Extended dependency random access sample point samples in media files

Abstract

A mechanism for processing media data is disclosed. In one aspect, a method includes determining that a track identifier (ID) identifying a reference track of the media data is included in a track reference type box (TrackReferenceTypeBox) having a reference type (reference_type) equal to an associated external stream track ('aest'). The method also includes performing a conversion between the media data and a media data file based on the track identifier.

Description

[0001] Cross-reference to related applications

[0002] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 410,827, filed September 28, 2022, which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to the generation, storage, and use of digital audio and video media information in file formats. Background Technology

[0004] Digital video consumes the largest share of bandwidth on the internet and other digital communication networks. As the number of networked user devices capable of receiving and displaying video increases, the bandwidth demand for digital video is likely to continue to grow. Summary of the Invention

[0005] The first aspect relates to a method for processing media data, comprising: determining that a track identifier (ID) identifying a reference track of the media data is included in a track reference type box (TrackReferenceTypeBox) whose reference type (reference_type) is equal to the associated external stream track ('aest'); and performing a conversion between the media data and a media data file based on the track identifier.

[0006] Alternatively, in any of the foregoing aspects, another implementation of this aspect specifies that the track ID is the first entry in the TrackReferenceTypeBox where the reference_type is equal to 'aest'.

[0007] Alternatively, in any of the foregoing aspects, another implementation of this aspect specifies that when there exists a TrackReferenceTypeBox with reference_type equal to 'aest', the TrackReferenceTypeBox includes only the track identifier and does not include any track group identifier.

[0008] Alternatively, in any of the foregoing aspects, another implementation of this aspect specifies that when there exists a TrackReferenceTypeBox with reference_type equal to 'aest', the TrackReferenceTypeBox includes the track identifier in the first entry and includes a group track identifier in subsequent entries, if there is a group track identifier.

[0009] Alternatively, in any of the foregoing aspects, another implementation of this aspect specifies that the first entry in the TrackReferenceTypeBox where the reference_type is equal to 'aest' must be the track identifier.

[0010] Alternatively, in any of the foregoing aspects, another implementation of that aspect specifies that the media data file specifies whether random access from an Extended Dependent Random Access Point (EDRAP) sample requires a recent upstream access point (SAP) sample of type 1, 2, or 3.

[0011] Optionally, in any of the foregoing aspects, another implementation of this aspect specifies that: an EDRAP sample is a sample for which all subsequent samples can be correctly decoded in both the decoding order and the output order, provided that a required preceding SAP or EDRAP sample is available to decode the sample and subsequent samples, and wherein the required preceding SAP or EDRAP sample includes one or more of a sample set, which starts with the most recent preceding SAP sample (closestSapSample) of type 1, 2, or 3 in the decoding order, and includes all EDRAP samples between the closestSapSample and the sample in the decoding order.

[0012] Optionally, in any of the foregoing aspects, another implementation of this aspect specifies that: an EDRAP sample is a sample for which all subsequent samples can be correctly decoded in both the decoding order and the output order, provided that a required preceding SAP or EDRAP sample is available to decode the sample and subsequent samples, wherein the required preceding SAP or EDRAP sample includes zero or more of a sample set starting from the most recent preceding SAP sample (closestSapSample) of type 1, 2, or 3 in the decoding order, and includes all EDRAP samples between the closestSapSample and the sample in the decoding order.

[0013] Optionally, in any of the foregoing aspects, another implementation of this aspect specifies that when a media track has a reference_type of 'aest', for each EDRAP sample A in the media track, there must be one and only one sample B in the referenced track that has the same decoding time as sample A, and wherein sample B must include all media data of the most recent SAP sample of type 1, 2 or 3 that precedes sample A in decoding order, as well as all media data of the preceding SAP or EDRAP sample required by sample A.

[0014] Alternatively, in any of the foregoing aspects, another implementation of this aspect specifies that for any EDRAP sample sampleA mapped to the EDRAP sample group, the sample sequence (sampleSeq) is a sequence of samples that includes SAP or EDRAP samples identified by ref_sap_or_edrap_idx_delta[i], where i ranges from 0 to num_ref_sap_or_edrap_samples_minus1 in decoding order, including the endpoint, sampleA, and all samples in the track following sampleA in both decoding and output order.

[0015] Alternatively, in any of the foregoing aspects, another implementation of this aspect specifies that for each sample B in sampleSeq, all data required to process sampleB must be accessible in the referenced sample entry, in sampleB, or in any sample in sampleSeq that precedes sampleB in the decoding order.

[0016] Alternatively, in any of the foregoing aspects, another implementation of this aspect specifies that VisualEdrapEntry() is defined as follows:

[0017]

[0018] Alternatively, in any of the foregoing aspects, another implementation of this aspect specifies that: num_ref_sap_or_edrap_samples_minus1 plus 1 indicates the number of samples required in the preceding SAP or EDRAP samples, which are earlier than the EDRAP samples in the decoding order, and which are required to correctly decode the EDRAP samples and all samples following the EDRAP samples in the decoding and output order when decoding begins from the EDRAP samples.

[0019] Optionally, in any of the foregoing aspects, another implementation of this aspect specifies that: ref_sap_or_edrap_idx_delta[i] indicates the i-th required preceding SAP or EDRAP sample of the current EDRAP sample, wherein the list of SAP or EDRAP samples associated with SAP samples of type 1, 2, or 3 includes the SAP sample and all EDRAP samples after the SAP sample and before the next SAP sample, wherein the SAP_or_EDRAP sample index is an index to the list of SAP or EDRAP samples, wherein ref_sap_or The value of _edrap_idx_delta[i] is equal to the difference between the SAP_or_EDRAP sample index of the current EDRAP sample and the SAP_or_EDRAP sample index of the i-th required preceding SAP or EDRAP sample, wherein value 1 indicates that the i-th required SAP or EDRAP sample is the last SAP or EDRAP sample before the EDRAP sample in the decoding order, and wherein value 2 indicates that the i-th required SAP or EDRAP sample is the second-to-last EDRAP sample before the EDRAP sample in the decoding order.

[0020] Alternatively, in any of the foregoing aspects, another implementation of that aspect specifies that the conversion includes encoding the media data into a bitstream.

[0021] Alternatively, in any of the foregoing aspects, another implementation of that aspect specifies that the conversion includes decoding the media data from the bitstream.

[0022] The second aspect relates to an apparatus for processing media data, comprising: a processor; and a non-transitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform any of the disclosed methods.

[0023] The third aspect relates to a non-transitory computer-readable medium comprising a computer program product for use by a video codec apparatus, the computer program product comprising computer-executable instructions stored on the non-transitory computer-readable medium, causing the video codec apparatus to perform any of the disclosed methods when executed by a processor.

[0024] The fourth aspect relates to a non-transitory computer-readable recording medium that stores a bitstream of video generated by a method performed by a video processing apparatus, wherein the method includes any of the disclosed methods.

[0025] The fifth aspect relates to a method for storing a bitstream of video, which includes any of the disclosed methods.

[0026] The sixth aspect relates to a method, apparatus, or system described in this disclosure.

[0027] For clarity, any of the foregoing embodiments may be combined with one or more of the other foregoing embodiments to create new embodiments within the scope of this disclosure.

[0028] These and other features will become clearer from the following detailed description taken in conjunction with the accompanying drawings and claims. Attached Figure Description

[0029] To gain a more complete understanding of this disclosure, reference is now made to the following brief description in conjunction with the accompanying drawings and specific embodiments, wherein the same reference numerals denote the same parts.

[0030] Figure 1 This is a schematic diagram of an example mechanism for random access when using Intra-Frame Random Access Point (IRAP) image decoding bitstream.

[0031] Figure 2 This is a schematic diagram of an example mechanism for random access when using a DRAP-dependent image decoding bitstream.

[0032] Figure 3 This is a schematic diagram of an example mechanism for random access when using Extended Dependency Random Access Point (EDRAP) image decoding bitstream.

[0033] Figure 4 This is a schematic diagram of an example mechanism for supporting EDRAP-based random access by transmitting an external bit stream via signaling.

[0034] Figure 5 An example of EDRAP-based random access is shown.

[0035] Figure 6 This is a block diagram illustrating an example video processing system.

[0036] Figure 7 This is a block diagram of an example video processing apparatus.

[0037] Figure 8 This is a flowchart of an example method for video processing.

[0038] Figure 9 This is a block diagram illustrating an example video codec system.

[0039] Figure 10 This is a block diagram illustrating an example encoder.

[0040] Figure 11 This is a block diagram illustrating an example decoder.

[0041] Figure 12 This is a schematic diagram of an example encoder. Detailed Implementation

[0042] First, it should be understood that although exemplary implementations of one or more embodiments are provided below, the disclosed systems and / or methods can be implemented using any number of techniques, whether currently known or yet to be developed. This disclosure should not be limited in any way to the exemplary embodiments, drawings, and techniques shown below, including the exemplary designs and implementations shown and described herein, but modifications can be made within the full scope of the appended claims and their equivalents.

[0043] The chapter headings used in this disclosure are for ease of understanding and are not intended to limit the techniques and embodiments disclosed in each chapter to only that chapter. Furthermore, the use of H.266 terminology in some descriptions is for ease of understanding only and not to limit the scope of the disclosed techniques. Therefore, the techniques described in this disclosure are also applicable to other video codec protocols and designs. In this disclosure, regarding draft specifications based on the Universal Video Codec (VVC) specification or the International Organization for Standardization (ISO) Media File Format (ISOBMFF) file format specification, editable changes to the text are indicated by bold italics to indicate undoing text and bold text to indicate addition text.

