film grain is not modelled on the c-th colour component, where c equal to 0 refers to the luma component, c equal to 1 refers to the Cb component, and c equal to 2 refers to the Cr component. fg_comp_model_present_flag[ c ] equal to 1 indicates that syntax elements specifying modelling of film grain on colour component c are present in the SEI message.

[0061] When fg_separate_colour_description_present_flag is equal to 0 and ChromaFormatIdc is equal to 0, the value of fg_comp_model_present_flag

[0001] and fg_comp_model_present_flag

[0002] shall be equal to 0.

[0062] fg_num_intensity_intervals_minus1[ c ] plus 1 specifies the number of intensity intervals for which a specific set of model values has been estimated.

[0063] NOTE 6 – The intensity intervals could overlap in order to simulate multi-generational film grain.

[0064] fg_num_model_values_minus1[ c ] plus 1 specifies the number of model values present for each intensity interval in which the film grain has been modelled. The value of fg_num_model_values_minus1[ c ] shall be in the range of 0 to 5, inclusive.

[0065] fg_intensity_interval_lower_bound[ c ][ i ] specifies the lower bound of the i-th intensity interval for which the set of model values applies.

[0066] fg_intensity_interval_upper_bound[ c ][ i ] specifies the upper bound of the i-th intensity interval for which the set of model values applies.

[0067] The variable intensityIntervalIdx[ c ][ x ][ y ][ j ] represents the j-th index to the list of intensity intervals selected for the sample value Î[ c ][ x ][ y ] for c = 0..2, x = 0..PicWidthInLumaSamples − 1, y = 0..PicHeightInLumaSamples − 1, and j = 0..numApplicableIntensityIntervals[ c ][ x ][ y ] − 1, where numApplicableIntensityIntervals[ c ][ x ][ y ] is derived below.

[0068] Depending on the value of fg_model_id, the selection of the one or more intensity intervals for the sample value Î[ c ][ x ][ y ] is specified as follows: – The variable numApplicableIntensityIntervals[ c ][ x ][ y ] is initially set equal to 0. – If fg_model_id is equal to 0, the following applies: – The top-left sample location ( xB, yB ) of the current 8x8 block b that contains the sample value Î[ c ][ x ][ y ] is derived as ( xB, yB ) = ( x / 8, y / 8 ). – The average value bavgof the current 8x8 block b is derived as follows: sum8x8 = 0 for( i = 0; i < 8; i++ )for( j = 0; j < 8; j++ ) sum8x8 += Î[ c ][ xB * 8 + i ][yB * 8 + j ] (23) – Theif( bavg>= fg_intensity_interval_lower_bound[ c ][ i ] && bavg<= fg_intensity_interval_upper_bound[ c ][ i ] ) { intensityIntervalIdx[ c ][ x ][ y ][ j ] = i (24)}[ c ][ x ][ y ] = j – Otherwise (fg_model_id is equal to 1), the value of intensityIntervalIdx[ c ][ x ][ y ][ j ] is derived as follows: I8[ c ][ x ][ y ] = ( fgBitDepth[ c ] = = 8 ) ? ( Î[ c ][ x ][ y ] : Clip3( 0, 255, ( Î[ c ][ x ][ y ] + ( 1 << ( fgBitDepth[ c ] − 9 ) ) ) >> ( fgBitDepth[ c ] − 8 ) ) for( i = 0, j = 0; i <= fg_num_intensity_intervals_minus1[ c ]; i++ ) if( I8[ c ][ x ][ y ] >= fg_intensity_interval_lower_bound[ c ][ i ] && (25) I8[ c ][ x ][ y ] <= fg_intensity_interval_upper_bound[ c ][ i ] ) { intensityIntervalIdx[ c ][ x ][ y ][ j ] = i j++ } [ c ][ x ][ y ] = j

[0069] Samples that do not fall into any of the defined intervals (i.e., those samples for which the value of numApplicableIntensityIntervals[ c ][ x ][ y ] is equal to 0) are not modified by the grain generation function. Samples that fall into more than one interval (i.e., those samples for which the value of numApplicableIntensityIntervals[ c ][ x ][ y ] is greater than 1) will originate multi-generation grain. Multi-generation grain results from adding the grain computed independently for each of the applicable intensity intervals.

[0070] In the equations in the remainder of this clause, the variable sj in each instance of the list fg_comp_model_value[ c ][ sj ] is the value of intensityIntervalIdx[ c ][ x ][ y ][ j ] derived for the sample value Î[ c ][ x ][ y ].

[0071] fg_comp_model_value[ c ][ i ][ j ] specifies the j-th model value for the colour component c and the i-th intensity interval. The set of model values has different meaning depending on the value of fg_model_id.

[0072] The value of fg_comp_model_value[ c ][ i ][ j ] is constrained as follows, and could be additionally constrained as specified elsewhere in this clause: – If fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ][ j ] shall be in the range of 0 to 2fgBitDepth[ c ]− 1, inclusive. – Otherwise (fg_model_id is equal to 1), fg_comp_model_value[ c ][ i ][ j ] shall be in the range of −2( fgBitDepth[ c ] − 1 )to 2( fgBitDepth[ c ] − 1 )− 1, inclusive.

[0073] Depending on the value of fg_model_id, the synthesis of the film grain is modelled as follows: – If fg_model_id is equal to 0, a frequency filtering model enables simulating the original film grain for c = 0..2, x = 0..PicWidthInLumaSamples − 1, and y = 0..PicHeightInLumaSamples − 1 as specified by: G[ c ][ x ][ y ] = ( fg_comp_model_value[ c ][ sj]

[0000] * Q[ c ][ x ][ y ] + fg_comp_model_value[ c ][ sj]

[0005] * G[ c − 1 ][ x ][ y ] ) >> fg_log2_scale_factor (26)distributed Gaussian random variable samples with zero mean and unity variance) and where the value of an element G[ c − 1 ][ x ][ y ] used in the right-hand side of the equation is inferred to be equal to 0 when c − 1 is less than 0.

[0074] NOTE 7 – A normalized Gaussian random variable can be generated from two independent, uniformly distributed random values over the interval from 0 to 1 (and not equal to 0), denoted as uRv0 and uRv1, using the Box- Muller transformation specified by: gaussRvi,j = Sqrt( −2 * Ln( uRv0 ) ) * Cos( 2 * π * uRv1 ) (27) where ^ is Archimedes' constant 3.141592653589793....

[0075] The band-pass filtering of blocks gaussRv can be performed in the discrete cosine transform (DCT) domain as follows: for( y = 0; y < 16; y++ ) for( x = 0; x < 16; x++ ) if( ( x < fg_comp_model_value[ c ][ sj]

[0003] && y < fg_comp_model_value[ c ][ sj]

[0004] ) | | (28) x > fg_comp_model_value[ c ][ sj]

[0001] | | y > fg_comp_model_value[ c ][ sj]

[0002] ) gaussRv[ x ][ y ] = 0 filteredRv = IDCT16x16( gaussRv ) where IDCT16x16( z ) refers to a unitary inverse discrete cosine transformation (IDCT) operating on a 16x16 matrix argument z as specified by: IDCT16x16( z ) = r * z * rT(29) where the superscript T indicates a matrix transposition and r is the 16x16 matrix with elements rij specified by: r^ ^ ^ ^ ^ ^ ^ ? ^ ∶ ^^^^^ ^ ^i * ^ 2 * j + 1 ^ * π ^,^ = ^ ∗ Cos ^32 ^ (30)Q[ c ] is formed by the frequency-filtered blocks filteredRv.

[0076] NOTE 8 – Coded model values are based on blocks of size 16x16, but a decoder implementation could use other block sizes. For example, decoders implementing the IDCT on 8x8 blocks could down-convert by a factor of two the set of coded model values fg_comp_model_value[ c ][ sj ][ i ] for i equal to 1..4.

[0077] NOTE 9 – To reduce the degree of visible blocks that result from mosaicking the frequency-filtered blocks filteredRv, decoders could apply a low-pass filter to the boundaries between frequency-filtered blocks.– Otherwise (fg_model_id is equal to 1), an auto-regression model enables simulating the original film grain for c = 0..2, x = 0..PicWidthInLumaSamples − 1, and y = 0..PicHeightInLumaSamples − 1 as specified by: G[ c ][ x ][ y ] = ( fg_comp_model_value[ c ][ sj ]

[0000] * n[ c ][ x][ y ] + fg_comp_model_value[ c ][ sj ]

[0001] * ( G[ c ][ x − 1 ][ y ] + ( ( fg_comp_model_value[ c ][ sj]

[0004] * G[ c ][ x ][ y − 1 ] ) >> fg_log2_scale_factor ) ) + fg_comp_model_value[ c ][ sj]

[0003] * ( ( fg_comp_model_value[ c ][ sj]

[0004] * ( G[ c ][ x − 1 ][ y − 1 ] + G[ c ][ x + 1 ][ y − 1 ] ) ) >> (31) fg_log2_scale_factor ) + fg_comp_model_value[ c ][ sj ]

[0005] * ( G[ c ][ x − 2 ][ y ] + ( ( fg_comp_model_value[ c ][ sj ]

[0004] * fg_comp_model_value[ c ][ sj ]

[0004] * G[ c ][ x ][ y − 2 ] ) >> ( 2 * fg_log2_scale_factor ) ) ) + fg_ comp_model_value[ c ][ sj ]

[0002] * G[ c − 1 ][ x ][ y ] ) >> fg_log2_scale_factor where n[ c ][ x ][ y ] is a random value with normalized Gaussian distribution (independent and identically distributed Gaussian random variable samples with zero mean and unity variance for each value of c, x, and y) and where the value of an element G[ c ][ x ][ y ] used in the right-hand side of the equation is inferred to be equal to 0 when any of the following conditions are true: – c is less than 0, – x is less than 0, – y is less than 0.

[0078] fg_comp_model_value[ c ][ i ]

[0000] provides the first model value for the model as specified by fg_model_id. fg_comp_model_value[ c ][ i ]

[0000] corresponds to the standard deviation of the Gaussian noise term in the generation functions specified in Equations 26 through 31.

[0079] fg_comp_model_value[ c ][ i ]

[0001] provides the second model value for the model as specified by fg_model_id. When fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0001] shall be greater than or equal to 0 and less than 16.

[0080] When not present in the film grain characteristics SEI message, fg_comp_model_value[ c ][ i ]

[0001] is inferred as follows: – If fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0001] is inferred to be equal to 8. – Otherwise (fg_model_id is equal to 1), fg_comp_model_value[ c ][ i ]

[0001] is inferred to be equal to 0.

[0081] fg_comp_model_value[ c ][ i ]

[0001] is interpreted as follows: – If fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0001] indicates the horizontal high cut frequency to be used to filter the DCT of a block of 16x16 random values. – Otherwise (fg_model_id is equal to 1), fg_comp_model_value[ c ][ i ]

[0001] indicates the first order spatial correlation for neighbouring samples ( x − 1, y ) and ( x, y − 1 ).

[0082] fg_comp_model_value[ c ][ i ]

[0002] provides the third model value for the model as specified by fg_model_id. When fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0002] shall be greater than or equal to 0 and less than 16.

[0083] When not present in the film grain characteristics SEI message, fg_comp_model_value[ c ][ i ]

[0002] is inferred as follows: – If fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0002] is inferred to be equal to fg_comp_model_value[ c ][ i ]

[0001] – Otherwise (fg_model_id is equal to 1), fg_comp_model_value[ c ][ i ]

[0002] is inferred to be equal to 0.

[0084] fg_comp_model_value[ c ][ i ]

[0002] is interpreted as follows: – If fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0002] indicates the vertical high cut frequency to be used to filter the DCT of a block of 16x16 random values. – Otherwise (fg_model_id is equal to 1), fg_comp_model_value[ c ][ i ]

[0002] indicates the colour correlation between consecutive colour components.

[0085] fg_comp_model_value[ c ][ i ]

[0003] provides the fourth model value for the model as specified by fg_model_id. When fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0003] shall be greater than or equal to 0 and less than or equal to fg_comp_model_value[ c ][ i ]

[0001] .

[0086] When not present in the film grain characteristics SEI message, fg_comp_model_value[ c ][ i ]

[0003] is inferred to be equal to 0.

[0087] fg_comp_model_value[ c ][ i ]

[0003] is interpreted as follows: – If fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0003] indicates the horizontal low cut frequency to be used to filter the DCT of a block of 16x16 random values. – Otherwise (fg_model_id is equal to 1), fg_comp_model_value[ c ][ i ]

[0003] indicates the first order spatial correlation for neighbouring samples ( x − 1, y − 1 ) and ( x + 1, y − 1 ).

[0088] fg_comp_model_value[ c ][ i ]

[0004] provides the fifth model value for the model as specified by fg_model_id. When fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0004] shall be greater than or equal to 0 and less than or equal to fg_comp_model_value[ c ][ i ]

[0002] .

[0089] When not present in the film grain characteristics SEI message, fg_comp_model_value[ c ][ i ]

[0004] is inferred to be equal to fg_model_id.

[0090] fg_comp_model_value[ c ][ i ]

[0004] is interpreted as follows: – If fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0004] indicates the vertical low cut frequency to be used to filter the DCT of a block of 16x16 random values. – Otherwise (fg_model_id is equal to 1), fg_comp_model_value[ c ][ i ]

[0004] indicates the aspect ratio of the modelled grain.

[0091] fg_comp_model_value[ c ][ i ]

[0005] provides the sixth model value for the model as specified by fg_model_id.

[0092] When not present in the film grain characteristics SEI message, fg_comp_model_value[ c ][ i ]

[0005] is inferred to be equal to 0.

[0093] fg_comp_model_value[ c ][ i ]

[0005] is interpreted as follows: – If fg_model_id is equal to 0, fg_comp_model_value[ c ][ i ]

[0005] indicates the colour correlation between consecutive colour components.– Otherwise (fg_model_id is equal to 1), fg_comp_model_value[ c ][ i ]

[0005] indicates the second order spatial correlation for neighbouring samples ( x, y − 2 ) and ( x − 2, y ).

[0094] fg_characteristics_persistence_flag specifies the persistence of the film grain characteristics SEI message for the current layer.

[0095] fg_characteristics_persistence_flag equal to 0 specifies that the film grain characteristics SEI message persists for the current decoded picture only.

[0096] fg_characteristics_persistence_flag equal to 1 specifies that the film grain characteristics SEI message persists for the current decoded picture and all subsequent pictures of the current layer in output order until one or more of the following conditions are true: – A new CLVS of the current layer begins. – The bitstream ends. – A picture in the current layer in an access unit (AU) associated with a film grain characteristics SEI message is output that follows the current picture in output order. 8.6 Frame packing arrangement SEI message 8.6.1 Frame packing arrangement SEI message syntax frame_packing_arrangement( payloadSize ) { Descriptor f rr n m nt id (v)} fp_upsampled_aspect_ratio_flag u(1) 8.6

[0097] Use of this SEI message requires the definition of the following variables: – The variable SeiProcStgIdx, indicating the processing stage index associated with the frame packing arrangement (FPA) SEI message within a chosen processing chain. – The list CandInputPicList[ SeiProcStgIdx ], containing a list of pictures in output order from which the input picture for the process implied by the FPA SEI mesage is selected. When SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ SeiProcStgIdx ] are cropped decoded output pictures.

[0098] NOTE 1 – When SeiProcStgIdx is greater than 0, the list CandInputPicList[ SeiProcStgIdx ] contains pictures after the application of the process(es) implied by the SEI message(s) associated with processing stage index values less than SeiProcStgIdx.

[0099] This SEI message informs the decoder that the the input pictures from CandInputPicList[ SeiProcStgIdx ] contain samples of multiple distinct spatially packed constituent frames that are packed into one frame, or that the input pictures from CandInputPicList[ SeiProcStgIdx ] in output order form a temporal interleaving of alternating first and second constituent frames, using an indicated frame packing arrangement scheme. This information can be used by the decoder to appropriately rearrange the samples and process the samples of the constituent frames appropriately for display or other purposes (which are outside the scope of this Specification).

[0100] This SEI message may be associated with pictures that are either frames or fields (as determined outside the scope of this Specification). The frame packing arrangement of the samples is specified in terms of the sampling structure of a frame in order to define a frame packing arrangement structure that is invariant with respect to whether a picture is a single field of such a packed frame or is a complete packed frame.

[0101] NOTE 1 – The interpretation of frame_packing_arrangement_type is in alignment with the code point specifications in Rec. ITU-T H.273 | ISO / IEC 23091-2. However, more values of frame_packing_arrangement_type are specified in Rec. ITU-T H.273 | ISO / IEC 23091-2 than are specified for use herein.

[0102] The process implied by the FPA SEI message may be applied to each picture in CandInputPicList[ SeiProcStgIdx ] that is the corresponding picture or an associated inserted picture of a picture for which the FPA SEI message persists. When the process implied by the FPA SEI message is applied to such a picture, that picture is considered as the input picture.

[0103] fp_arrangement_id contains an identifying number that may be used to identify the usage of the frame packing arrangement SEI message. The value of fp_arrangement_id shall be in the range of 0 to 232− 2, inclusive.

[0104] Values of fp_arrangement_id from 0 to 255, inclusive, and from 512 to 231− 1, inclusive, may be used as determined by the application. Values of fp_arrangement_id from 256 to 511, inclusive, and from 231to 232− 2,inclusive, are reserved for future use by ITU-T | ISO / IEC. Decoders encountering a value of fp_arrangement_id in the range of 256 to 511, inclusive, or in the range of 231to 232− 2, inclusive, shall ignore it.

[0105] fp_arrangement_cancel_flag equal to 1 indicates that the SEI message cancels the persistence of any previous frame packing arrangement SEI message in output order that applies to the current layer. fp_arrangement_cancel_flag equal to 0 indicates that frame packing arrangement information follows.

[0106] fp_arrangement_type identifies the indicated interpretation of the sample arrays of the output cropped decoded picture as specified in Table 3.

[0107] When fp_arrangement_type is equal to 3 or 4, each component plane of the input pictures from CandInputPicList[ SeiProcStgIdx ] contain all samples (when ffi_field_pic_flag is equal to 0) or the samples corresponding to the top or bottom field (when ffi_field_pic_flag is equal to 1) of the samples of a frame packing arrangement structure.

[0108] FIG. 1 is a flowchart for an example 100 rearrangement and upconversion of side-by-side packing arrangement with fp_arrangement_type equal to 3, fp_quincunx_sampling_flag equal to 0 and ( x, y ) equal to ( 0, 0 ) or ( 4, 8 ) for both constituent frames.

