Placement of parameter sets and synchronization samples in video coding

Abstract

The file format and parsing and decoding of video data are defined to facilitate more efficient random accessibility of the decoded video data. Constraints may be imposed on the placement of parameter sets in the video file and the definition of synchronization samples. For non-synchronized samples, parameter set data for the video data may be decoded only in the sample entry of the sample, the sample, the previous sample in decoding order that is a synchronization sample, or in samples that appear in decoding order between the sample and the previous sample in decoding order that is a synchronization sample.

Description

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 115,013, filed February 11, 2015, the entire contents of which are incorporated herein by reference.

[0002] This application is a divisional application of application number 201680009265.5 entitled “Placement of parameter sets and synchronization samples in video decoding”. Technical Field

[0003] The present invention relates to video coding and compression, and signaling data associated with compressed video in a bitstream. Background Art

[0004] Digital video functionality can be incorporated into a wide range of devices, including digital televisions, digital live broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video game devices, video game consoles, cellular or satellite radio telephones, so-called "smartphones," video teleconferencing devices, video streaming devices, and the like. Digital video devices implement video compression techniques, such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264 / MPEG-4 Part 10, Advanced Video Coding (AVC), ITU-T H.265, High Efficiency Video Coding (HEVC), and extensions of such standards. By implementing such video compression techniques, video devices can more efficiently transmit, receive, encode, decode, and / or store digital video information.

[0005] Video compression techniques perform spatial (intra-picture) prediction and / or temporal (inter-picture) prediction to reduce or remove redundancy inherent in video sequences. For block-based video coding, a video slice (i.e., a video frame or portion of a video frame) may be partitioned into video blocks, which may also be referred to as treeblocks, coding units (CUs), and / or coding nodes. Video blocks in an intra-coded (I) slice of a picture are encoded using spatial prediction with respect to reference samples in neighboring blocks in the same picture. Video blocks in an inter-coded (P or B) slice of a picture may use spatial prediction with respect to reference samples in neighboring blocks in the same picture or temporal prediction with respect to reference samples in other reference pictures. Pictures may be referred to as frames, and reference pictures may be referred to as reference frames.

[0006] Spatial or temporal prediction produces a prediction block for the block to be coded. Residual data represents the pixel differences between the original block to be coded and the prediction block. Inter-coded blocks are encoded according to a motion vector pointing to a block of reference samples forming the prediction block and residual data indicating the difference between the coded block and the prediction block. Intra-coded blocks are encoded according to an intra-coding mode and the residual data. For further compression, the residual data can be transformed from the pixel domain to the transform domain, thereby producing residual transform coefficients, which can then be quantized. The quantized transform coefficients, initially arranged in a two-dimensional array, can be scanned to produce a one-dimensional vector of transform coefficients, and entropy coding can be applied to achieve even more compression. Summary of the Invention

[0007] The techniques of this disclosure relate to the definition of file formats and the parsing and / or decoding of video data. For example, in video decoding, parameter sets may include sequence-level header information that does not need to be repeated for each sequence or picture, or picture-level information that changes infrequently, thereby improving decoding efficiency. Various aspects of the present disclosure may achieve efficient random accessibility of decoded video data by imposing restrictions on the placement of parameter sets in a video bitstream and limiting synchronized samples and unsynchronized samples in a video file. For example, for synchronized samples, parameter set data for video data may be decoded only in the sample entry for the sample or in the sample itself. For unsynchronized samples, parameter set data for video data may be decoded only in the sample entry for the sample, the sample itself, the previous sample in decoding order that is a synchronized sample, or in one or more samples that appear in decoding order between the unsynchronized sample and the previous sample in decoding order that is a synchronized sample.

[0008] In one example, a method of decoding video data includes determining whether a sample of the video data is a synchronization sample and, based on determining that the sample is not a synchronization sample, determining parameter set data for the video data only from sample entries for the sample, the sample, a previous sample in decoding order that is a synchronization sample, or from samples that occur in decoding order between the sample and the previous sample in decoding order that is a synchronization sample.

[0009] In another example, a method for encoding video data includes determining whether a sample of the video data is a synchronization sample, and based on determining that the sample is not a synchronization sample, encoding parameter set data for the video data only in a sample entry for the sample, the sample, a previous sample in decoding order that is a synchronization sample, or in samples that appear in decoding order between the sample and the previous sample in decoding order that is a synchronization sample.

[0010] In another example, an apparatus for decoding video data includes a memory configured to store the video data and one or more processors configured to determine whether a sample of the video data is a synchronization sample and, based on determining that the sample is not a synchronization sample, determine parameter set data for the video data only from sample entries for the sample, the sample, a previous sample in decoding order that is a synchronization sample, or from samples that appear in decoding order between the sample and the previous sample in decoding order that is a synchronization sample.

[0011] In another example, an apparatus for encoding video data includes a memory configured to store the video data and one or more processors configured to determine whether a sample of the video data is a synchronization sample and, based on determining that the sample is not a synchronization sample, include parameter set data for the video data only in a sample entry for the sample, the sample, a previous sample in decoding order that is a synchronization sample, or samples that appear in decoding order between the sample and the previous sample in decoding order that is a synchronization sample.

[0012] In another example, an apparatus for decoding video data includes means for determining whether a sample of the video data is a synchronization sample, and means for determining parameter set data for the video data based on determining that the sample is not a synchronization sample, solely from sample entries for the sample, the sample, a previous sample in decoding order that is a synchronization sample, or from samples that appear in decoding order between the sample and the previous sample in decoding order that is a synchronization sample.

[0013] In another example, an apparatus for encoding video data includes means for determining whether a sample of the video data is a synchronization sample and means for including parameter set data for the video data only in a sample entry for the sample, the sample, a previous sample in decoding order that is a synchronization sample, or in samples that appear in decoding order between the sample and a previous sample in decoding order that is a synchronization sample based on determining that the sample is not a synchronization sample.

[0014] In another example, a non-transitory computer-readable medium includes instructions stored thereon that, when executed, cause one or more processors to determine whether a sample of video data is a synchronization sample and, based on determining that the sample is not a synchronization sample, determine parameter set data for the video data solely from sample entries for the sample, the sample, a previous sample in decoding order that is a synchronization sample, or samples that appear in decoding order between the sample and the previous sample in decoding order that is a synchronization sample.

[0015] In another example, a non-transitory computer-readable medium includes instructions stored thereon that, when executed, cause one or more processors to determine whether a sample of video data is a synchronization sample and, based on determining that the sample is not a synchronization sample, include parameter set data for the video data only in a sample entry for the sample, the sample, a previous sample in decoding order that is a synchronization sample, or samples that appear in decoding order between the sample and the previous sample in decoding order that is a synchronization sample.

[0016] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a block diagram illustrating an example video encoding and decoding system that may utilize the techniques described in this disclosure.

[0018] Figure 2 is a block diagram illustrating an example video encoder that may implement the techniques described in this disclosure.

[0019] Figure 3 is a block diagram illustrating an example video decoder that may implement the techniques described in this disclosure.

[0020] Figure 4 is a block diagram illustrating elements of an example video file.

[0021] Figure 5 is a flow chart illustrating a process for decoding parameter set data from a video bitstream.

[0022] Figure 6 is a flow chart illustrating a process for encoding parameter set data in a video bitstream. DETAILED DESCRIPTION

[0023] The techniques of this disclosure relate to storing video content in a file format. More specifically, the techniques can achieve efficient random accessibility of coded video data by enforcing restrictions on the placement of parameter sets and the definition of synchronous and asynchronous samples in video files.

[0024] Video coding standards include ITU-T H.261, ISO / IEC MPEG-1 Visual, ITU-T H.262 or ISO / IEC MPEG-2 Visual, ITU-T H.263, ISO / IEC MPEG-4 Visual, ITU-T H.264 or ISO / IEC MPEG-4 AVC, including its scalable video coding (SVC) and multi-view video coding (MVC) extensions, and High Efficiency Video Coding (HEVC), also known as ITU-T H.265 and ISO / IEC 23008-2, including its scalable coding extension (i.e., scalable high efficiency video coding, SHVC) and multi-view extension (i.e., multi-view high efficiency video coding, MV-HEVC).

[0025] Random access can refer to decoding a video bitstream starting from a decoded picture that is not the first decoded picture in the video bitstream. Random access to a bitstream is provided in many video applications, such as broadcast and streaming, for example, to enable a user to tune into a program at any time, switch between different channels, and jump to a specific part of the video, or switch to a different bitstream for stream adaptation (e.g., adaptation of bit rate, frame rate, spatial resolution, etc.). This feature is achieved by inserting random access pictures or random access points multiple times into the video bitstream at regular intervals.

[0026] Instantaneous decoding refresh (IDR) as specified in AVC or HEVC can be used for random access. Generally speaking, an IDR picture can contain intra-coded data and can cause pictures in the decoded picture buffer to be cleared and / or marked as unused for reference. However, since pictures following an IDR picture in decoding order cannot use pictures decoded before the IDR picture as references, relying on the bitstream of IDR pictures for random access can significantly reduce decoding efficiency.

[0027] To improve coding efficiency, HEVC introduces the concept of clean random access (CRA) pictures, allowing pictures following a CRA picture in decoding order but preceding it in output order to use pictures decoded before the CRA picture as reference. Pictures following a CRA picture in decoding order but preceding it in output order are referred to as leading pictures associated with the CRA picture (or leading pictures of a CRA picture). If decoding starts from an IDR or CRA picture preceding the current CRA picture, the leading pictures of the CRA picture can be correctly decoded. However, when random access occurs from a CRA picture, the leading pictures of this CRA picture may be undecodable; therefore, these leading pictures are typically discarded during random access decoding. To prevent error propagation from reference pictures that may be unavailable depending on where decoding starts, all pictures following a CRA picture in both decoding and output order should not use any pictures preceding the CRA picture in decoding or output order (including the leading pictures) as reference.

[0028] The concept of broken link access (BLA) pictures was introduced in HEVC after the introduction of CRA pictures and is based on the concept of CRA pictures. BLA pictures are usually derived from bitstream splicing at the location of CRA pictures (described in more detail below), and in the spliced bitstream, the splicing point CRA picture becomes a BLA picture.

[0029] IDR pictures, CRA pictures, and BLA pictures are collectively referred to as random access point (RAP) pictures. IDR pictures correspond to so-called closed group of pictures (GOP)-based RAPs, while CRA and BLA pictures correspond to conventional so-called open group of pictures-based RAPs.

[0030] One difference between BLA pictures and CRA pictures is that for CRA pictures, if decoding starts from a RAP picture that precedes the CRA picture in decoding order, the associated leading pictures are correctly decodable, and when random access occurs from the CRA picture (i.e., when decoding starts from the CRA picture, or in other words, when the CRA picture is the first picture in the bitstream), the associated leading pictures may not be correctly decodable. For BLA pictures, the associated leading pictures may not be decodable in all cases, even when decoding starts from a RAP picture that precedes the BLA picture in decoding order.

[0031] Random access to a video bitstream can also start from a progressive decoding refresh (GDR) picture, which is not intra-coded but, after a certain number of pictures have been decoded, all subsequent pictures in decoding order can be correctly decoded. For an overview of video techniques for implementing GDR, see Miska M. Hannuksela, Ye-Kui Wang, and Moncef Gabbouj, "Isolated regions in video coding," IEEE Transactions on Multimedia, Vol. 6, No. 2, pp. 259-267, April 2004.

[0032] In some examples, random access to a video bitstream can be performed during bitstream splicing. Bitstream splicing can refer to the concatenation of two or more bitstreams or portions thereof. For example, a first bitstream can be appended to a second bitstream, possibly with some modifications to one or both of the bitstreams, to produce a spliced bitstream. The first coded picture in the second bitstream is also referred to as a splice point. Thus, pictures that appear after the splice point in the spliced bitstream originate from the second bitstream, while pictures that appear before the splice point in the spliced bitstream originate from the first bitstream.

[0033] Bitstream splicing can be performed by a bitstream splicer. Bitstream splicers are typically lightweight and may be less intelligent than encoders. For example, a splicer may not be equipped with entropy decoding and encoding capabilities. In some instances, the bitstream splicer may be included in a server or other content preparation device. Bitstream switching can be used in adaptive streaming environments. A bitstream switching operation at a picture in the switched bitstream is effectively a bitstream splicing operation, where the splicing point is the bitstream switching point, i.e., the first picture in the switched bitstream.

[0034] In some cases, the decoded video data may be stored in a specific file format. An example file format standard includes the ISO Base Media File Format (ISOBMFF, ISO / IEC 14496-12). ISOBMFF serves as the basis for many codec encapsulation formats (e.g., the AVC file format) and many multimedia container formats (e.g., the MPEG-4 file format, the 3GPP file format (3GP), and the DVB file format). For example, other file formats derived from ISOBMFF include the MPEG-4 file format (ISO / IEC 14496-14), the 3GPP file format (3GPP TS 26.244), and the AVC file format (ISO / IEC 14496-15).

[0035] In addition to continuous media (e.g., audio and video) and static media (e.g., images), metadata can also be stored in files conforming to ISOBMFF. Files structured according to ISOBMFF can be used for many purposes, including local media file playback, watch-and-see downloads of remote files, segments for Dynamic Adaptive Streaming over HTTP (DASH), containers for content to be streamed and its packetization instructions, and recording received real-time media streams.

[0036] A box refers to the basic syntax structure in ISOBMFF, which includes a four-character encoding of the box type, the number of bytes in the box, and the payload. ISOBMFF files are composed of a series of boxes, and boxes can contain other boxes. The movie box ("moov") contains metadata for the continuous media stream present in the file, each of which is presented as a track in the file.

[0037] The metadata for a track is encapsulated in a track box ("trak"), while the media content of the track is either encapsulated in a media data box ("mdat") or directly in a separate file. The media content of a track consists of a series of samples (e.g., audio or video access units). Generally speaking, an access unit is a unit of data containing decoded picture data for a common time instance. A sample is an access unit as defined by a specific specification (e.g., the video coding specification described herein). A sample entry can provide a description of the corresponding sample.

[0038] ISOBMFF specifies the following types of tracks: media tracks (which contain the elementary media streams), hint tracks (which contain either media transport instructions or represent received packet streams), and timed metadata tracks (which include metadata for time synchronization).

[0039] Although ISOBMFF was originally designed for storage, it has proven valuable for streaming (e.g., download-as-you-go or DASH). For streaming purposes, movie fragments defined in ISOBMFF can be used. The metadata for each track contains a list of sample description entries (also referred to as sample entries), each sample description entry providing the coding or encapsulation format used in the track and the initialization data required to handle the format. Each sample can be associated with one of the sample description entries for the track. As described herein, a sample can correspond to an access unit in video coding. For example, a sample can correspond to a unit of video data that contains all view components for a common time instance (e.g., all network abstraction layer (NAL) units). A parameter set sample can be a sample in a parameter set stream that contains parameter set NAL units that are considered to be present in a video elementary stream at the same time instance.