[0044] 1. Preliminary Discussion

[0045] This disclosure relates to media file formats. Specifically, it relates to signaling notifications of Extended Dependency Random Access Point (EDRAP) samples in media files. These ideas can be applied individually or in various combinations to media files according to any media file format, such as ISOBMFF and file formats derived from ISOBMFF.

[0046] 2. Introduction to Video Encoding and Decoding

[0047] 2.1 Video codec standards

[0048] Video coding standards have evolved primarily through the development of standards by the International Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T) and the ISO / IEC. ITU-T produced H.261 and H.263, ISO / IEC produced Moving Picture Experts Group (MPEG-1) and MPEG-4 Vision, and the two organizations jointly produced the H.262 / MPEG-2 Video and H.264 / MPEG-4 Advanced Video Codec (AVC) and H.265 / High Efficiency Video Codec (HEVC) standards [1]. Since H.262, video coding standards have been based on a hybrid video coding structure, which utilizes temporal prediction plus transform coding.

[0049] Recently, the Multi-Functional Video Coding (VVC) standard (ITU-TH.266|ISO / IEC 23090-3)[2] and the associated Multi-Functional Supplemental Enhancement Information (VSEI) standard (ITU-TH.274|ISO / IEC 23002-7)[3] have been designed for the widest range of applications, including traditional uses (such as television broadcasting, video conferencing, or playback from storage media), as well as newer and more advanced use cases such as adaptive bitrate streaming, video region extraction, content composition and merging of video bitstreams from multiple codecs, multi-view video, scalable layered codecs, and viewport-adaptive 360° immersive media. The Basic Video Coding (EVC) standard (ISO / IEC 23094-1) is another video coding standard recently developed by MPEG.

[0050] 2.2 File Format Standards

[0051] Media streaming applications are based on Internet Protocol (IP), Transmission Control Protocol (TCP), and Hypertext Transfer Protocol (HTTP) transmission methods and rely on file formats such as ISO Basic Media File Format (ISOBMFF)[4]. One such streaming system is HTTP-based Dynamic Adaptive Streaming (DASH)[5]. For video formats using ISOBMFF and DASH, the video format-specific file format specification is also known as Network Abstraction Layer File Format (NALFF)[6], which includes file format specifications for all video codecs based on Network Abstraction Layer (NAL) units, such as AVC, HEVC, VVC, and their extensions, to encapsulate video content in ISOBMFF tracks and DASH representations and segments. Important information about the video bitstream, such as summaries, hierarchies, and levels, needs to be exposed as file format-level metadata and / or DASH Media Presentation Description (MPD) for content selection, such as selecting appropriate media segments for initialization at the start of a streaming session and for stream adaptation during a streaming session. Similarly, for image formats using ISOBMFF, there are file format specifications specific to the image format (e.g., AVC image file format and HEVC image file format in [7]).

[0052] 2.3 Random Access and its Support in HEVC and VVC

[0053] Random access refers to accessing and decoding a bitstream starting with an image that is not the first image in the bitstream according to the decoding order. To support tuning and channel switching in broadcast, multicast, and multi-party video conferencing, local playback and searching within the stream, and stream adaptation within the stream, the bitstream should include frequent random access points. These random access points can be intra-frame encoded images, but they can also be inter-frame encoded images, for example, in the case of progressive decoding and refresh.

[0054] HEVC includes signaling for Intra-Random Access Point (IRAP) pictures in the NAL unit header via NAL unit type. HEVC supports three types of IRAP pictures. These are Instant Decoder Refresh (IDR), Pure Random Access (CRA), and Broken Link In (BLA) pictures. IDR pictures restrict the inter-picture prediction structure so that they do not reference any picture before the current picture group (GOP). The reference picture in the current GOP can be called a closed GOP random access point. CRA pictures are less restricted and allow some pictures to reference pictures before the current GOP, all of which are discarded in the case of random access. CRA pictures can be called open GOP random access points. BLA pictures are usually derived from the concatenation of two bitstreams or a portion thereof at the CRA picture, for example, during stream switching. To enable the system to better utilize IRAP pictures, six different NAL units are defined to signal the properties of IRAP pictures. These properties can be used to better match the stream access point types defined in ISOBMFF[4], which are used for random access support in dynamic adaptive streams based on Hypertext Transfer Protocol (DASH)[5].

[0055] VVC supports three types of IRAP pictures, two types of IDR pictures (one type with an associated Random Access Decodeable Preamble (RADL) picture, and the other without an associated RADL picture), and one type of CRA picture. These pictures are used similarly to HEVC. The BLA picture type from HEVC is not included in VVC for two reasons. First, the basic functionality of a BLA picture can be achieved using a CRA picture with an end-of-sequence NAL unit, the presence of which indicates that a new codec video sequence (CVS) begins in the subsequent picture within a single-layer bitstream. Second, during the development of VVC, it was desirable to specify fewer NAL unit types than in HEVC, indicated by using five bits instead of six bits in the NAL unit type field in the NAL unit header.

[0056] Another difference between VVC and HEVC in terms of random access support is that VVC supports Gradual Decoding Refresh (GDR) in a more canonical manner. In GDR, decoding of the bitstream can begin with inter-frame codec pictures. At the start of access, the entire picture region cannot be correctly decoded. However, after several pictures, the entire picture region is correctly decoded. AVC and HEVC also support GDR by using Recovery Point Supplement Enhancement Information (SEI) messages to signal the GDR random access point and recovery point. In VVC, the NAL unit type is specified to indicate the GDR picture, and the recovery point is signaled in the picture header syntax structure. Codec Video Sequences (CVS) and bitstreams are allowed to begin with GDR pictures. This means that the entire bitstream is allowed to include only inter-frame codec pictures, excluding individual intra-frame codec pictures. The main benefit of specifying GDR support in this way is providing the standards-compliant behavior of GDR. GDR allows encoders to smooth the bitrate of the bitstream by distributing intra-frame codec stripes or blocks across multiple pictures, which is the opposite of intra-frame codec. This can significantly reduce end-to-end latency, which is considered even more important in many cases, as ultra-low latency applications such as wireless displays, online gaming, and drone-based applications become increasingly popular.

[0057] Another GDR-related feature in VVC is virtual boundary signaling. In the image between the GDR image and the corresponding recovery point, the boundary between the refreshed area (i.e., the correctly decoded area) and the unrefreshed area can be signaled as a virtual boundary. Loop filtering across the boundary is not applied during signaling. Therefore, some samples at or near the boundary will not experience decoding mismatches. This can be useful when the application determines which area is correctly decoded during GDR. IRAP images and GDR images can be collectively referred to as Random Access Point (RAP) images.

[0058] 2.4 Video Encoding, Decoding, Storage, and Streaming Based on Extended Dependency Random Access Point (EDRAP)

[0059] 2.4.1 Conceptual and Standard Support

[0060] This article describes the concepts of video encoding / decoding, storage, and streaming based on EDRAP.

[0061] like Figure 1 As shown, the application (e.g., an adaptive stream) determines the frequency of the Random Access Point (RAP), for example, a RAP period of 1 s or 2 s. In one example, the RAP is provided by the encoding and decoding of IRAP images. Note that the inter-frame prediction reference for non-critical images between RAP images is not shown, and the output order is from left to right. When randomly accessing from CRA4, the decoder receives and correctly decodes CRA4, CRA5, etc., as well as the associated inter-frame prediction images.

[0062] Figure 2 The DRAP method is illustrated, which improves encoding / decoding efficiency by allowing DRAP images (and subsequent images) to reference the preceding IRAP image for inter-frame prediction. Note that inter-frame prediction for non-critical images between RAP images is not shown, and the output order is from left to right. When randomly accessed from DRAP4, the decoder receives and correctly decodes IDR0, DRAP4, DRAP5, etc., as well as the associated inter-frame predicted images.

[0063] Figure 3 The EDRAP method is illustrated, which provides greater flexibility by allowing EDRAP images (and subsequent images) to reference some earlier RAP images (IRAP or EDRAP). Note that inter-frame predictions for non-critical images between RAP images are not shown and are presented in output order from left to right. When randomly accessed from EDRAP4, the decoder receives IDR0, EDRAP2, EDRAP4, EDRAP5, etc., along with the associated inter-frame prediction images and decodes them correctly.

[0064] Figure 4 An example of an EDRAP method using a main stream representation (MSR) fragment and an external stream representation (ESR) fragment is shown. Figure 5 An example of random access from EDRAP4 is shown. When randomly accessing or switching to a segment starting with EDRAP4, the decoder receives and correctly decodes segments including IDR0, EDRAP2, EDRAP4, EDRAP5, etc., as well as the associated inter-frame predicted images.

[0065] EDRAP-based video coding and decoding is supported by EDRAP Indicator Supplemental Enhancement Information (SEI) messages included in VSEI standard version 2 [3]; the storage portion is supported by EDRAP sample sets and associated external stream track references included in version [8] of the ISOBMFF standard; and the streaming portion is supported by Mainstream Representation (MSR) and External Stream Representation (ESR) descriptors included in the DASH standard amendment [9]. These standard supports are described below.

[0066] 2.4.2 EDRAP Instruction SEI Message

[0067] The syntax and semantics of the EDRAP instruction SEI message are as follows.

[0068]

[0069] The image associated with the Extended DRAP (EDRAP) Indicator SEI message is called the EDRAP image.