[0109] FIG. 2 is a flowchart for an example 200 rearrangement and upconversion of side-by-side packing arrangement with fp_arrangement_type equal to 3, fp_quincunx_sampling_flag equal to 0, ( x, y ) equal to ( 12, 8 ) for constituent frame 0 and ( x, y ) equal to ( 0, 0 ) or ( 4, 8 ) for constituent frame 1.

[0110] FIG. 3 is a flowchart for an example 300 rearrangement and upconversion of top-bottom packing arrangement with fp_arrangement_type equal to 4, fp_quincunx_sampling_flag equal to 0 and ( x, y ) equal to ( 0, 0 ) or ( 8, 4 ) for both constituent frames.

[0111] FIG. 4 is a flowchart for an example 400 rearrangement and upconversion of top-bottom packing arrangement with fp_arrangement_type equal to 4, fp_quincunx_sampling_flag equal to 0, ( x, y ) equal to ( 8, 12 ) for constituent frame 0 and ( x, y ) equal to ( 0, 0 ) or ( 8, 4 ) for constituent frame 1.

[0112] FIG. 5 is a flowchart for an example 500 for rearrangement and upconversion of side-by-side packing arrangement with quincunx sampling (fp_arrangement_type equal to 3 with fp_quincunx_sampling_flag equal to 1).

[0113] FIG. 6 is a flowchart for an example 600 for rearrangement of a temporal interleaving frame arrangement (fp_arrangement_type equal to 5). Table 3 – Definition of fp_arrangement_type Value Interpretation ng ng m

[0114] NOTE 2 – FIG.1 to FIG.5 provide typical examples of rearrangement and upconversion processing for various packing arrangement schemes. Actual characteristics of the constituent frames are signalled in detail by the subsequent syntax elements of the frame packing arrangement SEI message. In FIG. 1 to FIG. 5, an upconversion processing is performed on each constituent frame to produce frames having the same resolution as that of the frame in CandInputPicList[ SeiProcStgIdx ] corresponding to the current decoded frame. An example of the upsampling method to be applied to a quincunx sampled frame as shown in FIG. 5 is to fill in missing positions with an average of the available spatially neighbouring samples (the average of the values of the available samples above, below, to the left and to the right of each sample to be generated). The actual upconversion process to be performed, if any, is outside the scope of this Specification.

[0115] NOTE 3 – When the output time of the samples of constituent frame 0 differs from the output time of the samples of constituent frame 1 (i.e., when fp_field_views_flag is equal to 1 or fp_arrangement_type is equal to 5) and the display system in use presents two views simultaneously, the display time for constituent frame 0 could be delayed to coincide with the display time for constituent frame 1. (The display process is not specified in this Specification.)

[0116] NOTE 4 – When fp_field_views_flag is equal to 1 or fp_arrangement_type is equal to 5, the value 0 for fixed_pic_rate_within_cvs_flag is not expected to be prevalent in industry use of this SEI message.

[0117] NOTE 5 – fp_arrangement_type equal to 5 describes a temporal interleaving process of different views.

[0118] All other values of fp_arrangement_type are reserved for future use by ITU-T | ISO / IEC. It is a requirement of bitstream conformance that bitstreams conforming to this version of this Specification shall not contain such other values of fp_arrangement_type. Decoders shall ignore frame packing arrangement SEI messages that contain reserved values of fp_arrangement_type.

[0119] fp_quincunx_sampling_flag equal to 1 indicates that each colour component plane of each constituent frame is quincunx sampled as illustrated in FIG.5 and fp_quincunx_sampling_flag equal to 0 indicates that the colour component planes of each constituent frame are not quincunx sampled.

[0120] When fp_arrangement_type is equal to 5, it is a requirement of bitstream conformance that fp_quincunx_sampling_flag shall be equal to 0.

[0121] NOTE 6 – For any chroma format (monochrome, 4:2:0, 4:2:2 or 4:4:4), the luma plane and each chroma plane (as applicable) is quincunx sampled as illustrated in FIG.5 when fp_quincunx_sampling_flag is equal to 1.

[0122] fp_content_interpretation_type indicates the intended interpretation of the constituent frames as specified in Table 4. Values of fp_content_interpretation_type that do not appear in Table 4 are reserved for future specification by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this Specification. Decoders shall ignore frame packing arrangement SEI messages that contain reserved values of fp_content_interpretation_type.

[0123] For each specified frame packing arrangement scheme, there are two constituent frames that are referred to as frame 0 and frame 1. Table 4 – Definition of fp_content_interpretation_type Value Interpretation1 Indicates that the two constituent frames form the left and right views of a stereo view scene, with frame 0 being associated with the left view and frame 1 being associated with the right view th_ _ _ use of this SEI message. However, the value was specified herein for purposes of completeness.

[0125] fp_spatial_flipping_flag equal to 1, when fp_arrangement_type is equal to 3 or 4, indicates that one of the two constituent frames is spatially flipped relative to its intended orientation for display or other such purposes.

[0126] When fp_arrangement_type is equal to 3 or 4 and fp_spatial_flipping_flag is equal to 1, the type of spatial flipping that is indicated is as follows: – If fp_arrangement_type is equal to 3, the indicated spatial flipping is horizontal flipping. – Otherwise (fp_arrangement_type is equal to 4), the indicated spatial flipping is vertical flipping.

[0127] When fp_arrangement_type is not equal to 3 or 4, it is a requirement of bitstream conformance that fp_spatial_flipping_flag shall be equal to 0. When fp_arrangement_type is not equal to 3 or 4, the value 1 for fp_spatial_flipping_flag is reserved for future use by ITU-T | ISO / IEC. When fp_arrangement_type is not equal to 3 or 4, decoders shall ignore the value 1 for fp_spatial_flipping_flag.

[0128] fp_frame0_flipped_flag, when fp_spatial_flipping_flag is equal to 1, indicates which one of the two constituent frames is flipped.

[0129] When fp_spatial_flipping_flag is equal to 1, fp_frame0_flipped_flag equal to 0 indicates that frame 0 is not spatially flipped and frame 1 is spatially flipped and fp_frame0_flipped_flag equal to 1 indicates that frame 0 is spatially flipped and frame 1 is not spatially flipped.

[0130] When fp_spatial_flipping_flag is equal to 0, it is a requirement of bitstream conformance that fp_frame0_flipped_flag shall be equal to 0. When fp_spatial_flipping_flag is equal to 0, the value 1 for fp_spatial_flipping_flag is reserved for future use by ITU-T | ISO / IEC. When fp_spatial_flipping_flag is equal to 0, decoders shall ignore the value of fp_frame0_flipped_flag.

[0131] fp_field_views_flag equal to 1 indicates that all pictures in the current coded layer video sequence (CLVS) are coded as fields, all fields of a particular parity are considered a first constituent frame and all fields of the opposite parity are considered a second constituent frame. It is a requirement of bitstream conformance that the fp_field_views_flag shall be equal to 0, the value 1 for fp_field_views_flag is reserved for future use by ITU-T | ISO / IEC and decoders shall ignore the value of fp_field_views_flag.

[0132] fp_current_frame_is_frame0_flag equal to 1, when fp_arrangement is equal to 5, indicates that the frame in CandInputPicList[ SeiProcStgIdx ] corresponding to the current decoded frame is constituent frame 0 and the next frame in CandInputPicList[ SeiProcStgIdx ] in output order is constituent frame 1 and the display time of the constituent frame 0 should be delayed to coincide with the display time of constituent frame 1. fp_current_frame_is_frame0_flag equal to 0, when fp_arrangement is equal to 5, indicates that the frame in CandInputPicList[ SeiProcStgIdx ] corresponding to the current decoded frame is constituent frame 1 and the previous frame inCandInputPicList[ SeiProcStgIdx ] in output order is constituent frame 0 and the display time of the constituent frame 1 should not be delayed for purposes of stereo-view pairing.

[0133] When fp_arrangement_type is not equal to 5, the constituent frame associated with the upper-left sample of the frame in CandInputPicList[ SeiProcStgIdx ] corresponding to the current decoded frame is considered to be constituent frame 0 and the other constituent frame is considered to be constituent frame 1. When fp_arrangement_type is not equal to 5, it is a requirement of bitstream conformance that fp_current_frame_is_frame0_flag shall be equal to 0. When fp_arrangement_type is not equal to 5, the value 1 for fp_current_frame_is_frame0_flag is reserved for future use by ITU-T | ISO / IEC. When fp_arrangement_type is not equal to 5, decoders shall ignore the value of fp_current_frame_is_frame0_flag.

[0134] fp_frame0_self_contained_flag equal to 1 indicates that no inter prediction operations within the decoding process for the samples of constituent frame 0 of the CLVS refer to samples of any constituent frame 1. fp_frame0_self_contained_flag equal to 0 indicates that some inter prediction operations within the decoding process for the samples of constituent frame 0 of the CLVS might or might not refer to samples of some constituent frame 1. Within a CLVS, the value of fp_frame0_self_contained_flag in all frame packing arrangement SEI messages shall be the same.

[0135] fp_frame1_self_contained_flag equal to 1 indicates that no inter prediction operations within the decoding process for the samples of constituent frame 1 of the CLVS refer to samples of any constituent frame 0. fp_frame1_self_contained_flag equal to 0 indicates that some inter prediction operations within the decoding process for the samples of constituent frame 1 of the CLVS might or might not refer to samples of some constituent frame 0. Within a CLVS, the value of fp_frame1_self_contained_flag in all frame packing arrangement SEI messages shall be the same.

[0136] When fp_quincunx_sampling_flag is equal to 0 and fp_arrangement_type is not equal to 5, two ( x, y ) coordinate pairs are specified to determine the indicated luma sampling grid alignment for constituent frame 0 and constituent frame 1, relative to the upper left corner of the rectangular area represented by the samples of the corresponding constituent frame.

[0137] NOTE 8 – The location of chroma samples relative to luma samples could be indicated by the vui_chroma_sample_loc_type_frame or vui_chroma_sample_loc_type_top_field and vui_chroma_sample_loc_type_bottom_field syntax elements in the VUI parameters, when present.

[0138] fp_frame0_grid_position_x (when present) specifies the x component of the ( x, y ) coordinate pair for constituent frame 0.

[0139] fp_frame0_grid_position_y (when present) specifies the y component of the ( x, y ) coordinate pair for constituent frame 0.

[0140] fp_frame1_grid_position_x (when present) specifies the x component of the ( x, y ) coordinate pair for constituent frame 1.

[0141] fp_frame1_grid_position_y (when present) specifies the y component of the ( x, y ) coordinate pair for constituent frame 1.

[0142] When fp_quincunx_sampling_flag is equal to 0 and fp_arrangement_type is not equal to 5 the ( x, y ) coordinate pair for each constituent frame is interpreted as follows: – If the ( x, y ) coordinate pair for a constituent frame is equal to ( 0, 0 ), this indicates a default sampling grid alignment specified as follows: – If fp_arrangement_type is equal to 3, the indicated position is the same as for the ( x, y ) coordinate pair value ( 4, 8 ), as illustrated in FIG.1. – Otherwise (fp_arrangement_type is equal to 4), the indicated position is the same as for the ( x, y ) coordinate pair value ( 8, 4 ), as illustrated in FIG.3. – Otherwise, if the ( x, y ) coordinate pair for a constituent frame is equal to ( 15, 15 ), this indicates that the sampling grid alignment is unknown or unspecified or specified by other means not specified in this Specification. – Otherwise, the x and y elements of the ( x, y ) coordinate pair specify the indicated horizontal and vertical sampling grid alignment positioning to the right of and below the upper left corner of the rectangular area represented by the corresponding constituent frame, respectively, in units of one sixteenth of the luma sample grid spacing between the samples of the columns and rows of the constituent frame that are present in the frame in CandInputPicList[ SeiProcStgIdx ] corresponding to the current decoded frame (prior to any upsampling for display or other purposes).

[0143] NOTE 9 – The spatial location reference information fp_frame0_grid_position_x, fp_frame0_grid_position_y, fp_frame1_grid_position_x, and fp_frame1_grid_position_y is not provided when fp_quincunx_sampling_flag is equal to 1 because the spatial alignment in this case is assumed to be such that constituent frame 0 and constituent frame 1 cover corresponding spatial areas with interleaved quincunx sampling patterns as illustrated in FIG.5.

[0144] fp_arrangement_reserved_byte is reserved for future use by ITU-T | ISO / IEC. It is a requirement of bitstream conformance that the value of fp_arrangement_reserved_byte shall be equal to 0. All other values of fp_arrangement_reserved_byte are reserved for future use by ITU-T | ISO / IEC. Decoders shall ignore the value of fp_arrangement_reserved_byte.

[0145] fp_arrangement_persistence_flag specifies the persistence of the frame packing arrangement SEI message for the current layer.

[0146] fp_arrangement_persistence_flag equal to 0 specifies that the frame packing arrangement SEI message persists for the current decoded frame only.

[0147] fp_arrangement_persistence_flag equal to 1 specifies that the frame packing arrangement SEI message persists for the current decoded picture and all subsequent pictures of the current layer in output order until one or more of the following conditions are true: – A new CLVS of the current layer begins. – The bitstream ends. – A picture in the current layer in an AU associated with a frame packing arrangement SEI message is output that follows the current picture in output order.

[0148] fp_upsampled_aspect_ratio_flag equal to 1 indicates that the sample aspect ratio (SAR) indicated by the VUI parameters or the SAR information (SARI) supplememtal enhancement information (SEI) message identifies the SAR of the samples after the application of an upconversion process to produce a higher resolution frame from each constituent frame as illustrated in FIG.1 to FIG.5. fp_upsampled_aspect_ratio_flag equal to 0 indicates that the SAR indicated by the VUI parameters or the SARI SEI message identifies the SAR of the samples before the application of any such upconversion process.

[0149] NOTE 10 – The SAR indicated in the VUI parameters or the SARI SEI message could indicate the preferred display picture shape for the packed decoded frame output by a decoder that does not interpret the frame packing arrangement SEI message. When fp_upsampled_aspect_ratio_flag is equal to 1, the SAR produced in each up- converted colour plane is indicated to be the same as the SAR indicated in the VUI parameters or the SARI SEI message in the examples shown in FIG.1 to FIG.5. When fp_upsampled_aspect_ratio_flag is equal to 0, the SAR produced in each colour plane prior to upconversion is indicated to be the same as the SAR indicated in the VUI parameters or the SARI SEI message in the examples shown in FIG.1 to FIG.5. 8.15.5 Region-wise packing SEI message 8.15.5.1 Region-wise packing SEI message syntax regionwise_packing( payloadSize ) { Descriptor rw n l fl (1)rwp_packed_region_left[ i ] u(16) if( rwp_guard_band_flag[ i ] ) { 8.1

[0150] Use of this SEI message requires the definition of the following variables: – The variable SeiProcStgIdx, indicating the processing stage index associated with the region-wise packing (RWP) SEI message within a chosen processing chain. – The list CandInputPicList[ SeiProcStgIdx ], containing a list of pictures in output order from which the input picture for the process implied by the RWP SEI mesage is selected. When SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ SeiProcStgIdx ] are cropped decoded output pictures.

[0151] NOTE 1 – When SeiProcStgIdx is greater than 0, the list CandInputPicList[ SeiProcStgIdx ] contains pictures after the application of the process(es) implied by the SEI message(s) associated with processing stage index values less than SeiProcStgIdx. – A chroma format indicator, denoted herein by ChromaFormatIdc, as described in clause 7.3.

[0152] The RWP SEI message provides information to enable remapping of the colour samples of the input pictures from CandInputPicList[ SeiProcStgIdx ] onto projected pictures as well as information on the location and size of the guard bands, if any.

[0153] The process implied by the RWP SEI message may be applied to each picture in CandInputPicList[ SeiProcStgIdx ] that is the corresponding picture or an associated inserted picture of a picture for which the RWP SEI message persists. When the process implied by the RWP SEI message is applied to such a picture, that picture is considered as the input picture.

[0154] rwp_cancel_flag equal to 1 indicates that the SEI message cancels the persistence of any previous RWP SEI message in output order. rwp_cancel_flag equal to 0 indicates that RWP information follows.

[0155] rwp_persistence_flag specifies the persistence of the RWP SEI message for the current layer.

[0156] rwp_persistence_flag equal to 0 specifies that the RWP SEI message persists for the current decoded picture only.

[0157] rwp_persistence_flag equal to 1 specifies that the RWP SEI message persists for the current decoded picture and all subsequent pictures of the current layer in output order until one or more of the following conditions are true: – A new CLVS of the current layer begins. – The bitstream ends. – A picture in the current layer in an AU associated with a RWP SEI message is output that follows the current picture in output order.

[0158] When no omnidirectional video projection is indicated to apply to a picture, e.g., by an equirectangular projection SEI message with erp_cancel_flag equal to 0 or a generalized cubemap projection SEI message with gcmp_cancel_flag equal to 0 being present in the CLVS that applies to the current picture, a RWP SEI message with rwp_cancel_flag equal to 0 shall not be present in the CLVS that applies to the picture. Decoders shall ignore RWP SEI messages with rwp_cancel_flag equal to 0 for pictures to which no omnidirectional video projection is indicated to apply.

[0159] When an equirectangular projection SEI message with erp_cancel_flag equal to 0 and erp_guard_band_flag equal to 1 is present in the CLVS that applies to the current picture, a RWP SEI message with rwp_cancel_flag equal to 0 shall not be present in the CLVS that applies to the current picture.

[0160] When a generalized cubemap projection SEI message with gmcp_cancel_flag equal to 0 is present in the CLVS that applies to the current picture and precedes the RWP SEI message in decoding order, a RWP SEI message with rwp_cancel_flag equal to 0 shall not be present in the CLVS that applies to the current picture unless all the following conditions are true for the generalized cubemap projection SEI message: – The value of gcmp_packing_type is equal to 2; – The values of gcmp_face_index[ i ] for i from 0 to 5, inclusive, are equal to 5, 0, 4, 3, 1 and 2, respectively; – The value of gcmp_face_rotation[ i ] is equal to 0 for each value of i in the range of 0 to 5, inclusive; – The value of gcmp_guard_band_flag is equal to 0.

