HK1237170B - Design of sample entry and operation point signalling in a layered video file format - Google Patents

Description

Sample entry and operation point signaling design in layered video file format

This application claims the benefit of U.S. Provisional Patent Application No. 62/115,075, filed February 11, 2015, the entire contents of which are incorporated herein by reference.

Technical Field

The present invention relates to video decoding.

Background Art

Digital video capabilities 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), the High Efficiency Video Coding (HEVC) standard currently under development, and extensions to these standards. By implementing these video compression techniques, video devices can more efficiently transmit, receive, encode, decode, and/or store digital video information.

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 (e.g., a video frame or a 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.

After the video data has been encoded, the video data may be packetized for transmission or storage. The video data may be packaged into a video file that conforms to any of a variety of standards, such as the International Organization for Standardization (ISO) base media file format and its extensions, such as AVC.

Summary of the Invention

Generally, the present invention relates to the storage of video content in files. In some examples, the techniques of this invention are based on the International Organization for Standardization (ISO) Base Media File Format (ISOBMFF). Some examples of this invention relate to storage of video streams containing multiple coded layers, where each layer can be a scalable layer, a texture view, a depth view, etc., and the methods are applicable to storing Multi-View High Efficiency Video Coding (MV-HEVC), Scalable HEVC (SHVC), Three-Dimensional HEVC (3D-HEVC), and other types of video data.

In one example, a method of processing multi-layer video data includes obtaining the multi-layer video data; storing the multi-layer video data in a file format; storing representation format information for each operation point of the multi-layer video data in an operation point information (oinf) box of the file format; and generating a file of video data formatted according to the file format.

In another example, a method of processing multi-layer video data includes obtaining a file of multi-layer video data formatted according to a file format; determining representation format information for each operation point of the multi-layer video data in an operation point information (oinf) box of the file format; and decoding the multi-layer video data based on the determined representation format information.

In another example, a video device for processing multi-layer video data includes: a data storage medium configured to store the multi-layer video data; and one or more processors configured to: obtain the multi-layer video data; store the multi-layer video data in a file format; store representation format information for each operation point of the multi-layer video data in an operation point information (oinf) box of the file format; and generate a file of video data formatted according to the file format.

In another example, a video device for processing multi-layer video data includes: a data storage medium configured to store the multi-layer video data; and one or more processors configured to: obtain a file of multi-layer video data formatted according to a file format; determine representation format information for each operation point of the multi-layer video data in an operation point information (oinf) box of the file format; and decode the multi-layer video data based on the determined representation format information.

In another example, a video device for processing multi-layer video data includes: a device for obtaining the multi-layer video data; a device for storing the multi-layer video data in a file format; a device for storing representation format information for each operation point of the multi-layer video data in an operation point information (oinf) box of the file format; and a device for generating a file of video data formatted according to the file format.

In another example, a computer-readable storage medium stores instructions that, when executed, cause one or more processors to: obtain multi-layer video data; store the multi-layer video data in a file format; store representation format information for each operation point of the multi-layer video data in an operation point information (oinf) box in the file format; and generate a file of video data formatted according to the file format.

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 be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a block diagram illustrating an example video encoding and decoding system that may use the techniques described in this disclosure.

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

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

4 is a block diagram illustrating an example set of devices forming part of a network.

5A is a conceptual diagram illustrating an example structure of a file, in accordance with one or more techniques of this disclosure.

5B is a conceptual diagram illustrating an example structure of a file, in accordance with one or more techniques of this disclosure.

6 is a conceptual diagram illustrating an example structure of a file, in accordance with one or more techniques of this disclosure.

7 is a flowchart illustrating example operation of a file generation device, in accordance with one or more techniques of this disclosure.

8 is a flowchart illustrating example operation of a file reading device, in accordance with one or more techniques of this disclosure.

DETAILED DESCRIPTION

The ISO Base Media File Format (ISOBMFF) is a file format for storing media data. ISOBMFF is extensible to support the storage of video data conforming to specific video coding standards. For example, ISOBMFF has previously been extended to support the storage of video data conforming to the H.264/AVC and High Efficiency Video Coding (HEVC) video coding standards. Furthermore, ISOBMFF has previously been extended to support the storage of video data conforming to the Multi-View Coding (MVC) and Scalable Video Coding (SVC) extensions of H.264/AVC. MV-HEVC, 3D-HEVC, and SHVC are extensions of the HEVC video coding standard that support multi-layer video data. The features added to ISOBMFF for the storage of video data conforming to the MVC and SVC extensions of H.264/AVC are insufficient for the efficient storage of video data conforming to MV-HEVC, 3D-HEVC, and SHVC. In other words, if we were to attempt to use the extensions of ISOBMFF used for storage of video data compliant with the MVC and SVC extensions of H.264/AVC for storage of video data compliant with MV-HEVC, 3D-HEVC, and SHVC, various problems might arise.