[0070] The presence of the EDRAP Indicator SEI message indicates that the constraints on picture order and picture references specified in this clause apply. These constraints enable the decoder to correctly decode EDRAP pictures and pictures in the same layer that follow the EDRAP picture in both decoding and output order, without decoding any other pictures in the same layer, except for the picture list referenceablePictures, which includes a list of IRAP or EDRAP pictures in the same CLVS and identified by the edrap_ref_rap_id[i] syntax element in decoding order.

[0071] The constraints indicated by the presence of the EDRAP SEI message must all apply, as described below: The EDRAP picture is a trailing picture. The EDRAP picture has a time sublayer identifier equal to 0. The EDRAP picture does not include any picture in the same layer in its active entry in the reference picture list, except for referenceablePictures. Any picture in the same layer as the EDRAP picture and following the EDRAP picture in both decoding and output order is not included in the active entry in its reference picture list any picture in the same layer and preceding the EDRAP picture in either decoding or output order, except for referenceablePictures. Any picture in the list of referenceablePictures does not include any picture in the same layer in its active entry in the reference picture list, and that picture is not an earlier picture in the list of referenceablePictures. Note – Therefore, even if the first picture in referenceablePictures is an EDRAP picture and not an IRAP picture, it will not include any picture from the same layer in its active entry in the reference picture list.

[0072] The increment of 1 in edrap_rap_id_minus1 specifies the RAP image identifier for the EDRAP image, which is represented as RapPicId.

[0073] Each IRAP or EDRAP image is associated with a RapPicId value. The RapPicId value of an IRAP image is inferred to be equal to 0. The RapPicId values ​​of any two EDRAP images associated with the same IRAP image must be different.

[0074] The `edrap_leading_pictures_decodable_flag` setting of 1 specifies that the following two constraints apply: Any image on the same layer as the EDRAP image and decoded after it must, in output order, be after any image on the same layer and decoded before it. Any image on the same layer as the EDRAP image, decoded after it, and output before it, must not, in its active entry of the reference picture list, include any image on the same layer and decoded before it, except for `referenceablePictures`.

[0075] When edrap_leading_pictures_decodable_flag equals 0, these constraints are not applied.

[0076] In bitstreams conforming to this version of the specification, edrap_reserved_zero_12bits must be equal to 0. Other values ​​for edrap_reserved_zero_12bits are reserved for use by ITU-T|ISO / IEC. Decoders should ignore the value of edrap_reserved_zero_12bits.

[0077] The increment of 1 in edrap_num_ref_rap_pics_minus1 indicates the number of IRAP or EDRAP pictures that are in the same CLVS as the EDRAP pictures and can be included in the list of reference pictures for the EDRAP pictures in the active entry.

[0078] `edrap_ref_rap_id[i]` indicates the RapPicId of the i-th RAP image in the active entry of the list of reference images that can be included in the EDRAP image. The i-th RAP image must be one of the following: an IRAP image associated with the current EDRAP image, or an EDRAP image associated with an IRAP image that is the same as the current EDRAP image.

[0079] 2.4.3 EDRAP Sample Sets and Associated External Flow Track References

[0080] The specifications for the EDRAP sample group and associated external flow trajectory reference in [8] are as follows.

[0081] 3.1 Definition ...

[0083] EDRAP Example

[0084] A sample is one for which all subsequent samples can be correctly decoded, both in decoding order and output order, provided that the most recent preceding SAP sample of type 1, 2, or 3 and zero or more preceding EDRAP samples are available when decoding the sample and subsequent samples. (Entry Note 1.) The most recent preceding SAP sample of type 1, 2, or 3 as described above, along with zero or more preceding EDRAP samples, are referred to as the desired preceding SAP sample and EDRAP sample for the EDRAP sample. ...

[0086] 3.2 Abbreviations ...

[0088] EDRAP Extended Dependency on Random Access Point ...

[0090] 8.3.3.4.1 Associated External Flow Track Reference

[0091] Media tracks can include track references of type 'aest' (meaning "associated external stream track").

[0092] When a media track has a track reference of type 'aest', the following applies:

[0093] - The media track should have at least one sample that is identified as an EDRAP sample by being associated with the EDRAP sample group.

[0094] - The reference orbit must comply with the following constraints:

[0095] Each sample in the reference orbit must be identified as a synchronization sample.

[0096] ○ The reference track must have header flags track_in_movie and track_in_preview, both of which are equal to 0.

[0097] The reference orbit must use the following constraint scheme:

[0098] ■The scheme_type field in the SchemeTypeBox of the RestrictedSchemeInfoBox is equal to 'spkt', and the mode field in the SamplePackingInformationBox is equal to 1.

[0099] ■ The 0th bit of the flags field of SchemeTypeBox is equal to 0, so that the value of (flags&0x000001) is equal to 0.

[0100] - For each EDRAP sample A in the media track, there must be one and only one sample B in the reference track that has the same decoding time as sample A, and sample B must include all the media data required for sample A in the preceding SAP and EDRAP samples.

[0101] 8.15.6 Sample Grouping Track

[0102] 8.15.6.1 Introduction

[0103] When using a restricted scheme with SchemeType 'spkt' for an orbit, the sample associated with a sample entry can be a group of samples; for example, the group of samples can include more than one sample from the original orbit. Such a current orbit is called a sample grouped orbit.

[0104] 8.15.6.2 Sample Grouping Information Box

[0105] 8.15.6.2.1 Definition

[0106] Box type: 'spki'

[0107] Container: SchemeInformationBox

[0108] Forced: Yes (when SchemeType is 'spkt')

[0109] Quantity: 1

[0110] 8.15.6.2.2 Syntax

[0111] aligned(8)class SamplePackingInformationBox extends FullBox('spki',version=0,flags=0)

[0112] {

[0113] unsigned int(8)mode;

[0114] }

[0115] 8.15.6.2.1 Semantics

[0116] A mode value of 0 indicates that all samples from the original stream have been preserved. A value of 1 indicates that only some samples have been preserved. All other values ​​are reserved for future use.

[0117] 10.11 Extended DRAP (EDRAP) Sample Set

[0118] 10.11.1 Definition

[0119] The EDRAP sample set records some or all of the EDRAP samples in the track. This sample set is similar to the DRAP sample set; however, this sample set is capable of signaling additional samples, which can also be used for random access with more flexible dependencies.

[0120] Note 1: Similar to DRAP samples, EDRAP samples can only be used in conjunction with SAP samples of types 1, 2 and 3.

[0121] Note 2: DRAP samples are always EDRAP samples.

[0122] The following applies to any EDRAP sample sampleA mapped to the EDRAP sample group:

[0123] - Let sampleSeq be a sequence of samples arranged in the following order of bullet points:

[0124] ○ The most recent SAP sample of type 1, 2 or 3.

[0125] ○ An EDRAP sample identified by ref_edrap_idx_delta[i], where i ranges from 0 to num_ref_edrap_sample–1, inclusive, in the decoding order.

[0126] ○sampleA, and

[0127] ○ All samples in the track following sampleA, in both the decoding and output order.

[0128] - For each sample B in sampleSeq, all the data required to process sampleB must be accessible in the referenced sample entry, in sampleB itself, or in any sample in sampleSeq that precedes sampleB in the decoding order.

[0129] Note 3: For some video codecs, all the data required to process sample B includes the set of parameters needed to decode sample B.

[0130] 10.11.2 Syntax

[0131] class VisualEdrapEntry()extends VisualSampleGroupEntry('edrp'){

[0132] unsigned int(3)edrap_type;

[0133] unsigned int(3)num_ref_edrap_samples;

[0134] unsigned int(2)reserved=0;

[0135] for(i=0; i <num_ref_edrap_samples;i++)

[0136] unsigned int(16)ref_edrap_idx_delta[i];

[0137] }

[0138] 10.11.3 Semantics

[0139] `edrap_type` is a non-negative integer. When `edrap_type` is in the range of 1 to 3, `edrap_type` indicates the SAP_type that the EDRAP sample must correspond to (as specified in Annex I), provided that it does not depend on the most recent preceding SAP or other EDRAP sample. Other values ​​of `edrap_type` are reserved.

[0140] Note 1: An EDRAP sample and all subsequent samples in the same track may depend on the most recent preceding SAP and / or some preceding EDRAP samples, but not on any other sample preceding the EDRAP sample. Therefore, if the encoder chooses to encode an EDRAP sample such that it does not depend on the most recent preceding SAP or any preceding EDRAP sample, then the EDRAP sample becomes the SAP.

[0141] num_ref_edrap_sample indicates the number of other EDRAP samples that are decoded earlier than the EDRAP sample and are required when decoding starts from the EDRAP sample to correctly decode the EDRAP sample and all samples that follow the EDRAP sample in both decoding and output order.

[0142] Note 2: EDRAP samples are also DRAP samples, and their num_ref_edrap_sample is equal to 0.

[0143] The value of `reserved` must be 0. The semantics of this sub-clause apply only to sample group description entries where `reserved` equals 0. When `reserved` is greater than 0, the parser should ignore the sample group description entries.

[0144] `ref_edrap_idx_delta[i]` indicates the i-th required preceding EDRAP sample of the current EDRAP sample. Let the list of EDRAP samples associated with SAP samples of type 1, 2, or 3 be all EDRAP samples that follow the SAP sample and precede the next SAP sample, if they exist. The EDRAP sample index is defined as the index of this EDRAP sample list. The value of `ref_edrap_idx_delta[i]` is equal to the difference between the EDRAP sample index of the current EDRAP sample and the EDRAP sample index of the i-th required preceding EDRAP sample. A value of 1 indicates that the i-th EDRAP sample is the last EDRAP sample preceding it in decoding order, a value of 2 indicates that the i-th EDRAP sample is the second-to-last EDRAP sample preceding it in decoding order, and so on.