[0161] For the frame packing arrangement scheme indicated by a frame packing arrangement SEI message that persists for the current picture, if a RWP SEI message with rwp_cancel_flag equal to 0 is present that persists for the current picture, the frame packing arrangement scheme applies to the projected picture, otherwise, the frame packing arrangement scheme applies to the input pictures from CandInputPicList[ SeiProcStgIdx ].

[0162] If a frame packing arrangement SEI message with fp_arrangement_cancel_flag equal to 0, fp_arrangement_type equal to 3, 4, or 5, and fp_quincunx_sampling_flag equal to 0 is not present that applies to the current picture, the variables StereoFlag, TopBottomFlag, SideBySideFlag, and TempInterleavingFlag are all set equal to 0, the variables HorDiv1 and VerDiv1 are both set equal to 1. Otherwise the following applies: – StereoFlag is set equal to 1. – When the fp_arrangement_type is equal to 3, SideBySideFlag is set equal to 1, TopBottomFlag and TempInterleavingFlag are both set equal to 0, HorDiv1 is set equal to 2 and VerDiv1 is set equal to 1.– When the fp_arrangement_type is equal to 4, TopBottomFlag is set equal to 1, SideBySideFlag and TempInterleavingFlag are both set equal to 0, HorDiv1 is set equal to 1 and VerDiv1 is set equal to 2. – When the fp_arrangement_type is equal to 5, TempInterleavingFlag is set equal to 1, TopBottomFlag and SideBySideFlag are both set equal to 0, HorDiv1 and VerDiv1 are both set equal to 1.

[0163] rwp_constituent_picture_matching_flag equal to 1 specifies that the projected region information, packed region information, and guard band region information in this SEI message apply individually to each constituent picture and that the packed picture and the projected picture have the same stereoscopic frame packing format indicated by the frame packing arrangement SEI message. rwp_constituent_picture_matching_flag equal to 0 specifies that the projected region information, packed region information, and guard band region information in this SEI message apply to the projected picture.

[0164] When either of the following conditions is true, the value of rwp_constituent_picture_matching_flag shall be equal to 0: – StereoFlag is equal to 0. – StereoFlag is equal to 1 and fp_arrangement_type is equal to 5.

[0165] rwp_reserved_zero_5bits shall be equal to 0 in bitstreams conforming to this version of this Specification. Other values for rwp_reserved_zero_56bits[ i ] are reserved for future use by ITU-T | ISO / IEC. Decoders shall ignore the value of rwp_reserved_zero_5bits[ i ].

[0166] rwp_num_packed_regions specifies the number of packed regions when rwp_constituent_picture_matching_flag is equal to 0. The value of rwp_num_packed_regions shall be greater than 0. When rwp_constituent_picture_matching_flag is equal to 1, the total number of packed regions is equal to rwp_num_packed_regions * 2, and the information in each entry of the loop of rwp_num_packed_regions entries applies to each constituent picture of the projected picture and the packed picture.

[0167] rwp_proj_picture_width and rwp_proj_picture_height specify the width and height, respectively, of the projected picture, in relative projected picture sample units.

[0168] NOTE 1 – Relative project picture sample unit is the unit used for the width or height of a projected picture or projected region. When a projected picture is a region-wise packed picture (i.e., there is a one-to-one mapping between the projected picture samples and the region-wise packed picture samples and a relative project picture sample unit is equivalent to a relative region-wise packed picture sample unit), rwp_proj_picture_width and rwp_proj_picture_height would have such values that rwp_proj_picture_width is an integer multiple of cropPicWidth and rwp_proj_picture_height is an integer multiple of cropPicHeight, where cropPicWidth and cropPicHeight are the width and height, respectively, of the input pictures from CandInputPicList[ SeiProcStgIdx ], in units of luma samples.

[0169] The values of rwp_proj_picture_width and rwp_proj_picture_height shall both be greater than 0.

[0170] rwp_packed_picture_width and rwp_packed_picture_height specify the width and height, respectively, of the packed picture, in relative region-wise packed picture sample units.

[0171] The values of rwp_packed_picture_width and rwp_packed_picture_height shall both be greater than 0.

[0172] It is a requirement of bitstream conformance that rwp_packed_picture_width and rwp_packed_picture_height shall have such values that rwp_packed_picture_width is an integer multiple ofcropPicWidth and rwp_packed_picture_height is an integer multiple of cropPicHeight, where cropPicWidth and cropPicHeight are the width and height, respectively, of the input pictures from CandInputPicList[ SeiProcStgIdx ], in units of luma samples.

[0173] rwp_reserved_zero_4bits[ i ] shall be equal to 0 in bitstreams conforming to this version of this Specification. Other values for rwp_reserved_zero_4bits[ i ] are reserved for future use by ITU-T | ISO / IEC. Decoders shall ignore the value of rwp_reserved_zero_4bits[ i ].

[0174] rwp_transform_type[ i ] specifies the rotation and mirroring to be applied to the i-th packed region to remap to the i-th projected region. When rwp_transform_type[ i ] specifies both rotation and mirroring, rotation applies before mirroring. The values of rwp_transform_type[ i ] are specified in Table 5. Table 5 – rwp_transform_type[ i ] values Value Description 0 no transform y y

[0175] rwp_guard_band_flag[ i ] equal to 0 specifies that the i-th packed region does not have a guard band. rwp_guard_band_flag[ i ] equal to 1 specifies that the i-th packed region has a guard band.

[0176] rwp_proj_region_width[ i ], rwp_proj_region_height[ i ], rwp_proj_region_top[ i ] and rwp_proj_region_left[ i ] specify the width, height, top sample row, and the left-most sample column, respectively, of the i-th projected region, either within the projected picture (when rwp_constituent_picture_matching_flag is equal to 0) or within the constituent picture of the projected picture (when rwp_constituent_picture_matching_flag is equal to 1).

[0177] rwp_proj_region_width[ i ], rwp_proj_region_height[ i ], rwp_proj_region_top[ i ], and rwp_proj_region_left[ i ] are indicated in relative projected picture sample units.

[0178] NOTE 2 – Two projected regions could partially or entirely overlap with each other.

[0179] rwp_packed_region_width[ i ], rwp_packed_region_height[ i ], rwp_packed_region_top[ i ], and rwp_packed_region_left[ i ] specify the width, height, the top luma sample row, and the left-most luma sample column, respectively, of the packed region, either within the region-wise packed picture (when rwp_constituent_picture_matching_flag is equal to 0) or within each constituent picture of the region-wise packed picture (when rwp_constituent_picture_matching_flag is equal to 1).

[0180] rwp_packed_region_width[ i ], rwp_packed_region_height[ i ], rwp_packed_region_top[ i ], and rwp_packed_region_left[ i ] are indicated in relative region-wise packed picture sample units. rwp_packed_region_width[ i ], rwp_packed_region_height[ i ], rwp_packed_region_top[ i ], and rwp_packed_region_left[ i ] shall represent integer horizontal and vertical coordinates of luma sample units within the input pictures from CandInputPicList[ SeiProcStgIdx].

[0181] NOTE 3 – Two packed regions could partially or entirely overlap with each other.

[0182] rwp_left_guard_band_width[ i ] specifies the width of the guard band on the left side of the i-th packed region in relative region-wise packed picture sample units. When ChromaFormatIdc is equal to 1 (4:2:0 chroma format) or 2 (4:2:2 chroma format), rwp_left_guard_band_width[ i ] shall correspond to an even number of luma samples within the input pictures from CandInputPicList[ SeiProcStgIdx].

[0183] rwp_right_guard_band_width[ i ] specifies the width of the guard band on the right side of the i-th packed region in relative region-wise packed picture sample units. When ChromaFormatIdc is equal to 1 (4:2:0 chroma format) or 2 (4:2:2 chroma format), rwp_right_guard_band_width[ i ] shall correspond to an even number of luma samples within the input pictures from CandInputPicList[ SeiProcStgIdx].

[0184] rwp_top_guard_band_height[ i ] specifies the height of the guard band above the i-th packed region in relative region-wise packed picture sample units. When ChromaFormatIdc is equal to 1 (4:2:0 chroma format), rwp_top_guard_band_height[ i ] shall correspond to an even number of luma samples within the input pictures from CandInputPicList[ SeiProcStgIdx].

[0185] rwp_bottom_guard_band_height[ i ] specifies the height of the guard band below the i-th packed region in relative region-wise packed picture sample units. When ChromaFormatIdc is equal to 1 (4:2:0 chroma format), rwp_bottom_guard_band_height[ i ] shall correspond to an even number of luma samples within the input pictures from CandInputPicList[ SeiProcStgIdx].

[0186] When rwp_guard_band_flag[ i ] is equal to 1, rwp_left_guard_band_width[ i ], [ i ], or rwp_bottom_guard_band_height[ i ] shall be greater than 0.

[0187] The i-th packed region as specified by this SEI message shall not overlap with any other packed region specified by the same SEI message or any guard band specified by the same SEI message.

[0188] The guard bands associated with the i-th packed region, if any, as specified by this SEI message shall not overlap with any packed region specified by the same SEI message or any other guard bands specified by the same SEI message.

[0189] rwp_guard_band_not_used_for_pred_flag[ i ] equal to 0 specifies that the guard bands might or might not be used in the inter prediction process. rwp_guard_band_not_used_for_pred_flag[ i ] equal to 1 specifies that the sample values of the guard bands are not used in the inter prediction process.

[0190] NOTE 4 – When rwp_guard_band_not_used_for_pred_flag[ i ] is equal to 1, the sample values within guard bands in the input pictures from CandInputPicList[ SeiProcStgIdx ] could be rewritten even if the corresponding pictures of the input pictures from CandInputPicList[ SeiProcStgIdx ] were used as references for inter prediction ofsubsequent pictures to be decoded. For example, the content of a packed region could be seamlessly expanded to its guard band with decoded and re-projected samples of another packed region.

[0191] rwp_guard_band_type[ i ][ j ] indicates the type of the guard bands for the i-th packed region as follows, with j equal to 0, 1, 2, or 3 indicating that the semantics apply to the left, right, top, or bottom edge, respectively, of the packed region: – rwp_guard_band_type[ i ][ j ] equal to 0 indicates that the content of the guard bands in relation to the content of the packed regions is unknown or unspecified or specified by other means not specified in this Specification. When rwp_guard_band_not_used_for_pred_flag[ i ] is equal to 0, rwp_guard_band_type[ i ][ j ] shall not be equal to 0. – rwp_guard_band_type[ i ][ j ] equal to 1 indicates that the content of the guard bands suffices for interpolation of sample values at sub-pel sample fractional locations within the packed region and less than one sample outside of the boundary of the packed region.

[0192] NOTE 5 – rwp_guard_band_type[ i ][ j ] equal to 1 could be used when the boundary samples of a packed region have been copied horizontally or vertically to the guard band. – rwp_guard_band_type[ i ][ j ] equal to 2 indicates that the content of the guard bands represents actual picture content that is spherically adjacent to the content in the packed region and is on the surface of the packed region at quality that gradually changes from the picture quality of the packed region to that of the spherically adjacent packed region. – rwp_guard_band_type[ i ][ j ] equal to 3 indicates that the content of the guard bands represents actual picture content that is spherically adjacent to the content in the packed region and is on the surface of the packed region at a similar picture quality as within the packed region. – rwp_guard_band_type[ i ][ j ] values greater than 3 are reserved for future use by ITU-T | ISO / IEC. Decoders shall treat the value of rwp_guard_band_type[ i ][ j ] when the value is greater than 3 as equivalent to the value 0.

[0193] rwp_guard_band_reserved_zero_3bits[ i ] shall be equal to 0 in bitstreams conforming to this version of this Specification. Other values for rwp_guard_band_reserved_zero_3bits[ i ] are reserved for future use by ITU-T | ISO / IEC. Decoders shall ignore the value of rwp_guard_band_reserved_zero_3bits[ i ].

[0194] The variables NumPackedRegions, PackedRegionLeft[ n ], PackedRegionTop[ n ], PackedRegionWidth[ n ], PackedRegionHeight[ n ], ProjRegionLeft[ n ], ProjRegionTop[ n ], ProjRegionWidth[ n ], ProjRegionHeight[ n ], and TransformType[ n ] are derived as follows: – For n in the range of 0 to rwp_num_packed_regions − 1, inclusive, the following applies: – PackedRegionLeft[ n ] is set equal to rwp_packed_region_left[ n ]. – PackedRegionTop[ n ] is set equal to rwp_packed_region_top[ n ]. – PackedRegionWidth[ n ] is set equal to rwp_packed_region_width[ n ]. – PackedRegionHeight[ n ] is set equal to rwp_packed_region_height[ n ]. – ProjRegionLeft[ n ] is set equal to rwp_proj_region_left[ n ]. – ProjRegionTop[ n ] is set equal to rwp_proj_region_top[ n ]. – ProjRegionWidth[ n ] is set equal to rwp_proj_region_width[ n ]. – ProjRegionHeight[ n ] is set equal to rwp_proj_region_height[ n ].– TransformType[ n ] is set equal to rwp_transform_type[ n ]. – If rwp_constituent_picture_matching_flag is equal to 0, the following applies: – NumPackedRegions is set equal to rwp_num_packed_regions. – Otherwise (rwp_constituent_picture_matching_flag is equal to 1), the following applies: – NumPackedRegions is set equal to 2 * rwp_num_packed_regions. – When TopBottomFlag is equal to 1, the following applies: o projLeftOffset and packedLeftOffset are both set equal to 0. o projTopOffset is set equal to rwp_proj_picture_height / 2 and packedTopOffset is set equal to rwp_packed_picture_height / 2. – When SideBySideFlag is equal to 1, the following applies: o projLeftOffset is set equal to rwp_proj_picture_width / 2 and packedLeftOffset is set equal to rwp_packed_picture_width / 2. o projTopOffset and packedTopOffset are both set equal to 0. – For n in the range of NumPackedRegions / 2 to NumPackedRegions − 1, inclusive, the following applies: o nIdx is set equal to n − NumPackedRegions / 2. o PackedRegionLeft[ n ] is set equal to rwp_packed_region_left[ nIdx ] + packedLeftOffset. o PackedRegionTop[ n ] is set equal to rwp_packed_region_top[ nIdx ] + packedTopOffset. o PackedRegionWidth[ n ] is set equal to rwp_packed_region_width[ nIdx ]. o PackedRegionHeight[ n ] is set equal to rwp_packed_region_height[ nIdx ]. o ProjRegionLeft[ n ] is set equal to rwp_proj_region_left[ nIdx ] + projLeftOffset. o ProjRegionTop[ n ] is set equal to rwp_proj_region_top[ nIdx ] + projTopOffset. o ProjRegionWidth[ n ] is set equal to rwp_proj_region_width[ nIdx ]. o ProjRegionHeight[ n ] is set equal to rwp_proj_region_height[ nIdx ]. o TransformType[ n ] is set equal to rwp_transform_type[ nIdx ].

[0195] For each value of n in the range of 0 to NumPackedRegions − 1, inclusive, the values of ProjRegionWidth[ n ], ProjRegionHeight[ n ], ProjRegionTop[ n ], and ProjRegionLeft[ n ] are constrained as follows: – ProjRegionWidth[ n ] shall be in the range of 1 to rwp_proj_picture_width, inclusive. – ProjRegionHeight[ n ] shall be in the range of 1 to rwp_proj_picture_height, inclusive. – ProjRegionLeft[ n ] shall be in the range of 0 to rwp_proj_picture_width − 1, inclusive. – ProjRegionTop[ n ] shall be in the range of 0 to rwp_proj_picture_height − 1, inclusive. – If ProjRegionTop[ n ] is less than rwp_proj_picture_height / VerDiv1, the sum of ProjRegionTop[ n ] and ProjRegionHeight[ n ] shall be less than or equal to rwp_proj_picture_height / VerDiv1. Otherwise, the sum of ProjRegionTop[ n ] and ProjRegionHeight[ n ] shall be less than or equal to rwp_proj_picture_height / VerDiv1 * 2.

[0196] For each value of n in the range of 0 to NumPackedRegions − 1, inclusive, the values of PackedRegionWidth[ n ], PackedRegionHeight[ n ], PackedRegionTop[ n ], and PackedRegionLeft[ n ] are constrained as follows:– PackedRegionWidth[ n ] shall be in the range of 1 to rwp_packed_picture_width, inclusive. – ProjRegionHeight[ n ] shall be in the range of 1 to rwp_packed_picture_height, inclusive. – PackedRegionLeft[ n ] shall be in the range of 0 to rwp_packed_picture_width − 1, inclusive. – PackedRegionTop[ n ] shall be in the range of 0 to rwp_packed_picture_height − 1, inclusive. – If PackedRegionLeft[ n ] is less than rwp_packed_picture_width / HorDiv1, the sum of PackedRegionLeft[ n ] and PackedRegionWidth[ n ] shall be less than or equal to rwp_packed_picture_width / HorDiv1. Otherwise, the sum of PackedRegionLeft[ n ] and PackedRegionWidth[ n ] shall be less than or equal to rwp_packed_picture_width / HorDiv1 * 2. – If PackedRegionTop[ n ] is less than rwp_packed_picture_height / VerDiv1, the sum of PackedRegionTop[ n ] and PackedRegionHeight[ n ] shall be less than or equal to rwp_packed_picture_height / VerDiv1. Otherwise, the sum of PackedRegionTop[ n ] and PackedRegionHeight[ n ] shall be less than or equal to rwp_packed_picture_height / VerDiv1 * 2. – When ChromaFormatIdc is equal to 1 (4:2:0 chroma format) or 2 (4:2:2 chroma format), PackedRegionLeft[ n ] shall correspond to an even horizontal coordinate value of luma sample units, and PackedRegionWidth[ n ] shall correspond to an even number of luma samples, both within the input pictures from CandInputPicList[ SeiProcStgIdx ]. – When ChromaFormatIdc is equal to 1 (4:2:0 chroma format), PackedRegionTop[ n ] shall correspond to an even vertical coordinate value of luma sample units, and ProjRegionHeight[ n ] shall correspond to an even number of luma samples, both within the input pictures from CandInputPicList[ SeiProcStgIdx ]. 8.26 Colour transform information SEI message 8.26.1 Colour transform information SEI message syntax colour_transform_info( payloadSize ) { Descriptorcolour_transform_cross_comp_inferred_flag u(1) for( i = 0; i < colourTransformSize; i++ ) 8.2.