For example, unlike bitstreams conforming to the MVC or SVC extensions of H.264/AVC, bitstreams conforming to MV-HEVC, 3D-HEVC, or SHVC may include access units containing intra random access point (IRAP) pictures and non-IRAP pictures. Access units containing IRAP pictures and non-IRAP pictures can be used for random access in MV-HEVC, 3D-HEVC, and SHVC. However, ISOBMFF and its existing extensions do not provide a way to identify such access units. This situation can hinder the ability of computing devices to perform random access, layer switching, and other such functions associated with multi-layer video data.

Although much of the description of the techniques of this disclosure describes MV-HEVC, 3D-HEVC, and SHVC, the reader should appreciate that the techniques of this disclosure may be applicable to other video coding standards and/or extensions thereof.

As explained in more detail below, files conforming to the HEVC file format may contain a series of objects, referred to as boxes. A box may be an object-oriented building block defined by a unique type identifier and a length. This disclosure describes techniques related to generating files according to the file format, and more specifically, describes techniques for locating certain types of information within certain boxes to potentially improve a playback device's ability to process files containing multiple operation points.

Although much of the description of the techniques of this disclosure describes MV-HEVC, 3D-HEVC, and SHVC, the reader should appreciate that the techniques of this disclosure may be applicable to other video coding standards and/or extensions thereof.

FIG1 is a block diagram illustrating an example video encoding and decoding system 10 that may use the techniques described in this disclosure. As shown in FIG1 , system 10 includes a source device 12 that generates encoded video data to be later decoded by a destination device 14. 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 (such as so-called "smart" phones), so-called "smart" pads, televisions, cameras, display devices, digital media players, video game consoles, video stream transmission devices, or the like. In some cases, source device 12 and destination device 14 may be equipped for wireless communication. Source device 12 and destination device 14 may be considered video devices.

1 , source device 12 includes a video source 18, a video encoder 20, and an output interface 22. In some cases, output interface 22 may include a modulator/demodulator (modem) and/or a transmitter. In source device 12, video source 18 may include a source such as a video capture device (e.g., a video camera), a video disk containing previously captured video, a video feed interface for receiving video from a video content provider, and/or a computer graphics system for generating computer graphics data as source video, or a combination of such sources. However, the techniques described in this disclosure may be applicable to video coding in general and may be applied to wireless and/or wired applications.

Video encoder 20 may encode captured, pre-captured, or computer-generated video. Source device 12 may transmit the encoded video data directly to destination device 14 via output interface 22 of source device 12. The encoded video data may also (or alternatively) be stored on storage device 33 for later access by destination device 14 or other devices for decoding and/or playback.

Destination device 14 includes an input interface 28, a video decoder 30, and a display device 32. In some cases, input interface 28 may include a receiver and/or a modem. Input interface 28 of destination device 14 receives encoded video data via link 16. The encoded video data communicated via link 16 or provided on storage device 32 may include a variety of syntax elements generated by video encoder 20 for use by a video decoder, such as video decoder 30, in decoding the video data. Such syntax elements may be included within the encoded video data transmitted on a communication medium, stored on a storage medium, or stored on a file server.

Display device 32 may be integrated with destination device 14 or external to destination device 14. In some examples, destination device 14 may include an integrated display device and may also be configured to interface with an external display device. In other examples, destination device 14 may be a display device. In general, display device 32 displays decoded video data to a user and may include any of a variety of display devices, such as a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) display, or another type of display device.

Video encoder 20 and video decoder 30 may each be implemented as any of a variety of suitable encoder circuits, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic, software, hardware, firmware, or any combination thereof. When the techniques are implemented partially in software, the device may store the software instructions in a suitable non-transitory computer-readable medium and execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Each of video encoder 20 and video decoder 30 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined encoder/decoder (codec) in the respective device.

Destination device 14 may receive the encoded video data to be decoded via link 16. Link 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, link 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. The encoded video data may be modulated according to a communication standard, such as a wireless communication protocol, and transmitted to destination device 14. The communication medium may comprise 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, such as 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 suitable for facilitating communication from source device 12 to destination device 14.

Alternatively, output interface 22 may output the encoded data to storage device 33. Similarly, input interface 28 may access encoded data storage device 33. Storage device 33 may include any of a variety of distributed or locally accessible data storage media, such as a hard drive, Blu-ray disc, DVD, CD-ROM, flash memory, volatile or non-volatile memory, or any other suitable digital storage medium for storing encoded video data. In another example, storage device 33 may correspond to a file server or another intermediate storage device that can hold the encoded video generated by source device 12. Destination device 14 may access the stored video data from storage device 33 via streaming or downloading. A file server may be any type of server capable of storing encoded video data and transmitting that encoded video data to destination device 14. Example file servers include a web server (e.g., for a website), an FTP server, a network attached storage (NAS) device, or a local disk drive. Destination device 14 may access the encoded video data via any standard data connection, including an Internet connection. This data connection may include a wireless channel (e.g., a Wi-Fi connection) suitable for accessing encoded video data stored on a file server, a wired connection (e.g., DSL, cable modem, etc.), or a combination of both. The transmission of the encoded video data from storage device 33 may be a streaming transmission, a download transmission, or a combination of both.

The techniques of this disclosure are not necessarily limited to wireless applications or settings. The techniques may be applicable to video decoding to support any of a variety of multimedia applications, such as, for example, over-the-air television broadcasts, cable television transmissions, satellite television transmissions, streaming video transmissions via the Internet, encoding of digital video for storage on 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.