[0040] ISOBMFF implements sample-specific metadata specified through a variety of mechanisms. Certain boxes within the Sample Table box ("stbl") have been standardized to address common needs. For example, the Synchronous Sample box ("stss") is used to list random access samples for a track (described below). A sample grouping mechanism enables the mapping of samples into groups of samples sharing the same characteristics based on a four-character grouping type, specified as a sample group description entry in the file. Several grouping types have been specified in ISOBMFF.

[0041] The ISOBMFF specification specifies six types of stream access points (SAPs) for use with DASH. The first two SAP types (types 1 and 2) correspond to IDR pictures in H.264 / AVC and HEVC. The third SAP type (type 3) corresponds to an open GOP random access point; thus, it corresponds to a BLA or CRA picture in HEVC. The fourth SAP type (type 4) corresponds to a GDR random access point.

[0042] However, the term "random access point" can have multiple, potentially inconsistent definitions across ISOBMFF. For example, a video codec (e.g., a video encoder or a video decoder) that conforms to one part of ISOBMFF may determine whether a sample is a random access point differently than a video codec that conforms to another part of ISOBMFF. When random access points are interpreted differently by different devices (e.g., a device responsible for encoding / packaging video data and a device responsible for parsing / decoding video data), the file may not be properly delivered and / or played.

[0043] For example, due to different interpretations of the term "random access point" in ISOBMFF, restrictions on the placement of parameter sets in the AVC file format, SVC file format, MVC file format, and HEVC file format may be interpreted differently. As a result, a file may be considered ISOBMFF-compliant by some implementations but non-ISOBMFF-compliant by other implementations. Due to these inconsistencies, a video decoder may not be able to accurately and / or consistently determine whether conditions associated with random access points, such as conditions associated with parameter sets, have been met for a particular bitstream. In some cases, a file may be denied a request or playback.

[0044] The technology of the present invention can solve one or more of the above problems. For example, according to aspects of the present invention, the restrictions on the placement of parameter sets in the AVC file format, the SVC file format, the MVC file format, and the HEVC file format can be updated according to ISOBMFF to solve the interoperability issues mentioned above.

[0045] For example, according to aspects of this disclosure, a video coder (e.g., a video encoder or a video decoder) can determine whether a sample of video data (e.g., an access unit containing at least one coded picture for a particular time instance) is a synchronization sample. Generally speaking, a synchronization sample is a sample that can be used for synchronization (e.g., during bitstream switching or splicing). A sample can be considered a synchronization sample if conditions for random access (described in more detail below) are met so that the video decoder can begin properly decoding the synchronization sample and all samples that follow the synchronization sample in decoding order.

[0046] According to aspects of the present invention, based on determining that a sample is not a sync sample, the video decoder may decode parameter set data for the video data that appears only in the sample entry for the sample or in samples between, inclusive, the sample and, in decoding order, the preceding sample, inclusive, that is a sync sample. That is, the video decoder may determine the parameter set data required to decode the video data of the non-sync sample only from the sample entry for the non-sync sample, the non-sync sample itself, the preceding sync sample in decoding order, or one or more samples between the preceding sync sample and the non-sync sample. For example, if the sample is not a sync sample and the parameter set data is included in any other location in the bitstream other than those specified, the video decoder 30 may reject the file due to non-compliance and may not decode the sample. As described in more detail below, the parameter set may include sequence-level header information that does not need to be repeated for each sequence or picture, or picture-level information that does not change frequently (thereby improving decoding efficiency).

[0047] Figure 1 is a block diagram illustrating an example video encoding and decoding system 10 in which techniques for determining one or more target output layers may be used according to aspects of the present invention. Figure 1 As shown in , system 10 includes a source device 12 that provides encoded video data that is later decoded by a destination device 14. In particular, source device 12 provides the video data to destination device 14 via a computer-readable medium 16.

[0048] Source device 12 and destination device 14 may comprise any of a wide range of devices, including desktop computers, notebook (i.e., laptop) computers, tablet computers, set-top boxes, telephone handsets (e.g., so-called "smart" phones), so-called "smart" tablets, televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, or the like. In some cases, source device 12 and destination device 14 may be equipped for wireless communication.

[0049] Destination device 14 may receive the encoded video data to be decoded via computer-readable medium 16. Computer-readable medium 16 may comprise any type of medium or device capable of moving the encoded video data from source device 12 to destination device 14. In one example, computer-readable medium 16 may comprise a communication medium that enables source device 12 to transmit the encoded video data directly to destination device 14 in real-time.

[0050] The encoded video data may be modulated according to a communication standard (e.g., a wireless communication protocol) and transmitted to destination device 14. The communication medium may include any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form part of a packet-based network (e.g., a local area network, a wide area network, or a global network such as the Internet). The communication medium may include routers, switches, base stations, or any other equipment that can be used to facilitate communication from source device 12 to destination device 14.

[0051] In some examples, the encoded data may be output from output interface 22 to a storage device. Similarly, the encoded data may be accessed from the storage device via input interface 28. The storage device may include any of a variety of distributed or locally accessible data storage media, such as a hard drive, a Blu-ray disc, a DVD, a CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data. In another example, the storage device may correspond to a file server or another intermediate storage device that can store the encoded video generated by source device 12.

[0052] Destination device 14 may access the stored video data from the storage device via streaming or downloading. The file server may be any type of server capable of storing and transmitting the encoded video data to destination device 14. Example file servers include a network server (e.g., for a website), an FTP server, a network attached storage (NAS) device, or a local disk drive.

[0053] Destination device 14 may access the encoded video data through any standard data connection, including an Internet connection. This may include a wireless channel (e.g., a Wi-Fi connection), a wired connection (e.g., DSL, cable modem, etc.), or a combination of both, suitable for accessing encoded video data stored on a file server. The transmission of the encoded video data from the storage device may be a streaming transmission, a download transmission, or a combination thereof.

[0054] The techniques of this disclosure are not necessarily limited to wireless applications or settings. The techniques may be applied to video decoding to support any of a variety of multimedia applications, such as over-the-air television broadcasting, cable television transmission, satellite television transmission, Internet streaming video transmission (e.g., Dynamic Adaptive Streaming over HTTP (DASH)), digital video encoded onto a data storage medium, decoding of digital video stored on a data storage medium, or other applications. In some examples, system 10 may be configured to support one-way or two-way video transmission to support applications such as video streaming, video playback, video broadcasting, and / or video telephony.

[0055] exist Figure 1 In the example of , source device 12 includes a video source 18, a video encoder 20, an encapsulation unit 21, and an output interface 22. Destination device 14 includes an input interface 28, a decapsulation unit 29, a video decoder 30, and a display device 32. In other examples, the source and destination devices may include other components or arrangements. For example, source device 12 may receive video data from an external video source 18, such as an external camera. Similarly, destination device 14 may interface with an external display device rather than including an integrated display device.

[0056] Figure 1 The illustrated system 10 is merely one example. The techniques described herein may be performed by any digital video encoding and / or decoding device. Although the techniques of this disclosure are typically performed by a video encoding device, the techniques may also be performed by a video encoder / decoder (often referred to as a "codec"). Furthermore, the techniques of this disclosure may also be performed by a video preprocessor.

[0057] Source device 12 and destination device 14 are merely examples of such coding devices in which source device 12 generates coded video data for transmission to destination device 14. In some examples, devices 12, 14 may operate in a substantially symmetrical manner, such that each of devices 12, 14 includes video encoding and decoding components. Thus, system 10 may support one-way or two-way video transmission between video devices 12, 14, e.g., for video streaming, video playback, video broadcasting, or video telephony.

[0058] Video source 18 of source device 12 may include a video capture device, such as a video camera, a video archive containing previously captured video, and / or a video feed interface for receiving video from a video content provider. As another alternative, video source 18 may generate computer graphics-based data as the source video, or a combination of live video, archived video, and computer-generated video. In some cases, if video source 18 is a video camera, source device 12 and destination device 14 may form so-called camera phones or video phones. However, as mentioned above, the techniques described in this disclosure are generally applicable to video coding and may be applied to wireless and / or wired applications. In each case, the captured, pre-captured, or computer-generated video may be encoded by video encoder 20.

[0059] Video encoder 20 typically generates a stream of encoded video data. Each individual data stream (whether audio or video) may be referred to as an elementary stream. An elementary stream is a single digitally coded (possibly compressed) component of a representation. For example, the coded video or audio portion of the representation may be an elementary stream. An elementary stream may be converted into a packetized elementary stream (PES) before being encapsulated in a video file. In some instances, video encoder 20 may include a packetizer for forming PES packets from the encoded data. In other instances, video encoder 20 may interface with a corresponding packetizer for forming PES packets from the encoded data. In yet other instances, video encoder 20 may include a packetizer for forming PES packets from the encoded audio and video data.

[0060] Encapsulation unit 21 receives PES packets from video encoder 20 for elementary streams to be represented and forms corresponding NAL units from the PES packets. In the examples of H.264 / AVC and HEVC, decoded video segments are organized into NAL units that provide a "network-friendly" video representation that handles applications such as video telephony, storage, broadcast, or streaming. NAL units can be categorized as Video Coding Layer (VCL) NAL units and non-VCL NAL units. VCL units may contain the core compression engine and may include block, macroblock, and / or slice level data. Other NAL units may be non-VCL NAL units. In some examples, a decoded picture in a time instance (typically presented as a primary decoded picture) may be contained in an access unit, which may include one or more NAL units.

[0061] As noted above, an access unit is typically a unit that includes data for all view components (e.g., all NAL units) for a common time instance. The view components of an access unit are typically intended to be output together (i.e., output substantially simultaneously), where outputting a picture typically involves transferring the picture from a decoded picture buffer (DPB) (e.g., storing the picture from the DPB to external memory, sending the picture from the DPB to a display, removing the picture from the DPB, or the like).

[0062] Non-VCL NAL units can include parameter set NAL units and SEI NAL units, among others. Parameter sets can contain sequence-level header information (in a sequence parameter set (SPS)) and infrequently changing picture-level header information (in a picture parameter set (PPS)). With parameter sets (e.g., PPS and SPS), infrequently changing information does not need to be repeated for every sequence or picture, thus improving coding efficiency. Furthermore, the use of parameter sets enables out-of-band transmission of important header information, avoiding the need for redundant transmission for error recovery. In the out-of-band transmission example, parameter set NAL units can be transmitted on a different channel than other NAL units (e.g., SEI NAL units).

[0063] Supplementary Enhancement Information (SEI) may contain information that is not required for decoding coded picture samples from VCL NAL units, but may assist in processes related to decoding, display, error recovery, and other purposes. SEI messages may be included in non-VCL NAL units. SEI messages are a normative part of some standard specifications and are therefore not always required for standard-compliant decoder implementations. SEI messages may be sequence-level SEI messages or picture-level SEI messages. Some sequence-level information may be contained in SEI messages, such as scalability information SEI messages in the case of SVC and view scalability information SEI messages in MVC. These example SEI messages may convey information about, for example, the extraction of operation points and the characteristics of the operation points. In addition, encapsulation unit 21 may form a manifest file, such as a media presentation descriptor (MPD), that describes the characteristics of a representation. Encapsulation unit 21 may format the MPD according to Extensible Markup Language (XML).

[0064] Output interface 22 can output the encoded video onto computer-readable medium 16. Computer-readable medium 16 can include transient media, such as wireless broadcast or wired network transmission, or storage media (that is, non-transitory storage media) such as a hard disk, flash drive, compact disc, digital video disc, Blu-ray disc, or other computer-readable media. In some examples, a network server (not shown) can receive the encoded video data from source device 12 and provide the encoded video data to destination device 14, for example, via network transmission. Similarly, a computing device at a media production facility (e.g., a disc stamping facility) can receive the encoded video data from source device 12 and produce a disc containing the encoded video data. Thus, in various examples, computer-readable medium 16 can be understood to include one or more computer-readable media in various forms.

[0065] Input interface 28 of destination device 14 may receive data for a fragment of a particular representation. Decapsulation unit 29 may decapsulate the elements of the video file into constituent PES streams, decapsulate the PES streams to retrieve the encoded data, and send the encoded data to video decoder 30. Video decoder 30 decodes the encoded video data and sends the decoded video data (which may include multiple views of the stream) to display device 32. Display device 32 displays the decoded video data to a user and may include any of a variety of display devices, such as a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

[0066] The video encoder 20, encapsulation unit 21, decapsulation unit 29, and video decoder 30, the post-processing entity 27 and the network entity 79 described below, and other components described in this disclosure may each be implemented as any of a variety of suitable integrated circuit processing circuit systems, such as one or more processors, including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic circuit systems, software, hardware, firmware, or any combination thereof, as described in this disclosure. Thus, as described in this disclosure, the components of the video encoder 20, encapsulation unit 21, decapsulation unit 29, and video decoder 30, as well as the post-processing entity 27 and the network entity 79, may be formed by any of a variety of integrated processing circuit systems, including one or more processors implemented as fixed hardware processing circuit systems, programmable processing circuit systems, and / or a combination of both. Each of the video encoder 20 and the video decoder 30 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined video encoder / decoder (CODEC). An apparatus including video encoder 20, video decoder 30, encapsulation unit 21, and / or decapsulation unit 29 may include an integrated circuit, a microprocessor, and / or a wireless communication device, such as a cellular telephone.

[0067] This disclosure may generally refer to video encoder 20 (and / or server / content delivery network 34) "signaling" certain information to another device, such as video decoder 30. However, it should be understood that video encoder 20 and / or server / content delivery network 34 may signal information by associating certain syntax elements with various encoded portions of video data. That is, video encoder 20 and / or server / content delivery network 34 may "signal" data by storing certain syntax elements in the headers of various encoded portions of video data. In some cases, such syntax elements may be encoded and stored (e.g., to storage device 24) before being received and decoded by video decoder 30. Thus, the term "signaling" may generally refer to the transmission of syntax or other data for use in decoding compressed video data, regardless of whether such transmission occurs in real-time or near real-time or over a time span, such as when syntax elements are stored to a storage medium at encoding time, which may then be retrieved by a decoding device at any time after being stored to such medium.

[0068] Video encoder 20 and video decoder 30 may operate in accordance with a video compression standard, such as the ITU-T H.264 standard (alternatively referred to as MPEG-4 Part 10 Advanced Video Coding (AVC)), or extensions of such standards, such as Multi-View Video Coding (MVC) or Scalable Video Coding (SVC). The ITU-T H.264 / MPEG-4 (AVC) standard was developed by the ITU-T Video Coding Experts Group (VCEG) in conjunction with the ISO / IEC Moving Picture Experts Group (MPEG) as a product of a collective partnership known as the Joint Video Team (JVT). The H.264 standard is described in the ITU-T Study Group's "ITU-T Recommendation H.264, Advanced Video Coding for generic audiovisual services," dated March 2005, which may be referred to herein as the H.264 standard or H.264 specification or the H.264 / AVC standard or specification.