[0197] Use of this SEI message requires the definition of the following variables: – The variable SeiProcStgIdx, indicating the processing stage index associated with the colour transform information (CTI) SEI message within a chosen processing chain. – The list CandInputPicList[ SeiProcStgIdx ], containing a list of pictures in output order from which the input picture for the process implied by the CTI SEI mesage is selected. When SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ SeiProcStgIdx ] are cropped decoded output pictures. NOTE – When SeiProcStgIdx is greater than 0, the list CandInputPicList[ SeiProcStgIdx ] contains pictures after the application of the process(es) implied by the SEI message(s) associated with processing stage index values less than SeiProcStgIdx. – A chroma format indicator of the input pictures, denoted herein by ChromaFormatIdc, as described in clause 7.3.

[0198] The CTI SEI message provides information to enable remapping of the reconstructed colour samples of the input pictures from CandInputPicList[ SeiProcStgIdx ] for purposes such as converting the input pictures to a representation that is more suitable for an alternative display. The colour transform model used in the CTI SEI message is composed of a first piece-wise linear function applied to the first colour component. Depending on the values of syntax elements colour_transform_cross_component_flag, colour_transform_cross_comp_inferred_flag, and colour_transform_lut2_present_flag, one or two additional piece-wise linear functions may be signalled for the second and third colour components.

[0199] When ChromaFormatIdc is equal to 0 (monochrome), the CTI SEI message shall not be present, although decoders shall also allow such messages to be present and shall ignore any such CTI SEI messages when present.

[0200] The process implied by the CTI SEI message may be applied to each picture in CandInputPicList[ SeiProcStgIdx ] that is the corresponding picture or an associated inserted picture of a picture for which the CTI SEI message persists. When the process implied by the CTI SEI message is applied to such a picture, that picture is considered as the input picture.

[0201] colour_transform_id contains an identifying number that may be used to identify the purpose of the CTI. The value of colour_transform_id may be used (in a manner not specified in this Specification) to indicate that the input to the remapping process is the output of some conversion process that is not specified in this Specification, such as a conversion of the picture to some alternative colour representation (e.g., conversion from a luma, blue difference chroma, red difference chroma (YCbCr) colour representation to a green, blue, red (GBR) colour representation). When more than one CTI SEI message is present with the same value of colour_transform_id, the content of these CTI SEI messages shall be the same. When CTI SEI messages are present that have more than one value of colour_transform_id, this may indicate that the remapping processes indicated by the different values of colour_transform_id are alternatives that are provided for different purposes or that a cascading of remapping processes is to be applied in a sequential order (an order that is not specified in this Specification). The value of colour_transform_id shall be in the range of 0 to 232− 2, inclusive.

[0202] Values of colour_transform_id from 0 to 255 and from 512 to 231− 1 may be used as determined by the application. Values of colour_transform_id from 256 to 511, inclusive, and from 231to 232− 2, inclusive, are reserved for future use by ITU-T | ISO / IEC. Decoders shall ignore the CTI SEI messages containing a value of colour_transform_id in the range of 256 to 511, inclusive, or in the range of 231to 232− 2, inclusive, and bitstreams conforming to this version of this Specification shall not contain colour_transform_id with such values.

[0203] NOTE – The colour_transform_id can be used to support different remapping processes that are suitable for different display scenarios. For example, different values of colour_transform_id may correspond to different remapped colour spaces supported by displays.

[0204] colour_transform_cancel_flag equal to 1 indicates that the CTI SEI message cancels the persistence of any previous CTI SEI message in output order that applies to the current layer. colour_transform_cancel_flag equal to 0 indicates that CTI follows.

[0205] colour_transform_persistence_flag specifies the persistence of the CTI SEI message for the current layer.

[0206] colour_transform_persistence_flag equal to 0 specifies that the CTI SEI message persists for the current decoded picture only.

[0207] colour_transform_persistence_flag equal to 1 specifies that the CTI SEI message persists for the current decoded picture and all subsequent pictures of the current layer in output order until one or more of the following conditions are true: – A new CLVS of the current layer begins. – The bitstream ends. – A picture in the current layer in an AU associated with a CTI SEI message is output that follows the current picture in output order.

[0208] colour_transform_video_signal_info_present_flag equal to 1 specifies that syntax elements colour_transform_full_range_flag, colour_transform_primaries, colour_transform_transfer_function and colour_transform_matrix_coefficients are present, colour_transform_video_signal_info_present_flag equal to 0 specifies that syntax elements colour_transform_full_range_flag, colour_transform_primaries, colour_transform_transfer_function and colour_transform_matrix_coefficients are not present.

[0209] colour_transform_full_range_flag has the same semantics as specified in clause 7.3 for the vui_full_range_flag syntax element, except that colour_transform_full_range_flag identifies the colour space of the remapped reconstructed picture, rather than the colour space used for the CLVS. When not present, the value of colour_transform_full_range_flag is inferred to be equal to the value of vui_full_range_flag.

[0210] colour_transform_primaries has the same semantics as specified in clause 7.3 for the vui_colour_primaries syntax element, except that colour_transform_primaries identifies the colour space of the remapped reconstructed picture, rather than the colour space used for the CLVS. When not present, the value of colour_transform_primaries is inferred to be equal to the value of vui_colour_primaries.

[0211] colour_transform_transfer_function has the same semantics as specified in clause 7.3 for the vui_transfer_characteristics syntax element, except that colour_transform_transfer_function identifies the colour space of the remapped reconstructed picture, rather than the colour space used for the CLVS. When not present, the value of colour_transform_transfer_function is inferred to be equal to the value of vui_transfer_characteristics.

[0212] colour_transform_matrix_coefficients has the same semantics as specified in clause 7.3 for the vui_matrix_coeffs syntax element, except that colour_transform_matrix_coefficients identifies the colour space of the remapped reconstructed picture, rather than the colour space used for the CLVS. When not present, the value of colour_transform_matrix_coefficients is inferred to be equal to the value of vui_matrix_coeffs.

[0213] colour_transform_bit_depth_minus8 plus 8 specifies the bit depth of the colour components of the associated pictures for purposes of interpretation of the CTI SEI message. When any CTI SEI message is present with the value of colour_transform_bit_depth plus 8 not equal to the bit depth of the colour components of the input pictures, the SEI message refers to the hypothetical result of a conversion operation performed to convert the colour component samples of the input pictures to the bit depth equal to colour_transform_input_bit_depth plus 8.

[0214] The value of colour_transform_bit_depth plus 8 shall be in the range of 8 to 16, inclusive. Values of colour_transform_bit_depth from in the range of 17 to 23, inclusive, are reserved for future use by ITU-T | ISO / IEC. Decoders shall ignore the CTI SEI messages that contain a value of colour_transform_bit_depth in the range of 17 to 23, inclusive, and bitstreams conforming to this version of this Specification shall not contain colour_transform_bit_depth with such values.

[0215] bitDepth is set equal to ( colour_transform_bit_depth + 8 ).

[0216] colour_transform_log2_number_of_points_per_lut_minus1 specifies the log2 of the number of pivot points in the piece-wise linear remapping functions minus 1.

[0217] log2numLutPoints is set equal to ( colour_transform_log2_number_of_points_per_lut_minus1 + 1 ).

[0218] numLutPoints is set equal to ( 1 << log2numLutPoints ).

[0219] colourTransformSize is set equal to ( numLutPoints + 1 ).

[0220] log2distX is set equal to ( bitDepth − log2numLutPoints ).

[0221] colour_transform_cross_component_flag equal to 1 indicates that the remapping of the second and third colour components is performed as cross-component remapping based on the first colour component. colour_transform_cross_component_flag equal to 0 indicates that intra-component remapping is applied to the second and third colour components.

[0222] maxIntraComp is set equal to ( 2 * ( 1 − colour_transform_cross_component_flag ) ).

[0223] colour_transform_cross_comp_inferred_flag equal to 1 indicates that the remapping piece-wise linear functions of the second and third colour components are inferred from the remapping piece-wise linear function of the first colour component. colour_transform_cross_comp_inferred_flag equal to 0 indicates that the remapping piece-wise linear functions of the second and third colour components are signalled. When not present, the value of colour_transform_cross_comp_inferred_flag is inferred to be equal to 0.

[0224] colour_transf_lut[ c ][ i ] specifies the piecewise linear remapping function of the colour component of index c. When colour_transf_lut

[0001] [ i ] is present and colour_transf_lut

[0002] [ i ] is not present, the value of colour_transf_lut

[0002] [ i ] is inferred to be equal to colour_transf_lut

[0001] [ i ]. The length of colour_transf_lut[ c ][ i ] is 2 + bitDepth – log2numLutPoints bits.

[0225] colour_transform_lut2_present_flag equal to 1 specifies that colour_transf_lut

[0002] [ i ] is present in the CTI SEI message. colour_transform_lut2_present_flag equal to 0 specifies that colour_transf_lut

[0002] [ i ] is not present in the CTI SEI message. When not present, the value of colour_transform_lut2_present_flag is inferred to be equal to 0.

[0226] colour_transform_chroma_offset specifies the CTI chroma offset. When not present, colour_transform_chroma_offset is inferred to be equal to 0. The length of colour_transform_chroma_offset is 2 + bitDepth – log2numLutPoints bits.

[0227] The remapping process of the input picture components rec[ c ], with width and height equal to picWidth[ c ] and picHeight[ c ], respectively, to the output remapped picture components map[ c ], for c=0..2, is performed as follows.

[0228] The array pivotPointX is derived as follows. – For j=0..( numLutPoints − 1 ), pivotPointX[ j ] is set equal to ( j << log2distX ).

[0229] For c=0..maxIntraComp, the arrays pivotPointY[ c ] and slope[ c ] are derived as follows: – pivotPointY[ c ]

[0000] is set equal to colour_transf_lut[ c ]

[0000] – For j=1..( numLutPoints − 1 ), pivotPointY[ c ][ j ] is derived as follows: pivotPointY[ c ][ j ] = pivotPointY[ c ][ j − 1 ] + colour_transf_lut[ c ][ j ] (68) – For j=0..( numLutPoints − 1 ), slope[ c ][ j ] is derived as follows: slope[ c ][ j ] = ( ( colour_transf_lut[ c ][ j + 1 ] << 11 ) + ( 1 << ( log2distX − 1 ) ) ) >> log2distX (69)

[0230] When colour_transform_cross_component_flag is equal to 1, the arrays ccPivotPointY[ c ] and ccSlope[ c ] are derived as follows, for c=1..2: – If colour_transform_cross_comp_inferred_flag is equal to 0, ccPivotPointY[ c ] is derived as follows:– For j=0..numLutPoints, ccPivotPointY[ c ][ j ] is set equal to ( colour_transf_lut[ c ][ j ] << ( 11 − log2distX ) ). – Otherwise (colour_transform_cross_comp_inferred_flag is equal to 1), ccPivotPointY[ c ] is derived as follows: – For j=0..( numLutPoints − 1 ), tmpPivotPt[ j ] is derived as follows: – If colour_transf_lut

[0000] [ j + 1 ] is equal to 0, tmpPivotPt[ j ] is set equal to ( 1 << 11 ). – Otherwise, tmpPivotPt[ j ] is derived as follows: tmpPivotPt[ j ] = ( colour_transf_lut

[0000] [ j + 1 ] + colour_transform_chroma_offset ) << (70) ( 11 – log2distX ) – The array ccPivotPointY[ c ] is derived as follows: – For j=1..( numLutPoints − 1 ), ccPivotPointY[ c ][ j ] is derived as follows: ccPivotPointY[ c ][ j ] = ( tmpPivotPt[ j ] + tmpPivotPt[ j − 1 ] + 1 ) / 2 (71) – ccPivotPointY[ c ]

[0000] is set equal to tmpPivotPt

[0000] . – ccPivotPointY[ c ][ numLutPoints ] is set equal to tmpPivotPt[ numLutPoints − 1 ]. – For j=0..( numLutPoints − 1 ), the value of ccSlope[ c ][ j ] is set equal to ( ccPivotPointY[ c ][ j + 1 ] − ccPivotPointY[ c ][ j ] ).

[0231] For c=0..maxIntraComp, the intra-component remapping process of the input samples picture rec[ c ] into the remapped samples picture map[ c ] is performed as follows. – for i=0..picWidth[ c ] − 1, j=0..picHeight[ c ] − 1, the following applies: idx = rec[ c ][ i ][ j ] >> log2distX map[ c ][ i ][ j ] = Clip3( 0, ( 1 << bitDepth ) − 1, pivotPointY[ c ][ idx ] + (72) ( ( slope[ c ][ idx ] * ( rec[ i ][ j ] − pivotPointX[ idx ] ) + ( 1 << 10 ) ) >> 11 ) )

[0232] When colour_transform_cross_component_flag is equal to 1, for c=1..2, the cross-component remapping process of the input samples picture rec[ c ] into the remapped samples picture map[ c ] is performed as follows: – offset is set equal to ( 1 << ( bitDepth − 1 ) ). – subWc and subHc are set equal to ( picWidth

[0000] / picWidth[ c ] ) and ( picHeight

[0000] / picHeight[ c ] ), respectively. – For i=0..picWidth[ c ] − 1, j=0..picHeight[ c ] − 1, the following applies: coloc = rec

[0000] [ i * SubWc ][ j * SubHc ] idx = coloc >> log2distX (73) scale = ccPivotPointY[ c ][ idx ] + ( ( ccSlope[ c ][ idx ] * ( coloc − pivotPointX[ idx ] ) ) >> log2distX ) map[ c ][ i ][ j ] = Clip3( 0, ( 1 << bitDepth ) − 1, ( ( offset << 11 ) + scale * ( rec[ c ][ i ][ j ] − offset ) + ( 1 << 10 ) ) >> 11 ) 2.4 The SEI processing order (SPO) SEI message

[0233] JVET-AI2006 [4] includes the specification of an SEI message named the SEI processing order (SPO) SEI message, for carrying information indicating the preferred processing order, as determined by the encoder (i.e., the content producer), for a group of types of SEI messages that may be present in a coded video sequence (CVS).

[0234] An improved version of the specification of the SPO SEI message in JVET-AI2006 is as follows.8.30.1 SEI processing order SEI message 8.30.1.1 SEI processing order SEI message syntax sei_processing_order( payloadSize ) { Descriptor po_id u(8)8.30.1.2 SEI processing order SEI message semantics

[0235] The SEI processing order (SPO) SEI message carries information indicating the preferred processing order, as determined by the encoder (i.e., the content producer), for a group of types of SEI messages that may be present in a CVS.

[0236] Use of this SEI message requires the definition of the following: – Two lists of payloadType values, SeiProcessingOrderSeiList and SpoProcessSeiList.

[0237] The semantics of the SPO SEI message uses the concept of types of SEI messages. SEI messages that have different payloadType values are considered different types of SEI messages. Additionally, different SEI messages that have the same payloadType value but are differentiated by values of syntax elements in the SEI payload are considereddifferent types of SEI messages. Such differentiation by values of syntax elements in the SEI payload is to be performed by comparing values sent using po_sei_prefix_data_bit[ i ][ j ] syntax elements (when present) or values sent as SEI messages within a processing order nesting SEI message (when present). For example, neural-network post-filter (NNPF) characteristics (NNPFC) SEI messages can be differentiated by having different nnpfc_id values.

[0238] When the i-th SEI message seiA in any SPO SEI message has po_sei_wrapping_flag[ i ] and po_sei_prefix_flag[ i ] both equal to 0, there shall be no other SEI message seiB included in the same SPO SEI message or in a different SPO SEI message in the current CVS for which all of the following are true: – The value of po_sei_payload_type[ i ] of seiB is the same as that for seiA. – The value of po_sei_wrapping_flag[ i ] of seiB is equal to 0. – The value of po_sei_prefix_flag[ i ] of seiB is equal to 1.

[0239] When an SPO SEI message with a particular value of po_id is present in any access unit of a CVS, an SPO SEI message with that particular value of po_id shall be present in the first access unit of the CVS in decoding order. The number of SEI messages and the payloadType codes of the SEI messages indicated within each SPO SEI message with the same value of po_id persist in decoding order from the current access unit until the end of the CVS in output order.

[0240] The SPO SEI message can carry one or more SEI prefix indications of a particular payloadType. When present, each SEI prefix indication is a bit string that follows the SEI payload syntax of that value of payloadType and contains a number of complete syntax elements starting from the first syntax element in the SEI payload. These SEI prefix indications should provide sufficient information to determine the specific processing order for types of SEI messages having the same value of payloadType but a different preferred processing order.

[0241] po_id contains an identifying number to identify the SPO SEI message.

[0242] A processing chain consists of a list of types of SEI messages identified by an SPO SEI message in the preferred processing order indicated in the SPO SEI message.

[0243] Each type of SEI message in the processing chain indicated by an SPO SEI message is identified by the syntax elements po_sei_payload_type[ i ], po_sei_wrapping_flag[ i ], po_sei_processing_order[ i ] and, when present, po_num_bits_in_prefix_indication_minus1[ i ] and po_prefix_data_bit[ i ][ j ].

[0244] An SEI message type is not required to belong to any processing chain and may belong to any number of processing chains identified by SPO SEI messages with different po_id values.

[0245] Each SEI message of an SEI message type identified within the SPO SEI message has the same persistence scope as if the SEI message was carried outside of the SPO SEI message and not identified within an SPO SEI message.

[0246] NOTE 1 – When an SEI message specifies a process and is not associated with a processing chain specified by any SPO SEI message, it is implicitly a processing chain by itself. Some standards, such as Rec. ITU-T H.266 | ISO / IEC 23090-3, have specified an implicit processing chain of a super-resolution NNPF followed by another NNPF. Implicitly specified processing chains are treated like processing chains specified by SPO SEI messages when selecting SEI messages to be applied.

[0247] NOTE 2 – Processing chains can be alternatives to each other, i.e., such that at most processing chain is chosen to be applied, or they can be complementary, i.e., such that more than one processing chain is chosen and applied separately, with each processing chain generating one output.

[0248] po_for_human_viewing_idc equal to 3 specifies that the intended optimal usage of the video resulting from the processing chain specified by this SPO SEI message includes for human viewing. po_for_human_viewing_idc equal to 2 specifies that that the video resulting from the processing chain specified by this SPO SEI message is suitable but not specifically optimized for human viewing. po_for_human_viewing_idc equal to 1 specifies that the video resulting from the processing chain specified by this SPO SEI message is unsuitable for human viewing. po_for_human_viewing_idc equal to 0 specifies that it is unknown if the video resulting from the processing chain specified by this SPO SEI message is suitable for human viewing.