Furthermore, in the example of FIG. 1 , video coding system 10 may include file generation device 34. File generation device 34 may receive the encoded video data generated by source device 12 and generate a file including the encoded video data. Destination device 14 may receive the file generated by file generation device 34 directly or via storage device 33. In various examples, file generation device 34 may include various types of computing devices. For example, file generation device 34 may include a media-aware network element (MANE), a server computing device, a personal computing device, a special-purpose computing device, a commercial computing device, or another type of computing device. In some examples, file generation device 34 is part of a content delivery network. File generation device 34 may receive the encoded video data from source device 12 via a channel such as link 16. Furthermore, destination device 14 may receive the file from file generation device 34 via a channel such as link 16.

In some configurations, file generation device 34 may be a separate video device from source device 12 and destination device 14, while in other configurations, file generation device 34 may be implemented as a component of source device 12 or destination device 14. In implementations where file generation device 34 is a component of source device 12 or destination device 14, file generation device 34 may share some of the same resources, such as memory, processor, and other hardware, utilized by video encoder 20 and video decoder 30. In implementations where file generation device 34 is a separate device, the file generation device may include its own memory, processor, and other hardware units.

In other examples, source device 12 or another computing device may generate a file including the encoded video data. However, for ease of explanation, this disclosure describes file generation device 34 as generating a file. However, it should be understood that, in general, such descriptions apply to computing devices.

Video encoder 20 and video decoder 30 may operate according to a video compression standard such as the High Efficiency Video Coding (HEVC) standard or its extensions. The HEVC standard may also be referred to as ISO/IEC 23008-2. The design of HEVC was recently finalized by the Joint Collaboration Team on Video Coding (JCT-VC) of the ITU-T Video Coding Experts Group (VCEG) and the ISO/IEC Motion Picture Experts Group (MPEG). The latest HEVC draft specification (hereinafter referred to as HEVC WD) is available at http://phenix.int-evry.fr/jct/doc_end_user/documents/14_Vienna/wg11/JCTVC-N1003-v1.zip. A multi-view extension to HEVC, namely MV-HEVC, is also being developed by JCT-3V. The most recent working draft (WD) of MV-HEVC, entitled "MV-HEVC Draft Text 5" and hereinafter referred to as MV-HEVC WD5, is available at http://phenix.it-sudparis.eu/jct2/doc_end_user/documents/5_Vienna/wg11/JCT3V-E1004-v6.zip. A scalable extension to HEVC, SHVC, is also being developed by JCT-VC. The most recent working draft (WD) of SHVC, entitled "High Efficiency Video Coding (HEVC) scalable extension draft 3" and hereinafter referred to as SHVC WD3, is available at http://phenix.it-sudparis.eu/jct/doc_end_user/documents/14_Vienna/wg11/JCTVC-N1008-v3.zip. A recent working draft (WD) of the range extension of HEVC is available at http://phenix.int-evry.fr/jct/doc_end_user/documents/14_Vienna/wg11/JCTVC-N1005-v3.zip. A recent working draft (WD) of the 3D extension of HEVC, i.e., 3D-HEVC, entitled “3D-HEVC Draft Text 1,” is available at http://phenix.int-evry.fr/jct2/doc_end_user/documents/5_Vienna/wg11/JCT3V-E1001-v3.zip. Video encoder 20 and video decoder 30 may operate according to one or more of these standards.

Alternatively, video encoder 20 and video decoder 30 may operate according to other proprietary or industry standards, 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. However, the techniques of this disclosure are not limited to any particular coding standard. Other examples of video compression 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, and ITU-T H.264 (also known as ISO/IEC MPEG-4 AVC), including its scalable video coding (SVC) and multi-view video coding (MVC) extensions.

Although not shown in FIG1 , in some aspects, video encoder 20 and video decoder 30 may each be integrated with an audio encoder and decoder and may include appropriate MUX-DEMUX units or other hardware and software to handle the encoding of both audio and video in a common data stream or separate data streams. If applicable, in some examples, the MUX-DEMUX units may conform to the ITU H.223 multiplexer protocol or other protocols such as the User Datagram Protocol (UDP).

The JCT-VC developed the HEVC standard. The HEVC standardization effort is based on an evolved model of a video coding device, known as the HEVC Test Model (HM). The HM assumes several additional capabilities of video coding devices compared to existing devices, based on, for example, ITU-T H.264/AVC. For example, while H.264/AVC provides nine intra-frame prediction coding modes, the HM can provide up to 33 intra-frame prediction coding modes.

In general, the HM's working model describes how a video frame or picture can be divided into a sequence of treeblocks, or largest coding units (LCUs), that include both luma and chroma samples. A treeblock may also be referred to as a coding tree unit (CTU). A treeblock serves a similar purpose to a macroblock in the H.264/AVC standard. A slice comprises a number of consecutive treeblocks in coding order. A video frame or picture can be partitioned into one or more slices. Each treeblock can be split into coding units (CUs) according to a quadtree. For example, a treeblock, which is the root node of a quadtree, can be split into four child nodes, and each child node can, in turn, be a parent node and split into another four child nodes. The last unsplit child node, which is a leaf node of the quadtree, comprises a coding node (i.e., a coded video block). Syntax data associated with the coded bitstream may define the maximum number of times a treeblock can be split and may also define the minimum size of a coding node.