[0069] In other examples, video encoder 20 and video decoder 30 may operate according to the HEVC video coding standard (also known as ITU-T H.265 and ISO / IEC 23008-2) or extensions of HEVC, such as Scalable High Efficiency Video Coding (SHVC) or Multi-view High Efficiency Video Coding (MV-HEVC). The final HEVC standard document was published as “ITU-T H.265, Series H: Audiovisual and Multimedia Systems Infrastructure of audiovisual services—Coding of moving video—High efficiency video coding,” Telecommunication Standardization Sector of the International Telecommunication Union (ITU), April 2013.

[0070] HEVC allows a video picture to be divided into a sequence of treeblocks, or largest coding units (LCUs), that include both luma and chroma samples. Syntax data within the bitstream may define the size of the LCU, which is the largest coding unit in terms of the number of pixels. A slice comprises multiple consecutive coding tree units (CTUs). Each CTU may comprise a coding treeblock of luma samples, two corresponding coding treeblocks of chroma samples, and syntax structures for coding the samples of the coding treeblocks. In black and white pictures or pictures with three separate color planes, a CTU may comprise a single coding treeblock and syntax structures for coding the samples of the coding treeblock.

[0071] A video picture may be partitioned into one or more slices. Each tree block may be split into several coding units (CUs) according to a quadtree. In general, a quadtree data structure includes one node for each CU, with one root node corresponding to the tree block. If a CU is split into four sub-CUs, the node corresponding to the CU includes four leaf nodes, where each of the leaf nodes corresponds to one of the sub-CUs. A CU may include a coding block of luma samples of a picture having a luma sample array, a Cb sample array, and a Cr sample array, and two corresponding coding blocks of chroma samples, and a syntax structure for coding the samples of the coding block. In a black and white picture or a picture with three separate color planes, a CU may include a single coding block and a syntax structure for coding the samples of the coding block. A coding block is an N×N block of samples.

[0072] Each node of the quadtree data structure may provide syntax data for the corresponding CU. For example, a node in the quadtree may include a split flag indicating whether the CU corresponding to the node is split into sub-CUs. Syntax elements for a CU may be defined recursively and may depend on whether the CU is split into sub-CUs. If a CU is not further split, it is referred to as a leaf-CU. In this disclosure, the four sub-CUs of a leaf-CU will also be referred to as leaf-CUs, even if there is no explicit splitting of the original leaf-CU. For example, if a 16×16 sized CU is not further split, then the four 8×8 sub-CUs will also be referred to as leaf-CUs, even though the 16×16 CU has never been split.

[0073] CUs have similar purposes to macroblocks of the H.264 standard, except that CUs do not have a size distinction. For example, a treeblock can be split into four child nodes (also called sub-CUs), and each child node can be a parent node and can be split into another four child nodes. The last unsplit child node (called a leaf node of the quadtree) comprises a coding node, also called a leaf CU. Syntax data associated with the coded bitstream can define the maximum number of times a treeblock can be split, called the maximum CU depth, and can also define the minimum size of a coding node. Therefore, the bitstream can also define a smallest coding unit (SCU). This disclosure uses the term "block" to refer to any of a CU, PU, or TU in the case of HEVC, or similar data structures in the case of other standards (e.g., macroblocks and subblocks in H.264 / AVC).

[0074] A CU includes a coding node and the prediction units (PUs) and transform units (TUs) associated with the coding node. The size of a CU corresponds to the size of the coding node and must be square in shape. The size of a CU can vary from 8×8 pixels to a treeblock size of 64×64 pixels or larger. Each CU may contain one or more PUs and one or more TUs.

[0075] In general, a PU represents a spatial region corresponding to all or a portion of the corresponding CU and may include data for retrieving reference samples for the PU. In addition, a PU includes data related to prediction. For example, when the PU is intra-mode encoded, the data for the PU may be included in a residual quadtree (RQT), which may include data describing the intra-prediction mode for the TU corresponding to the PU. As another example, when the PU is inter-mode encoded, the PU may include data defining one or more motion vectors for the PU. A prediction block may be a rectangular (i.e., square or non-square) block of samples on which the same prediction is applied. A PU of a CU may include a prediction block of luma samples of a picture, two corresponding prediction blocks of chroma samples of the picture, and a syntax structure for predicting the prediction block samples. In a black and white picture or a picture with three separate color planes, a PU may include a single prediction block and a syntax structure for predicting the prediction block samples.

[0076] After applying a transform (e.g., a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform) to the residual video data, a TU may include coefficients in the transform domain. The residual data may correspond to pixel differences between pixels of an unencoded picture and prediction values corresponding to the PU. Video encoder 20 may form a TU containing the residual data for a CU and then transform the TU to produce transform coefficients for the CU. A transform block may be a rectangular block of samples to which the same transform is applied. A transform unit (TU) of a CU may include a transform block of luma samples, two corresponding transform blocks of chroma samples, and syntax structures for transforming the transform block samples. In black and white pictures or pictures with three separate color planes, a TU may include a single transform block and syntax structures for transforming the transform block samples.

[0077] After performing intra-predictive or inter-predictive coding using a PU of a CU, video encoder 20 may calculate residual data for the TUs of the CU. A PU may include syntax data describing a method or mode for generating predictive pixel data in the spatial domain (also called the pixel domain), and a TU may include coefficients in the transform domain after applying a transform (e.g., a discrete cosine transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform) to the residual video data. The residual data may correspond to pixel differences between pixels of an unencoded picture and prediction values corresponding to the PU. Video encoder 20 may form the TUs containing the residual data for the CU and then transform the TUs to produce transform coefficients for the CU. After any transforms used to produce transform coefficients, video encoder 20 may perform quantization of the transform coefficients. Quantization generally refers to the process by which transform coefficients are quantized to potentially reduce the amount of data used to represent the coefficients, thereby providing further compression. After quantization, the video encoder may scan the transform coefficients, producing a one-dimensional vector from a two-dimensional matrix containing the quantized transform coefficients.

[0078] After scanning the quantized transform coefficients to form a one-dimensional vector, video encoder 20 may entropy encode the one-dimensional vector, e.g., according to context-adaptive variable length coding (CAVLC), context-adaptive binary arithmetic coding (CABAC), syntax-based context-adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy (PIPE) coding, or another entropy encoding method. Video encoder 20 may also entropy encode syntax elements associated with the encoded video data for use by video decoder 30 in decoding the video data.

[0079] exist Figure 1In the example shown in FIG, system 10 also includes a server / content delivery network 34 having a router 36. In some examples, as described above, source device 12 can communicate with server / content delivery network 34 via a variety of wireless and / or wired transmission or storage media. Figure 1 , but in some examples, source device 12 and server / content delivery network 34 comprise the same device. Server / content delivery network 34 may store one or more versions of the coded video data (from video encoder 20 of source device 12) and may make such coded video data accessible to destination device 14 and video decoder 30.

[0080] In some examples, router 36 may be responsible for providing the coded video data to destination device 14 in the requested format. In other examples, encapsulation unit 21 may be responsible for encapsulating the encoded video data in a particular format. File format standards include the ISO Base Media File Format (ISOBMFF, ISO / IEC 14496-12) and other formats derived from ISOBMFF, including the MPEG-4 file format (ISO / IEC 14496-14), the 3GPP file format (3GPP TS 26.244), and the AVC file format (ISO / IEC 14496-15). Additionally, server / content delivery network 34 may be responsible for splicing and / or switching bitstreams.

[0081] As follows Figure 4 In more detail, a box refers to a syntax structure in ISOBMFF that contains a four-character encoding of the box type, the number of bytes in the box, and the payload. An ISOBMFF file consists of a series of boxes, and boxes can contain other boxes. The movie box ("moov") contains metadata for the continuous media streams present in the file, each of which is presented as a track in the file.

[0082] The metadata for a track is encapsulated in a track box ("trak"), while the media content of the track is either encapsulated in a media data box ("mdat") or directly in a separate file. The media content of a track consists of a series of samples (e.g., audio access units or video access units). In general, an access unit is a data unit containing coded picture data for a common time instance. A sample is an access unit as defined by a specific specification (e.g., the video coding specification described herein).

[0083] A sample entry may provide a description of the corresponding sample. For example, a sample entry may include a four-character code describing the characteristics of the corresponding sample, such as the format of the corresponding sample. Example sample entries for AVC tracks and SVC tracks are included in the following table:

[0084]

[0085] The above table is for illustrative purposes only. Various other sample entries may be used to describe other types of samples.

[0086] The video encoder 20 (or encapsulation unit 21) may generate certain parameter sets and the video decoder 30 (or decapsulation unit 29) may receive certain parameter sets that may be used when decoding video data. For example, as noted above, a parameter set may include an SPS, PPS, or VPS, which improves efficiency by signaling information that changes infrequently. According to the ISOBMFF file format, a parameter set sample may be a sample in a parameter set stream that includes a parameter set NAL unit that is considered to be present in the video elementary stream at the same time instance. A parameter set sample also exists at each point in a parameter set update. Each parameter set may include sequence and picture parameter sets required for decoding the relevant segment of the video elementary stream. A synchronization sample in the parameter set track may indicate that all parameter sets required from that decoding time forward in the video elementary stream are in that parameter stream sample or in a subsequent parameter stream sample.

[0087] However, in some cases, decapsulation unit 29 and / or video decoder 30 may not properly identify and decode parameter sets. For example, as noted above, because there are different interpretations of the term random access point (RAP) in ISOBMFF, the restrictions on the placement of parameter sets in the AVC file format, the SVC file format, the MVC file format, and the HEVC file format may have different interpretations, and a file may be considered compliant by some embodiments but not compliant by other embodiments. When random access points are interpreted by different devices (e.g., where the different devices may include a device responsible for encoding / packaging video data and a device responsible for parsing / decoding video data), the file may not be properly delivered and / or played.

[0088] For example, in ISOBMFF, a video coder can interpret RAP in at least three different ways, depending on the specific portion of ISOBMFF to which the video coder conforms. In a first example, a RAP can correspond to any of SAP types 1, 2, or 3, but not to other SAP types. For example, a portion of section 3.1.11 of ISOBMFF is reproduced below: 3.1.11

[0090] Random Access Point (RAP)

[0091] A sample in a track that starts at an ISAU of a SAP of type 1, 2, or 3 (as defined in Annex I); informally, a sample such that decoding starting from this sample correctly decodes the sample itself and all subsequent samples in composition order.

[0092] In the above example (referred to as Interpretation 1), RAPs correspond only to SAP types 1 to 3; therefore a progressive decoding refresh (GDR) start point cannot be considered as a RAP.

[0093] In another example, a RAP may correspond to any one of SAP types 1, 2, 3, or 4, but not to other SAP types. For example, a portion of section 10.1.1.3 of ISOBMFF is reproduced below: 10.1.1.3

[0095] roll_distance is a signed integer that gives the number of samples that must be decoded in order to correctly decode the sample. A positive value indicates the number of samples after the sample that is a member of the group that must be decoded so that the recovery is finally complete (i.e., the final sample is correct). A negative value indicates the number of samples before the sample that is a member of the group that must be decoded in order to complete the recovery at the marked sample. A value of zero shall not be used; the sync sample table records random access points where roll recovery is not required.

[0096] In the above example (referred to as Interpretation 2), the GDR starting point may be considered as a RAP, which is inconsistent with the definition of RAP in clause 3.1.11 (mentioned above).

[0097] In a third example, random access points may correspond to synchronization samples, which are codec specific. For example, a portion of section A.7 of ISOBMFF is reproduced below:

[0098] A.7 Random Access

[0099] …

[0100] 3) The sample originally found in step 1 may not be a synchronization sample. A synchronization sample table indicates which samples are actual random access points. Using this table, it is possible to locate which sample is the first synchronization sample before a specified time. The absence of a synchronization sample table indicates that all samples are synchronization points, making this problem simpler. After consulting the synchronization sample table, it is likely that one would want to find which generated sample is closest to (but precedes) the sample found in step 1.

[0101] In the above example (referred to as Explanation 3), the RAP is the Sync sample, and vice versa.

[0102] The interpretation mentioned above may cause parsing and / or decoding difficulties by decapsulation unit 29 or video decoder 30. For example, decapsulation unit 29 or video decoder 30 may determine whether a particular bitstream conforms to a particular standard and, therefore, include information at expected locations based on whether the sample is identified as a RAP. In one example for purposes of illustration, decapsulation unit 29 or video decoder 30 may parse parameter sets from different locations of the bitstream, depending on whether decapsulation unit 29 or video decoder 30 determines that the sample is a RAP sample.

[0103] The following includes example sections of ISO / IEC 14496-15 (referred to herein as ISOBMFF, which includes the AVC file format, the SVC file format, the MVC file format, and the HEVC file format. In these examples, decapsulation unit 29 or video decoder 30 may interpret RAPs differently between different sections (e.g., as mentioned above with respect to Interpretation 1, Interpretation 2, and Interpretation 3), which may affect proper parsing and / or decoding of parameter sets of the bitstream.

[0104] By way of example, a portion of Section 4.8 of ISOBMFF is reproduced below:

[0105] 4.8 Synchronous Sample (IDR)

[0106] …

[0107] When the sample entry name is 'avc3' or 'avc4', the following applies:

[0108] 1. If the sample is an IDR access unit, all parameter sets required to decode the sample shall be contained in the sample entry or the sample itself.

[0109] 2. Otherwise (sample is not an IDR access unit), all parameter sets required to decode the sample shall be contained in the sample entry or in any of the samples since the previous random access point (inclusive) to the sample itself (inclusive).

[0110] In the above example, the decapsulation unit 29 or the video decoder 30 can determine the location of the parameter set of the bitstream based on the definition of the random access point. However, as noted above, the decapsulation unit 29 or the video decoder 30 can inconsistently determine the definition of the random access point, for example, as mentioned above with respect to Explanations 1, 2, and 3. Thus, the decapsulation unit 29 or the video decoder 30 can determine that the bitstream does not conform to a particular video coding standard based on one definition of the random access point, when in fact the bitstream does conform to the video coding standard based on another definition of the random access point. The same issue applies to sections 6.5.5 and 7.5.3 of the ISOBMFF for the SVC file format and the MVC file format, respectively (both having the same title as section 4.8).

[0111] As another example, a portion of Section 8.4.3 of ISOBMFF is reproduced below:

[0112] 8.4.3 Synchronous Samples

[0113] …

[0114] An HEVC sample is considered a sync sample if the VCL NAL unit in the sample indicates that the coded picture included in the sample is an Instantaneous Decoding Refresh (IDR) picture, a Clean Random Access (CRA) picture, or a Broken Link Access (BLA) picture.

[0115] When the sample entry name is 'hev1', the following applies:

[0116] If the sample is a random access point, all parameter sets required to decode the sample shall be contained in the sample entry or in the sample itself.

[0117] • Otherwise (sample is not a random access point), all parameter sets required to decode the sample shall be contained in the sample entry or in any of the samples from the previous random access point (inclusive) to the sample itself (inclusive).

[0118] Likewise, different possible random access point interpretations may affect restrictions on the placement of parameter sets, and interoperability issues may arise when a formatter (e.g., video encoder 20 or encapsulation unit 21) and a parser (e.g., decapsulation unit 29 or video decoder 30) use two different interpretations.