[0249] po_for_machine_analysis_idc equal to 3 specifies that the intended optimal usage of the video resulting from the processing chain specified by this SPO SEI message includes machine analysis. po_for_machine_analysis_idc equal to 2 specifies that the video resulting from the processing chain specified by this SPO SEI message is suitable but not specifically optimized for machine analysis. po_for_machine_analysis_idc equal to 1 specifies that the video resulting from the processing chain specified by this SPO SEI message is unsuitable for machine analysis. po_for_machine_analysis_idc equal to 0 specifies that it is unknown if the video resulting from the processing chain specified by this SPO SEI message is suitable for machine analysis.

[0250] It is a requirement of bitstream conformance that the value of po_for_human_viewing_idc and po_for_machine_analysis_idc shall not be both equal to 1.

[0251] NOTE 3 – The values of po_for_human_viewing_idc and po_for_machine_analysis_idc are in force for the output of a processing chain instead of the respective syntax elements in an encoder optimization information (EOI) SEI message (eoi_for_human_viewing_idc and eoi_for_machine_analysis_idc) or a neural-network post-filter characteristics (NNPFC) SEI message (nnpfc_for_human_viewing_idc and nnpfc_for_machine_analysis_idc), when the EOI or NNPFC SEI message is associated with the processing chain.

[0252] po_reserved_zero_4bits shall be equal to 0. Values greater than 0 for po_reserved_zero_4bits are reserved for future use by ITU-T | ISO / IEC and shall not be present in bitstreams conforming to this version of this Specification. Decoders conforming to this version of this Specification shall allow any value of po_reserved_zero_4bits in the range of 0 to 15, inclusive.

[0253] po_num_sei_messages_minus2 plus 2 indicates the number of types of SEI messages for which the preferred order of processing is indicated in the SPO SEI message. The variable PoNumProcStgs is set equal to po_num_sei_messages_minus2 + 2.

[0254] po_breadth_first_flag equal to 1 specifies that the breadth-first handling of a processing chain specified in clause 8.30.3.2 shall be applied to determine the pictures that are used for interpreting the semantics of the SEI messages applied as a part of the processing chain specified by this SPO SEI message. po_breadth_first_flag equal to 0 specifies that the breadth-first handling of a processing chain specified in clause 8.30.3.2 or the depth-first handling of a processing chain specified in clause 8.30.3.3 shall be applied to determine the pictures that are used for interpreting the semantics of the SEI messages applied as a part of the processing chain specified by this SPO SEI message.

[0255] NOTE 4 – When po_breadth_first_flag is equal to 0, the processing chain can be performed for a picture without processing any SEI messages applying to subsequent picture units in output order.

[0256] po_sei_wrapping_flag[ i ] equal to 1 specifies that an SEI message that applies as the i-th SEI message type in the processing chain specified in this SPO SEI message, if present, is an SEI message that is included in a PON SEI message for which both of the following conditions are true: – pon_target_po_id[ j ] with any value of j is equal to po_id. – There is a k-th loop entry in the processing order nesting SEI message such that the payloadType of the k-th nested SEI message is equal to po_sei_payload_type[ i ] and pon_processing_order[ k ] is equal to po_sei_processing_order[ i ].

[0257] po_sei_wrapping_flag[ i ] equal to 0 specifies that an SEI message that applies as the i-th SEI message type in the processing chain specified in this SPO SEI message, if present, is an SEI message that is not included in a PON SEI message and for which both of the following conditions are true: – The payloadType of the SEI message is equal po_sei_payload_type[ i ]. – po_sei_prefix_flag[ i ] is equal to 0, or when po_sei_prefix_flag[ i ] is equal to 1, the payload of the SEI message starts with the values of po_sei_prefix_data_bit[ i ][ j ].

[0258] NOTE 5 – po_sei_wrapping_flag[ i ] equal to 1 enables SEI messages to be carried within the processing order nesting SEI message to prevent such SEI messages from being incorrectly interpreted by decoders that do not process the SPO SEI message. Thus, po_sei_wrapping_flag[ i ] equal to 1 is intended to be used when po_sei_wrapping_flag[ i ] equal to 0 can lead to unintended results being produced by such decoders.

[0259] po_sei_importance_flag[ i ] equal to 1 affects the derivation of PoSeiList, which is the list of SEI messages that a decoding system should process for a particular picture picA, as specified below.

[0260] po_sei_importance_flag[ i ] equal to 0 specifies that when the decoding system cannot interpret or does not support the functionality indicated by the i-th SEI message type, it shall ignore all data associated with the loop variable value of i and exclude the i-th SEI message type from the processing chain performed by the decoding system.

[0261] po_sei_processing_degree_flag[ i ] affects the derivation of PoSeiList as specified below.

[0262] po_sei_payload_type[ i ] specifies the payloadType value of the i-th type of SEI message.

[0263] po_sei_prefix_flag[ i ] equal to 1 specifies that po_num_bits_in_prefix_indication_minus1[ i ] and some po_sei_prefix_data_bit[ i ][ j ] syntax elements are present. po_sei_prefix_flag[ i ] equal to 0 specifies that these syntax elements are not present.

[0264] The value of po_sei_payload_type[ i ] for each i in the range of 0 to po_num_sei_messages_minus2 + 1, inclusive, shall be equal to a value in SeiProcessingOrderSeiList.

[0265] When po_sei_payload_type[ i ] is equal to any value in SpoProcessSeiList, the i-th type of SEI message indicates a process.

[0266] spoPropertySeiList is set to consist of the payloadType values included in SeiProcessingOrderSeiList excluding the paylaodType values included in SpoProcessSeiList. When po_sei_payload_type[ i ] is equal to any value in spoPropertySeiList, the i-th type of SEI message indicates a property.

[0267] po_sei_processing_order[ i ] indicates the preferred order of processing of the i-th type of SEI message for which preferred processing order information is provided in the SPO SEI message. For any two different integer values of m and n, po_sei_processing_order[ m ] less than po_sei_processing_order[ n ] indicates that the type of SEI message associated with index m should be processed before the type of SEI message associated with index n, and po_sei_processing_order[ m ] equal to po_sei_processing_order[ n ] indicates that there is no preferred order of processing between the types of SEI messages associated with indexes m and n (e.g., they can indicate different properties that are both applicable at that stage, or one can indicate a property and the other can indicate a process).

[0268] For i greater than 0, po_sei_processing_order[ i ] shall be greater than or equal to po_sei_processing_order[ i − 1 ].

[0269] Let seiMsgA be an SEI message that applies as the i-th SEI message type in the processing chain specified in this SPO SEI message, persists for a particular picture picA, and is associated with po_sei_processing_order[ i ] equal to poValA.

[0270] Let seiMsgSet be a set of of SEI messages that consists of each SEI message for which all of the following conditions are true: – The SEI message applies as the k-th SEI message type in the processing chain specified in this SPO SEI message with any value of k less than i. – The SEI message persists for picA. – po_sei_processing_order[ k ] is less than poValA. – The payloadType value of the SEI message is among the values included in SpoProcessSeiList.

[0271] The pictures to which the semantics of seiMsgA apply are specified as follows: – If seiMsgSet is non-empty, the semantics of seiMsgA apply to all the pictures generated by the process implied by the SEI message that has the greatest value of po_sei_processing_order[ k ] among the SEI messages in seiMsgSet. – Otherwise, the semantics of seiMsgA apply to picA.

[0272] NOTE 6 – When an NNPF process outputs more than one NNPF-generated picture, the semantics of an SEI message that follows the NNPF in the processing order apply to all these NNPF-generated pictures.

[0273] po_num_bits_in_prefix_indication_minus1[ i ] and po_sei_prefix_data_bit[ i ][ j ], when present, have the same semantics as the num_bits_in_prefix_indication_minus1[ i ] and sei_prefix_data_bit[ i ][ j ] syntax elements of the SEI prefix indication SEI message, with prefix_sei_payload_type replaced by po_sei_payload_type[ i ].

[0274] When more than one SPO SEI message with a particular value of po_id is present in a CVS, the values of po_num_sei_messages_minus2 and, for each value of i, the values of po_sei_wrapping_flag[ i ], po_sei_prefix_flag[ i ], po_sei_importance_flag[ i ], po_sei_payload_type[ i ], po_sei_processing_order[ i ] shall be the same as in the other SPO SEI messages in the CVS with the same value of po_id.

[0275] po_byte_alignment_bit_equal_to_one shall be equal to 1.

[0276] The lists PoProcStgIdx, indicating the processing stage indices of the SEI message types in the processing chain, and PoSeiTypeIdx, indicating the SEI message type indices of the processing stages in the processing chain, are derived as follows:– For each of the SEI message types of in the processing chain, the following applies in a non-decreasing order of the corresponding po_sei_processing_order[ i ] values, with j being set equal to 0 initially: PoProcStgIdx[ i ] = j PoSeiTypeIdx[ j ] = i (xx) j++ Where PoProcStgIdx[ i ] indicates the processing stage index of the i-th SEI message type in the processing chain, and [ j ] indicates the SEI message type index of the j-th processing stage in the processing chain.

[0277] For a picture, the list PoSeiList, indicting the list of SEI messages, associated with SEI message types in the processing chain indicated by the SPO SEI message, that may be applied to the picture, the list PoSeiTypeList, indicating the SEI message type indices of the SEI messages that may be applied to the picture, and the variable PoNumSeiMsgs, indicating the number of SEI messages that may be applied to the picture, are derived as follows: – PoSeiList is initially empty, and j and PoNumSeiMsgs are both initially set equal to 0. – The following applies in the same non-decreasing order of po_sei_processing_order[ i ] values as above for deriving the lists PoProcStgIdx and PoSeiTypeIdx for all values of i in the range of 0 to po_num_sei_messages_minus2 + 1, inclusive, unless terminated earlier as specified below: – When an SEI message seiA associated with the i-th SEI message type persists for picA, the following applies: – If the decoding system can interpret and supports the functionality indicated by seiA, seiA is added at the end of PoSeiList, PoSeiTypeList[ j ] is set equal to i, PoNumSeiMsgs is set equal to PoNumSeiMsgs + 1, and j is set equal to j + 1. – Otherwise, if po_sei_importance_flag[ i ] is equal to 1 and po_sei_processing_degree_flag[ i ] is equal to 0, the derivation of PoSeiList, PoSeiTypeList, and PoNumSeiMsgs are terminated. – Otherwise, if po_sei_importance_flag[ i ] is equal to 1 and po_sei_processing_degree_flag[ i ] is equal to 1, the processing chain specified by this SPO SEI message should not be performed for picA, PoSeiList is set to be empty, PoNumSeiMsgs is set equal to 0, and the derivation of PoSeiList, PoSeiTypeList, and PoNumSeiMsgs are terminated. 2.5 Handling of a processing chain

[0278] As can be seen from the semantics of the SPO SEI message, a processing chain consists of a list of types of SEI messages identified by an SPO SEI message in the preferred processing order indicated in the SPO SEI message.

[0279] An improved version of the specification for handling of a processing chain specified in JVET-AI2006 is as follows.

[0280] In clause 3, add the following definitions (adjust the subclause numbering when adding): 3.1 corresponding picture: For a particular picture picA, the corresponding picture in a picture list is the picture in the picture list that is either picA itself or a processed version of picA generated when the process implied by an SEI message is applied. NOTE – The particular picture picA could be a picture that is not in the picture list, in which case the corresponding picture in the picture list is a processed version of picA. When picA is in the picture list, it's corresponding picture in the picture list is itself.3.2 inserted picture: A picture that was interpolated or extrapolated when the process implied by an SEI message (e.g., an NNPF activation (NNPFA) SEI message activating an NNPF with PictureRateUpsamplingFlag or TemporalExtrapolationFlag equal to 1) is applied. 3.3 associated inserted picture: For a particular picture picA, an associated inserted picture in a picture list is a picture picB in the picture list that is the corresponding picture of an inserted picture generated when applying the process implied by an SEI message to a corresponding picture of picA.

[0281] NOTE – The particular picture picA could be a picture that is not in the picture list. 8.30.2 Handling of a processing chain 8.30.2.1 General

[0282] Processing chains are alternatives to each other, i.e., at most one processing chain can be chosen to be applied by a decoding system at one time.

[0283] A special NNPF cascading case is defined as the case when such two NNPFs are both activated for a picture: one of the two NNPFs has nnpfc_purpose equal to 4 and the other has multiple input pictures, and neither of the two NNPFs is associated with an SPO SEI message. In this case, the two NNPFs are implicitly considered as belonging to one processing chain and the processing chain only contains these two NNPFs.

[0284] Except for the special NNPF cascading case, each processing chain containing multiple SEI message types is indicated by an SPO SEI message with a particular value of po_id. Except for the special NNPF cascading case, any SEI message for which the payloadType is present in SpoProcessSeiList but is not indicated by an SPO SEI message is in its own processing chain.

[0285] In the special NNPF cascading case, PoNumProcStgs is set equal to 2, PoNumSeiMsgs is set equal to 2, and the following applies: 1) If both of the NNPFs have nnpfc_purpose equal to 4 and multiple input pictures, either of the two is chosen to be applied first, and for the one chosen to be applied first, PoProcStgIdx[ i ] is set equal to 0, and PoSeiList

[0000] is set to be the NNPFA SEI message activating the NNPF, and for the other, PoProcStgIdx[ i ] is set equal to 1, and PoSeiList

[0001] is set to be the NNPFA SEI message activating the NNPF. 2) Otherwise, PoProcStgIdx[ i ] corresponding to the NNPF with nnpfc_purpose equal to 4 is set equal to 0, PoProcStgIdx[ i ] corresponding to the NNPF with multiple input pictures is set equal to 1, PoSeiList

[0000] is set to be the NNPFA SEI message activating the NNPF with nnpfc_purpose equal to 4, and PoSeiList

[0001] is set to be the NNPFA SEI message activing the NNPF with multiple input pictures. 3) The values of po_sei_importance_flag

[0000] and po_sei_importance_flag

[0001] are both inferred to be equal to 0.

[0286] In case of a single SEI message in its own processing chain, PoNumProcStgs is set equal to 1, PoNumSeiMsgs is set equal to 1, PoProcStgIdx

[0000] is set equal to 0, po_sei_importance_flag

[0000] is inferred to be equal to 0, and PoSeiList

[0000] is set to be the single SEI message.

[0287] The PoSeiList for a corresponding picture of picA or for an associated inserted picture of picA is derived to be the same as the PoSeiList derived for picA.

[0288] A decoding system may choose and apply a processing chain according to the following ordered steps: 1) The bitstream is decoded and a processing chain is chosen, and the following applies:– The list PoCdoPicList is set to be the list of the cropped decoded output pictures in output order resulted from decoding the bitstream. – When the SEI message type indicated by PoSeiTypeIdx

[0000] of the chosen processing chain corresponds to a film grain characteristics SEI message, the list PoDecPicList is set to be the list of the decoded pictures in output order resulted from decoding the bitstream. 2) If the SEI message type indicated by PoSeiTypeIdx

[0000] of the chosen processing chain does not correspond to a film grain characteristics SEI message, the list CandInputPicList

[0000] is set to be identical to PoCdoPicList. Otherwise, the list CandInputPicList

[0000] is set to be identical to PoDecPicList. 3) For each i in the range of 1 to PoNumProcStgs, inclusive, the list CandInputPicList[ i ] is set to be identical to PoCdoPicList.

[0289] NOTE 1 – The lists CandInputPicList[ i ] for i in the range of 1 to PoNumProcStgs, inclusive, may be updated during the next step. The list CandInputPicList[ PoNumProcStgs ] is for temporally storing the final output of the chosen processing chain. 4) If the chosen processing chain is indicated by an SPO SEI message and po_breadth_first_flag in the SPO SEI message is equal to 1, the breadth-first handling of a processing chain is invoked. Otherwise, either the depth-first handling of a processing chain or the breadth-first handling of a processing chain is invoked. – When applying an NNPF to a picture during the invocation of a process for handling of a processing chain, the following applies: – The filtered and / or interpolated pictures are generated by the NNPF by applying the NNPF process specified in the semantics of the NNPFC SEI message, in a patch-wise manner, to the current picture. – The order of the pictures generated by the NNPF by applying the NNPF process being stored into the output tensor of the NNPF is in output order. 5) The list PoOutputPicList is set to be identical to CandInputPicList[ PoNumProcStgs ].

[0290] Regardless of which processing chain was chosen to be processed, the following constraints apply: – Within PoOutputPicList there shall not be two pictures having the same output order. – The pictures in PoOutputPicList shall be in increasing output order.

[0291] For each processing stage with processing stage index i in the range of 0 to PoNumProcStgs − 1, inclusive, the following applies: – For any particular pair of pictures inputPicA and inputPicB consecutive in output order in CandInputPicList[ i ], which is the list of candidate input pictures for the processing stage, when there are one or more pictures intermediatePicSetA between inputPicA and inputPicB in output order added to CandInputPicList[ i + 1 ] when applying the process implied by a particular SEI message of the processing stage, one and only one of the following shall apply: – The pictures in intermediatePicSetA shall be among the pictures that were output by applying a particular NNPF nnpfA with PictureRateUpsamplingFlag equal to 1 of the processing stage when a particular picture currPicA in CandInputPicList[ i ] was the current picture.– The pictures in intermediatePicSetA shall be among the pictures that were output by applying a particular NNPF nnpfA with TemporalExtrapolationFlag equal to 1 of the processing stage when a particular picture currPicA in CandInputPicList[ i ] was the current picture. – The application of the process implied by the particular SEI message when another picture other than currPicA was the current picture or the application of the process implied by of another SEI message of the same processing stage when any picture (including currPicA) was the current picture shall not output any picture between the inputPicA and inputPicB in output order.