A CU comprises a coding node and prediction units (PUs) and transform units (TUs) associated with the coding node. The size of the CU corresponds to the size of the coding node and must be square in shape. The size of a CU can range from 8×8 pixels up to the size of a treeblock with a maximum of 64×64 pixels or larger. Each CU may contain one or more PUs and one or more TUs. Syntax data associated with a CU may describe, for example, the partitioning of the CU into one or more PUs. The partitioning mode may differ depending on whether the CU is skip or direct mode coded, intra-prediction mode coded, or inter-prediction mode coded. A PU may be partitioned into a non-square shape. Syntax data associated with a CU may also describe, for example, the partitioning of the CU into one or more TUs according to a quadtree. The shape of a TU may be square or non-square.

The HEVC standard allows for transforms to be performed on a per-TU basis, which may be different for different CUs. TUs are typically sized based on the size of the PUs within a given CU defined for a partitioned LCU, but this may not always be the case. TUs are typically the same size as or smaller than the PUs. In some examples, a quadtree structure known as a "residual quadtree" (RQT) may be used to subdivide the residual samples corresponding to a CU into smaller units. The leaf nodes of the RQT may be referred to as TUs. Pixel difference values associated with a TU may be transformed to produce transform coefficients that may be quantized.

In general, a PU includes data related to the prediction process. For example, when the PU is intra-mode encoded, the PU may include data describing the intra-prediction mode used for the PU. As another example, when the PU is inter-mode encoded, the PU may include data defining a motion vector for the PU. The data defining the motion vector for the PU may describe, for example, the horizontal component of the motion vector, the vertical component of the motion vector, the resolution of the motion vector (e.g., quarter-pixel precision or eighth-pixel precision), the reference picture to which the motion vector points, and/or the reference picture list for the motion vector (e.g., List 0, List 1, or List C).

In general, TUs are used for transform and quantization processes. A given CU having one or more PUs may also include one or more transform units (TUs). After prediction, video encoder 20 may calculate residual values corresponding to the PUs. The residual values include pixel difference values, which can be transformed into transform coefficients, quantized, and scanned using the TUs to produce serialized transform coefficients for use in entropy coding. This disclosure generally uses the term "video block" to refer to a coding node (i.e., a coding block) of a CU. In some specific cases, this disclosure may also use the term "video block" to refer to a treeblock (i.e., an LCU or CU), which includes a coding node as well as a PU and a TU.

A video sequence typically comprises a series of video frames or pictures. A group of pictures (GOP) generally includes one or more of a series of video pictures. A GOP may include syntax data in a header of the GOP, a header of one or more of the pictures, or elsewhere that describes the number of pictures included in the GOP. Each slice of a picture may include slice syntax data that describes the coding mode for the respective slice. Video encoder 20 typically operates on video blocks within individual video slices to encode the video data. A video block may correspond to a coding node within a CU. A video block may have a fixed or varying size and may be sized differently according to a specified coding standard.

As an example, the HM supports prediction with various PU sizes. Assuming a particular CU is 2N×2N, the HM supports intra prediction with PU sizes of 2N×2N or N×N, and inter prediction with symmetric PU sizes of 2N×2N, 2N×N, N×2N, or N×N. The HM also supports asymmetric partitioning for inter prediction with PU sizes of 2N×nU, 2N×nD, nL×2N, and nR×2N. In an asymmetric partitioning, the CU is unpartitioned in one direction and partitioned into 25% and 75% in the other direction. The portion of the CU corresponding to the 25% partition is indicated by an "n" followed by an indication of "Up," "Down," "Left," or "Right." Thus, for example, "2N×nU" refers to a 2N×2N CU partitioned horizontally with a 2N×0.5N PU at the top and a 2N×1.5N PU at the bottom.

In this disclosure, "NxN" and "N by N" may be used interchangeably to refer to the pixel dimensions of a video block in terms of vertical and horizontal dimensions, e.g., 16x16 pixels or 16 by 16 pixels. Generally, a 16x16 block has 16 pixels in the vertical direction (y=16) and 16 pixels in the horizontal direction (x=16). Similarly, an NxN block typically has N pixels in the vertical direction and N pixels in the horizontal direction, where N represents a non-negative integer value. The pixels in a block may be arranged in rows and columns. Furthermore, a block need not necessarily have the same number of pixels in the horizontal direction as in the vertical direction. For example, a block may comprise NxM pixels, where M is not necessarily equal to N.

After performing intra-predictive or inter-predictive coding using the PUs of a CU, video encoder 20 may calculate residual data for the TUs of the CU. A PU may include pixel data in the spatial domain (also referred to as 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 TUs including the residual data for the CU, and then transform the TUs to produce transform coefficients for the CU.