[0119] According to aspects of this disclosure, video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30 may impose restrictions on the placement of parameter sets for proper decoding and playback of video files. Example syntax and semantics for coding parameter sets, according to various techniques of this disclosure, are provided below. As mentioned, the syntax and semantics described are relative to the syntax and semantics of, for example, AVC, HEVC, SVC, MVC, or the like.

[0120] In the example description, the following syntax table and semantics, related standard additions are used Bold and underline Required are presented and deleted using [[double brackets]]. In general, statements regarding "requirements" should be understood as forming part of the text of a standard or standard extension, rather than being requirements for the purposes of the techniques of this disclosure. In some cases, such "requirements" may include bitstream restrictions that may be determined to be applicable and then complied with by, for example, a video coder based on that determination.

[0121] In one example, according to aspects of the present disclosure, video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30 may conform to an updated version of section 4.8 of the AVC file format, in which “random access point” is replaced with “a sample that is an IDR access unit” as follows:

[0122] 4.8 Synchronous Sample (IDR)

[0123] A sample is considered a sync sample if [[all of the following conditions are met]] the video data NAL unit in the sample indicates that the primary picture contained in the sample is an instantaneous decoding refresh (IDR) picture.

[0124] When the sample entry name is 'avc3' or 'avc4', the following applies:

[0125] 1. If the sample is an IDR access unit, all parameter sets required to decode the sample shall be contained in the sample entry or the sample itself.

[0126] 2. Otherwise (the sample is not an IDR access unit), all parameter sets required to decode the sample shall be contained in the sample entry or from For IDR access unit Previous [[Random Access Point]] sample (inclusive) to any of the samples from the sample itself (inclusive).

[0127] The same changes apply to sections 6.5.5 and 7.5.3 of the ISOBMFF for the SVC and MVC file formats, respectively (both with the same title as section 4.8). In this example, the video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be configured to determine that a sample is a synchronization sample if the video data NAL unit in the sample indicates that the primary picture contained in the sample is an IDR picture. The video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be further configured such that, if the sample is an IDR access unit, all parameter sets required for decoding the sample are included (e.g., encoded, stored, or located) in the sample's sample entry or in the sample itself. Thus, when the sample is an IDR access unit, by including all parameter sets required for decoding the sample in this manner, the video decoder 30 can determine parameter set data for the synchronization sample's video data simply from the sample's sample entry or the sample itself. Determining the parameter set data may, for example, refer to parsing, decoding, retrieving, or acquiring the parameter set data.

[0128] In this example, all parameter sets required to decode the sample are contained in the sample's sample entry or the sample itself. Thus, parameter set data for decoding the sample's video data is contained solely in the sample's sample entry or the sample itself. Similarly, to decode the sample's video data, all parameter set data required to decode the sample's video data is determined from the sample's sample entry or the sample itself. Thus, to decode, parameter set data for the video data is determined solely from the sample's sample entry or the sample itself.

[0129] Furthermore, in this example, the video encoder 20, the encapsulation unit 21, the decapsulation unit 29, and / or the video decoder 30, or other devices, may be configured such that, if the sample is not an IDR access unit, all parameter sets required for decoding the sample are included (e.g., encoded, stored, or placed) in the sample entry of the sample, or in any of the samples from (including) a previous sample that is an IDR access unit to (including) the sample that is not an IDR access unit. That is, if the sample is not an IDR access unit, all parameter sets required for decoding the sample are included in the sample entry of the sample that is not an IDR access unit, the sample that is not an IDR access unit, the previous sample that is an IDR access unit, or a sample that follows the previous sample that is an IDR access unit and precedes the sample itself (i.e., before the sample that is not an IDR access unit). With all parameter sets required for decoding a sample that is not an IDR access unit included in this manner, video decoder 30 can determine parameter set data for the video data of a sample solely from the sample's sample entry, the sample itself, a previous sample that is an IDR access unit, or from samples occurring between a sample that is not an IDR access unit and its previous sample that is an IDR access unit.

[0130] In this example, all parameter sets required for decoding a sample that is not an IDR access unit are contained in the sample's sample entry, the sample itself, a previous sample that is an IDR access unit, or a sample that occurs between the sample that is not an IDR access unit and its previous sample that is an IDR access unit. Thus, parameter set data for decoding the video data of the sample is contained only in the sample's sample entry, the sample itself, a previous sample that is an IDR access unit, or a sample that occurs between the sample that is not an IDR access unit and its previous sample that is an IDR access unit. Similarly, to decode the video data of the sample, all parameter set data required for decoding the video data of the sample is determined from the sample's sample entry, the sample itself, a previous sample that is an IDR access unit, or a sample that occurs between the sample that is not an IDR access unit and its previous sample that is an IDR access unit. Therefore, in order to decode the video data of a sample, the parameter set data of the video data is determined only from the sample entry of the sample, the sample itself, the previous sample which is an IDR access unit, or from samples occurring between a sample which is not an IDR access unit and the previous sample which is an IDR access unit.

[0131] In some examples, the video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be further configured such that if a sample is an IDR access unit and the sample entry name is a specific name (e.g., 'avc3' or 'avc4'), all parameter sets required for decoding the synchronization sample are included (e.g., encoded, stored, or located) in the sample entry for the sample or in the sample itself. Thus, by including all parameter sets required for decoding the sample in this manner, the video decoder 30 can determine that parameter set data for the sample's video data is only in the sample entry for the sample or in the sample itself if the sample is an IDR access unit and the sample entry name is a specific name (e.g., 'avc3' or 'avc4'). Thus, parameter set data can be determined in this manner based on determining that the sample is an IDR access unit and further based on the sample entry name, e.g., the sample entry name being a specific name or one of a set of specific names (e.g., 'avc3' or 'avc4'). If the sample entry name is not a specific name, the placement or determination of parameter set data may be handled differently.

[0132] In some examples, the video encoder 20, the encapsulation unit 21, the decapsulation unit 29, and / or the video decoder 30, or other devices, may be further configured such that, if the sample is not an IDR access unit and the sample entry name is a specific name (e.g., 'avc3' or 'avc4'), all parameter sets required to decode the synchronization sample are included (e.g., encoded, stored, or placed) in the sample entry of the sample that is not an IDR access unit, the sample itself that is not an IDR access unit, the previous sample that is an IDR access unit, or a sample that follows the previous sample that is an IDR access unit and precedes the sample itself (i.e., before the sample that is not an IDR access unit). Thus, with all parameter sets required for decoding a sample included in this manner, if the sample is not an IDR access unit and the sample entry name is a specific name (e.g., 'avc3' or 'avc4'), video decoder 30 can determine that parameter set data for the video data of the sample is only in the sample entry of the sample that is not an IDR access unit, the sample itself that is not an IDR access unit, the previous sample that is an IDR access unit, or a sample that is after the previous sample that is an IDR access unit and before the sample itself (i.e., before the sample that is not an IDR access unit). Thus, parameter set data can be decoded in this manner based on a determination that the sample is not an IDR access unit and further based on the sample entry name, e.g., the sample entry name being a specific name or one of a set of specific names (e.g., 'avc3' or 'avc4'). If the sample entry name is not a specific name, the placement or determination of parameter set data may be handled differently.

[0133] In another example, according to aspects of the present invention, for example, video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30 may conform to an updated version of section 4.8 of the AVC file format as follows:

[0134] 4.8 Synchronous Sample (IDR)

[0135] A sample is considered a sync sample if [[all of the following conditions are met]] the video data NAL unit in the sample indicates that the primary picture contained in the sample is an instantaneous decoding refresh (IDR) picture.

[0136] When the sample entry name is 'avc3' or 'avc4', the following applies:

[0137] 1. If the sample is an [[IDR access unit]] Synchronous samples , then all parameter sets required to decode the sample will be contained in the sample entry or the sample itself.

[0138] 2. Otherwise (the sample is not an [[IDR access unit]] Synchronous samples ), all parameter sets required to decode the sample will be contained in the sample entry or from the previous [[random access point]] Synchronous samples (included) into any of the samples that the sample itself (includes).

[0139] Likewise, the same changes apply to sections 6.5.5 and 7.5.3 of the ISOBMFF for the SVC file format and the MVC file format, respectively (both having the same title as section 4.8). In this example, the video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be configured to determine that a sample is a synchronization sample if the video data NAL unit in the sample indicates that the primary picture contained in the sample is an IDR picture. The video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be further configured such that, if the sample is a synchronization sample, all parameter sets required for decoding the synchronization sample are included (e.g., by the video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or another device) in the sample entry for the synchronization sample or in the synchronization sample itself. Thus, by decoding all parameter sets required for the synchronization sample included in this manner, the video decoder 30 can determine that the parameter set data for the video data of the synchronization sample is only in the sample entry for the sample or in the sample itself. Determining parameter set data may refer to, for example, parsing, decoding, retrieving, or obtaining the parameter set data.

[0140] In this example, all parameter sets required to decode the sync sample are contained within the sample entry for the sync sample or the sync sample itself. Thus, parameter set data for decoding the video data of the sync sample is contained solely within the sample entry for the sync sample or the sync sample itself. Similarly, to decode the video data of the sync sample, all parameter set data required to decode the video data of the sync sample is determined from the sample entry for the sync sample or the sync sample itself. Thus, for decoding, parameter set data for the video data is determined by the decoder 30 solely from the sample entry for the sync sample or the sync sample itself.

[0141] Furthermore, in this example, video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be configured such that, if a sample is not a sync sample, all parameter sets required for decoding the sample are included in either the sample entry for the sample or samples from (including) the previous sync sample up to (including) the sample itself. That is, if the sample is not a sync sample, all parameter sets required for decoding the sample that is not a sync sample are included (e.g., encoded, stored, or located) in the sample entry for the sample that is not a sync sample, the sample itself that is not a sync sample, the previous sync sample, or one or more samples after the previous sample and before the sample itself (i.e., before the sample that is not a sync sample). Samples that are not sync samples may also be referred to as non-sync samples. By decoding all parameter sets required for the non-sync sample included in this manner, video decoder 30 can determine parameter set data for the video data of the non-sync sample solely from the sample entry for the sample, the sample itself, the previous sync sample, or samples occurring between the non-sync sample and the previous sync sample.

[0142] In this example, all parameter sets required for decoding an unsynchronized sample are contained in the sample entry for the unsynchronized sample, the unsynchronized sample itself, the previous sample that is the synchronized sample, or a sample that occurs between the unsynchronized sample and the previous synchronized sample. Thus, parameter set data for decoding video data for an unsynchronized sample is contained only in the sample entry for the unsynchronized sample, the unsynchronized sample itself, the previous sample that is the synchronized sample, or a sample that occurs between the unsynchronized sample and the previous synchronized sample. Similarly, to decode video data for an unsynchronized sample, all parameter set data required for decoding the video data for an unsynchronized sample is determined from the sample entry for the unsynchronized sample, the unsynchronized sample itself, the previous synchronized sample, or a sample that occurs between the unsynchronized sample and the previous synchronized sample. Thus, to decode video data for an unsynchronized sample, parameter set data for the video data is determined only from the sample entry for the unsynchronized sample, the unsynchronized sample itself, the previous synchronized sample, or a sample that occurs between the unsynchronized sample and the previous synchronized sample.

[0143] In some examples, video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be further configured such that if a sample is a sync sample and the sample entry name is a specific name (e.g., 'avc3' or 'avc4'), all parameter sets required for decoding the sync sample are included (e.g., encoded, stored, or located) within the sample entry for the sync sample or within the sync sample itself. Thus, by decoding all parameter sets required for the sample included in this manner, video decoder 30 can determine that parameter set data for the video data of the sync sample is only within the sample entry for the sync sample or within the sync sample itself if the sample is a sync sample and the sample entry name is a specific name (e.g., 'avc3' or 'avc4'). Thus, parameter set data can be decoded in this manner based on determining that the sample is a sync sample and further based on the sample entry name, e.g., the sample entry name being a specific name or one of a set of specific names (e.g., 'avc3' or 'avc4'). If the sample entry name is not a specific name, the placement or determination of parameter set data may be handled differently.

[0144] In some examples, the video encoder 20, the encapsulation unit 21, the decapsulation unit 29, and / or the video decoder 30, or other devices, may be further configured such that, if the sample is not a synchronization sample and the sample entry name is 'avc3' or 'avc4', all parameter sets required for decoding the sample are included (e.g., encoded, stored, or located) in the sample entry of the sample that is not a synchronization sample, the sample itself that is not a synchronization sample, the previous synchronization sample, or a sample that is after the previous synchronization sample and before the sample itself (i.e., before the sample that is not a synchronization sample). Thus, by decoding all parameter sets required for the sample included in this manner, the video decoder 30 may determine that, if the sample is not a synchronization sample and the sample entry name is a specific name (e.g., 'avc3' or 'avc4'), parameter set data for the video data of the sample is only in the sample entry of the sample that is not a synchronization sample, the sample itself that is not a synchronization sample, the previous synchronization sample, or one or more samples that are after the previous synchronization sample and before the sample itself (i.e., before the sample that is not a synchronization sample). Thus, parameter set data can be determined in this manner based on determining that the sample is not a synchronization sample and further based on the sample's entry name, for example, the sample entry name is a specific name or one of a set of specific names (e.g., 'avc3' or 'avc4'). If the sample entry name is not a specific name, the placement or determination of parameter set data can be handled differently.

[0145] With respect to HEVC, in another example according to the techniques of this disclosure, video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30 may conform to an updated version of section 8.4.3 of the HEVC file format, in which “random access points” are replaced with “synchronization samples,” as follows:

[0146] 8.4.3 Synchronous Samples

[0147] …

[0148] An HEVC sample is considered a sync sample if the VCL NAL unit in the sample indicates that the coded picture included in the sample is an Instantaneous Decoding Refresh (IDR) picture, a Clean Random Access (CRA) picture, or a Broken Link Access (BLA) picture.

[0149] When the sample entry name is 'hev1', the following applies:

[0150] If the sample is a [[random access point]] Synchronous samples , then all parameter sets required to decode the sample will be contained in the sample entry or the sample itself.

[0151] Otherwise (the sample is not a [[random access point]] Synchronous samples ), all parameter sets required to decode the sample will be contained in the sample entry or from the previous [[random access point]] Synchronous samples (inclusive) to any of the samples from the sample itself (inclusive).

[0152] In this example, video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be configured to determine that a sample is a synchronization sample if a VCL NAL unit in the sample indicates that the coded picture contained in the sample is an instantaneous decoding refresh (IDR) picture, a clean random access (CRA) picture, or a broken link access (BLA) picture. Video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be further configured such that, if the sample is a synchronization sample, all parameter sets required to decode the video data of the synchronization sample are included in the sample entry for the synchronization sample or in the synchronization sample itself. Thus, by decoding all parameter sets required for the synchronization sample included in this manner, video decoder 30 can determine parameter set data for the video data of the sample from only the sample entry for the sample or from the sample itself for the synchronization sample. Determining parameter set data may refer to, for example, parsing, decoding, retrieving, or obtaining parameter set data.