[0292] NOTE 2 – The intent of the constraints expressed above is to disallow generating output pictures between any particular pair of consecutive input pictures more than once within a processing stage. 8.30.3.2 Breadth-first handling of a processing chain

[0293] For each SEI message types, with SEI message type index i, of the chosen processing chain, the following applies in increasing order of the corresponding processing stage index PoProcStgIdx[ i ] values: – The following applies for each picture picA in CandInputPicList[ PoProcStgIdx[ i ] ] in output order, when an SEI message associated with the i-th SEI message type is present in PoSeiList of picA: – When PoProcStgIdx[ i ] is greater than 0, the following applies for the interpretation of the SEI message: – The interface variables for purposes of interpretation of the SEI message are derived from picA. – The semantics of the SEI message, or the semantics of the SEI message and, when the SEI message is an NNPFA SEI message, the associated NNPFC SEI message, apply to pictures in CandInputPicList[ PoProcStgIdx[ i ] ]. – When the SEI payloadType value of the i-th SEI message type is present in SpoProcessingSeiList, the process implied by the SEI message is performed and each list CandInputPicList[ PoProcStgIdx[ i ] + j ] with j in the range of 1 to PoNumProcStgs − PoProcStgIdx[ i ], inclusive, is updated by replacing pictures with the corresponding processed pictures, if any, resulting from the process and inserting the other pictures, if any, resulting from the process into CandInputPicList[ PoProcStgIdx[ i ] + j ] so that the output order is obeyed. When the SEI message is a film grain characteristics SEI message, PoProcStgIdx[ i ] is equal to 0, and j is equal to 1, during the replacement of a picture in CandInputPicList

[0001] with the corresponding processed picture or inserting a picture into CandInputPicList

[0001] , the corresponding processed picture or the picture to be inserted is first cropped, in the same manner as generating a cropped decoded output picture from the corresponding decoded picture, and the cropped picture is used for the replacement or insertion. 8.30.3.3 Depth-first handling of a processing chain

[0294] The following is repeatedly applied, in output order, for each picture picA in CandInputPicList

[0000] : – The following applies for each SEI message with SEI message index seiIdx in PoSeiList of picA in increasing order of list indexes for PoSeiList: – When PoProcStgIdx[ PoSeiTypeList[ seiIdx ] ] is greater than 0, the following applies for the interpretation of the SEI message:– The interface variables for purposes of interpretation of the SEI message are derived from the pictures in CandInputPicList[ PoProcStgIdx[ PoSeiTypeList[ seiIdx ] ] ]. – The semantics of the SEI message, or of the SEI message and, when the SEI message is an NNPFA SEI message, the associated NNPFC SEI message, apply to pictures in CandInputPicList[ PoProcStgIdx[ PoSeiTypeList[ seiIdx ] ] ]. – When the SEI payloadType value of the SEI message is present in SpoProcessSeiList, the process implied by the SEI message is invoked repeatedly, in output order, for picA and each of the pictures in CandInputPicList[ PoProcStgIdx[ PoSeiTypeList[ seiIdx ] ] ] that is picA or an associated inserted picture of picA. After each invocation of the process, each list CandInputPicList[ PoProcStgIdx[ PoSeiTypeList[ seiIdx ] ] + j ] with j in the range of 1 to PoNumProcStgs − PoProcStgIdx[ PoSeiTypeList[ seiIdx ] ], inclusive, is updated by replacing pictures with the corresponding processed pictures, if any, resulting from the process and inserting the other pictures, if any, resulting from the process into CandInputPicList[ PoProcStgIdx[ PoSeiTypeList[ seiIdx ] ] + j ] so that the output order is obeyed. When the SEI message is a film grain characteristics SEI message, PoProcStgIdx[ PoSeiTypeList[ seiIdx ] ] is equal to 0, and j is equal to 1, during the replacement of a picture in CandInputPicList

[0001] with the corresponding processed picture or inserting a picture into CandInputPicList

[0001] , the corresponding processed picture or the picture to be inserted is first cropped, in the same manner as generating a cropped decoded output picture from the corresponding decoded picture, and the cropped picture is used for the replacement or insertion. 2.6 VVC SEI payloadType values and use of the NNPFC and NNPFA SEI messages in a VVC bitstream 2.6.1. VVC SEI payloadType values

[0295] In the semantics of the SPO SEI message, two lists are used, SeiProcessingOrderSeiList and SpoProcessSeiList, which are defined in JVET-AI2005 [5] as follows: SeiProcessingOrderSeiList is set to consist of the SEI payloadType values 3, 4, 5, 19, 137, 142, 144, 147, 148, 149, 150, 153, 155, 165, 177, 210, and 211, and SpoProcessSeiList is set to consist of the payloadType values 19, 142, 155, 210, and 211.

[0296] An improved definition of SeiProcessingOrderSeiList and SpoProcessSeiList is as follows (excluding 210, the SEI payloadType value for the NNPFC SEI message, and adding 45, the SEI payloadType value for the frame packing arrangement SEI message): SeiProcessingOrderSeiList is set to consist of the SEI payloadType values 3, 4, 5, 19, 45, 137, 142, 144, 147, 148, 149, 150, 153, 155, 165, 177, and 211, and SpoProcessSeiList is set to consist of the payloadType values 19, 45, 142, 155, and 211.

[0297] These SEI payloadType values are all included in the following syntax table in JVET-AI2005, which defines SEI payloadType values for all SEI messages that may be used in a VVC bitstream: sei_payload( payloadType, payloadSize ) { Descriptorpic_timing( payloadSize ) else if( payloadType = = 3 )else if( payloadType = = 147 ) / * Specified in Rec. ITU-T H.274 | ISO / IEC 23002-7 * / else if( payloadType = = 180 ) / * Specified in Rec. ITU-T H.274 | ISO / IEC 23002-7 * / phase_indication( payloadSize ) else if( payloadType = = 213 ) / * Specified in Rec. ITU-T H.274 | ISO / IEC 23002-7else if( payloadType = = 215 ) / * Specified in Rec. ITU-T H.274 | ISO / IEC 23002-7 * / 2.6., ,

[0298] JVET-AI2005 [5] and version 3 of the VVC standard [2] include the specifications of use of the FGC SEI message, the RWP SEI message, and the CTI SEI message in VVC bitstreams, as in below. D.12 Use of SEI messages specified in other specifications D.12.1 General

[0299] The SEI messages having syntax structures identified in clause D.2.1 that are specified in other specifications, including Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, or ISO / IEC 23090-13, may be used together with bitstreams specified by this Specification.

[0300] When any particular SEI message specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, or ISO / IEC 23090-13 is included in a bitstream specified by this Specification, the SEI payload syntax shall be as specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, or ISO / IEC 23090-13, respectively, that syntax shall be included into the sei_payload( ) syntax structure as specified in clause D.2.1 and shall use the payloadType value specified in clause D.2.1, the corresponding semantics specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, or ISO / IEC 23090-13 shall apply, and, additionally, any SEI-message-specific constraints, variables, and semantics specified in this annex for that particular SEI message shall apply.

[0301] The value of PayloadBits, as specified in clause D.2.2, is passed to the parser of the SEI message syntax structures specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, and ISO / IEC 23090-13.

[0302] NOTE – The definition of IRAP picture in the VSEI specification is as follows: A coded picture starting from which all pictures in the same layer in both decoding order and output order can be decoded without first decoding any picture in the same layer earlier in decoding order in the coded video bitstream. Consequently, a gradual decoderrefresh (GDR) picture with ph_recovery_poc_cnt equal to 0 in a VVC bitsream is an intra random access picture (IRAP) picture according to the IRAP picture definition in the VSEI specification. D.12.2 Use of the the film grain characteristics SEI message

[0303] For purposes of interpretation of the film grain characteristics SEI message, the following variables are specified:

[0304] If the film grain characteristics SEI message is not applied as part of a processing chain indicated by an SEI processing order SEI message or is applied as the first processing step of the processing chain indicated by an SEI processing order SEI message, the following applies: – PicWidthInLumaSamples and PicHeightInLumaSamples are set equal to pps_pic_width_in_luma_samples and pps_pic_height_in_luma_samples, respectively. – ChromaFormatIdc is set equal to sps_chroma_format_idc. – BitDepthY and BitDepthC are both set equal to BitDepth.

[0305] Otherwise (the film grain characteristics SEI message is applied as the second or a later processing step of the processing chain indicated by an SEI processing order SEI message), prevPic is a picture resulting from the previous processing step of the processing chain indicated by the SEI processing order SEI message, and the following applies: – PicWidthInLumaSamples and PicHeightInLumaSamples are set equal to the picture width and picture height of prevPic, respectively. – ChromaFormatIdc is set equal to the picture chroma format indicator of prevPic. – BitDepthY and BitDepthC are set equal to the luma bit depth and chroma bit depth of prevPic, respectively. D.12.5 Use of the equirectangular projection, generalized cubemap projection, and region-wise packing SEI messages

[0306] For purposes of interpretation of the equirectangular projection, generalized cubemap projection, and region-wise packing SEI message, the following variable is specified: – ChromaFormatIdc is set equal to sps_chroma_format_idc. D.12.9 Use of the colour transform information SEI message

[0307] For purposes of interpretation of the colour transform information SEI message, the following variable is specified: – ChromaFormatIdc is set equal to sps_chroma_format_idc. 3. Technical problems solved by disclosed technical solutions

[0308] An example design for use of the film grain characteristics (FGC) SEI message, the frame packing arrangement (FPA) SEI message, the region-wise packing (RWP) SEI message, and the colour transform information (CTI) SEI message in a coded video bitstream has the following problems when they are used in the context of a processing chain:

[0309] First, the process implied by an FGC message may also be applied to a processed version of a decoded picture, or an inserted (interpolated or extrapolated) picture, not just a decoded picture. However, that aspect is missing.

[0310] Second, the process implied by an FPA, RWP, or CTI SEI message may also be applied to a processed version of a cropped decoded output picture, or an inserted (interpolated or extrapolated) picture, not just a cropped decoded output picture. However, that aspect is missing. 4. A listing of solutions and embodiments

[0311] To solve the above-described problems, methods as summarized below are disclosed. The aspects should be considered as examples to explain the general concepts and should not be interpreted in a narrow way. Furthermore, these examples can be applied individually or combined in any manner. 1) In one example, it is specified that the variable SeiProcStgIdx indicates the processing stage index associated with the FGC, FPA, RWP, or CTI SEI message within a chosen processing chain. a. In one example, it is specified that, if the FGC, FPA, RWP, or CTI SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, the value of SeiProcStgIdx is provided by that process; otherwise, the value of SeiProcStgIdx is inferred to be equal to 0. 2) In one example, it is specified that the list CandInputPicList[ SeiProcStgIdx ] contains a list of pictures in output order from which the input pictures for the process implied by the FGC SEI message is selected. a. In one example, it is specified that, when SeiProcStgIdx is equal to 0, pictures in CandInputPicList

[0000] are decoded pictures. b. In one example, it is specified that, if the FGC SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, the list CandInputPicList[ SeiProcStgIdx ] is provided by that process; otherwise, the list CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to the list of cropped decoded output pictures in output order resulted from decoding the bitstream. 3) In one example, it is specified that the list CandInputPicList[ SeiProcStgIdx ] contains a list of pictures in output order from which the input pictures for the process implied by the FPA, RWP, or CTI SEI message is selected. a. In one example, it is specified that, when SeiProcStgIdx is equal to 0, pictures in CandInputPicList

[0000] are cropped decoded output pictures. b. In one example, it is specified that, if the FPA, RWP, or CTI SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002- 7, the list CandInputPicList[ SeiProcStgIdx ] is provided by that process; otherwise, the list CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to the list of cropped decoded output pictures in output order resulted from decoding the bitstream. 4) In one example, it is specified that, let currDecPic be a decoded picture for which the FGC SEI message persists, let currPic be a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currDecPic or is an associated inserted picture of currDecPic, the following applies: – If SeiProcStgIdx is equal to 0, the following applies: – PicWidthInLumaSamples and PicHeightInLumaSamples are set equal to pps_pic_width_in_luma_samples and pps_pic_height_in_luma_samples, respectively.– ChromaFormatIdc is set equal to sps_chroma_format_idc. – BitDepthY and BitDepthC are both set equal to BitDepth. – Otherwise (SeiProcStgIdx is greater than 0), the following applies: – PicWidthInLumaSamples and PicHeightInLumaSamples are set equal to the picture width and picture height of currPic, respectively. – ChromaFormatIdc is set equal to the picture chroma format indicator of currPic. – BitDepthYand BitDepthCare set equal to the luma bit depth and chroma bit depth, respectively, of currPic. 5) In one example, it is specified that, let currCdoPic be a cropped decoded output picture for which the RWP or CTI SEI message persists, let currPic be a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currCdoPic or is an associated inserted picture of currCdoPiclet, the following applies: – If SeiProcStgIdx is equal to 0, the following applies: – ChromaFormatIdc is set equal to sps_chroma_format_idc. – Otherwise (SeiProcStgIdx is greater than 0), the following applies: – ChromaFormatIdc is set equal to the picture chroma format indicator of currPic. 5. Embodiments

[0312] Below are some example embodiments for some of the aspects summarized above in Section 4. Added or modified texts are shown enclosed in {{ }}, and some of the deleted parts are shown enclosed in [[[ ]]]. 5.1 First embodiment D.12 Use of SEI messages specified in other specifications D.12.1 General

[0313] The SEI messages having syntax structures identified in clause D.2.1 that are specified in other specifications, including Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, or ISO / IEC 23090-13, may be used together with bitstreams specified by this Specification.

[0314] When any particular SEI message specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, or ISO / IEC 23090-13 is included in a bitstream specified by this Specification, the SEI payload syntax shall be as specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, or ISO / IEC 23090-13, respectively, that syntax shall be included into the sei_payload( ) syntax structure as specified in clause D.2.1 and shall use the payloadType value specified in clause D.2.1, the corresponding semantics specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, or ISO / IEC 23090-13 shall apply, and, additionally, any SEI-message-specific constraints, variables, and semantics specified in this annex for that particular SEI message shall apply.

[0315] The value of PayloadBits, as specified in clause D.2.2, is passed to the parser of the SEI message syntax structures specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, ISO / IEC 23001-11, and ISO / IEC 23090-13.

[0316] NOTE – The definition of IRAP picture in the VSEI specification is as follows: A coded picture starting from which all pictures in the same layer in both decoding order and output order can be decoded without first decoding any picture in the same layer earlier in decoding order in the coded video bitstream. Consequently, a GDR picture with ph_recovery_poc_cnt equal to 0 in a VVC bitsream is an IRAP picture according to the IRAP picture definition in the VSEI specification.

[0317] {{Besides definitions in clause 3, the following definitions apply for specifying the use of SEI messages in remaining subclauses of subclause D.12:}}

[0318] {{corresponding picture: For a particular picture picA, the corresponding picture in a picture list is the picture in the picture list that is either picA itself or a processed version of picA generated when the process implied by an SEI message is applied. }}

[0319] {{NOTE – The particular picture picA could be a picture that is not in the picture list, in which case the corresponding picture in the picture list is a processed version of picA. When picA is in the picture list, it's corresponding picture in the picture list is itself. }}

[0320] {{inserted picture: A picture that was interpolated or extrapolated when the process implied by an SEI message (e.g., an NNPFA SEI message activating an NNPF with PictureRateUpsamplingFlag or TemporalExtrapolationFlag equal to 1) is applied. }}

[0321] {{associated inserted picture: For a particular picture picA, an associated inserted picture in a picture list is a picture picB in the picture list that is the corresponding picture of an inserted picture generated when applying the process implied by an SEI message to a corresponding picture of picA. }}

[0322] {{NOTE – The particular picture picA could be a picture that is not in the picture list.}} ... D.12.2 Use of the film grain characteristics SEI message

[0323] For purposes of interpretation of the film grain characteristics (FGC) SEI message, the following variables {{or lists}} are specified: {{– The variable SeiProcStgIdx, indicating the processing stage index associated with the FGC SEI message within a chosen processing chain. If the FGC SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, the value of SeiProcStgIdx is provided by that process. Otherwise, the value of SeiProcStgIdx is inferred to be equal to 0.}} {{– The list CandInputPicList[ SeiProcStgIdx ], containing a list of pictures in output order from which the input picture for the process implied by the FGC SEI mesage is selected. When SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ SeiProcStgIdx ] are decoded pictures. If the FGC SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, the list CandInputPicList[ SeiProcStgIdx ] is provided by that process. Otherwise, the list CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to the list of decoded pictures in output order resulted from decoding the bitstream. }}

[0324] {{NOTE – When SeiProcStgIdx is greater than 0, the list CandInputPicList[ SeiProcStgIdx ] contains pictures after the application of the process(es) implied by the SEI message(s) associated with processing stage index values less than SeiProcStgIdx. }}

[0325] {{Let currDecPic be a decoded picture for which the FGC SEI message persists. Let currPic be a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currDecPic or is an associated inserted picture of currDecPic. For purposes of interpretation of the FGC SEI message, additionally the following variables are specified: }}– If [[[the film grain characteristics SEI message is not applied as part of a processing chain indicated by an SEI processing order SEI message or is applied as the first processing step of the processing chain indicated by an SEI processing order SEI message]]] {{SeiProcStgIdx is equal to 0}}, the following applies: – PicWidthInLumaSamples and PicHeightInLumaSamples are set equal to pps_pic_width_in_luma_samples and pps_pic_height_in_luma_samples, respectively. – ChromaFormatIdc is set equal to sps_chroma_format_idc. – BitDepthYand BitDepthCare both set equal to BitDepth. – Otherwise [[[(the film grain characteristics SEI message is applied as the second or a later processing step of the processing chain indicated by an SEI processing order SEI message), prevPic is a picture resulting from the previous processing step of the processing chain indicated by the SEI processing order SEI message, and ]]] {{(SeiProcStgIdx is greater than 0),}} the following applies: – PicWidthInLumaSamples and PicHeightInLumaSamples are set equal to the picture width and picture height of [[[prevPic]]] {{currPic}}, respectively. – ChromaFormatIdc is set equal to the picture chroma format indicator {{of currPic}}. – BitDepthY and BitDepthC are set equal to the luma bit depth and chroma bit depth, respectively, of [[[prevPic]]] {{currPic}}. D.12.5 Use of the equirectangular projection, generalized cubemap projection, and region-wise packing SEI messages {{D.12.5.1 Use of the the equirectangular projection and generalized cubemap projection SEI messages}}

[0326] [[[For purposes of interpretation of the equirectangular projection, generalized cubemap projection, and region-wise packing SEI message, the following variable is specified:]]]

[0327] {{For purposes of interpretation of the equirectangular projection or generalized cubemap projection SEI message, the following variable is specified:}} – ChromaFormatIdc is set equal to sps_chroma_format_idc. {{D.12.5.2 Use of the region-wise packing SEI message}}