After performing any transforms to produce transform coefficients, video encoder 20 may perform quantization on the transform coefficients. Quantization generally refers to the process of quantizing the transform coefficients to potentially reduce the amount of data used to represent the coefficients, thereby providing further compression. The quantization process may reduce the bit depth associated with some or all coefficients. For example, an n-bit value may be truncated to an m-bit value during quantization, where n is greater than m.

In some examples, video encoder 20 may scan the quantized transform coefficients using a predefined scan order to generate a serialized vector that can be entropy encoded. In other examples, video encoder 20 may perform an adaptive scan. After scanning the quantized transform coefficients to form a one-dimensional vector, video encoder 20 may entropy encode the one-dimensional vector, for example, 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 when decoding the video data.

To perform CABAC, video encoder 20 may assign a context within a context model to a symbol to be transmitted. The context may relate to, for example, whether neighboring values of a symbol are nonzero. To perform CAVLC, video encoder 20 may select a variable length code for the symbol to be transmitted. Codewords in variable length coding (VLC) may be constructed such that relatively shorter codes correspond to more likely symbols, while longer codes correspond to less likely symbols. In this way, using VLC may achieve bit savings relative to, for example, using equal-length codewords for each symbol to be transmitted. Probability determinations may be made based on the context assigned to the symbol.

Video encoder 20 may output a bitstream that includes a sequence of bits that form a representation of a coded picture and associated data. The term "bitstream" may be a collective term used to refer to a stream of network abstraction layer (NAL) units (e.g., a series of NAL units) or a stream of bytes (e.g., a stream of NAL units containing a start code prefix and the encapsulation of NAL units as specified by Annex B of the HEVC standard). A NAL unit is a syntax structure that contains an indication of the type of data in the NAL unit and bytes containing that data in the form of a raw byte sequence payload (RBSP), interspersed with emulation prevention bits as needed. Each NAL unit may include a NAL unit header and may encapsulate an RBSP. The NAL unit header may include a syntax element that indicates a NAL unit type code. The NAL unit type code specified by the NAL unit header of a NAL unit indicates the type of the NAL unit. The RBSP may be a syntax structure that contains an integer number of bytes encapsulated within the NAL unit. In some cases, the RBSP comprises zero bits.

Different types of NAL units can encapsulate different types of RBSPs. For example, a first type of NAL unit can encapsulate an RBSP for a PPS, a second type of NAL unit can encapsulate an RBSP for a slice segment, a third type of NAL unit can encapsulate an RBSP for SEI, and so on. NAL units that encapsulate RBSPs for video coding data (as opposed to RBSPs for parameter sets and SEI messages) can be referred to as video coding layer (VCL) NAL units. NAL units that contain parameter sets (e.g., VPS, SPS, PPS, etc.) can be referred to as parameter set NAL units.

This disclosure may refer to the RBSP that encapsulates a slice slice as a NAL unit of a coded slice NAL unit. As defined in HEVC WD, a slice segment is an integer number of CTUs that are sequentially ordered in a tile scan and contained in a single NAL unit. In contrast, in HEVC WD, a slice may be an integer number of CTUs contained in an independent slice segment and all subsequent dependent slice segments (if any) preceding the next independent slice segment (if any) within the same access unit. An independent slice segment is a slice segment in which the values of the syntax elements of the slice segment header are not inferred from the values of the previous slice segment. A dependent slice segment is a slice segment in which the values of some syntax elements of the slice segment header are inferred from the values of the previous independent slice segment in decoding order. The RBSP of a coded slice NAL unit may include a slice segment header and slice data. The slice segment header is a portion of a coded slice segment that contains data elements related to the first or all CTUs represented in the slice segment. The slice header is a slice segment header of an independent slice segment, which is either the current slice segment or the most recent independent slice segment that precedes the current dependent slice segment in decoding order.

A VPS is a syntax structure that includes syntax elements applicable to zero or more complete coded video sequences (CVSs). An SPS is a syntax structure that contains syntax elements applicable to zero or more complete CVSs. An SPS may include syntax elements that identify the VPS that is active when the SPS is active. Thus, the syntax elements of a VPS may be more generally applicable than the syntax elements of an SPS.

A parameter set (e.g., VPS, SPS, PPS, etc.) may contain an identification referenced directly or indirectly from a slice header of a slice. The reference procedure is referred to as "activation." Thus, when video decoder 30 is decoding a particular slice, a parameter set referenced directly or indirectly by a syntax element in the slice header of that particular slice is said to be "activated." Depending on the parameter set type, activation may occur on a per-picture or per-sequence basis. For example, a slice header of a slice may include a syntax element identifying a PPS. Thus, when the video coder decodes the slice, the PPS may be activated. Furthermore, the PPS may include a syntax element identifying an SPS. Thus, when the PPS identifying the SPS is activated, the SPS may be activated. The SPS may include a syntax element identifying a VPS. Thus, when the SPS identifying the VPS is activated, the VPS is activated.