[0153] In this example, all parameter sets required to decode the synchronization sample are contained within the sample entry for the synchronization sample or the synchronization sample itself. Thus, parameter set data for decoding the video data of the synchronization sample is contained solely within the sample entry for the synchronization sample or the synchronization sample itself. Similarly, to decode the video data of the synchronization sample, all parameter set data required to decode the video data of the synchronization sample is determined from the sample entry for the synchronization sample or the synchronization sample itself. Thus, to decode, parameter set data for the video data is determined solely from the sample entry for the synchronization sample or the synchronization sample itself, for example, by the decoder 30.

[0154] In this example, the video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be configured such that, if a sample is not a sync sample, all parameter sets required for decoding the sample are included in the sample entry for the sample or in any of the samples from the previous sync sample (inclusive) to the sample itself (inclusive). That is, if the sample is not a sync sample, all parameter sets required for decoding the sample are included in the sample entry for the sample that is not a sync sample, the sample itself that is not a sync sample, the previous sync sample, or a sample after the previous sync sample and before the sample itself (i.e., before the sample that is not a sync sample). Samples that are not sync samples may also be referred to as out-of-sync samples. Thus, by decoding all parameter sets required for the out-of-sync sample included in this manner, the video decoder 30 can determine parameter set data for decoding the video data of the out-of-sync sample solely from the sample entry for the out-of-sync sample, the out-of-sync sample itself, the previous sync sample, or from one or more samples occurring between the out-of-sync sample and the previous sync sample.

[0155] In this example, all parameter sets required to decode the unsynchronized sample are contained in the sample entry for the unsynchronized sample, the unsynchronized sample itself, the previous sample that is the synchronized sample, or a sample that occurs between the unsynchronized sample and the previous synchronized sample. Thus, parameter set data for decoding the video data of the unsynchronized sample is contained only in the sample entry for the unsynchronized sample, the unsynchronized sample itself, the previous sample that is the synchronized sample, or a sample that occurs between the unsynchronized sample and the previous synchronized sample. Similarly, to decode the video data of the unsynchronized sample, all parameter set data required to decode the video data of the unsynchronized sample is determined from the sample entry for the unsynchronized sample, the unsynchronized sample itself, the previous synchronized sample, or a sample that occurs between the unsynchronized sample and the previous synchronized sample. Thus, to decode the video data of the unsynchronized sample, parameter set data for the video data is determined, for example, by the video decoder 30, only from the sample entry for the unsynchronized sample, the unsynchronized sample itself, the previous synchronized sample, or one or more samples that occur between the unsynchronized sample and the previous synchronized sample.

[0156] In some examples, video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be further configured such that if a sample is a sync sample and the sample entry name is a specific name (e.g., 'hev1'), all parameter sets required for decoding the sync sample are included (e.g., encoded, stored, or placed) in the sample entry for the sample or in the sample itself. Thus, by decoding all parameter sets required for the sample included in this manner, video decoder 30 can determine that parameter set data for decoding the video data of the sample is only in the sample entry for the sync sample or in the sync sample itself if the sample is a sync sample and the sample entry name is a specific name (e.g., 'hev1'). Thus, parameter set data can be determined in this manner based on determining that the sample is a sync sample and further based on the sample entry name, e.g., the sample entry name being a specific name or one of a set of specific names, e.g., 'hev1'. If the sample entry name is not a specific name, the placement of the parameter sets may be handled differently.

[0157] In some examples, the video encoder 20, the encapsulation unit 21, the decapsulation unit 29, and / or the video decoder 30, or other devices, may be further configured such that if a sample is not a sync sample and the sample entry name is 'hev1', all parameter sets required for decoding the sync sample are included (e.g., encoded, stored, or located) in the sample entry of the sample that is not a sync sample, the sample itself that is not a sync sample, the previous sync sample, or one or more samples after the previous sync sample and before the sample itself (i.e., before the sample that is not a sync sample). Thus, by including all parameter sets required for decoding the sample in this manner, if the sample is not a sync sample (i.e., it is an out-of-sync sample) and the sample entry name is a specific name (e.g., 'hev1'), the video decoder 30 can determine that parameter set data for decoding the video data of the out-of-sync sample is only in the sample entry of the out-of-sync sample, the out-of-sync sample itself, the previous sync sample, or one or more samples after the previous sync sample and before the out-of-sync sample itself (i.e., before the sample that is not a sync sample). Thus, parameter set data can be decoded in this manner based on a determination that the sample is not a synchronization sample and further based on the sample's entry name, e.g., the sample entry name is a specific name or one of a set of specific names, e.g., 'hev1.' If the sample entry name is not a specific name, then the determination of the parameter set data can be handled differently.

[0158] Other aspects of the present invention relate to determining whether a sample is a synchronization sample. For example, according to aspects of the present invention, the definition of synchronization samples in the layered HEVC file format of a layered HEVC bitstream can be updated to be consistent with and backward compatible with the definition of synchronization samples in the HEVC file format. In general, the general name layered HEVC (L-HEVC) can be used for all HEVC extensions that use the same layered design. An L-HEVC bitstream can be a collection of layers, each of which helps to adjust the visual presentation in quality, resolution, frame rate, view, depth, etc. Collections of related layers are grouped together as layer sets. The layers in any layer set are uniquely identified by their layer identifiers (L-ids). A layer can be a member of one or more layer sets. The NAL units belonging to a layer can be further segmented based on their temporal identifiers (T-ids). Each such segmentation is called a sublayer.

[0159] In the HEVC file format, an HEVC sample can be considered a synchronization sample if the VCL NAL unit in the sample indicates that the coded picture contained in the sample is an IDR picture, a CRA picture, or a BLA picture. However, in the draft L-HEVC file format, an L-HEVC sample can be considered a synchronization sample if every coded picture in an access unit is an intra random access point (IRAP) picture without a random access skip leading edge (RASL) picture. For example, both SHVC and MV-HEVC use the same layered design.

[0160] In the above example, the definition of synchronization samples in the draft layered HEVC file format may not be consistent with that in the HEVC file format, where the mismatch is whether the presence of RASL pictures in IRAP pictures will not allow the sample to be a synchronization sample. This mismatch can cause a problem in that the definition of synchronization samples in the L-HEVC file format is not backward compatible with the HEVC file format when using HEVC compatible sample entries (i.e., one of 'hvc1', 'hev1', 'hvc2', and 'hev2').

[0161] According to aspects of this disclosure, the video encoder 20, the encapsulation unit 21, the decapsulation unit 29, and / or the video decoder 30 may be configured to conform to the updated definition of the synchronization sample of the L-HEVC file format to be consistent with and backward compatible with the definition of the HEVC file format. For example, depending on the sample entry name, the synchronization sample of the L-HEVC file format is defined as follows:

[0162] - When the sample entry name is 'hvc1', 'hev1', 'hvc2', or 'hev2', if the base layer picture in the access unit is an IRAP picture as defined in ISO / IEC 23008-2, the L-HEVC sample is considered a synchronization sample.

[0163] - When the sample entry name is 'lhv1' or 'lhe1', an L-HEVC sample is considered to be a synchronization sample if every coded picture in the access unit is an IRAP picture as defined in ISO / IEC 23008-2.

[0164] Alternatively, regardless of the same entry name, if the base layer picture in the access unit is an IRAP picture as defined in ISO / IEC 23008-2, then the video encoder 20, encapsulation unit 21, decapsulation unit 29 and / or video decoder 30 may be configured to determine that the L-HEVC sample is a synchronization sample.

[0165] Alternatively, regardless of the same entry name, if each coded picture in the access unit is an IRAP picture as defined in ISO / IEC 23008-2, the video encoder 20, the encapsulation unit 21, the decapsulation unit 29, and / or the video decoder 30 may be configured to determine that the L-HEVC sample is a synchronization sample. The synchronization sample is recorded by the synchronization sample table and may be further recorded by the stream access point 'sap.' sample group.

[0166] Figure 2is a block diagram illustrating an example video encoder 20 that can implement the techniques described in this disclosure. Video encoder 20 may include memory for storing video data and one or more processors configured to perform video coding operations, such as encoding video data and including parameter set data for decoded samples in specific locations, as described in this disclosure. Video encoder 20 may be configured to output video to post-processing entity 27, another example device that can implement techniques for encoding video data, as described in this disclosure. For example, post-processing entity 27 may implement techniques for including parameter set data for decoded samples in specific locations and / or for determining parameter set data for decoded samples from specific locations, as described in this disclosure. Post-processing entity 27 is intended to represent an example of a video entity, such as a media-aware network element (MANE), a splicing / editing device, or another intermediate device that can process encoded video data from video encoder 20. In some cases, post-processing entity 27 may be an example of a network entity. In some video encoding systems, post-processing entity 27 and video encoder 20 may be parts of separate devices, while in other cases the functionality described with respect to post-processing entity 27 may be performed by the same device that includes video encoder 20.

[0167] Video encoder 20 may perform intra- and inter-coding on video blocks within a video slice. Intra-coding relies on spatial prediction to reduce or remove spatial redundancy in video within a given video frame or picture. Inter-coding relies on temporal prediction to reduce or remove temporal redundancy in video within adjacent frames or pictures of a video sequence. Intra-mode (I-mode) may refer to any of several spatial-based compression modes. Inter-mode, such as uni-directional prediction (P-mode) or bi-directional prediction (B-mode), may refer to any of several temporal-based compression modes.

[0168] exist Figure 2In the example of , the video encoder 20 includes a segmentation unit 35, a video memory 37, a prediction processing unit 41, a filter unit 63, a reference picture memory 64, a summer 50, a transform processing unit 52, a quantization unit 54, and an entropy coding unit 56. The prediction processing unit 41 includes a motion estimation unit 42, a motion compensation unit 44, and an intra-prediction processing unit 46. The video memory 37 and the reference picture memory 64 may be part of the same memory device or separate memory devices. The memory device may be any form of computer-readable medium or data storage medium described in the present invention, such as RAM, ROM, flash memory, or the like, or a combination thereof. For video block reconstruction, the video encoder 20 also includes an inverse quantization unit 58, an inverse transform processing unit 60, and a summer 62. The filter unit 63 is intended to represent one or more loop filters, such as a deblocking filter, an adaptive loop filter (ALF), and a sample adaptive offset (SAO) filter. Although in Figure 2 Filter unit 63 is shown as an in-loop filter in FIG, but in other configurations, filter unit 63 may be implemented as a post-loop filter.

[0169] like Figure 2 As shown in , video encoder 20 receives video data to be encoded (e.g., in video memory 37), and partitioning unit 35 partitions the video data in video memory 37 into video blocks. This partitioning may also include partitioning into slices, tiles, or other larger units, as well as video block partitioning according to a quadtree structure, such as LCUs and CUs. Video encoder 20 generally illustrates the components that encode video blocks within a video slice to be encoded. A slice may be divided into multiple video blocks (and possibly into sets of video blocks referred to as tiles). Prediction processing unit 41 may select one of multiple possible coding modes, such as one of multiple intra-coding modes or one of multiple inter-coding modes, for the current video block based on error results (e.g., coding rate and distortion level). Prediction processing unit 41 may provide the resulting intra- or inter-coded block to summer 50 to generate residual block data and to summer 62 to reconstruct the coded block for use as a reference picture.

[0170] Intra-prediction processing unit 46 within prediction processing unit 41 may perform intra-predictive coding of the current video block relative to one or more neighboring blocks in the same frame or slice as the current block to be coded to provide spatial compression. Motion estimation unit 42 and motion compensation unit 44 within prediction processing unit 41 may perform inter-predictive coding of the current video block relative to one or more prediction blocks in one or more reference pictures to provide temporal compression.

[0171] Motion estimation unit 42 may be configured to determine an inter-prediction mode for a video slice according to a predetermined pattern for a video sequence. The predetermined pattern may indicate a video slice in the sequence as a P slice or a B slice. Motion estimation unit 42 and motion compensation unit 44 may be highly integrated but are illustrated separately for conceptual purposes. Motion estimation performed by motion estimation unit 42 is the process of generating motion vectors, which estimate the motion of video blocks. For example, a motion vector may indicate the displacement of a PU of a video block within a current video frame or picture relative to a prediction block within a reference picture.

[0172] A prediction block is a block that is found to closely match a PU of the video block to be coded in terms of pixel difference, which may be determined by sum of absolute difference (SAD), sum of squared difference (SSD), or other difference metrics. In some examples, video encoder 20 may calculate values for sub-integer pixel positions of a reference picture stored in reference picture memory 64. For example, video encoder 20 may interpolate values for quarter-pixel positions, eighth-pixel positions, or other fractional pixel positions of the reference picture. Thus, motion estimation unit 42 may perform a motion search relative to integer and fractional pixel positions and output a motion vector with fractional pixel precision.

[0173] Motion estimation unit 42 calculates a motion vector for a PU of a video block in an inter-coded slice by comparing the position of the PU to the position of a prediction block of a reference picture. The reference picture may be selected from a first reference picture list (List 0) or a second reference picture list (List 1), each of which identifies one or more reference pictures stored in reference picture memory 64. Motion estimation unit 42 sends the calculated motion vector to entropy encoding unit 56 and motion compensation unit 44.

[0174] Motion compensation performed by motion compensation unit 44 may involve extracting or generating a prediction block based on a motion vector determined by motion estimation (possibly performing interpolation to sub-pixel precision). Upon receiving the motion vector for the PU of the current video block, motion compensation unit 44 may locate the prediction block to which the motion vector points in one of the reference picture lists. Video encoder 20 forms a residual video block by subtracting the pixel values of the prediction block from the pixel values of the current video block being coded, forming pixel difference values. The pixel difference values form residual data for the block and may include both luma and chroma difference components. Summer 50 represents one or more components that perform this subtraction operation. Motion compensation unit 44 may also generate syntax elements associated with the video block and video slice for use by video decoder 30 when decoding the video block of the video slice.

[0175] As an alternative to the inter-prediction performed by motion estimation unit 42 and motion compensation unit 44 as described above, intra-prediction unit 46 may perform intra-prediction on the current block. Specifically, intra-prediction unit 46 may determine an intra-prediction mode to use to encode the current block. In some examples, e.g., during a separate encoding pass, intra-prediction unit 46 may encode the current block using various intra-prediction modes, and intra-prediction unit 46 (or, in some examples, mode selection unit 40) may select a suitable intra-prediction mode to use from test modes, e.g., by calculating rate-distortion values using a rate-distortion analysis for the various test intra-prediction modes and selecting the intra-prediction mode from the test modes having the best rate-distortion characteristics.

[0176] In any case, after selecting an intra-prediction mode for a block, intra-prediction unit 46 may provide information indicating the selected intra-prediction mode for the block to entropy encoding unit 56. Entropy encoding unit 56 may encode the information indicating the selected intra-prediction mode according to the techniques of this disclosure. Video encoder 20 may include configuration data in the transmitted bitstream, which may include multiple intra-prediction mode index tables and multiple modified intra-prediction mode index tables (also referred to as codeword mapping tables), definitions of coding contexts for various blocks, and indications of the most probable intra-prediction mode, intra-prediction mode index tables, and modified intra-prediction mode index tables for each of the contexts.