[0328] {{For purposes of interpretation of the region-wise packing (RWP) SEI message, the following variables or lists are specified: }} {{– The variable SeiProcStgIdx, indicating the processing stage index associated with the RWP SEI message within a chosen processing chain. If the RWP SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, the value of SeiProcStgIdx is provided by that process. Otherwise, the value of SeiProcStgIdx is inferred to be equal to 0. }} {{– The list CandInputPicList[ SeiProcStgIdx ], containing a list of pictures in output order from which the input picture for the process implied by the RWP SEI mesage is selected. When SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ SeiProcStgIdx ] are cropped decoded output pictures. If the RWP SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002- 7, the list CandInputPicList[ SeiProcStgIdx ] is provided by that process. Otherwise, the listCandInputPicList[ SeiProcStgIdx ] is inferred to be identical to the list of cropped decoded output pictures in output order resulted from decoding the bitstream. }}

[0329] {{NOTE – When SeiProcStgIdx is greater than 0, the list CandInputPicList[ SeiProcStgIdx ] contains pictures after the application of the process(es) implied by the SEI message(s) associated with processing stage index values less than SeiProcStgIdx. }}

[0330] {{Let currCdoPic be a cropped decoded output picture for which the RWP SEI message persists. Let currPic be a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currCdoPic or is an associated inserted picture of currCdoPic. For purposes of interpretation of the RWP SEI message, additionally the following variable is specified: }} {{– If SeiProcStgIdx is equal to 0, the following applies: }} {{– ChromaFormatIdc is set equal to sps_chroma_format_idc. }} {{– Otherwise (SeiProcStgIdx is greater than 0), the following applies: }} {{– ChromaFormatIdc is set equal to the picture chroma format indicator of currPic.}} D.12.9 Use of the colour transform information SEI message

[0331] For purposes of interpretation of the colour transform information {{(CTI)}} SEI message, the following [[[variable is]]] {{variables or lists are}} specified: {{– The variable SeiProcStgIdx, indicating the processing stage index associated with the CTI SEI message within a chosen processing chain. If the CTI SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, the value of SeiProcStgIdx is provided by that process. Otherwise, the value of SeiProcStgIdx is inferred to be equal to 0. }} {{– The list CandInputPicList[ SeiProcStgIdx ], containing a list of pictures in output order from which the input picture for the process implied by the CTI SEI mesage is selected. When SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ SeiProcStgIdx ] are cropped decoded output pictures. If the CTI SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002- 7, the list CandInputPicList[ SeiProcStgIdx ] is provided by that process. Otherwise, the list CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to the list of cropped decoded output pictures in output order resulted from decoding the bitstream. }}

[0332] {{NOTE – When SeiProcStgIdx is greater than 0, the list CandInputPicList[ SeiProcStgIdx ] contains pictures after the application of the process(es) implied by the SEI message(s) associated with processing stage index values less than SeiProcStgIdx. }}

[0333] {{Let currCdoPic be a cropped decoded output picture for which the CTI SEI message persists. Let currPic be a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currCdoPic or is an associated inserted picture of currCdoPic. For purposes of interpretation of the CTI SEI message, additionally the following variable is specified: }} {{– If SeiProcStgIdx is equal to 0, the following applies:}} – ChromaFormatIdc is set equal to sps_chroma_format_idc. {{– Otherwise (SeiProcStgIdx is greater than 0), the following applies:}}{{– ChromaFormatIdc is set equal to the picture chroma format indicator of currPic.}} D.12.14 Use of the frame packing arrangement SEI message

[0334] {{For purposes of interpretation of the frame packing arrangement (FPA) SEI message, the following variables or lists are specified:}} {{– The variable SeiProcStgIdx, indicating the processing stage index associated with the FPA SEI message within a chosen processing chain. If the FPA SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002-7, the value of SeiProcStgIdx is provided by that process. Otherwise, the value of SeiProcStgIdx is inferred to be equal to 0.}} {{– The list CandInputPicList[ SeiProcStgIdx ], containing a list of pictures in output order from which the input picture for the process implied by the FPA SEI mesage is selected. When SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ SeiProcStgIdx ] are cropped decoded output pictures. If the FPA SEI message is used during the invocation of a process for handling of the processing chain as specified in Rec. ITU-T H.274 | ISO / IEC 23002- 7, the list CandInputPicList[ SeiProcStgIdx ] is provided by that process. Otherwise, the list CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to the list of cropped decoded output pictures in output order resulted from decoding the bitstream.}}

[0335] {{NOTE – When SeiProcStgIdx is greater than 0, the list CandInputPicList[ SeiProcStgIdx ] contains pictures after the application of the process(es) implied by the SEI message(s) associated with processing stage index values less than SeiProcStgIdx.}} 6. References [1] ITU-T and ISO / IEC, “High efficiency video coding”, Rec. ITU-T H.265 | ISO / IEC 23008-2 (in force edition). [2] ITU-T and ISO / IEC, “Versatile Video Coding”, Rec. ITU-T H.266 | ISO / IEC 23090-3. [3] ITU-T and ISO / IEC, “Versatile Supplemental Enhancement Information Messages for Coded Video Bitstreams”, Rec. ITU-T Rec. H.274 | ISO / IEC 23002-7. [4] J. Boyce, J. Chen, S. Deshpande, M. M. Hannuksela, S. McCarthy, G. J. Sullivan, H. Tan, and Y.-K. Wang (editors), JVET-AI2006, “Additional SEI messages for VSEI version 4 (Draft 3)”. [5] G. J. Sullivan, B. Bross, M. M. Hannuksela, and Y.-K. Wang (editors), JVET-AI2005, “Additions and corrections for VVC version 4 (Draft 9)”.

[0336] FIG.7 is a block diagram showing an example video processing system 4000 in which various techniques disclosed herein may be implemented. Various implementations may include some or all of the components of the system 4000. The system 4000 may include input 4002 for receiving video content. The video content may be received in a raw or uncompressed format, e.g., 8 or 10 bit multi-component pixel values, or may be in a compressed or encoded format. The input 4002 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interface include wired interfaces such as Ethernet, passive optical network (PON), etc. and wireless interfaces such as Wi-Fi or cellular interfaces.

[0337] The system 4000 may include a coding component 4004 that may implement the various coding or encoding methods described in the present document. The coding component 4004 may reduce the average bitrate of video from the input 4002 to the output of the coding component 4004 to produce a coded representation of the video.The coding techniques are therefore sometimes called video compression or video transcoding techniques. The output of the coding component 4004 may be either stored, or transmitted via a communication connected, as represented by the component 4006. The stored or communicated bitstream (or coded) representation of the video received at the input 4002 may be used by a component 4008 for generating pixel values or displayable video that is sent to a display interface 4010. The process of generating user-viewable video from the bitstream representation is sometimes called video decompression. Furthermore, while certain video processing operations are referred to as “coding” operations or tools, it will be appreciated that the coding tools or operations are used at an encoder and corresponding decoding tools or operations that reverse the results of the coding will be performed by a decoder.

[0338] Examples of a peripheral bus interface or a display interface may include universal serial bus (USB) or high definition multimedia interface (HDMI) or Displayport, and so on. Examples of storage interfaces include serial advanced technology attachment (SATA), peripheral component interconnect (PCI), integrated drive electronics (IDE) interface, and the like. The techniques described in the present document may be embodied in various electronic devices such as mobile phones, laptops, smartphones or other devices that are capable of performing digital data processing and / or video display.

[0339] FIG.8 is a block diagram of an example video processing apparatus 4100. The apparatus 4100 may be used to implement one or more of the methods described herein. The apparatus 4100 may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on. The apparatus 4100 may include one or more processors 4102, one or more memories 4104 and video processing circuitry 4106. The processor(s) 4102 may be configured to implement one or more methods described in the present document. The memory (memories) 4104 may be used for storing data and code used for implementing the methods and techniques described herein. The video processing circuitry 4106 may be used to implement, in hardware circuitry, some techniques described in the present document. In some embodiments, the video processing circuitry 4106 may be at least partly included in the processor 4102, e.g., a graphics co-processor.

[0340] FIG.9 is a flowchart for an example method 4200 of video processing. The method 4200 determines that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain at step 4202. A conversion between a visual media data and a bitstream is perfomed based on the processing chain at step 4204. The conversion may include encoding at an encoder, decoding at a decoder, or combinations thereof.

[0341] It should be noted that the method 4200 can be implemented in an apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, such as video encoder 4400, video decoder 4500, and / or encoder 4600. In such a case, the instructions upon execution by the processor, cause the processor to perform the method 4200. Further, the method 4200 can be performed by a non-transitory computer readable medium comprising a computer program product for use by a video coding device. The computer program product comprises computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method 4200.

[0342] FIG. 10 is a block diagram that illustrates an example video coding system 4300 that may utilize the techniques of this disclosure. The video coding system 4300 may include a source device 4310 and a destination device 4320. Source device 4310 generates encoded video data which may be referred to as a video encoding device. Destination device 4320 may decode the encoded video data generated by source device 4310 which may be referred to as a video decoding device.

[0343] Source device 4310 may include a video source 4312, a video encoder 4314, and an input / output (I / O) interface 4316. Video source 4312 may include a source such as a video capture device, an interface to receive video data from a video content provider, and / or a computer graphics system for generating video data, or a combination of such sources. The video data may comprise one or more pictures. Video encoder 4314 encodes the video data from video source 4312 to generate a bitstream. The bitstream may include a sequence of bits that form a coded representation of the video data. The bitstream may include coded pictures and associated data. The coded picture is a coded representation of a picture. The associated data may include sequence parameter sets, picture parameter sets, and other syntax structures. I / O interface 4316 may include a modulator / demodulator (modem) and / or a transmitter. The encoded video data may be transmitted directly to destination device 4320 via I / O interface 4316 through network 4330. The encoded video data may also be stored onto a storage medium / server 4340 for access by destination device 4320.

[0344] Destination device 4320 may include an I / O interface 4326, a video decoder 4324, and a display device 4322. I / O interface 4326 may include a receiver and / or a modem. I / O interface 4326 may acquire encoded video data from the source device 4310 or the storage medium / server 4340. Video decoder 4324 may decode the encoded video data. Display device 4322 may display the decoded video data to a user. Display device 4322 may be integrated with the destination device 4320, or may be external to destination device 4320, which can be configured to interface with an external display device.

[0345] Video encoder 4314 and video decoder 4324 may operate according to a video compression standard, such as the High Efficiency Video Coding (HEVC) standard, Versatile Video Coding (VVC) standard and other current and / or further standards.

[0346] FIG.11 is a block diagram illustrating an example of video encoder 4400, which may be video encoder 4314 in the system 4300 illustrated in FIG.10. Video encoder 4400 may be configured to perform any or all of the techniques of this disclosure. The video encoder 4400 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of video encoder 4400. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

[0347] The functional components of video encoder 4400 may include a partition unit 4401, a prediction unit 4402 which may include a mode select unit 4403, a motion estimation unit 4404, a motion compensation unit 4405, an intra prediction unit 4406, a residual generation unit 4407, a transform processing unit 4408, a quantization unit 4409, an inverse quantization unit 4410, an inverse transform unit 4411, a reconstruction unit 4412, a buffer 4413, and an entropy encoding unit 4414.

[0348] In other examples, video encoder 4400 may include more, fewer, or different functional components. In an example, prediction unit 4402 may include an intra block copy (IBC) unit. The IBC unit may perform prediction in an IBC mode in which at least one reference picture is a picture where the current video block is located.

[0349] Furthermore, some components, such as motion estimation unit 4404 and motion compensation unit 4405 may be highly integrated, but are represented in the example of video encoder 4400 separately for purposes of explanation.

[0350] Partition unit 4401 may partition a picture into one or more video blocks. Video encoder 4400 and video decoder 4500 may support various video block sizes.

[0351] Mode select unit 4403 may select one of the coding modes, intra or inter, e.g., based on error results, and provide the resulting intra or inter coded block to a residual generation unit 4407 to generate residual block data and to a reconstruction unit 4412 to reconstruct the encoded block for use as a reference picture. In some examples, mode select unit 4403 may select a combination of intra and inter prediction (CIIP) mode in which the prediction is based on an inter prediction signal and an intra prediction signal. Mode select unit 4403 may also select a resolution for a motion vector (e.g., a sub-pixel or integer pixel precision) for the block in the case of inter prediction.

[0352] To perform inter prediction on a current video block, motion estimation unit 4404 may generate motion information for the current video block by comparing one or more reference frames from buffer 4413 to the current video block. Motion compensation unit 4405 may determine a predicted video block for the current video block based on the motion information and decoded samples of pictures from buffer 4413 other than the picture associated with the current video block.

[0353] Motion estimation unit 4404 and motion compensation unit 4405 may perform different operations for a current video block, for example, depending on whether the current video block is in an I slice, a P slice, or a B slice.

[0354] In some examples, motion estimation unit 4404 may perform uni-directional prediction for the current video block, and motion estimation unit 4404 may search reference pictures of list 0 or list 1 for a reference video block for the current video block. Motion estimation unit 4404 may then generate a reference index that indicates the reference picture in list 0 or list 1 that contains the reference video block and a motion vector that indicates a spatial displacement between the current video block and the reference video block. Motion estimation unit 4404 may output the reference index, a prediction direction indicator, and the motion vector as the motion information of the current video block. Motion compensation unit 4405 may generate the predicted video block of the current block based on the reference video block indicated by the motion information of the current video block.

[0355] In other examples, motion estimation unit 4404 may perform bi-directional prediction for the current video block, motion estimation unit 4404 may search the reference pictures in list 0 for a reference video block for the current video block and may also search the reference pictures in list 1 for another reference video block for the current video block. Motion estimation unit 4404 may then generate reference indexes that indicate the reference pictures in list 0 and list 1 containing the reference video blocks and motion vectors that indicate spatial displacements between the reference video blocks and the current video block. Motion estimation unit 4404 may output the reference indexes and the motion vectors of the current video block as the motion information of the current video block. Motion compensation unit 4405 may generate the predicted video block of the current video block based on the reference video blocks indicated by the motion information of the current video block.

[0356] In some examples, motion estimation unit 4404 may output a full set of motion information for decoding processing of a decoder. In some examples, motion estimation unit 4404 may not output a full set of motion informationfor the current video. Rather, motion estimation unit 4404 may signal the motion information of the current video block with reference to the motion information of another video block. For example, motion estimation unit 4404 may determine that the motion information of the current video block is sufficiently similar to the motion information of a neighboring video block.

[0357] In one example, motion estimation unit 4404 may indicate, in a syntax structure associated with the current video block, a value that indicates to the video decoder 4500 that the current video block has the same motion information as another video block.

[0358] In another example, motion estimation unit 4404 may identify, in a syntax structure associated with the current video block, another video block and a motion vector difference (MVD). The motion vector difference indicates a difference between the motion vector of the current video block and the motion vector of the indicated video block. The video decoder 4500 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0359] As discussed above, video encoder 4400 may predictively signal the motion vector. Two examples of predictive signaling techniques that may be implemented by video encoder 4400 include advanced motion vector prediction (AMVP) and merge mode signaling.

[0360] Intra prediction unit 4406 may perform intra prediction on the current video block. When intra prediction unit 4406 performs intra prediction on the current video block, intra prediction unit 4406 may generate prediction data for the current video block based on decoded samples of other video blocks in the same picture. The prediction data for the current video block may include a predicted video block and various syntax elements.

[0361] Residual generation unit 4407 may generate residual data for the current video block by subtracting the predicted video block(s) of the current video block from the current video block. The residual data of the current video block may include residual video blocks that correspond to different sample components of the samples in the current video block.

[0362] In other examples, there may be no residual data for the current video block for the current video block, for example in a skip mode, and residual generation unit 4407 may not perform the subtracting operation.

[0363] Transform processing unit 4408 may generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to a residual video block associated with the current video block.

[0364] After transform processing unit 4408 generates a transform coefficient video block associated with the current video block, quantization unit 4409 may quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values associated with the current video block.

[0365] Inverse quantization unit 4410 and inverse transform unit 4411 may apply inverse quantization and inverse transforms to the transform coefficient video block, respectively, to reconstruct a residual video block from the transform coefficient video block. Reconstruction unit 4412 may add the reconstructed residual video block to corresponding samples from one or more predicted video blocks generated by the prediction unit 4402 to produce a reconstructed video block associated with the current block for storage in the buffer 4413.

[0366] After reconstruction unit 4412 reconstructs the video block, the loop filtering operation may be performed to reduce video blocking artifacts in the video block.

[0367] Entropy encoding unit 4414 may receive data from other functional components of the video encoder 4400. When entropy encoding unit 4414 receives the data, entropy encoding unit 4414 may perform one or more entropy encoding operations to generate entropy encoded data and output a bitstream that includes the entropy encoded data.

[0368] FIG.12 is a block diagram illustrating an example of video decoder 4500 which may be video decoder 4324 in the system 4300 illustrated in FIG.10. The video decoder 4500 may be configured to perform any or all of the techniques of this disclosure. In the example shown, the video decoder 4500 includes a plurality of functional components. The techniques described in this disclosure may be shared among the various components of the video decoder 4500. In some examples, a processor may be configured to perform any or all of the techniques described in this disclosure.

[0369] In the example shown, video decoder 4500 includes an entropy decoding unit 4501, a motion compensation unit 4502, an intra prediction unit 4503, an inverse quantization unit 4504, an inverse transformation unit 4505, a reconstruction unit 4506, and a buffer 4507. Video decoder 4500 may, in some examples, perform a decoding pass generally reciprocal to the encoding pass described with respect to video encoder 4400.

[0370] Entropy decoding unit 4501 may retrieve an encoded bitstream. The encoded bitstream may include entropy coded video data (e.g., encoded blocks of video data). Entropy decoding unit 4501 may decode the entropy coded video data, and from the entropy decoded video data, motion compensation unit 4502 may determine motion information including motion vectors, motion vector precision, reference picture list indexes, and other motion information. Motion compensation unit 4502 may, for example, determine such information by performing the AMVP and merge mode.

[0371] Motion compensation unit 4502 may produce motion compensated blocks, possibly performing interpolation based on interpolation filters. Identifiers for interpolation filters to be used with sub-pixel precision may be included in the syntax elements.

[0372] Motion compensation unit 4502 may use interpolation filters as used by video encoder 4400 during encoding of the video block to calculate interpolated values for sub-integer pixels of a reference block. Motion compensation unit 4502 may determine the interpolation filters used by video encoder 4400 according to received syntax information and use the interpolation filters to produce predictive blocks.