Video decoder 30 may receive a bitstream generated by video encoder 20. Furthermore, video decoder 30 may parse the bitstream to obtain syntax elements from the bitstream. Video decoder 30 may reconstruct a picture of the video data based, at least in part, on the syntax elements obtained from the bitstream. The process of reconstructing the video data may be generally inverse to the process performed by video encoder 20. For example, video decoder 30 may use the motion vectors of the PUs to determine the predictive blocks of the PUs of the current CU. Furthermore, video decoder 30 may inversely quantize the coefficient blocks of the TUs of the current CU. Video decoder 30 may perform an inverse transform on the coefficient blocks to reconstruct the transform blocks of the TUs of the current CU. Video decoder 30 may reconstruct the coding blocks of the current CU by adding samples of the predictive blocks of the PUs of the current CU to corresponding samples of the transform blocks of the TUs of the current CU. By reconstructing the coding blocks of each CU of the picture, video decoder 30 may reconstruct the picture.

In HEVC WD, a CVS can start with an instantaneous decoding refresh (IDR) picture, a broken link access (BLA) picture, or a clean random access (CRA) picture that is the first picture in the bitstream, including all subsequent pictures that are not IDR or BLA pictures. IDR pictures contain only I slices (i.e., slices that use only intra prediction). IDR pictures can be the first picture in the bitstream in decoding order, or they can appear later in the bitstream. Each IDR picture is the first picture in the CVS in decoding order. In HEVC WD, an IDR picture can be an intra random access point (IRAP) picture, for which each VCL NAL unit has nal_unit_type equal to IDR_W_RADL or IDR_N_LP.

IDR pictures can be used for random access. However, pictures that follow an IDR picture in decoding order cannot use pictures decoded before the IDR picture as references. Therefore, a bitstream that relies on IDR pictures for random access can have significantly lower coding efficiency than a bitstream that uses additional types of random access pictures. In at least some examples, an IDR access unit is an access unit that contains an IDR picture.

HEVC introduces the concept of CRA pictures to allow pictures that follow a CRA picture in decoding order but precede it in output order to reference pictures decoded before the CRA picture. Pictures that follow a CRA picture in decoding order but precede it in output order are referred to as preceding pictures associated with the CRA picture (or preceding pictures of the CRA picture). That is, to improve coding efficiency, HEVC introduces the concept of CRA pictures to allow pictures that follow a CRA picture in decoding order but precede it in output order to reference pictures decoded before the CRA picture. A CRA access unit is an access unit whose coded picture is a CRA picture. In HEVC WD, a CRA picture is an intra random access picture, for which each VCL NAL unit has a nal_unit_type equal to CRA_NUT.

The preceding pictures of a CRA picture can be correctly decodable if decoding starts with an IDR picture or a CRA picture that occurs before the CRA picture in decoding order. However, when random access occurs from a CRA picture, the preceding pictures of a CRA picture may be non-decodable. Therefore, a video decoder typically decodes the preceding pictures of a CRA picture during random access decoding. To prevent error propagation from reference pictures that may be unavailable depending on where decoding starts, pictures that follow the CRA picture in both decoding order and output order may not use any pictures that precede the CRA picture in decoding order or output order (including the preceding pictures) for reference.

The concept of 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 a bitstream spliced at the position of a CRA picture, and in the spliced bitstream, the splicing point CRA picture is changed to a BLA picture. Therefore, a BLA picture may be a CRA picture at the original bitstream, and the CRA picture is changed to a BLA picture by the bitstream splicer after the bitstream is spliced at the position of the CRA picture. In some cases, an access unit containing a RAP picture may be referred to herein as a RAP access unit. A BLA access unit is an access unit containing a BLA picture. In HEVC WD, a BLA picture may be an intra-frame random access picture, for which each VCL NAL unit has a nal_unit_type equal to BLA_W_LP, BLA_W_RADL, or BLA_N_LP.

In general, an IRAP picture contains only I slices and can be a BLA picture, a CRA picture, or an IDR picture. For example, HEVC WD indicates that an IRAP picture can be a coded picture for which each VCL NAL unit has a nal_unit_type in the range of BLA_W_LP to RSV_IRAP_VCL23, inclusive. Furthermore, HEVC WD indicates that the first picture in the bitstream in decoding order must be an IRAP picture. Table 7-1 of HEVC WD shows the NAL unit type code and NAL unit type category. Table 7-1 of HEVC WD is reproduced below.

Table 7-1 - NAL unit type code and NAL unit type category

One difference between BLA pictures and CRA pictures is as follows. For a CRA picture, if decoding starts with a RAP picture that precedes the CRA picture in decoding order, the associated preceding pictures can be correctly decoded. However, when random access occurs from a CRA picture (i.e., when decoding starts with the CRA picture, or in other words, when the CRA picture is the first picture in the bitstream), the preceding pictures associated with the CRA picture cannot be correctly decoded. In contrast, there may not be a situation where the preceding pictures associated with a BLA picture are decodable, even when decoding starts with a RAP picture that precedes the BLA picture in decoding order.