[0145] 3. The technical problem solved by the disclosed technical solution

[0146] An example design for the storage portion of media encoding / decoding, storage, and streaming based on EDRAP is related to the following issues.

[0147] First, as with any orbital reference, an 'aest' orbital reference can reference multiple orbits or groups of orbits unless otherwise permitted. Therefore, the term "referenced orbit" is ambiguous.

[0148] Secondly, it is assumed that random access from an EDRAP sample always requires the most recent preceding SAP sample of type 1, 2, or 3. However, this assumption is inconsistent with the EDRAP design in the VSEI specification, where random access from an EDRAP image may or may not require the preceding IRAP image in the decoding order.

[0149] 4. List of solutions and implementation examples

[0150] To address the aforementioned issues, methods summarized below are disclosed. These examples should be considered as illustrations of general concepts, rather than being interpreted narrowly. Furthermore, these examples can be applied individually or in combination in any way.

[0151] Example 1

[0152] To address the first problem, in one example, one of the following is specified, and the referenced track is the track whose track ID is the first entry in the TrackReferenceTypeBox with reference_type equal to 'aest'.

[0153] When a TrackReferenceTypeBox with reference_type equal to 'aest' exists, the TrackReferenceTypeBox must contain only track identifiers and must not contain any track group identifiers.

[0154] When a TrackReferenceTypeBox with reference_type equal to 'aest' exists, the TrackReferenceTypeBox must include the track identifier in the first entry, and the other entries must include the track group identifier, if any.

[0155] When a TrackReferenceTypeBox with reference_type equal to 'aest' exists, the first entry in the TrackReferenceTypeBox must be a track identifier.

[0156] Example 2

[0157] To address the second issue, in one example, it is specified that random access from an EDRAP sample may or may not require the most recent preceding SAP sample of type 1, 2, or 3. One or more of the following aspects are specified.

[0158] In one example, the term EDRAP sample is defined as follows: An EDRAP sample is a sample for which all subsequent samples can be correctly decoded in both decoding and output order, provided that a required preceding SAP or EDRAP sample is available to decode the sample and subsequent samples, wherein the required preceding SAP or EDRAP sample consists of one or more samples in a sample set that starts with the most recent preceding SAP sample (closestSapSample) of type 1, 2, or 3 in decoding order, and includes all EDRAP samples between the closestSapSample and the sample in decoding order.

[0159] In one example, the term EDRAP sample is defined as follows: An EDRAP sample is a sample for which all subsequent samples can be correctly decoded in both decoding and output order, provided that the required preceding SAP or EDRAP sample is available to decode the sample and subsequent samples, wherein the required preceding SAP or EDRAP sample consists of zero or more samples in a sample set that starts with the most recent preceding SAP sample (closestSapSample) of type 1, 2 or 3 in decoding order, and includes all EDRAP samples between the closestSapSample and the sample in decoding order.

[0160] In one example, when a media track has a track reference of type 'aest', for each EDRAP sample A in the media track, the referenced track must have one and only one sample B with the same decoding time as sample A, and sample B must include all the media data of sample A in the preceding SAP or EDRAP samples.

[0161] In one example, for any EDRAP sample sampleA mapped to the EDRAP sample group, the following applies:

[0162] – Let sampleSeq be the sequence of samples arranged in the following order of bullet points:

[0163] ○ The SAP or EDRAP sample identified by ref_sap_or_edrap_idx_delta[i], where i ranges from 0 to num_ref_sap_or_edrap_samples_minus1, inclusive, in the decoding order.

[0164] ○sampleA, and

[0165] ○ All samples in track A following sampleA, in the order of decoding and output.

[0166] – For each sample B in sampleSeq, all the data required to process sampleB must be accessible in the referenced sample entry, in sampleB itself, or in any sample in sampleSeq that precedes sampleB in the decoding order.

[0167] In one example, the syntax for VisualEdrapEntry() is as follows:

[0168]

[0169] In one example, the semantics of num_ref_sap_or_edrap_samples_minus1 are defined as follows.

[0170] The increment of 1 in num_ref_sap_or_edrap_samples_minus1 indicates the number of samples required in the preceding SAP or EDRAP samples that are earlier than the EDRAP samples in the decoding order and are needed when decoding starts from the EDRAP samples to be able to correctly decode the EDRAP samples and all samples that follow the EDRAP samples in the decoding and output order.

[0171] In one example, the semantics of ref_sap_or_edrap_idx_delta[i] are defined as follows:

[0172] `ref_sap_or_edrap_idx_delta[i]` indicates the i-th required preceding SAP or EDRAP sample for the current EDRAP sample. Let the list of EDRAP samples associated with SAP or EDRAP samples of type 1, 2, or 3 be the SAP sample and all EDRAP samples following the SAP sample and preceding the next SAP sample, if they exist. The SAP_or_EDRAP sample index is defined as the index of this SAP or EDRAP sample list. The value of `ref_sap_or_edrap_idx_delta[i]` is equal to the difference between the SAP_or_EDRAP sample index of the current EDRAP sample and the SAP_or_EDRAP sample index of the i-th required preceding SAP or EDRAP sample. Value 1 indicates that the i-th required SAP or EDRAP sample is the last SAP or EDRAP sample preceding the EDRAP sample in the decoding order, and value 2 indicates that the i-th required SAP or EDRAP sample is the second-to-last EDRAP sample preceding the EDRAP sample in the decoding order, and so on.

[0173] 5. Examples

[0174] The following are some example embodiments of some of the disclosed content items summarized in Section 4 above. Most of the relevant parts that have been added or modified are shown in bold, and some deleted parts are shown in italic bold. There may also be some other changes that are editorial in nature and therefore are not highlighted.

[0175] 5.1 First Embodiment

[0176] This embodiment is for projects 1 and 2.

[0177] 3.1 Definition ...

[0179] EDRAP Example

[0180] For a sample, all subsequent samples of that sample can be correctly decoded according to both the decoding order and the output order, provided that the most recent preceding SAP sample of type 1, 2, or 3 and zero or more preceding EDRAP samples are available when decoding the sample and subsequent samples. The required preceding SAP or EDRAP sample can be used to decode the sample and subsequent samples, wherein the required preceding SAP or EDRAP sample consists of one or more samples from a set of samples starting from the most recent preceding SAP sample (closestSapSample) of type 1, 2, or 3 in the decoding order, and includes all EDRAP samples between the closestSapSample and the sample in the decoding order.

[0181] Entry Note 1: The most recent preceding SAP sample of type 1, 2 or 3 as described above, as well as zero or more preceding EDRAP samples, are referred to as the preceding SAP sample and EDRAP sample required for the EDRAP sample. ...

[0183] 8.3.3.4.1 Associated External Flow Track Reference

[0184] Media tracks can include track references of type 'aest' (meaning "associated external stream track"). When a TrackReferenceTypeBox with reference_type equal to 'aest' exists, the TrackReferenceTypeBox must include only the track identifier and must not include any track group identifier.

[0185] When a media track has a track reference of type 'aest', the following applies:

[0186] - The media track should have at least one sample that is identified as an EDRAP sample by being associated with the EDRAP sample group.

[0187] - The reference orbit must comply with the following constraints:

[0188] Each sample in the reference orbit should be identified as a synchronization sample.

[0189] ○ The reference track must have header flags track_in_movie and track_in_preview, both of which are equal to 0.

[0190] The reference orbit should use the following constraint scheme:

[0191] ■The scheme_type field in the SchemeTypeBox of the RestrictedSchemeInfoBox is equal to 'spkt', and the mode field in the SamplePackingInformationBox is equal to 1.

[0192] ■ The 0th bit of the flags field of SchemeTypeBox is equal to 0, so that the value of (flags&0x000001) is equal to 0.

[0193] - For each EDRAP sample sampleA in the media track, there must be one and only one sample sampleB in the reference track that has the same decoding time as sampleA, and sampleB must include all the media data required for sampleA in the preceding SAP and / or EDRAP samples.

[0194] 10.11 EDRAP Sample Group

[0195] 10.11.1 Definition

[0196] The EDRAP sample set records some or all of the EDRAP samples in the track. This sample set is similar to the DRAP sample set; however, this sample set is capable of signaling additional samples, which can also be used for random access with more flexible dependencies.

[0197] Note 1: Similar to DRAP samples, EDRAP samples can only be used in conjunction with SAP samples of types 1, 2, and 3.

[0198] Note 1: DRAP samples are always EDRAP samples.

[0199] The following applies to any EDRAP sample sampleA that is mapped to the EDRAP sample group:

[0200] - Let sampleSeq be a sequence of samples arranged in the following order of bullet points:

[0201] ○ The most recent SAP sample of type 1, 2 or 3.

[0202] ○ The SAP or EDRAP sample identified by ref_sap_or_edrap_idx_delta[i], where i ranges from 0 to num_ref_edrap_samples–1num_ref_sap_or_edrap_samples_minus1 in the decoding order, inclusive.

[0203] ○sampleA, and

[0204] ○ All samples in track A following sampleA, in the order of decoding and output.

[0205] - For each sample B in sampleSeq, all the data required to process sampleB must be accessible in the referenced sample entry, in sampleB itself, or in any sample in sampleSeq that precedes sampleB in the decoding order.