[0373] Motion compensation unit 4502 may use some of the syntax information to determine sizes of blocks used to encode frame(s) and / or slice(s) of the encoded video sequence, partition information that describes how each macroblock of a picture of the encoded video sequence is partitioned, modes indicating how each partition is encoded, one or more reference frames (and reference frame lists) for each inter coded block, and other information to decode the encoded video sequence.

[0374] Intra prediction unit 4503 may use intra prediction modes for example received in the bitstream to form a prediction block from spatially adjacent blocks. Inverse quantization unit 4504 inverse quantizes, i.e., de-quantizes, the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 4501. Inverse transform unit 4505 applies an inverse transform.

[0375] Reconstruction unit 4506 may sum the residual blocks with the corresponding prediction blocks generated by motion compensation unit 4502 or intra prediction unit 4503 to form decoded blocks. If desired, a deblocking filter may also be applied to filter the decoded blocks in order to remove blockiness artifacts. The decoded video blocks are then stored in buffer 4507, which provides reference blocks for subsequent motion compensation / intra prediction and also produces decoded video for presentation on a display device.

[0376] FIG. 13 is a schematic diagram of an example encoder 4600. The encoder 4600 is suitable for implementing the techniques of VVC. The encoder 4600 includes three in-loop filters, namely a deblocking filter (DF) 4602, a sample adaptive offset (SAO) 4604, and an adaptive loop filter (ALF) 4606. Unlike the DF 4602, which uses predefined filters, the SAO 4604 and the ALF 4606 utilize the original samples of the current picture to reduce the mean square errors between the original samples and the reconstructed samples by adding an offset and by applying a finite impulse response (FIR) filter, respectively, with coded side information signaling the offsets and filter coefficients. The ALF 4606 is located at the last processing stage of each picture and can be regarded as a tool trying to catch and fix artifacts created by the previous stages.

[0377] The encoder 4600 further includes an intra prediction component 4608 and a motion estimation / compensation (ME / MC) component 4610 configured to receive input video. The intra prediction component 4608 is configured to perform intra prediction, while the ME / MC component 4610 is configured to utilize reference pictures obtained from a reference picture buffer 4612 to perform inter prediction. Residual blocks from inter prediction or intra prediction are fed into a transform (T) component 4614 and a quantization (Q) component 4616 to generate quantized residual transform coefficients, which are fed into an entropy coding component 4618. The entropy coding component 4618 entropy codes the prediction results and the quantized transform coefficients and transmits the same toward a video decoder (not shown). Quantization components output from the quantization component 4616 may be fed into an inverse quantization (IQ) components 4620, an inverse transform component 4622, and a reconstruction (REC) component 4624. The REC component 4624 is able to output images to the DF 4602, the SAO 4604, and the ALF 4606 for filtering prior to those images being stored in the reference picture buffer 4612.

[0378] A listing of solutions preferred by some examples is provided next.

[0379] The following solutions show examples of techniques discussed herein.

[0380] 1. A method for processing media data comprising: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a chosen processing chain; and performing a conversion between a visual media data and a bitstream based on the chosen processing chain.

[0381] 2. The method of solution 1, wherein when the FGC, FPA, RWP, or CTI SEI message is used during the invocation of a process for handling of the processing chain, the value of SeiProcStgIdx is provided by that process; and otherwise, the value of SeiProcStgIdx is inferred to be equal to 0.

[0382] 3. The method of any of solutions 1-2, wherein a candidate input picture list (CandInputPicList), which is indexed by a SeiProcStgIdx (CandInputPicList[ SeiProcStgIdx ]), contains a list of pictures in output order from which the input pictures for the process implied by the FGC SEI message is selected.

[0383] 4. The method of any of solutions 1-3, wherein when SeiProcStgIdx is equal to 0, pictures in CandInputPicList

[0000] are decoded pictures, or wherein when the FGC SEI message is used during the invocation of a process for handling of the processing chain, the list CandInputPicList[ SeiProcStgIdx ] is provided by that process; and otherwise, the list CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to the list of cropped decoded output pictures in output order resulted from decoding the bitstream.

[0384] 5. The method of any of solutions 1-4, wherein the list CandInputPicList[ SeiProcStgIdx ] contains a list of pictures in output order from which the input pictures for the process implied by the FPA SEI message, RWP SEI message, or CTI SEI message is selected.

[0385] 6. The method of any of solutions 1-5, wherein when SeiProcStgIdx is equal to 0, pictures in CandInputPicList

[0000] are cropped decoded output pictures, or wherein when the FPA SEI message, RWP SEI message, or CTI SEI message is used during the invocation of a process for handling of the processing chain, the list CandInputPicList[ SeiProcStgIdx ] is provided by that process; otherwise, the list CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to the list of cropped decoded output pictures in output order resulted from decoding the bitstream.

[0386] 7. The method of any of solutions 1-6, wherein the FGC SEI message applies to a current decoded picture (currDecPic), and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currDecPic or is an associated inserted picture of currDecPic, the following applies: when SeiProcStgIdx is equal to 0, the following applies: picture width in luma samples (PicWidthInLumaSamples) and picture height in lume samples (PicHeightInLumaSamples) are set equal to picture parameter set (PPS) picture width in luma samples (pps_pic_width_in_luma_samples) and PPS picture height in luma samples (pps_pic_height_in_luma_samples), respectively; chroma format indentification code (ChromaFormatIdc) is set equal to sequence parameter set (SPS) chroma format identification code (sps_chroma_format_idc); and luma bit depth (BitDepthY) and chroma bit depth (BitDepthC) are both set equal to bit depth (BitDepth).

[0387] 8. The method of any of solutions 1-7, wherein the FGC SEI message applies to a currDecPic, and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currDecPic or is an associated inserted picture of currDecPic, the following applies: when SeiProcStgIdx is greater than 0, the following applies: PicWidthInLumaSamples and PicHeightInLumaSamples are set equal to the picture width and picture height of current picture (currPic), respectively; ChromaFormatIdc is set equal to the picture chroma format indicator of currPic; and BitDepthY and BitDepthC are set equal to the luma bit depth and chroma bit depth, respectively, of currPic.

[0388] 9. The method of any of solutions 1-8, wherein the RWP SEI message or the CTI SEI message applies to a current cropped decoded output (CDO) pictrure (currCdoPic), and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currCdoPic or is an associated inserted picture of currCdoPic the following applies: when SeiProcStgIdx is equal to 0 ChromaFormatIdc is set equal to sps_chroma_format_idc.

[0389] 10. The method of any of solutions 1-9, wherein the RWP SEI message or the CTI SEI message applies a currCdoPic, and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currCdoPic or is an associated inserted picture of currCdoPic the following applies: when SeiProcStgIdx is greater than 0 ChromaFormatIdc is set equal to the picture chroma format indicator of currPic.

[0390] 11. The method of any of solutions 1-10, wherein the conversion includes encoding the visual media data into the bitstream.

[0391] 12. The method of any of solutions 1-10, wherein the conversion includes decoding the visual media data from the bitstream.

[0392] 13. An apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of solutions 1-12.

[0393] 14. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non- transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of solutions 1-12.

[0394] 15. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a chosen processing chain; and generating a bitstream based on the determining.

[0395] 16. A method for storing bitstream of a video comprising: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a chosen processing chain; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

[0396] 17. A method, apparatus, or system described in the present document.

[0397] The following solutions show further examples of techniques discussed herein.

[0398] 1. A method for processing media data comprising: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain; and performing a conversion between a visual media data and a bitstream based on the processing chain.

[0399] 2. The method of solution 1, wherein when the FGC, FPA, RWP, or CTI SEI message is used during an invocation of a process for handling of the processing chain, a value of SeiProcStgIdx is provided by the process, and otherwise, the value of SeiProcStgIdx is inferred to be equal to 0.

[0400] 3. The method of any of solutions 1-2, wherein a candidate input picture list (CandInputPicList), which is indexed by SeiProcStgIdx (CandInputPicList[ SeiProcStgIdx ]), contains a list of pictures in output order from which input pictures for a process implied by the FGC SEI message is selected.

[0401] 4. The method of any of solutions 1-3, wherein when SeiProcStgIdx is equal to 0, pictures in CandInputPicList

[0000] are decoded pictures.

[0402] 5. The method of any of solutions 1-4, wherein when the FGC SEI message is used during invocation of a process for handling of the processing chain, CandInputPicList[ SeiProcStgIdx ] is provided by the process, and otherwise, CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to a list of cropped decoded output pictures in output order resulting from decoding the bitstream.

[0403] 6. The method of any of solutions 1-5, wherein CandInputPicList[ SeiProcStgIdx ] contains a list of pictures in output order from which input pictures for aprocess implied by the FPA SEI message, RWP SEI message, or CTI SEI message is selected.

[0404] 7. The method of any of solutions 1-6, wherein when SeiProcStgIdx is equal to 0, pictures in CandInputPicList

[0000] are cropped decoded output pictures.

[0405] 8. The method of any of solutions 1-7, wherein when the FPA SEI message, RWP SEI message, or CTI SEI message is used during invocation of a process for handling of the processing chain, CandInputPicList[ SeiProcStgIdx ] is provided by the process, and otherwise, CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to a list of cropped decoded output pictures in output order resulting from decoding the bitstream.

[0406] 9. The method of any of solutions 1-8, wherein the FGC SEI message persists for a current decoded picture (currDecPic), and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currDecPic or is an associated inserted picture of currDecPic, the following applies: when SeiProcStgIdx is equal to 0, the following applies: picture width in luma samples (PicWidthInLumaSamples) and picture height in lume samples (PicHeightInLumaSamples) are set equal to picture parameter set (PPS) picture width in luma samples (pps_pic_width_in_luma_samples) and PPS picture height in luma samples (pps_pic_height_in_luma_samples), respectively; chroma format indentification code (ChromaFormatIdc) is set equal to sequence parameter set (SPS) chroma format identification code (sps_chroma_format_idc); and luma bit depth (BitDepthY) and chroma bit depth (BitDepthC) are both set equal to bit depth (BitDepth).

[0407] 10. The method of any of solutions 1-9, wherein the FGC SEI message persists for a currDecPic, and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currDecPic or is an associated inserted picture of currDecPic, the following applies: when SeiProcStgIdx is greater than 0, the following applies: PicWidthInLumaSamples and PicHeightInLumaSamples are set equal to the picture width and picture height of current picture (currPic), respectively; ChromaFormatIdc is set equal to a picture chroma format indicator of currPic; and BitDepthY and BitDepthC are set equal to a luma bit depth and a chroma bit depth, respectively, of currPic.

[0408] 11. The method of any of solutions 1-10, wherein the RWP SEI message or the CTI SEI message persists for a current cropped decoded output (CDO) pictrure (currCdoPic), and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currCdoPic or is an associated inserted picture of currCdoPic the following applies: when SeiProcStgIdx is equal to 0, ChromaFormatIdc is set equal to sps_chroma_format_idc.

[0409] 12. The method of any of solutions 1-11, wherein the RWP SEI message or the CTI SEI message persists for currCdoPic, and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture ofcurrCdoPic or is an associated inserted picture of currCdoPic the following applies: when SeiProcStgIdx is greater than 0, ChromaFormatIdc is set equal to a picture chroma format indicator of currPic.

[0410] 13. The method of any of solutions 1-12, wherein the conversion includes encoding the visual media data into the bitstream.

[0411] 14. The method of any of solutions 1-12, wherein the conversion includes decoding the visual media data from the bitstream.

[0412] 15. An apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of solutions 1-14.

[0413] 16. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non- transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of solutions 1-14.

[0414] 17. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain; and generating a bitstream based on the determining.

[0415] 18. A method for storing bitstream of a video comprising: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

[0416]

[0417] In the solutions described herein, an encoder may conform to the format rule by producing a coded representation according to the format rule. In the solutions described herein, a decoder may use the format rule to parse syntax elements in the coded representation with the knowledge of presence and absence of syntax elements according to the format rule to produce decoded video.

[0418] In the present document, the term “video processing” may refer to video encoding, video decoding, video compression or video decompression. For example, video compression algorithms may be applied during conversion from pixel representation of a video to a corresponding bitstream representation or vice versa. The bitstream representation of a current video block may, for example, correspond to bits that are either co-located or spread in different places within the bitstream, as is defined by the syntax. For example, a macroblock may be encoded in terms of transformed and coded error residual values and also using bits in headers and other fields in the bitstream. Furthermore, during conversion, a decoder may parse a bitstream with the knowledge that some fields may be present,or absent, based on the determination, as is described in the above solutions. Similarly, an encoder may determine that certain syntax fields are or are not to be included and generate the coded representation accordingly by including or excluding the syntax fields from the coded representation.

[0419] The disclosed and other solutions, examples, embodiments, modules and the functional operations described in this document can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer readable medium for execution by, or to control the operation of, data processing apparatus. The computer readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine- readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus.

[0420] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0421] The processes and logic flows described in this document can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an field programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

[0422] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or opticaldisks. However, a computer need not have such devices. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and compact disc read-only memory (CD ROM) and Digital versatile disc-read only memory (DVD-ROM) disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0423] While this patent document contains many specifics, these should not be construed as limitations on the scope of any subject matter or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular techniques. Certain features that are described in this patent document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0424] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Moreover, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

[0425] Only a few implementations and examples are described and other implementations, enhancements and variations can be made based on what is described and illustrated in this patent document.

[0426] A first component is directly coupled to a second component when there are no intervening components, except for a line, a trace, or another medium between the first component and the second component. The first component is indirectly coupled to the second component when there are intervening components other than a line, a trace, or another medium between the first component and the second component. The term “coupled” and its variants include both directly coupled and indirectly coupled. The use of the term “about” means a range including ±10% of the subsequent number unless otherwise stated.

[0427] While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.

[0428] In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled maybe directly connected or may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.

Claims

CLAIMS What is claimed is:

1. A method for processing media data comprising: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain; and performing a conversion between a visual media data and a bitstream based on the processing chain.

2. The method of claim 1, wherein when the FGC, FPA, RWP, or CTI SEI message is used during an invocation of a process for handling of the processing chain, a value of SeiProcStgIdx is provided by the process, and otherwise, the value of SeiProcStgIdx is inferred to be equal to 0.

3. The method of any of claims 1-2, wherein a candidate input picture list (CandInputPicList), which is indexed by SeiProcStgIdx (CandInputPicList[ SeiProcStgIdx ]), contains a list of pictures in output order from which input pictures for a process implied by the FGC SEI message is selected.

4. The method of any of claims 1-3, wherein when SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ 0 ] are decoded pictures.

5. The method of any of claims 1-4, wherein when the FGC SEI message is used during invocation of a process for handling of the processing chain, CandInputPicList[ SeiProcStgIdx ] is provided by the process, and otherwise, CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to a list of cropped decoded output pictures in output order resulting from decoding the bitstream.

6. The method of any of claims 1-5, wherein CandInputPicList[ SeiProcStgIdx ] contains a list of pictures in output order from which input pictures for aprocess implied by the FPA SEI message, RWP SEI message, or CTI SEI message is selected.

7. The method of any of claims 1-6, wherein when SeiProcStgIdx is equal to 0, pictures in CandInputPicList[ 0 ] are cropped decoded output pictures.

8. The method of any of claims 1-7, wherein when the FPA SEI message, RWP SEI message, or CTI SEI message is used during invocation of a process for handling of the processing chain, CandInputPicList[ SeiProcStgIdx ] is provided by the process, and otherwise, CandInputPicList[ SeiProcStgIdx ] is inferred to be identical to a list of cropped decoded output pictures in output order resulting from decoding the bitstream.

9. The method of any of claims 1-8, wherein the FGC SEI message persists for a current decoded picture (currDecPic), and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currDecPic or is an associated inserted picture of currDecPic, the following applies: when SeiProcStgIdx is equal to 0, the following applies: picture width in luma samples (PicWidthInLumaSamples) and picture height in lume samples (PicHeightInLumaSamples) are set equal to picture parameter set (PPS) picture width in luma samples (pps_pic_width_in_luma_samples) and PPS picture height in luma samples (pps_pic_height_in_luma_samples), respectively; chroma format indentification code (ChromaFormatIdc) is set equal to sequence parameter set (SPS) chroma format identification code (sps_chroma_format_idc); and luma bit depth (BitDepthY) and chroma bit depth (BitDepthC) are both set equal to bit depth (BitDepth).

10. The method of any of claims 1-9, wherein the FGC SEI message persists for a currDecPic, and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currDecPic or is an associated inserted picture of currDecPic, the following applies: when SeiProcStgIdx is greater than 0, the following applies: PicWidthInLumaSamples and PicHeightInLumaSamples are set equal to the picture width and picture height of current picture (currPic), respectively; ChromaFormatIdc is set equal to a picture chroma format indicator of currPic; and BitDepthY and BitDepthC are set equal to a luma bit depth and a chroma bit depth, respectively, of currPic.

11. The method of any of claims 1-10, wherein the RWP SEI message or the CTI SEI message persists for a current cropped decoded output (CDO) pictrure (currCdoPic), and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currCdoPic or is an associated inserted picture of currCdoPic the following applies: when SeiProcStgIdx is equal to 0, ChromaFormatIdc is set equal to sps_chroma_format_idc.

12. The method of any of claims 1-11, wherein the RWP SEI message or the CTI SEI message persists for currCdoPic, and when currPic is a picture in CandInputPicList[ SeiProcStgIdx ] that is a corresponding picture of currCdoPic or is an associated inserted picture of currCdoPic the following applies: when SeiProcStgIdx is greater than 0, ChromaFormatIdc is set equal to a picture chroma format indicator of currPic.

13. The method of any of claims 1-12, wherein the conversion includes encoding the visual media data into the bitstream.

14. The method of any of claims 1-12, wherein the conversion includes decoding the visual media data from the bitstream.

15. An apparatus for processing video data comprising: a processor; and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to perform the method of any of claims 1-14.

16. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non- transitory computer readable medium such that when executed by a processor cause the video coding device to perform the method of any of claims 1-14.

17. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain; and generating a bitstream based on the determining.

18. A method for storing bitstream of a video comprising: determining that a variable supplemental enhancement information (SEI) processing stage index (SeiProcStgIdx) indicates a processing stage index associated with a film grain characteristics (FGC) SEI message, frame packing arrangement (FPA) SEI message, region-wise packing (RWP) SEI message, or colour transform information (CTI) SEI message within a processing chain; generating a bitstream based on the determining; and storing the bitstream in a non-transitory computer-readable recording medium.

Images