Some of the leading pictures associated with a particular CRA picture or a particular BLA picture may be correctly decodable, even when the particular CRA picture or the particular BLA picture is the first picture in the bitstream. Such leading pictures may be referred to as decodable leading pictures (DLPs) or random access decodable leading (RADL) pictures. In HEVC WD, a RADL picture may be a coded picture with nal_unit_type equal to RADL_R or RADL_N for each VCL NAL unit. Furthermore, HEVC WD indicates that all RADL pictures are leading pictures and that RADL pictures are not used as reference pictures for the decoding of trailing pictures for the same associated IRAP picture. When present, all RADL pictures precede all trailing pictures for the same associated IRAP picture in decoding order. HEVC WD indicates that a RADL access unit may be an access unit whose coded picture is a RADL picture. A trailing picture may be a picture that follows the associated IRAP picture in output order (i.e., the preceding IRAP picture in decoding order).

Other preceding pictures may be referred to as non-decodable preceding pictures (NLPs) or random access skip preceding (RASL) pictures. In HEVC WD, RASL pictures may be coded pictures with nal_unit_type equal to RASL_R or RASL_N for each VCL NAL unit. All RASL pictures are preceding pictures of the associated BLA or CRA pictures.

Assuming the necessary parameter sets are available when they are needed for activation, an IRAP picture and all subsequent non-RASL pictures in decoding order can be correctly decoded without performing the decoding process for any pictures that precede the IRAP picture in decoding order. There may be pictures in the bitstream that contain only I slices that are not IRAP pictures.

In multi-view coding, there may be multiple views of the same scene from different viewpoints. The term "access unit" may be used to refer to a set of pictures corresponding to the same time instance. Thus, video data may be conceptualized as a series of access units occurring over time. A "view component" may be a coded representation of a view in a single access unit. In this disclosure, a "view" may refer to a sequence or group of view components associated with the same view identifier. A view component may contain a texture view component and a depth view component. In this disclosure, a "view" may refer to a group or sequence of one or more view components associated with the same view identifier.

A texture view component (i.e., a texture picture) may be a coded representation of the texture of a view in a single access unit. A texture view may be a sequence of texture view components associated with the same value of a view order index. The view order index of a view may indicate the camera position of the view relative to other views. A depth view component (i.e., a depth picture) may be a coded representation of the depth of a view in a single access unit. A depth view may be a group or sequence of one or more depth view components associated with the same value of a view order index.

In MV-HEVC, 3D-HEVC, and SHVC, a video encoder may generate a bitstream comprising a series of NAL units. Different NAL units of the bitstream may be associated with different layers of the bitstream. A layer may be defined as a set of VCL NAL units and associated non-VCL NAL units with the same layer identifier. A layer may be equivalent to a view in multi-view video coding. In multi-view video coding, a layer may contain all view components of the same layer at different time instances. Each view component may be a coded picture of a video scene belonging to a specific view at a specific time instance. In some examples of 3D video coding, a layer may contain all coded depth pictures of a specific view or coded texture pictures of a specific view. In other examples of 3D video coding, a layer may contain both texture view components and depth view components of a specific view. Similarly, in the case of scalable video coding, a layer typically corresponds to a coded picture having different video characteristics than coded pictures in other layers. Such video characteristics typically include spatial resolution and quality level (e.g., signal-to-noise ratio). In HEVC and its extensions, temporal scalability can be achieved within a layer by defining groups of pictures with specific temporal levels as sub-layers.

For each respective layer of a bitstream, data in lower layers can be decoded without reference to data in any higher layers. In scalable video coding, for example, data in a base layer can be decoded without reference to data in enhancement layers. In general, a NAL unit may encapsulate data for only a single layer. Thus, a NAL unit encapsulating data for the highest remaining layer of the bitstream can be removed from the bitstream without affecting the decodability of data in the remaining layers of the bitstream. In multi-view coding and 3D-HEVC, higher layers may include additional view components. In SHVC, higher layers may include signal-to-noise ratio (SNR) enhancement data, spatial enhancement data, and/or temporal enhancement data. In MV-HEVC, 3D-HEVC, and SHVC, a layer may be referred to as a "base layer" if a video decoder can decode pictures in the layer without reference to data in any other layer. The base layer may conform to the HEVC base specification (e.g., HEVC WD).

In SVC, layers other than the base layer may be referred to as "enhancement layers" and may provide information that enhances the visual quality of video data decoded from the bitstream. SVC may enhance spatial resolution, signal-to-noise ratio (i.e., quality), or temporal rate. In scalable video coding (e.g., SHVC), a "layer representation" may be a coded representation of a spatial layer in a single access unit. For ease of explanation, this disclosure may refer to view components and/or layer representations as "view components/layer representations" or simply as "pictures."

To implement layers in HEVC, the header of a NAL unit includes the nuh_layer_id syntax element, previously referred to as the nuh_reserved_zero_6bits syntax element in various working drafts prior to the final HEVC standard. In the base HEVC standard, the nuh_layer_id syntax element is limited to a value of 0. However, in MV-HEVC, 3D-HEVC, and SVC, the nuh_layer_id syntax element can be greater than 0 to specify a layer identifier. NAL units of a bitstream that specify different values for the nuh_layer_id syntax element belong to different layers of the bitstream.