[0177] After prediction processing unit 41 generates a prediction block for the current video block via inter-prediction or intra-prediction, video encoder 20 forms a residual video block by subtracting the prediction block from the current video block. The residual video data in the residual block may be contained in one or more TUs and applied to transform processing unit 52. Transform processing unit 52 transforms the residual video data into residual transform coefficients using a transform, such as a discrete cosine transform (DCT) or a conceptually similar transform. Transform processing unit 52 may convert the residual video data from the pixel domain to a transform domain, such as the frequency domain.

[0178] Transform processing unit 52 may send the resulting transform coefficients to quantization unit 54. Quantization unit 54 quantizes the transform coefficients to further reduce the bit rate. The quantization process may reduce the bit depth associated with some or all of the coefficients. The degree of quantization may be modified by adjusting a quantization parameter. In some examples, quantization unit 54 may then perform a scan of the matrix containing the quantized transform coefficients. Alternatively, entropy encoding unit 56 may perform the scan.

[0179] After quantization, entropy encoding unit 56 entropy encodes the quantized transform coefficients. For example, entropy encoding unit 56 may perform context adaptive variable length coding (CAVLC), context adaptive binary arithmetic coding (CABAC), syntax-based context adaptive binary arithmetic coding (SBAC), probability interval partitioning entropy (PIPE) coding, or another entropy coding method or technique. Following entropy encoding by entropy encoding unit 56, the encoded bitstream may be transmitted to video decoder 30 or archived for later transmission or retrieval by video decoder 30. Entropy encoding unit 56 may also entropy encode the motion vectors and other syntax elements for the current video slice being coded.

[0180] Inverse quantization unit 58 and inverse transform processing unit 60 apply inverse quantization and inverse transform, respectively, to reconstruct the residual block in the pixel domain for later use as a reference block for a reference picture. Motion compensation unit 44 may calculate a reference block by adding the residual block to a prediction block of one of the reference pictures in one of the reference picture lists. Motion compensation unit 44 may also apply one or more interpolation filters to the reconstructed residual block to calculate sub-integer pixel values for motion estimation. Summer 62 adds the reconstructed residual block to the motion compensated prediction block produced by motion compensation unit 44 to produce a reference block for storage in reference picture memory 64. The reference block may be used by motion estimation unit 42 and motion compensation unit 44 as a reference block for inter-frame prediction of a block in a subsequent video frame or picture.

[0181] In this way, Figure 2 The video encoder 20 of FIG. 5 represents an example of a video encoder configured to implement one or more of the techniques described herein. In one example, entropy encoding unit 56 may perform the techniques described herein with respect to parameter sets and synchronization samples. Figure 2 Post-processing entity 27 of is another example device that may implement the techniques described in this disclosure with respect to parameter sets and synchronization samples.

[0182] Figure 3 is a block diagram illustrating an example video decoder 30 that may implement the techniques described in this disclosure. Video decoder 30 may include a memory for storing video data and one or more processors configured to perform video coding operations, e.g., to decode video data and to determine parameter set data for decoding samples from a particular location, as described in this disclosure. Figure 3In the example of , video decoder 30 includes entropy decoding unit 80, video memory 83, prediction processing unit 81, inverse quantization unit 86, inverse transform unit 88, summer 90, filter unit 91, and reference picture memory 92. Prediction processing unit 81 includes motion compensation unit 82 and intra-prediction processing unit 84. In some examples, video decoder 30 may perform substantially the same Figure 2 The decoding pass is the inverse of the encoding pass described for video encoder 20 .

[0183] During the decoding process, video decoder 30 receives an encoded video bitstream representing video blocks and associated syntax elements of an encoded video slice from video encoder 20. For example, video memory 83 may receive the encoded video bitstream. In some examples, video memory 83 may be a coded picture buffer. Video decoder 30 may receive the encoded video bitstream from network entity 79 (which, in some examples, may correspond to a decoded picture buffer). Figure 1 The network entity 79 receives the encoded video bitstream from a router 36 (e.g., a video memory 83). For example, the network entity 79 may be a server, a MANE, a video editor / splicer, or other such device configured to implement one or more of the techniques for decoding video data described above. The network entity 79 may or may not include a video encoder, such as the video encoder 20. Before the network entity 79 transmits the encoded video bitstream to the video decoder 30, the network entity 79 may implement some of the techniques described in this disclosure. In some examples, the network entity 79 may implement techniques for including parameter set data for decoding samples in specific locations and / or determining parameter set data for decoding samples from specific locations, as described in this disclosure. In some video decoding systems, the network entity 79 and the video decoder 30 may be parts of separate devices, while in other cases, the functionality described with respect to the network entity 79 may be performed by the same device that includes the video decoder 30.

[0184] Entropy decoding unit 80 of video decoder 30 entropy decodes the bitstream to produce quantized coefficients, motion vectors, and other syntax elements. Entropy decoding unit 80 forwards the motion vectors and other syntax elements to prediction processing unit 81. Video decoder 30 may receive syntax elements at the video slice level and / or the video block level.

[0185] When the video slice is coded as an intra-coded (I) slice, intra-prediction processing unit 84 of prediction processing unit 81 may generate prediction data for the video block of the current video slice based on the signaled intra-prediction mode and data from previously decoded blocks of the current frame or picture. When the video frame is coded as an inter-coded (i.e., B or P) slice, motion compensation unit 82 of prediction processing unit 81 generates a prediction block for the video block of the current video slice based on the motion vectors and other syntax elements received from entropy decoding unit 80. The prediction block may be generated from one of the reference pictures within one of the reference picture lists. Video decoder 30 may construct reference frame lists: List 0 and List 1 using a default construction technique based on the reference pictures stored in reference picture memory 92.

[0186] Motion compensation unit 82 determines prediction information for a video block of the current video slice by parsing motion vectors and other syntax elements, and uses the prediction information to generate a prediction block for the decoded current video block. For example, motion compensation unit 82 uses some of the received syntax elements to determine a prediction mode (e.g., intra or inter prediction) for coding the video block of the video slice, an inter-prediction slice type (e.g., B slice or P slice), construction information for one or more of the reference picture lists for the slice, a motion vector for each inter-coded video block of the slice, an inter-prediction status for each inter-coded video block of the slice, and other information for decoding the video blocks in the current video slice.

[0187] Motion compensation unit 82 may also perform interpolation based on interpolation filters. Motion compensation unit 82 may calculate interpolated values for sub-integer pixels of a reference block using interpolation filters as used by video encoder 20 during encoding of the video block. In this case, motion compensation unit 82 may determine the interpolation filters used by video encoder 20 from received syntax elements and use the interpolation filters to produce the prediction block.

[0188] Inverse quantization unit 86 inverse quantizes (i.e., dequantizes) the quantized transform coefficients provided in the bitstream and decoded by entropy decoding unit 80. The inverse quantization process may include using quantization parameters calculated by video encoder 20 for each video block in a video slice to determine the degree of quantization, and similarly, the degree of inverse quantization that should be applied. Inverse transform processing unit 88 applies an inverse transform (e.g., an inverse DCT, an inverse integer transform, or a conceptually similar inverse transform process) to the transform coefficients in order to produce residual blocks in the pixel domain.

[0189] After motion compensation unit 82 generates a prediction block for the current video block based on the motion vector and other syntax elements, video decoder 30 forms a decoded video block by summing the residual block from inverse transform processing unit 88 with the corresponding prediction block generated by motion compensation unit 82. Summer 90 represents one or more components that may perform this summing operation. If desired, loop filters may also be used (in the decoding loop or after the decoding loop) to smooth pixel transitions or otherwise improve video quality. Filter unit 91 is intended to represent one or more loop filters, such as a deblocking filter, an adaptive loop filter (ALF), and a sample adaptive offset (SAO) filter. Although in Figure 3 Filter unit 91 is shown as an in-loop filter in FIG, but in other configurations, filter unit 91 may be implemented as a post-loop filter. The decoded video blocks in a given frame or picture are then stored in reference picture memory 92, which stores reference pictures used for subsequent motion compensation. Reference picture memory 92 also stores decoded video for later presentation on a display device (e.g., Figure 1 The reference picture memory 92 may be referred to as a decoded picture buffer. The video memory 83 and the reference picture memory 92 may be part of the same memory device or separate memory devices. The memory device may be any form of computer-readable medium or data storage medium described in this disclosure, such as RAM, ROM, flash memory, or the like, or a combination thereof.

[0190] In this way, Figure 3 The video decoder 30 of TX represents an example of a video encoder configured to implement one or more of the techniques described herein. In one example, entropy decoding unit 80 may perform the techniques described herein with respect to parameter sets and synchronization samples. In addition, Figure 3 Network entity 79 (which may be a media-knowledgeable network element) is another example device that may implement the techniques described in this disclosure with respect to parameter sets and synchronization samples.

[0191] Figure 4 1 is a block diagram illustrating elements of an example video file 150. A video file 150 may be referred to as encapsulating a segment. As described herein, a video file according to the ISO Base Media File Format (ISOBMFF) and its extensions stores data in a series of objects referred to as "boxes." Figure 4 In the example of , the video file 150 includes a file type (FTYP) box 152, a movie (MOOV) box 154, a segment index (sidx) box 162, a movie segment (MOOF) box 164, and a movie segment random access (MFRA) box 166. Although Figure 4An example of a video file is shown, but it should be understood that other media files may contain other types of media data (e.g., audio data, timed text data, or the like) similarly structured to the data of video file 150 according to the ISO base media file format and its extensions.

[0192] The file type (FTYP) box 152 generally describes the file type of the video file 150. The file type box 152 may contain data identifying specifications describing the optimal use of the video file 150. The file type box 152 may alternatively be placed before the MOOV box 154, the movie fragment box 164, and / or the MFRA box 166.

[0193] exist Figure 4 In the example of , the MOOV box 154 includes a movie header (MVHD) box 156, a track (TRAK) box 158, and one or more movie extension (MVEX) boxes 160. In general, the MVHD box 156 may describe general characteristics of the video file 150. For example, the MVHD box 156 may include data describing when the video file 150 was originally generated, when the video file 150 was last modified, the time scale of the video file 150, the duration of playback of the video file 150, or other data generally describing the video file 150.

[0194] The TRAK box 158 may contain data for a track of the video file 150. The TRAK box 158 may contain a track header (TKHD) box that describes characteristics of the track corresponding to the TRAK box 158. In some examples, the TRAK box 158 may contain decoded video pictures, while in other examples, the decoded video pictures of the track may be contained in movie fragments 164, which may be referenced by data in the TRAK box 158 and / or the sidx box 162.

[0195] In some examples, the video file 150 may include more than one track. Therefore, the MOOV box 154 may include a number of TRAK boxes equal to the number of tracks in the video file 150. The TRAK box 158 may describe the characteristics of the corresponding track of the video file 150. For example, the TRAK box 158 may describe the time and / or spatial information of the corresponding track. When the encapsulation unit 21 ( Figure 1 ) is included in a parameter set track in a video file (e.g., video file 150), a TRAK box similar to TRAK box 158 of MOOV box 154 may describe characteristics of the parameter set track.

[0196] For example, a synchronization sample in the parameter set track may indicate that all parameter sets required from that decoding time onward in the video elementary stream are in that parameter stream sample or in subsequent parameter stream samples. Parameter set samples are also present at each point in a parameter set update. Each parameter set may contain the sequence and picture parameter sets required to decode the associated segment of the video elementary stream. The encapsulation unit 21 may signal the presence of sequence-level SEI messages in the parameter set track within a TRAK box that describes the parameter set track.

[0197] The MVEX box 160 may describe characteristics of the corresponding movie fragments 164, e.g., to signal that, in addition to the video data (if present) contained within the MOOV box 154, the video file 150 also includes the movie fragments 164. In the case of streaming video data, coded video pictures may be contained in the movie fragments 164 rather than in the MOOV box 154. Thus, all coded video samples may be contained in the movie fragments 164 rather than in the MOOV box 154.

[0198] The MOOV box 154 may include a number of MVEX boxes 160 equal to the number of movie fragments 164 in the video file 150. Each of the MVEX boxes 160 may describe characteristics of a corresponding one of the movie fragments 164. For example, each MVEX box may include a Movie Extension Header Box (MEHD) box that describes the duration of the corresponding one of the movie fragments 164.

[0199] As noted above, the encapsulation unit 21 may store sequence data sets in video samples that do not contain actual coded video data. A video sample may typically correspond to an access unit, which is a representation of one or more coded pictures at a particular time instance. In the case of AVC, a coded picture contains one or more VCL NAL units that contain information to construct all pixels of an access unit and other associated non-VCL NAL units (e.g., SEI messages). Thus, the encapsulation unit 21 may include a sequence data set that may include a sequence-level SEI message in one of the movie fragments 164. The encapsulation unit 21 may further signal the presence of the sequence data set and / or sequence-level SEI message as being present in one of the movie fragments 164 within one of the MVEX boxes 160 corresponding to one of the movie fragments 164.

[0200] SIDX box 162 is an optional element of video file 150. That is, video files conforming to the 3GPP file format or other such file formats do not necessarily contain SIDX box 162. According to the example of the 3GPP file format, the SIDX box can be used to identify sub-segments of a fragment (e.g., a fragment contained within video file 150). The 3GPP file format defines a sub-segment as "an independent set of one or more consecutive Movie Fragment boxes with corresponding Media Data boxes, and the Media Data boxes containing data referenced by the Movie Fragment boxes must follow the Movie Fragment boxes and precede the next Movie Fragment box containing information about the same track." The 3GPP file format also specifies that the SIDX box "contains a sequence of references to sub-segments of a (sub) fragment recorded by the boxes." The referenced sub-segments are continuous in presentation time. Similarly, the bytes referred to by the Segment Index box are always continuous within a fragment. The referenced size provides a count of the number of bytes in the referenced material.

[0201] SIDX box 162 generally provides information representing one or more sub-segments of a segment contained in video file 150. For example, such information may include the playback time at which the sub-segment begins and / or ends, the byte offset of the sub-segment, whether the sub-segment contains a SAP (e.g., starts with a SAP), the type of SAP (e.g., whether the SAP is an IDR picture, a CRA picture, a BLA picture, or the like), the location of the SAP in the sub-segment (in terms of playback time and / or byte offset), and so on.

[0202] The movie fragments 164 may include one or more decoded video pictures. In some instances, the movie fragments 164 may include one or more GOPs, each of which may include multiple decoded video pictures. Furthermore, as described above, in some instances, the movie fragments 164 may include sequence data sets. Each of the movie fragments 164 may include a movie fragment header box (MFHD, in Figure 4 (not shown in FIG. 1 ). The MFHD box may describe characteristics of the corresponding movie fragment, such as the sequence number of the movie fragment. The movie fragments 164 may be included in the order of the sequence numbers in the video file 150.