[0206] Note 2: For some video codecs, all the data required to process sample B includes the set of parameters needed to decode sample B.

[0207] 10.11.2 Syntax

[0208]

[0209] 10.11.3 Semantics

[0210] `edrap_type` is a non-negative integer. When `edrap_type` is in the range of 1 to 3, `edrap_type` indicates the SAP_type that the EDRAP sample should correspond to (as specified in Annex I), provided that it does not depend on the most recent preceding SAP or other EDRAP sample. Other values ​​of `edrap_type` are reserved.

[0211] Note 1: An EDRAP sample and all subsequent samples in the same track may depend on the most recent preceding SAP and / or some preceding EDRAP samples, but not on any other sample preceding the EDRAP sample. Therefore, if the encoder chooses to encode an EDRAP sample such that it does not depend on the most recent preceding SAP or any preceding EDRAP sample, then the EDRAP sample will become the SAP.

[0212] num_ref_edrap_sample indicates the number of other EDRAP samples that are decoded earlier than the EDRAP sample and are required when decoding starts from the EDRAP sample to correctly decode the EDRAP sample and all samples that follow the EDRAP sample in both decoding and output order.

[0213] Note 2: EDRAP samples are also DRAP samples, and their num_ref_edrap_sample is equal to 0.

[0214] If it is in the preceding SAP or any preceding EDRAP, then the EDRAP sample becomes SAP.

[0215] The increment of 1 in num_ref_sap_or_edrap_samples_minus1 indicates the number of samples required in the preceding SAP or EDRAP samples that are earlier than the EDRAP samples in the decoding order. This sample is required when decoding starts from the EDRAP samples to ensure that the EDRAP samples, as well as all samples that are after the EDRAP samples in the decoding and output order, can be decoded correctly.

[0216] Note 2: For EDRAP samples that are also DRAP samples, the value of num_ref_sap_or)edrap_samples_minus1 is equal to 0.

[0217] The value of `reserved` must be 0. The semantics of this sub-clause apply only to sample group description entries where `reserved` equals 0. When `reserved` is greater than 0, the parser should ignore the sample group description entries.

[0218] `ref_edrap_idx_delta[i]` indicates the i-th required preceding EDRAP sample of the current EDRAP sample. Let the list of EDRAP samples associated with SAP samples of type 1, 2, or 3 be all EDRAP samples that follow the SAP sample and precede the next SAP sample, if they exist. The EDRAP sample index is defined as the index of this EDRAP sample list. The value of `ref_edrap_idx_delta[i]` is equal to the difference between the EDRAP sample index of the current EDRAP sample and the EDRAP sample index of the i-th required preceding EDRAP sample. A value of 1 indicates that the i-th EDRAP sample is the last EDRAP sample preceding it in decoding order, a value of 2 indicates that the i-th EDRAP sample is the second-to-last EDRAP sample preceding it in decoding order, and so on.

[0219] `ref_sap_or_edrap_idx_delta[i]` indicates the i-th required preceding SAP or EDRAP sample for the current EDRAP sample. Let the list of EDRAP samples associated with SAP or EDRAP samples of type 1, 2, or 3 be the SAP sample and all EDRAP samples following the SAP sample and preceding the next SAP sample, if they exist. The SAP_or_EDRAP sample index is defined as the index of this SAP or EDRAP sample list. The value of `ref_sap_or_edrap_idx_delta[i]` is equal to the difference between the SAP_or_EDRAP sample index of the current EDRAP sample and the SAP_or_EDRAP sample index of the i-th required preceding SAP or EDRAP sample. Value 1 indicates that the i-th required SAP or EDRAP sample is the last SAP or EDRAP sample preceding the EDRAP sample in the decoding order, and value 2 indicates that the i-th required SAP or EDRAP sample is the second-to-last EDRAP sample preceding the EDRAP sample in the decoding order, and so on.

[0220] 6. References

[0221] [1]ITU-T and ISO / IEC, "High efficiency video coding", Rec.ITU-T H.265|ISO / IEC 23008-2 (in force edition).

[0222] [2]Rec.ITU-T H.266|ISO / IEC 23090-3, "Versatile Video Coding".

[0223] [3]Rec.ITU-T Rec.H.274|ISO / IEC 23002-7, "Versatile SupplementalEnhancement Information Messages for Coded Video Bitstreams".

[0224] [4]ISO / IEC 14496-12: "Information technology—Coding of audio-visualobjects—Part 12:ISO base media file format".

[0225] [5]ISO / IEC 23009-1:"Information technology—Dynamic adaptivestreaming over HTTP(DASH)—Part 1:Media presentation description and segmentformats".

[0226] [6]ISO / IEC 14496-15:"Information technology—Coding of audio-visualobjects—Part 15:Carriage of network abstraction layer(NAL)unit structuredvideo in the ISO base media file format".

[0227] [7]ISO / IEC 23008-12:"Information technology—High efficiency codingand media delivery in heterogeneous environments—Part 12:Image File Format".

[0228] [8]ISO / IEC JTC 1 / SC 29 / WG 03output document N0651,"Text of ISO / IECDIS14496-12 8th edition ISO Base Media File Format",Sept.2022.

[0229] ISO / IEC JTC 1 / SC 29 / WG 03output document N0630,"WD of ISO / IEC 23009-15th edition AMD 2EDRAP streaming and other extensions",Jul.2022.

[0230] Figure 6This is a block diagram illustrating an exemplary video processing system 4000 in which various technologies disclosed herein may be implemented. Various implementations may include some or all of the components of system 4000. System 4000 may include an input 4002 for receiving video content. The video content may be received in a raw or uncompressed format (e.g., 8-bit or 10-bit multi-component pixel values), or may be received in a compressed or encoded format. Input 4002 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interfaces include wired interfaces such as Ethernet, Passive Optical Networking (PON), etc., and wireless interfaces such as Wi-Fi or cellular interfaces.

[0231] System 4000 may include an encoding / decoding component 4004, which may implement the various encoding / decoding or coding methods described in this disclosure. Encoding / decoding component 4004 may reduce the average bit rate of the video from input 4002 to output to produce an encoded / decoded representation of the video. Therefore, encoding / decoding techniques are sometimes referred to as video compression or video transcoding techniques. The output of encoding / decoding component 4004 may be stored or transmitted via a connected communication, as represented by component 4006. The stored or transmitted bitstream (or encoded / decoded) representation of the video received at input 4002 may be used by component 4008 to generate pixel values ​​or displayable video, which is then sent to display interface 4010. The process of generating user-visible video from the bitstream representation is sometimes referred to as video decompression. Furthermore, although some video processing operations are referred to as “encoding / decoding” operations or tools, it should be understood that encoding / decoding tools or operations are used in the encoder, and the decoder will execute the corresponding decoding tool or operation that inverses the encoding / decoding result.

[0232] Examples of peripheral bus interfaces or display interfaces may include Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), or DisplayPort. Examples of storage interfaces include Serial Advanced Technology Attachment (SATA), Peripheral Component Interconnect (PCI), Integrated Drive Electronic Devices (IDE), etc. The technologies described in this disclosure can be embodied in a variety of electronic devices, such as mobile phones, laptops, smartphones, or other devices capable of performing digital data processing and / or video display.

[0233] Figure 7This is a block diagram of an example video processing apparatus 4100. Apparatus 4100 can be used to implement one or more methods described herein. Apparatus 4100 can be embodied in a smartphone, tablet computer, computer, Internet of Things (IoT) receiver, etc. Apparatus 4100 may include one or more processors 4102, one or more memories 4104, and video processing circuitry 4106. Processor 4102 can be configured to implement one or more methods described herein. Memory (multiple memories) 4104 can be used to store data and code for implementing the methods and techniques described herein. Video processing circuitry 4106 can be used to implement some of the techniques described herein in hardware circuitry. In some embodiments, video processing circuitry 4106 may be at least partially included in processor 4102 (e.g., a graphics coprocessor).

[0234] Figure 8 This is a flowchart of an example method 4200 for video processing. At step 4202, method 4200 determines a track, including a track identifier. The track identifier is the first entry in the TrackReferenceTypeBox where reference_type equals 'aest'. At step 4204, a conversion between media data and a media data file is performed based on the track identifier. Furthermore, the conversion in step 4204 may include encoding to a media data file or decoding from a media data file.

[0235] It should be noted that method 4200 can be implemented in an apparatus for processing video data, including a processor and a non-transitory memory having instructions thereon, such as a video encoder 4400, a video decoder 4500, and / or an encoder 4600. In this case, the instructions, when executed by the processor, cause the processor to perform method 4200. Furthermore, method 4200 can be executed by a non-transitory computer-readable medium comprising a computer program product for use by a video encoding / decoding device. The computer program product includes computer-executable instructions stored on the non-transitory computer-readable medium, causing the video encoding / decoding device to perform method 4200 when executed by a processor.

[0236] Figure 9 This is a block diagram illustrating an example video encoding / decoding system 4300 that can utilize the techniques disclosed herein. The video encoding / decoding system 4300 may include a source device 4310 and a target device 4320. The source device 4310 generates encoded video data; this source device may be referred to as a video encoding / decoding device. The target device 4320 can decode the encoded video data generated by the source device 4310; this target device may be referred to as a video decoding device.