[0203] MFRA box 166 may describe random access points within the movie fragments 164 of video file 150. This may assist in performing trick modes, for example, performing seeks to specific temporal locations (i.e., play times) within the fragments encapsulated by video file 150. In some instances, MFRA box 166 is generally optional and need not be included in the video file. Similarly, a client device (e.g., destination device 14) does not necessarily need to reference MFRA box 166 to correctly decode and display the video data of video file 150. MFRA box 166 may include a number of track fragment random access (TFRA) boxes (not shown) equal to the number of tracks in video file 150, or, in some instances, a number of track fragment random access (TFRA) boxes (not shown) equal to the number of media tracks (e.g., non-hint tracks) in video file 150.

[0204] In some examples, a movie fragment 164 may include one or more SAPs, such as IDR pictures. Similarly, an MFRA block 166 may provide an indication of the location of the SAP within the video file 150. Thus, a temporal subsequence of the video file 150 may be formed from the SAPs of the video file 150. The temporal subsequence may also include other pictures, such as P frames and / or B frames that depend on the SAPs. Frames and / or slices of the temporal subsequence may be arranged within the fragment so that frames / slices of the temporal subsequence that depend on other frames / slices of the subsequence can be properly decoded. For example, in a hierarchical arrangement of data, data used to predict other data may also be included in the temporal subsequence.

[0205] According to the techniques of this disclosure, a video decoder (e.g., decapsulation unit 29 and / or video decoder 30 ( Figure 1 )) may be configured to determine parameter set data based on a sample or sample entry of video data. For example, decapsulation unit 29 and / or video decoder 30 may be configured to determine whether a sample of video data included in movie fragment 164 is a synchronization sample. In some examples, decapsulation unit 29 and / or video decoder 30 may determine whether such a sample is a synchronization sample in accordance with ISOBMFF, e.g., based on the conditions set forth in sections 4.8 (AVC), 6.5.5 (SVC), 7.5.3 (MVC), and 8.4.3 (HEVC) of ISOBMFF. Decapsulation unit 29 and / or video decoder 30 may evaluate such conditions based on the sample itself or based on a description associated with MRFA block 166.

[0206] For decoding of video data of a sample, decapsulation unit 29 and / or video decoder 30 may determine that parameter set data is different for a sample that is a synchronization sample than for a sample that is not a synchronization sample. For example, decapsulation unit 29 and / or video decoder 30 may be configured to determine parameter set data for a synchronization sample only from a sample entry associated with the sample or from the sample itself. On the other hand, decapsulation unit 29 and / or video decoder 30 may be configured to decode parameter set data for an unsynchronized sample only from a sample entry associated with an unsynchronized sample, from the unsynchronized sample itself, from a synchronization sample that precedes the unsynchronized sample in decoding order, or from a sample that precedes the unsynchronized sample in decoding order but occurs after the preceding synchronization sample in decoding order.

[0207] Figure 5 is a flowchart illustrating a process for decoding parameter set data from a video bitstream. Although for illustrative purposes relative to video decoder 30 ( Figure 1 and 3 ) is described, but it should be understood that Figure 5 The process or part thereof may also be performed by the decapsulation unit 29 ( Figure 1 ), network entity 79( Figure 3 ) or other processing units configured to parse and / or decode video data. For example, decapsulation unit 29 or network entity 79 may perform techniques for including parameter set data for decoding samples in specific locations or determining parameter set data for decoding samples from specific locations, as described in this disclosure and in Figure 5 Instructions.

[0208] exist Figure 5 In an example of , video decoder 30 may receive a file of video data (180) that includes one or more samples of video data. For example, the file may conform to ISOBMFF, as described herein. Furthermore, the one or more samples may each correspond to an access unit of the video data.

[0209] Video decoder 30 may determine whether any of the one or more samples is a sync sample (182). For example, before decoding the video data of the sample, video decoder 30 may analyze the bitstream containing the sample to ensure compliance with a particular video coding standard. Video decoder 30 may determine whether any of the samples can be processed as a sync sample, as defined by the particular coding standard. In an example for illustrative purposes, video decoder 30 may determine whether any of the samples is a sync sample based on the restrictions set forth in sections 4.8 (AVC), 6.5.5 (SVC), 7.5.3 (MVC), and 8.4.3 (HEVC) of ISOBMFF.

[0210] Based on determining that the sample is not a sync sample, i.e., the sample is an out-of-sync sample, video decoder 30 or another device may determine (e.g., by parsing, decoding, retrieving, or otherwise obtaining) parameter set data for the out-of-sync sample only from a sample entry corresponding to the out-of-sync sample, the out-of-sync sample itself, a previous sample that occurs before the out-of-sync sample in decoding order and is a sync sample, or one or more samples that occur between the out-of-sync sample and the previous sync sample in decoding order (184). For example, video decoder 30 may be limited to certain locations in the bitstream from which parameter set data for the sample may be decoded. For a given bitstream having samples arranged in decoding order, video decoder 30 may not decode parameter set data for video data for the out-of-sync sample from any location other than a sample entry corresponding to the out-of-sync sample, the out-of-sync sample itself, a previous sample that was decoded as a sync sample before the out-of-sync sample in decoding order, or a sample that occurs before the out-of-sync sample in decoding order but is after the previous sample that was decoded as a sync sample in decoding order. All parameter set data required for decoding the video data of the non-sync sample is contained in the sample entry corresponding to the non-sync sample, the non-sync sample itself, a previous sample that was decoded as a sync sample before the non-sync sample in decoding order, or a sample that occurs before the non-sync sample in decoding order but after the previous sample that was decoded as a sync sample in decoding order.

[0211] In other words, for a current sample that is not a sync sample, the video decoder 30 may determine parameter set data only in the sample entry for the non-sync sample or only in any sample from the previous sync sample (inclusive) to the current non-sync sample (i.e., including the previous sync sample, samples after the previous sync sample but before the current non-sync sample, and including the current non-sync sample). The video decoder 30 may be configured to determine parameter set data for the non-sync sample only from these restricted locations because, if the sample is not a sync sample, all parameter sets required for decoding the sample may be included in the sample entry for the sample or in any sample from the previous sync sample (inclusive) to the sample itself. For example, the video encoder 20, the encapsulation unit 21, the decapsulation unit 29, and / or the video decoder 30, or other devices, may be configured such that, if the sample is not a sync sample, all parameter sets required for decoding the sample are included in the sample entry for the sample or in any sample from the previous sync sample (inclusive) to the sample itself.

[0212] Based on determining that the sample is a sync sample, the video decoder 30 may determine parameter set data for the sample only from the sample entry for the sync sample or the sync sample itself (185). All parameter set data required for decoding the video data of the sync sample is contained in the sample entry corresponding to the sync sample or the sync sample itself. Therefore, for the sync sample, the video decoder 30 may determine parameter set data for the sync sample only in the sample entry or the sample itself, and not in other samples or locations. The video decoder 30 may be configured to determine (e.g., by parsing, decoding, retrieving, or otherwise obtaining) parameter set data for non-sync samples only from these restricted locations because, if the sample is a sync sample, all parameter sets required for decoding the sync sample are contained in the sample entry for the sample or in the sample itself. For example, the video encoder 20, encapsulation unit 21, decapsulation unit 29, and / or video decoder 30, or other devices, may be configured such that, if the sample is a sync sample, all parameter sets required for decoding the sample are contained in the sample entry for the sample or in the sample itself. Video decoder 30 may then decode the video data of the sample based on the determined parameter set data (186). The previous synchronization sample may be the most recent synchronization sample in decoding order. In some examples, video decoder 30 may discard a previously stored parameter set after receiving a new synchronization sample.

[0213] Figure 6 is a flowchart illustrating a process for encoding parameter set data in a video bitstream. Although for illustrative purposes relative to video encoder 20 ( Figure 1 and 2 ) for description, but it should be understood that Figure 6 The process or part thereof can also be performed by the encapsulation unit 21 ( Figure 1 ), post-processing entity 27( Figure 2 ) or other processing units or devices configured to generate, encode and / or process video data. For example, encapsulation unit 21 or post-processing entity 27 may perform techniques for including parameter set data for decoding samples in specific locations, as described in this disclosure and in Figure 6 Instructions.

[0214] exist Figure 6In an example of , video encoder 20 may encode a sample based on parameter set data for a sample of video data (190). The encoded sample may correspond to an access unit of the video data. Video encoder 20 may encode a sample of one or more samples as a synchronization sample or a non-synchronization sample, as defined by a particular video coding standard. Video encoder 20 may generate a bitstream including the sample to ensure compliance with the particular video coding standard. For synchronization samples defined based on the restrictions set forth in sections 4.8 (AVC), 6.5.5 (SVC), 7.5.3 (MVC), and 8.4.3 (HEVC) of ISOBMFF, video encoder 20 or another device may include all parameter set data required for decoding the synchronization sample in a sample entry corresponding to the synchronization sample or in the synchronization sample itself (192). In this way, video encoder 20 or another device may include parameter set data for decoding the synchronization sample only in a sample entry corresponding to the synchronization sample or in the synchronization sample itself.

[0215] For non-sync samples (as defined based on the limitations set forth in sections 4.8 (AVC), 6.5.5 (SVC), 7.5.3 (MVC), and 8.4.3 (HEVC) of ISOBMFF), video encoder 20 or another device may include all parameter set data for the non-sync sample in a sample entry corresponding to the non-sync sample, in the non-sync sample itself, in a previous sync sample that precedes the non-sync sample in decoding order, or in a sample that occurs before the non-sync sample and after the previous sync sample in decoding order (194). In this manner, video encoder 20 or another device may include parameter set data for decoding the sync sample only in a sample entry corresponding to the non-sync sample, in the non-sync sample itself, in a previous sync sample in decoding order, or in a sample that occurs before the non-sync sample and after the previous sync sample in decoding order. Thus, the video encoder 20 may restrict parameter set data for a sample to certain locations such that the video decoder 30 may not decode parameter set data for an unsynchronized sample from any location other than a sample entry corresponding to the unsynchronized sample, the unsynchronized sample itself, a previous sample coded as a unsynchronized sample, or one or more samples that occur before the unsynchronized sample in decoding order but after the previous sample decoded as a unsynchronized sample in decoding order. In other words, for a current sample that is not a unsynchronized sample, the video encoder 20 may encode parameter set data only in a sample entry or in any sample from the previous unsynchronized sample (inclusive) to the current sample (inclusive) (i.e., samples after the previous unsynchronized sample but before the current unsynchronized sample, inclusive of the current unsynchronized sample and the previous unsynchronized sample).

[0216] Video encoder 20 may then generate a file (196) containing samples of the video data. As described above, the samples in the file may include synchronized samples and / or asynchronous samples. A file may contain multiple samples, including one or more synchronized samples and one or more asynchronous samples. In this way, Figure 6 An example of the operation of video encoder 20 or another device is described to determine whether a sample of video data is a sync sample and, based on a determination that the sample is not a sync sample (i.e., is an out-of-sync sample), include parameter set data for the video data only in a sample entry for the out-of-sync sample, in the out-of-sync sample itself, in a sample that precedes the out-of-sync sample in decoding order and is a sync sample, or in one or more samples that appear in decoding order between the out-of-sync sample and the preceding sample in decoding order that is a sync sample. Similarly, Figure 6 An example of operation of video encoder 20 or another device is described to determine whether a second sample of video data is a sync sample and, based on determining that the second sample is a sync sample, include parameter set data for the video data only in sample entries for or in the sync sample. In some examples, video encoder 20 may further avoid encoding the sync sample and subsequent samples (in coding order) with reference to parameter sets (e.g., PPS and SPS) that were encoded before the sync sample in coding order.

[0217] It should be appreciated that, depending on the example, certain actions or events of any of the techniques described herein may be performed in a different order, may be added, combined, or omitted entirely (e.g., not all described actions or events are required to practice the techniques). Furthermore, in some examples, actions or events may be performed simultaneously rather than sequentially, for example, through multithreading, interrupt processing, or multiple processors.

[0218] As described in this disclosure, a video decoder may refer to a video encoder or a video decoder. Similarly, a video decoding unit may refer to a video encoder or a video decoder. Similarly, video decoding may refer to video encoding or video decoding, where applicable.

[0219] In one or more instances, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored or transmitted as one or more instructions or codes on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media corresponding to tangible media (e.g., data storage media), or communication media including, for example, any media that facilitates the transfer of a computer program from one location to another according to a communication protocol. In this manner, computer-readable media may generally correspond to (1) tangible computer-readable storage media that is non-transitory, or (2) communication media, such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, codes, and / or data structures for implementing the techniques described in the present invention. A computer program product may include computer-readable media.

[0220] By way of example and not limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage, flash memory, or any other medium that can be used to store the desired program code in the form of instructions or data structures and that can be accessed by a computer. Furthermore, any connection is properly referred to as a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of medium. However, it should be understood that the computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but are actually directed to non-transitory tangible storage media. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disks typically reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0221] The instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Thus, the term "processor," as used herein, may refer to any of the aforementioned structures or any other structures suitable for implementing the techniques described herein. Additionally, in some aspects, the functionality described herein may be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into a combined codec. Furthermore, the techniques may be fully implemented in one or more circuits or logic elements.

[0222] The techniques of this disclosure can be implemented in a wide variety of devices or apparatuses, including a wireless handset, an integrated circuit (IC), or a set of ICs (e.g., a chipset). The various components, modules, or units described in this disclosure are intended to emphasize the functional aspects of a device configured to perform the disclosed techniques, but do not necessarily require implementation by different hardware units. In fact, as described above, the various units may be combined in a codec hardware unit in conjunction with appropriate software and / or firmware, or provided by a collection of interoperable hardware units, including one or more processors as described above.

[0223] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. A method for decoding video data, the method comprising: accessing a track of the video data in a file, wherein the track comprises a series of samples; determining whether a sample in the series of samples is a sync sample, wherein determining whether the sample in the series of samples is a sync sample comprises determining whether a video coding layer (VCL) network abstraction layer (NAL) unit of the sample indicates that a coded picture included in the sample is an instantaneous decoding refresh (IDR) picture, a clean random access (CRA) picture, or a broken link access (BLA) picture; in response to determining that the sample is not a synchronization sample, determining parameter set data for the video data of the sample in accordance with a bitstream constraint, the bitstream constraint requiring the parameter set data to be located only in specific locations in the file and not at locations other than the specific locations, the specific locations in the file comprising a sample entry containing a description of a configuration for the sample, the sample, a previous sample in decoding order that is a synchronization sample, and samples that occur in decoding order between the sample and the previous sample in decoding order that is the synchronization sample, wherein the specific locations for the parameter set data are determined independently of any random access points having inconsistent definitions in ISOBMFF, wherein the parameter set data comprises one or more non-VCL NAL units including at least one of picture parameter set data or sequence parameter set data, wherein each of the specific locations in the file corresponds to a specific box within the file, each box in the file comprising a box type identifier and payload data; as well as The video data is decoded based on the determined parameter set data.