[0237] Source device 4310 may include video source 4312, video encoder 4314, and input / output (I / O) interface 4316. Video source 4312 may include, for example, a video capture device, an interface for receiving video data from a video content provider, and / or a source of a computer graphics system for generating video data, or a combination of such sources. Video data may include one or more pictures. Video encoder 4314 encodes the video data from video source 4312 to generate a bitstream. The bitstream may include a series of bits that form a coded and decoded representation of the video data. The bitstream may include coded and decoded pictures and associated data. A coded and decoded picture is a coded and decoded representation of a picture. 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. Encoded video data may be transmitted directly to target device 4320 via network 4330 through I / O interface 4316. Encoded video data may also be stored on storage medium / server 4340 for access by target device 4320.

[0238] Target device 4320 may include I / O interface 4326, video decoder 4324, and 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 source device 4310 or 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 target device 4320 or may be external to target device 4320, which may be configured to interface with an external display device.

[0239] The video encoder 4314 and the video decoder 4324 can operate according to video compression standards such as the High Efficiency Video Codec (HEVC) standard, the Multi-Functional Video Codec (VVM) standard, and other current and / or additional standards.

[0240] Figure 10 This is a block diagram illustrating an example of a video encoder 4400, which can be... Figure 9 The system 4300 shown includes a video encoder 4314. The video encoder 4400 can be configured to perform any or all of the techniques described in this disclosure. The video encoder 4400 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of the video encoder 4400. In some examples, a processor can be configured to perform any or all of the techniques described in this disclosure.

[0241] The functional components of the video encoder 4400 may include a segmentation unit 4401, a prediction unit 4402 (which may include a mode selection unit 4403, a motion estimation unit 4404, a motion compensation unit 4405, and an intra-frame 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 coding unit 4414.

[0242] In other examples, the video encoder 4400 may include more, fewer, or different functional components. In one example, the prediction unit 4402 may include an intra-block copy (IBC) unit. The IBC unit can perform prediction in IBC mode, where at least one reference picture is the picture in which the current video block is located.

[0243] In addition, some components (such as motion estimation unit 4404 and motion compensation unit 4405) may be highly integrated, but are shown separately in the example of video encoder 4400 for illustrative purposes.

[0244] The segmentation unit 4401 can segment an image into one or more video blocks. The video encoder 4400 and the video decoder 4500 can support various video block sizes.

[0245] The mode selection unit 4403 can, for example, select one of the encoding / decoding modes based on the error result, and provide the resulting intra-frame or inter-frame encoded / decoded block to the residual generation unit 4407 to generate residual block data, and provide it to the reconstruction unit 4412 to reconstruct the coded block for use as a reference picture. In some examples, the mode selection unit 4403 can select a combination of intra-frame and inter-frame prediction (CIIP) modes, where the prediction is based on the inter-frame prediction signal and the intra-frame prediction signal. The mode selection unit 4403 can also select the resolution of the motion vector for the block (e.g., sub-pixel or integer pixel precision) in the case of inter-frame prediction.

[0246] To perform inter-frame prediction on the current video block, motion estimation unit 4404 can generate motion information for the current video block by comparing one or more reference frames from buffer 4413 with the current video block. Motion compensation unit 4405 can determine the predicted video block for the current video block based on the motion information and decoded samples of the images from buffer 4413 (rather than the images associated with the current video block).

[0247] The motion estimation unit 4404 and the motion compensation unit 4405 can perform different operations on the current video block, depending on whether the current video block is in an I-band, P-band, or B-band.

[0248] In some examples, motion estimation unit 4404 can perform unidirectional prediction on the current video block, and can search for a reference video block for the current video block in the reference images of list 0 or list 1. Motion estimation unit 4404 can then generate a reference index indicating a reference image in list 0 or list 1, which includes a reference video block and a motion vector indicating the spatial displacement between the current video block and the reference video block. Motion estimation unit 4404 can output the reference index, prediction direction indicator, and motion vector as motion information for the current video block. Motion compensation unit 4405 can generate a predicted video block for the current block based on the reference video block indicated by the motion information of the current video block.

[0249] In other examples, motion estimation unit 4404 can perform bidirectional prediction on the current video block. Motion estimation unit 4404 can search for a reference video block for the current video block in the reference images in list 0, and can also search for another reference video block for the current video block in the reference images in list 1. Motion estimation unit 4404 can then generate a reference index indicating the reference images in lists 0 and 1, which include the reference video block and a motion vector indicating the spatial displacement between the reference video block and the current video block. Motion estimation unit 4404 can output the reference index and motion vector of the current video block as motion information for the current video block. Motion compensation unit 4405 can generate a predicted video block for the current video block based on the reference video block indicated by the motion information of the current video block.

[0250] In some examples, the motion estimation unit 4404 may output a complete set of motion information for the decoder's decoding process. In some examples, the motion estimation unit 4404 may not output a complete set of motion information for the current video. More precisely, the motion estimation unit 4404 may signal the motion information of the current video block by referencing the motion information of another video block. For example, the motion estimation unit 4404 may determine that the motion information of the current video block is sufficiently similar to the motion information of adjacent video blocks.

[0251] In one example, the motion estimation unit 4404 may indicate a value in the syntax structure associated with the current video block that indicates to the video decoder 4500 that the current video block has the same motion information as another video block.

[0252] In another example, motion estimation unit 4404 can identify another video block and motion vector difference (MVD) in the syntax structure associated with the current video block. The motion vector difference indicates the difference between the motion vector of the current video block and the motion vector of the indicated video block. Video decoder 4500 can use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0253] As discussed above, the video encoder 4400 can predictively signal motion vectors. Two examples of predictive signaling techniques that can be implemented by the video encoder 4400 include Advanced Motion Vector Prediction (AMVP) and Combined Mode Signaling.

[0254] Intra-prediction unit 4406 can perform intra-prediction on the current video block. When intra-prediction unit 4406 performs intra-prediction on the current video block, it can generate prediction data for the current video block based on decoded samples of other video blocks in the same frame. The prediction data for the current video block may include the predicted video block and various syntax elements.

[0255] The residual generation unit 4407 can generate residual data for the current video block by subtracting (or more) predicted video blocks from the current video block. The residual data for the current video block may include residual video blocks corresponding to different sample components of the samples in the current video block.

[0256] In other examples, such as in skip mode, there may be no residual data for the current video block and the residual generation unit 4407 may not perform subtraction operations.

[0257] The transform processing unit 4408 can generate a transform coefficient video block for the current video block by applying one or more transforms to the residual video block associated with the current video block.

[0258] After the transform processing unit 4408 generates a transform coefficient video block associated with the current video block, the quantization unit 4409 can 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.

[0259] The inverse quantization unit 4410 and the inverse transform unit 4411 can apply inverse quantization and inverse transform to the transform coefficient video block, respectively, to reconstruct the residual video block from the transform coefficient video block. The reconstruction unit 4412 can add the reconstructed residual video block to the corresponding sample from one or more predicted video blocks generated by the prediction unit 4402 to produce a reconstructed video block associated with the current block, so as to be stored in the buffer 4413.

[0260] After the video block is reconstructed by reconstruction unit 4412, a loop filtering operation can be performed to reduce video block artifacts in the video block.

[0261] The entropy encoding unit 4414 can receive data from other functional components of the video encoder 4400. When the entropy encoding unit 4414 receives data, it can perform one or more entropy encoding operations to generate entropy-encoded data and output a bit stream including the entropy-encoded data.

[0262] Figure 11 This is a block diagram illustrating an example of a video decoder 4500, which can be... Figure 9 The system 4300 shown includes a video decoder 4324. The video decoder 4500 can be configured to perform any or all of the techniques described in this disclosure. In the example shown, the video decoder 4500 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of the video decoder 4500. In some examples, the processor can be configured to perform any or all of the techniques described in this disclosure.

[0263] In the example shown, the video decoder 4500 includes an entropy decoding unit 4501, a motion compensation unit 4502, an intra-frame prediction unit 4503, an inverse quantization unit 4504, an inverse transform unit 4505, a reconstruction unit 4506, and a buffer 4507. In some examples, the video decoder 4500 can perform a decoding channel, which typically corresponds to the encoding channel described with respect to the video encoder 4400.

[0264] The entropy decoding unit 4501 can retrieve the encoded bitstream. The encoded bitstream may include entropy-coded video data (e.g., encoded video data blocks). The entropy decoding unit 4501 can decode the entropy-coded video data, and the motion compensation unit 4502 can determine motion information based on the entropy-coded video data. This motion information includes motion vectors, motion vector precision, reference image list index, and other motion information. The motion compensation unit 4502 can determine this information, for example, by performing AMVP and merging modes.

[0265] The motion compensation unit 4502 can generate motion compensation blocks, thereby potentially performing interpolation based on an interpolation filter. The identifier of the interpolation filter used at sub-pixel precision can be included in the syntax element.

[0266] The motion compensation unit 4502 can use the interpolation filter used by the video encoder 4400 during the encoding of the video block to calculate the sub-integer pixel interpolation of the reference block. The motion compensation unit 4502 can determine the interpolation filter used by the video encoder 4400 based on the received syntax information, and use the interpolation filter to generate the prediction block.

[0267] The motion compensation unit 4502 may use some syntax information to determine the size of the blocks used to encode (multiple) frames and / or (multiple) stripes of the encoded video sequence, segmentation information describing how each macroblock of the picture of the encoded video sequence is segmented, a mode indicating how each segment is encoded, one or more reference frames (and a list of reference frames) for each inter-frame codec block, and other information used to decode the encoded video sequence.

[0268] Intra-prediction unit 4503 can use, for example, an intra-prediction mode received in the bitstream to form prediction blocks from spatially adjacent blocks. Inverse quantization unit 4504 performs inverse quantization, i.e., dequantization, on the video block coefficients provided in the bitstream and decoded and quantized by entropy decoding unit 4501. Inverse transform unit 4505 applies an inverse transform.

[0269] The reconstruction unit 4506 can add the residual block to the corresponding prediction block generated by the motion compensation unit 4502 or the intra-frame prediction unit 4503 to form a decoded block. If necessary, a deblocking filter can also be applied to filter the decoded block to eliminate block artifacts. The decoded video block is then stored in a buffer 4507, which provides a reference block for subsequent motion compensation / intra-frame prediction and also generates decoded video for presentation on a display device.

[0270] Figure 12 This is a schematic diagram of an example encoder 4600. Encoder 4600 is suitable for implementing VVC technology. Encoder 4600 includes three loop filters: a deblocking filter (DF) 4602, a sample adaptive offset (SAO) 4604, and an adaptive loop filter (ALF) 4606. Unlike DF 4602, which uses predefined filters, SAO 4604 and ALF 4606 utilize the original samples of the current image to reduce the mean square error between the original and reconstructed samples by adding an offset and applying a finite impulse response (FIR) filter, respectively, and by using encoder-decoder side information signaling to inform the offset and filter coefficients. ALF 4606 is used in the final processing stage of each image and can be considered as a tool to attempt to capture and repair artifacts created by previous stages.

[0271] The encoder 4600 also includes an intra-frame prediction component 4608 and a motion estimation / compensation (ME / MC) component 4610 configured to receive input video. The intra-frame prediction component 4608 is configured to perform intra-frame prediction, while the ME / MC component 4610 is configured to perform inter-frame prediction using a reference image obtained from a reference image buffer 4612. Residual blocks from inter-frame or intra-frame prediction are fed into a transform (T) component 4614 and a quantization (Q) component 4616 to generate quantized residual transform coefficients, which are then fed into an entropy codec component 4618. The entropy codec component 4618 entropy codes the prediction results and the quantized transform coefficients and sends them to a video decoder (not shown). Quantized components output from the quantization component 4616 can be fed into an inverse quantization (IQ) component 4620, an inverse transform component 4622, and a reconstruction (REC) component 4624. REC component 4624 can output images to DF 4602, SAO 4604 and ALF 4606 for filtering before these images are stored in reference image buffer 4612.

[0272] The following is a list of preferred solutions based on some examples.

[0273] The following solutions illustrate examples of the techniques discussed in this article.

[0274] The following solutions illustrate example embodiments of the techniques discussed in previous chapters.

[0275] 1. A method for processing media data, comprising: determining that a track includes a track identifier, the track identifier being a first entry in a TrackReferenceTypeBox where reference_type is equal to 'aest'; and performing a conversion between the media data and a media data file based on the track identifier.

[0276] 2. As described in Solution 1, the TrackReferenceTypeBox with reference_type equal to 'aest' must include only track identifiers and must not include any track group identifiers.

[0277] 3. The method as described in any one of solutions 1 to 2, wherein the TrackReferenceTypeBox with reference_type equal to 'aest' must include the track identifier in the first entry and other entries including the track group identifier.

[0278] 4. The method as described in any one of solutions 1 to 3, wherein the first entry in the TrackReferenceTypeBox where reference_type equals 'aest' must be the track identifier.

[0279] 5. The method of any one of solutions 1 to 4, wherein the media data file specifies whether random access from an Extended Dependent Random Access Point (EDRAP) sample requires the most recent upstream access point (SAP) sample of type 1, 2, or 3.

[0280] 6. The method of any one of solutions 1 to 5, wherein the EDRAP sample is a sample for which all subsequent samples can be correctly decoded in both decoding order and output order, provided that a required preceding SAP or EDRAP sample is available for decoding the sample and subsequent samples, and wherein the required preceding SAP or EDRAP sample comprises one or more of a sample set, the sample set starting with the most recent preceding SAP sample (closestSapSample) of type 1, 2 or 3 in decoding order, and including all EDRAP samples between the closestSapSample and the sample in decoding order.

[0281] 7. The method of any one of solutions 1 to 6, wherein the EDRAP sample is a sample for which all subsequent samples can be correctly decoded in both decoding order and output order, provided that a required preceding SAP or EDRAP sample is available for decoding the sample and subsequent samples, wherein the required preceding SAP or EDRAP sample comprises zero or more of a sample set starting from the most recent preceding SAP sample (closestSapSample) of type 1, 2 or 3 in decoding order, and includes all EDRAP samples between the closestSapSample and the sample in decoding order.

[0282] 8. The method of any one of solutions 1 to 7, wherein when the media track has a track reference of type 'aest', for each EDRAP sample A in the media track, there must be one and only one sample B in the referenced track that has the same decoding time as sample A, and wherein sample B must include all media data of the required preceding SAP or EDRAP sample of sample A.

[0283] 9. The method of any one of solutions 1 to 8, wherein for any EDRAP sample sampleA mapped to an EDRAP sample group, sampleSeq is a sequence of samples including SAP or EDRAP samples identified by ref_sap_or_edrap_idx_delta[i], wherein i ranges from 0 to num_ref_sap_or_edrap_samples_minus1 in decoding order, including the endpoint, sampleA, and all samples in the track that follow sampleA in both decoding and output order, and for each sample sampleB in sampleSeq, all data required to process sampleB must be accessible in the referenced sample entry, in sampleB, or in any sample in sampleSeq that precedes sampleB in decoding order.

[0284] 10. The method of any one of solutions 1 to 9, wherein VisualEdrapEntry() is specified as follows:

[0285]

[0286] 11. The method of any one of solutions 1 to 10, wherein num_ref_sap_or_edrap_samples_minus1 plus 1 indicates the number of samples required in the preceding SAP or EDRAP samples, which are earlier than the EDRAP samples in the decoding order, and which are required to be referenced when decoding begins from the EDRAP samples in order to correctly decode the EDRAP samples and all samples following the EDRAP samples in the decoding and output order.

[0287] 12. The method of any one of solutions 1 to 11, wherein ref_sap_or_edrap_idx_delta[i] indicates the i-th required preceding SAP or EDRAP sample of the current EDRAP sample, wherein the list of SAP or EDRAP samples associated with SAP samples of type 1, 2, or 3 includes the SAP sample and all EDRAP samples after the SAP sample and before the next SAP sample, wherein the SAP_or_EDRAP sample index is an index to the list of SAP or EDRAP samples, wherein ref_sap_or_ The value of edrap_idx_delta[i] is equal to the difference between the SAP_or_EDRAP sample index of the current EDRAP sample and the SAP_or_EDRAP sample index of the i-th required preceding SAP or EDRAP sample, wherein value 1 indicates that the i-th required SAP or EDRAP sample is the last SAP or EDRAP sample before the EDRAP sample in the decoding order, and wherein value 2 indicates that the i-th required SAP or EDRAP sample is the second-to-last EDRAP sample before the EDRAP sample in the decoding order.

[0288] 13. An apparatus for processing video data, comprising: a processor; and a non-transitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform a method as described in any one of solutions 1 to 12.

[0289] 14. A non-transitory computer-readable medium comprising a computer program product for use by a video codec apparatus, the computer program product comprising computer-executable instructions stored on the non-transitory computer-readable medium, causing the video codec apparatus to perform the method as described in any one of solutions 1 to 12 when executed by a processor.

[0290] 15. A non-transitory computer-readable recording medium storing a bitstream of video generated by a method performed by a video processing apparatus, wherein the method comprises: determining a track including a track identifier, the track identifier being a first entry in a TrackReferenceTypeBox with reference_type equal to 'aest'; and generating a bitstream based on the determination.

[0291] 16. A method for storing a bitstream of video, comprising: determining a track including a track identifier, the track identifier being a first entry in a TrackReferenceTypeBox where reference_type is equal to 'aest'; generating a bitstream based on the determination; and storing the bitstream in a non-transitory computer-readable recording medium.

[0292] 17. A method, apparatus or system described in this patent document.

[0293] In the solution described in this paper, the encoder conforms to the format rules by generating a codec representation based on those rules. In the solution described in this paper, the decoder uses the format rules to parse the syntax elements in the codec representation, and, knowing the presence or absence of these syntax elements based on the format rules, generates the decoded video.

[0294] In this disclosure, the term "video processing" can refer to video encoding, video decoding, video compression, or video decompression. For example, a video compression algorithm may be applied during the conversion from a pixel representation of a video to a corresponding bitstream representation (or vice versa). For example, the bitstream representation of the current video block may correspond to bits at the same position or at different positions in the bitstream, as defined by the syntax. For example, macroblocks may be encoded based on the error residuals from the transform and encoding / decoding, and also using bits in the header and other fields in the bitstream. Furthermore, during the conversion, the decoder may resolve the bitstream based on determination and know that certain fields may or may not be present, as described in the solutions above. Similarly, the encoder may determine whether to include certain syntax fields and generate the encoding / decoding representation accordingly by including or excluding syntax fields in the encoding / decoding representation.