2. The method according to claim 1, further comprising: determining whether a second sample in the series of samples is a synchronization sample; as well as In response to determining that the second sample is a synchronization sample, parameter set data for the video data of the second sample is determined only from one or more second specific locations in the file, the one or more second specific locations in the file including a sample entry for the second sample and the second sample.

3. The method of claim 1 , wherein the sample conforms to at least one of: High Efficiency Video Coding (HEVC), High Efficiency Scalable Video Coding (SHVC), Multi-view High Efficiency Video Coding (MV-HEVC), Advanced Video Coding (AVC), Scalable Video Coding (SVC), and Multi-view Video Coding (MVC). 4 . The method of claim 1 , further comprising decoding the video data of the samples based on the determined parameter set data. 5 . The method of claim 1 , wherein determining parameter set data comprises determining the parameter set data in response to determining that the sample is not a synchronization sample and based on a sample entry name associated with the sample.

6. A method for encoding video data, the method comprising: storing a track of the video data in a file, wherein the track comprises a series of samples; determining whether a sample in the series of samples is a sync sample, wherein determining whether the sample in the series of samples is a sync sample comprises determining whether a video coding layer (VCL) network abstraction layer (NAL) unit of the sample indicates that a coded picture included in the sample is an instantaneous decoding refresh (IDR) picture, a clean random access (CRA) picture, or a broken link access (BLA) picture; In response to determining that the sample is not a synchronization sample, including parameter set data for the video data in accordance with a bitstream constraint, the bitstream constraint requiring the parameter set data to be located only in specific locations in the file and not at locations other than the specific locations, the specific locations in the file comprising a sample entry containing a description of a configuration for the sample, the sample, a previous sample in decoding order that is a synchronization sample, and samples that occur in decoding order between the sample and the previous sample in decoding order that is a synchronization sample, wherein the specific locations for the parameter set data are determined independently of any random access points having inconsistent definitions in ISOBMFF, wherein the parameter set data comprises one or more non-VCL NAL units including at least one of picture parameter set data or sequence parameter set data, wherein each of the specific locations in the file corresponds to a specific box within the file, each box in the file comprising a box type identifier and payload data; as well as The video data is encoded based on the determined parameter set data.

7. The method according to claim 6, further comprising: determining whether a second sample in the series of samples is a synchronization sample; as well as In response to determining that the second sample is a synchronization sample, parameter set data for the video data of the second sample is included only at one or more second specific locations in the file, the one or more second specific locations in the file including a sample entry for the second sample and the second sample.

8. The method of claim 6, wherein the sample conforms to at least one of: High Efficiency Video Coding (HEVC), High Efficiency Scalable Video Coding (SHVC), Multi-view High Efficiency Video Coding (MV-HEVC), Advanced Video Coding (AVC), Scalable Video Coding (SVC), and Multi-view Video Coding (MVC).

9. The method according to claim 6, further comprising: The video data of the samples is encoded based on the parameter set data.

10. The method of claim 6, wherein including parameter set data comprises including the parameter set data in response to determining that the sample is not a synchronization sample and based on a sample entry name associated with the sample.

11. An apparatus for decoding video data, the apparatus comprising: a memory configured to store video data; as well as One or more processors configured to: accessing a track of the video data in a file, wherein the track comprises a series of samples; determining whether a sample in the series of samples is a sync sample, wherein to determine whether the sample in the series of samples is a sync sample, the one or more processors are further configured to determine whether a video coding layer (VCL) network abstraction layer (NAL) unit of the sample indicates that a coded picture included in the sample is an instantaneous decoding refresh (IDR) picture, a clean random access (CRA) picture, or a broken link access (BLA) picture; in response to determining that the sample is not a synchronization sample, determining parameter set data for the video data of the sample in accordance with a bitstream constraint, the bitstream constraint requiring the parameter set data to be located only in specific locations in the file and not at locations other than the specific locations, the specific locations in the file comprising a sample entry containing a description of a configuration for the sample, the sample, a previous sample in decoding order that is a synchronization sample, and samples that occur in decoding order between the sample and the previous sample in decoding order that is a synchronization sample, wherein the specific locations for the parameter set data are determined independently of any random access points having inconsistent definitions in ISOBMFF, wherein the parameter set data comprises one or more non-VCL NAL units including at least one of picture parameter set data or sequence parameter set data, wherein each of the specific locations in the file corresponds to a specific box within the file, each box in the file comprising a box type identifier and payload data; as well as The video data is decoded based on the determined parameter set data.

12. The apparatus of claim 11 , wherein the one or more processors are configured to: determining whether a second sample in the series of samples is a synchronization sample; and In response to determining that the second sample is a synchronization sample, parameter set data for the video data of the second sample is determined only from one or more second specific locations in the file, the one or more second specific locations in the file including a sample entry for the second sample and the second sample.

13. The device of claim 11, wherein the samples conform to at least one of: High Efficiency Video Coding (HEVC), High Efficiency Scalable Video Coding (SHVC), Multi-view High Efficiency Video Coding (MV-HEVC), Advanced Video Coding (AVC), Scalable Video Coding (SVC), and Multi-view Video Coding (MVC).

14. The apparatus of claim 11, wherein to determine the parameter set data, the one or more processors are configured to determine the parameter set data in response to determining that the sample is not a synchronization sample and based on a sample entry name associated with the sample.

15. The device of claim 11, wherein the one or more processors are configured to decode the video data of the samples based on the parameter set data.

16. The device of claim 11, wherein the device comprises at least one of: an integrated circuit; microprocessor; and A wireless communication device includes a video decoder.

17. The device of claim 11, further comprising a display configured to display the video data.

18. An apparatus for encoding video data, the apparatus comprising: a memory configured to store video data; One or more processors configured to: storing a track of the video data in a file, wherein the track comprises a series of samples; determining whether a sample in the series of samples is a sync sample, wherein to determine whether the sample in the series of samples is a sync sample, the one or more processors are further configured to determine whether a video coding layer (VCL) network abstraction layer (NAL) unit of the sample indicates that a coded picture included in the sample is an instantaneous decoding refresh (IDR) picture, a clean random access (CRA) picture, or a broken link access (BLA) picture; and In response to determining that the sample is not a synchronization sample, including parameter set data for the video data in accordance with a bitstream constraint, the bitstream constraint requiring the parameter set data to be located only in specific locations in the file and not at locations other than the specific locations, the specific locations in the file comprising a sample entry containing a description of a configuration for the sample, the sample, a previous sample in decoding order that is a synchronization sample, and samples that occur in decoding order between the sample and the previous sample in decoding order that is a synchronization sample, wherein the specific locations for the parameter set data are determined independently of any random access points having inconsistent definitions in ISOBMFF, wherein the parameter set data comprises one or more non-VCL NAL units including at least one of picture parameter set data or sequence parameter set data, wherein each of the specific locations in the file corresponds to a specific box within the file, each box in the file comprising a box type identifier and payload data; as well as The video data is encoded based on the determined parameter set data.

19. The apparatus of claim 18, wherein the one or more processors are configured to: determining whether a second sample in the series of samples is a synchronization sample; and In response to determining that the second sample is a synchronization sample, parameter set data for the video data of the second sample is included only at one or more second specific locations in the file, the one or more second specific locations in the file including a sample entry for the second sample and the second sample.

20. The device of claim 18, wherein the samples conform to at least one of: High Efficiency Video Coding (HEVC), High Efficiency Scalable Video Coding (SHVC), Multi-view High Efficiency Video Coding (MV-HEVC), Advanced Video Coding (AVC), Scalable Video Coding (SVC), and Multi-view Video Coding (MVC).

21. The apparatus of claim 18, wherein to include parameter set data, the one or more processors are configured to include the parameter set data in response to determining that the sample is not a synchronization sample and based on a sample entry name associated with the sample.

22. The device of claim 18, wherein the one or more processors are configured to encode the video data of the samples based on the parameter set data.

23. The device of claim 18, wherein the device comprises at least one of: an integrated circuit; microprocessor; and A wireless communication device includes a video encoder.

24. The device of claim 18, further comprising a camera configured to acquire the video data.

25. An apparatus for decoding video data, the apparatus comprising: a unit for accessing a track of said video data in a file, wherein said track comprises a series of samples; means for determining whether a sample in a series of samples is a sync sample, wherein the means for determining whether the sample in the series of samples is a sync sample comprises means for determining whether a video coding layer (VCL) network abstraction layer (NAL) unit of the sample indicates that a coded picture included in the sample is an instantaneous decoding refresh (IDR) picture, a clean random access (CRA) picture, or a broken link access (BLA) picture; means for determining, in response to determining that the sample is not a sync sample, parameter set data for the video data in accordance with a bitstream constraint requiring the parameter set data to be located only in specific locations in the file and not at locations other than the specific locations, the specific locations in the file comprising a sample entry containing a description of a configuration for the sample, the sample, a previous sample in decoding order that is a sync sample, and samples that occur in decoding order between the sample and the previous sample in decoding order that is a sync sample, wherein the specific locations for the parameter set data are determined independently of any random access points having inconsistent definitions in ISOBMFF, wherein the parameter set data comprises one or more non-VCL NAL units including at least one of picture parameter set data or sequence parameter set data, wherein each of the specific locations in the file corresponds to a specific box within the file, each box in the file comprising a box type identifier and payload data; Means for decoding the video data based on the determined parameter set data.

26. The apparatus of claim 25, further comprising: means for determining whether a second sample in the series of samples is a synchronization sample; as well as Unit for determining parameter set data for the video data of the second sample from only one or more second specific locations in the file in response to determining that the second sample is a synchronization sample, the one or more second specific locations in the file including a sample entry for the second sample and the second sample.

27. The apparatus of claim 25, further comprising means for decoding the video data of the samples based on the parameter set data.

28. An apparatus for encoding video data, the apparatus comprising: a unit for accessing a track of said video data in a file, wherein said track comprises a series of samples; means for determining whether a sample in the series of samples is a sync sample, wherein the means for determining whether the sample in the series of samples is a sync sample comprises means for determining whether a video coding layer (VCL) network abstraction layer (NAL) unit of the sample indicates that a coded picture included in the sample is an instantaneous decoding refresh (IDR) picture, a clean random access (CRA) picture, or a broken link access (BLA) picture; means for including parameter set data for the video data in accordance with a bitstream restriction, in response to determining that the sample is not a synchronization sample, the bitstream restriction requiring the parameter set data to be located only in specific locations in the file and not at locations other than the specific locations, the specific locations in the file comprising a sample entry containing a description of a configuration for the sample, the sample, a previous sample in decoding order that is a synchronization sample, and samples that occur in decoding order between the sample and the previous sample in decoding order that is a synchronization sample, wherein the specific locations for the parameter set data are determined independently of any random access points having inconsistent definitions in ISOBMFF, wherein the parameter set data comprises one or more non-VCL NAL units including at least one of picture parameter set data or sequence parameter set data, wherein each of the specific locations in the file corresponds to a specific box within the file, each box in the file comprising a box type identifier and payload data; and Means for encoding the video data based on the determined parameter set data.

29. The apparatus according to claim 28, further comprising: means for determining whether a second sample in the series of samples is a synchronization sample; as well as A unit for including parameter set data for the video data of the second sample only from one or more second specific locations in the file in response to determining that the second sample is a synchronization sample, the one or more second specific locations in the file including a sample entry for the second sample and the second sample.

30. The apparatus of claim 28, further comprising means for encoding the video data of the samples based on the parameter set data.

31. A non-transitory computer-readable medium having stored thereon instructions that, when executed, cause one or more processors to: accessing a track of video data in a file, wherein the track comprises a series of samples; determining whether a sample in the series of samples is a synchronization sample, wherein To determine whether the sample in the series of samples is a synchronization sample, the instructions cause the one or more processors to determine whether a video coding layer (VCL) network abstraction layer (NAL) unit of the sample indicates that a coded picture included in the sample is an instantaneous decoding refresh (IDR) picture, a clean random access (CRA) picture, or a broken link access (BLA) picture; in response to determining that the sample is not a synchronization sample, determining parameter set data for the video data in accordance with a bitstream constraint, the bitstream constraint requiring the parameter set data to be located only in specific locations in the file and not at locations other than the specific locations, the specific locations in the file comprising a sample entry containing a description of a configuration for the sample, the sample, a previous sample in decoding order that is a synchronization sample, and samples that occur in decoding order between the sample and the previous sample in decoding order that is a synchronization sample, wherein the specific locations for the parameter set data are determined independently of any random access points having inconsistent definitions in ISOBMFF, wherein the parameter set data comprises one or more non-VCL NAL units including at least one of picture parameter set data or sequence parameter set data, wherein each of the specific locations in the file corresponds to a specific box within the file, each box in the file comprising a box type identifier and payload data; as well as The video data is decoded based on the determined parameter set data.

32. The non-transitory computer-readable medium of claim 31 , wherein the instructions cause the one or more processors to determine whether a second sample in the series of samples is a synchronization sample, and in response to determining that the second sample is a synchronization sample, determine parameter set data for the video data of the second sample only from one or more second specific locations in the file, the one or more second specific locations in the file including a sample entry for the second sample as well as the second sample.

33. The non-transitory computer-readable medium of claim 31, wherein the instructions cause the one or more processors to decode the video data of the samples based on the parameter set data.

34. A non-transitory computer-readable medium having stored thereon instructions that, when executed, cause one or more processors to: storing a path to video data in a file, wherein the path comprises a series of samples; determining whether a sample in the series of samples is a synchronization sample, wherein To determine whether the sample in the series of samples is a synchronization sample, the instructions cause the one or more processors to determine whether a video coding layer (VCL) network abstraction layer (NAL) unit of the sample indicates that a coded picture included in the sample is an instantaneous decoding refresh (IDR) picture, a clean random access (CRA) picture, or a broken link access (BLA) picture; and In response to determining that the sample is not a synchronization sample, including parameter set data for the video data in accordance with a bitstream constraint, the bitstream constraint requiring the parameter set data to be located only in specific locations in the file and not at locations other than the specific locations, the specific locations in the file comprising a sample entry containing a description of a configuration for the sample, the sample, a previous sample in decoding order that is a synchronization sample, and samples that occur in decoding order between the sample and the previous sample in decoding order that is a synchronization sample, wherein the specific locations for the parameter set data are determined independently of any random access points having inconsistent definitions in ISOBMFF, wherein the parameter set data comprises one or more non-VCL NAL units including at least one of picture parameter set data or sequence parameter set data, wherein each of the specific locations in the file corresponds to a specific box within the file, each box in the file comprising a box type identifier and payload data; as well as The video data is encoded based on the determined parameter set data.

35. The non-transitory computer-readable medium of claim 34, wherein the instructions cause the one or more processors to determine whether a second sample in the series of samples is a synchronization sample, and in response to determining that the second sample is a synchronization sample, include parameter set data for the video data of the second sample only in one or more second specific locations in the file, the one or more second specific locations in the file including a sample entry for the second sample as well as the second sample.

36. The non-transitory computer-readable medium of claim 34, wherein the instructions cause the one or more processors to encode the video data of the samples based on the parameter set data.

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