[0295] The disclosed and other solutions, examples, embodiments, modules, and functional operations described herein can be implemented in digital electronic circuits or computer software, firmware, or hardware, or a combination thereof, including the structures disclosed herein and their equivalents. The disclosed and other embodiments can be implemented as one or more computer program products encoded on a computer-readable medium for execution by or control of the operation of a data processing apparatus; that is, one or more modules of computer program instructions. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of substances influencing machine-readable propagation signals, or a combination thereof. The term "data processing apparatus" encompasses all means, devices, and machines for processing data, including, for example, a programmable processor, a computer, or multiple processors or computers. In addition to hardware, the apparatus may also include code that creates an execution environment for the computer program in question, such as code constituting processor firmware, a protocol stack, a database management system, an operating system, or a combination thereof. Propagation signals are artificially generated signals, such as machine-generated electrical, optical, or electromagnetic signals, which are generated to encode information for transmission to a suitable receiver device.

[0296] Computer programs (also referred to as programs, software, software applications, scripts, or code) can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as standalone programs or as modules, components, subroutines, or any 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 as a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), a single file dedicated to the program in question, or multiple coordinated files (e.g., a file storing portions of one or more modules, subroutines, or code). Computer programs can be deployed to execute on one or more computers located at a single site or distributed across multiple sites and interconnected by a communications network.

[0297] The processes or logical flows described in this disclosure can be executed by one or more programmable processors that execute one or more computer programs to perform functions by manipulating input data and generating outputs. The processes and logical flows can also be executed by special-purpose logic circuitry (e.g., field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs)), and the devices can also be implemented as special-purpose logic circuitry (e.g., field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs)).

[0298] As an example, processors suitable for executing computer programs include general-purpose and special-purpose microprocessors, as well as any one or more processors of any kind of digital computer. Typically, the processor receives instructions and data from read-only memory or random access memory, or both. The basic components of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Typically, a computer will also include one or more mass storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks) for storing data, or operatively coupled to receive data from or transfer data to one or more mass storage devices, or both. However, a computer does not necessarily 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, such as 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 optical disc read-only memory (CD ROM) and digital versatile optical disc read-only memory (DVD-ROM). The processor and memory may be supplemented or integrated therein by dedicated logic circuitry.

[0299] Although this disclosure includes numerous details, these details should not be construed as limiting any scope of subject matter or what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of a particular technology. Certain features described in this disclosure in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, although features may be described above as functioning in certain combinations and even initially claimed in this way, in some cases, one or more features from a claimed combination may be removed from that combination, and the claimed combination may involve sub-combinations or variations thereof.

[0300] Similarly, although operations are shown in a specific order in the figures, this should not be construed as requiring such operations to be performed in the shown specific order or sequential order, or performing all shown operations to achieve the desired result. Furthermore, the separation of the various system components described in this disclosure should not be construed as requiring such separation in all embodiments.

[0301] Only a few implementation methods and examples have been described, and other implementation methods, enhancements and modifications may be made based on what is described and shown in this disclosure.

[0302] When no intermediate component exists other than a line, trace, or other medium between the first and second components, the first component is directly coupled to the second component. When an intermediate component other than a line, trace, or other medium exists between the first and second components, the first component is indirectly coupled to the second component. The term "coupled" and its variations include direct coupling and indirect coupling. Unless otherwise stated, the use of the term "about" means including a range of ±10% of the subsequent value.

[0303] While several embodiments are provided in this disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of this disclosure. These examples are intended to be illustrative rather than restrictive and are not intended to be limited to the details given herein. For example, various elements or components may be combined or integrated into another system, or certain features may be omitted or not implemented.

[0304] Furthermore, without departing from the scope of this disclosure, the technologies, systems, subsystems, and methods described and illustrated as discrete or separate in the various embodiments may be combined or integrated with other systems, modules, technologies, or methods. Other items shown or discussed as coupled may be directly connected or indirectly coupled or communicated through some interface, device, or intermediate component, whether electrical, mechanical, or otherwise. Other examples of changes, substitutions, and modifications will be apparent to those skilled in the art, and such changes, substitutions, and modifications may be made without departing from the spirit and scope of this disclosure.

Claims

1. A method for processing media data, comprising: During the conversion between the media data and the media data file, it is determined whether the media track includes a track reference of type 'aest' associated external stream track; as well as The conversion is performed based on the determination; When a track reference type box with reference type equal to 'aest' exists, the track reference type box must include only track identifiers and must not include any track group identifiers.

2. The method as described in claim 1, wherein, When the media track has a track reference of type 'aest', for each extended dependent random access point EDRAP sample A in the media track, there must be one and only one sample B in the referenced track that has the same decoding time as sample A, and sample B must include all the media data required by sample A in the preceding stream access point SAP or EDRAP sample.

3. The method of claim 1, further comprising: The extended dependency of the media data on the random access point EDRAP sample is determined. Wherein, an EDRAP sample is a sample for which all subsequent samples can be correctly decoded in both decoding and output order, provided that the required preceding SAP or EDRAP sample is available for decoding the sample and subsequent samples, and wherein the required preceding SAP or EDRAP sample includes one or more of a sample set, the sample set starting with the most recent preceding SAP sample closestSapSample of type 1, 2 or 3 in decoding order, and including all EDRAP samples between closestSapSample and the sample in decoding order.

4. The method of claim 3, wherein, For any EDRAP sample sampleA mapped to the EDRAP sample group, the sample sequence sampleSeq is a sequence of samples arranged in the following order: i) SAP or EDRAP samples identified by the first syntax element in the decoding order, wherein the index of the first syntax element ranges from 0 to the value of the second syntax element, inclusive. ii) sampleA, and iii) All samples in the track following sampleA, in both the decoding order and the output order.

5. The method of claim 4, wherein, For each sample B in the sample sequence, all the data required to process sample B must be accessible in the referenced sample entry, in sample B itself, or in any sample in the sample sequence that precedes sample B in the decoding order.

6. The method of claim 4, wherein, The second syntax element plus 1 indicates the number of samples required in the preceding SAP or EDRAP sample, which are earlier than the EDRAP sample in the decoding order and are required when decoding starts from the EDRAP sample to be able to correctly decode the EDRAP sample and all samples following the EDRAP sample in the decoding and output order.

7. The method of claim 4, wherein, The first syntax element with index i indicates the i-th required previous SAP or EDRAP sample in the current EDRAP sample. The list of SAP or EDRAP samples associated with SAP samples of type 1, 2, or 3 includes the SAP sample and all EDRAP samples that follow the SAP sample and precede the next SAP sample, if any. The SAP_or_EDRAP sample index is an index of the SAP or EDRAP sample list.

8. The method of claim 7, wherein, The value of the first syntax element is equal to the difference between the SAP_or_EDRAP sample index of the current EDRAP sample and the SAP_or_EDRAP sample index of the i-th required previous SAP or EDRAP sample. Wherein, the value of the first syntax element equal to 1 indicates that the i-th required SAP or EDRAP sample is the last SAP or EDRAP sample preceding the EDRAP sample in the decoding order, and, The value of the first syntax element being equal to 2 indicates that the i-th required SAP or EDRAP sample is the penultimate EDRAP sample preceding the EDRAP sample in the decoding order.

9. The method of claim 4, wherein, The first syntax element is ref_sap_or_edrap_idx_delta, and the second syntax element is num_ref_sap_or_edrap_samples_minus1.

10. The method of claim 4, wherein, When present, the first and second syntax elements are included in the syntax structure of the visual EDRAP entry.

11. The method of claim 4, wherein, The first syntax element is encoded and decoded as a 16-bit unsigned integer, and the second syntax element is encoded and decoded as a 3-bit unsigned integer.

12. The method of claim 1, wherein, When the media track has a track reference of type 'aest', for each extended dependent random access point EDRAP sample A in the media track, there must be one and only one sample B in the referenced track that has the same decoding time as sample A, and sample B must include all media data of the nearest stream access point SAP sample of type 1, 2 or 3 that precedes sample A in decoding order, as well as all media data of the SAP or EDRAP sample required by sample A.

13. The method of claim 1, wherein, The conversion includes generating the media data file from the media data.

14. The method of claim 1, wherein, The conversion includes parsing the media data from the media data file.

15. An apparatus for processing media data, comprising: processor; and a non-transitory memory thereon containing instructions, wherein the instructions, when executed by the processor, cause the processor to perform: During the conversion between the media data and the media data file, it is determined whether the media track includes a track reference of type 'aest' associated external stream track; and The conversion is performed based on the determination; When a track reference type box with reference type equal to 'aest' exists, the track reference type box must include only track identifiers and must not include any track group identifiers.

16. The apparatus of claim 15, wherein, When the media track has a track reference of type 'aest', for each extended dependent random access point EDRAP sample A in the media track, there must be one and only one sample B in the referenced track that has the same decoding time as sample A, and sample B must include all the media data required by sample A in the preceding stream access point SAP or EDRAP sample.

17. A non-transitory computer-readable storage medium storing instructions that cause a processor to perform: during a conversion between media data and a media data file, determining whether a media track includes a track reference of type 'aest' associated external stream track; and The conversion is performed based on the determination; in, When a track reference type box with reference type equal to 'aest' exists, the track reference type box must include only track identifiers and must not include any track group identifiers.

18. The non-transitory computer-readable storage medium of claim 17, wherein, When the media track has a track reference of type 'aest', for each extended dependent random access point EDRAP sample A in the media track, there must be one and only one sample B in the referenced track that has the same decoding time as sample A, and sample B must include all the media data required by sample A in the preceding stream access point SAP or EDRAP sample.

19. A method for storing video media data files, comprising: Determine whether the media track includes a track reference of type 'aest' associated external stream track; The media data file is generated based on the determination; as well as The media data file is stored in a non-transitory computer-readable recording medium; When a track reference type box with reference type equal to 'aest' exists, the track reference type box must include only track identifiers and must not include any track group identifiers.

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