In some examples, if a NAL unit is associated with a base layer in multi-view coding (e.g., MV-HEVC), 3DV coding (e.g., 3D-HEVC), or scalable video coding (e.g., SHVC), the nuh_layer_id syntax element of the NAL unit is equal to 0. Data in the base layer of the bitstream can be decoded without reference to data in any other layer of the bitstream. If a NAL unit is not associated with a base layer in multi-view coding, 3DV, or scalable video coding, the nuh_layer_id syntax element of the NAL unit may have a non-zero value.

In addition, some view components/layer representations within a layer can be decodable without reference to other view components/layer representations within the same layer. Thus, NAL units that encapsulate data for certain view components/layer representations of a layer can be removed from the bitstream without affecting the decodability of other view components/layer representations in that layer. Removing the NAL units that encapsulate data for such view components/layer representations can reduce the frame rate of the bitstream. A subset of view components/layer representations within a layer that can be decodable without reference to other view components/layer representations within the layer may be referred to herein as a "sub-layer" or "temporal sub-layer."

A NAL unit may include a temporal_id syntax element that specifies the temporal identifier (i.e., TemporalId) of the NAL unit. The temporal identifier of a NAL unit identifies the sublayer to which the NAL unit belongs. Thus, each sublayer of a bitstream may have a different temporal identifier. In general, if the temporal identifier of the first NAL unit of a layer is less than the temporal identifier of the second NAL unit of the same layer, the data encapsulated by the first NAL unit can be decoded without reference to the data encapsulated by the second NAL unit.

A bitstream can be associated with multiple operation points. Each operation point of the bitstream is associated with a set of layer identifiers (e.g., a set of nuh_layer_id values) and a temporal identifier. The layer identifier set can be represented as OpLayerIdSet, and the temporal identifier can be represented as TemporalID. A NAL unit is associated with an operation point if its layer identifier is in the operation point's layer identifier set and its temporal identifier is less than or equal to the operation point's temporal identifier. Thus, an operation point can correspond to a subset of the NAL units in the bitstream. HEVC defines an operation point as a bitstream generated from a bitstream by the operation of a sub-bitstream extraction procedure, with the bitstream, target highest TemporalId, and target layer identifier list as input.

As introduced above, this disclosure relates to storing video content in files based on the ISO Base Media File Format (ISOBMFF). In other words, this disclosure describes various techniques for storing a video stream containing multiple coded layers, where each layer may be a scalable layer, a texture view, a depth view, or other types of layers or views. The techniques of this disclosure may be applicable, for example, to storing MV-HEVC video data, SHVC video data, 3D-HEVC video data, and/or other types of video data.

File formats and file format standards will now be briefly discussed. File format standards include the ISO base media file format (ISOBMFF, ISO/IEC 14496-12, hereinafter "ISO/IEC 14996-12") and other file format standards 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, hereinafter "ISO/IEC 14996-15"). Thus, ISO/IEC 14496-12 specifies the ISO base media file format. Other documents extend the ISO base media file format for specific applications. For example, ISO/IEC 14496-15 describes the carrying of NAL unit structured video in the ISO base media file format. H.264/AVC and HEVC, and their extensions, are examples of NAL unit structured video. ISO/IEC 14496-15 includes a section describing the carriage of H.264/AVC NAL units. In addition, Chapter 8 of ISO/IEC 14496-15 describes the carriage of HEVC NAL units.

ISOBMFF serves as the foundation for many codec encapsulation formats, such as the AVC file format, and for many multimedia container formats, such as the MPEG-4 file format, the 3GPP file format (3GP), and the DVB file format. In addition to continuous media, such as audio and video, static media, such as images, and metadata can be stored in files conforming to ISOBMFF. Files structured according to ISOBMFF can be used for many purposes, including local media file playback, progressive download of remote files, segments for Dynamic Adaptive Streaming over HTTP (DASH), containers for content to be streamed and its packetization instructions, and recording of received real-time media streams. Thus, although originally designed for storage, ISOBMFF has proven valuable for streaming, such as for progressive download or DASH. For streaming purposes, movie segments, as defined in ISOBMFF, can be used.

A file conforming to the HEVC file format may include a series of objects called boxes. A box may be an object-oriented building block defined by a unique type identifier and a length. For example, a box may be a basic syntax structure in ISOBMFF, comprising a four-character coded box type, a byte count for the box, and a payload. In other words, a box may be a syntax structure that includes a coded box type, a byte count for the box, and a payload. In some cases, all data in a file conforming to the HEVC file format may be contained within frames, and data may not exist in the file that is not in a box. Therefore, an ISOBMFF file may consist of a series of boxes, and a box may contain other boxes. For example, a box's payload may include one or more additional boxes. Figures 5A, 5B, and 6, described in detail elsewhere in this disclosure, show example boxes within a file according to one or more techniques of this disclosure.

An ISOBMFF-compliant file may contain various types of boxes. For example, an ISOBMFF-compliant file may include a file type box, a media data box, a movie box, a movie segment box, and so on. In this example, the file type box contains the file type and compatibility information. The media data box may contain samples (e.g., coded pictures). The movie box ("moov") contains metadata for the continuous media streams present in the file. Each of these continuous media streams may be represented in the file as a track. For example, a movie box may contain metadata about the movie (e.g., the logical and temporal relationships between samples, and pointers to the locations of the samples). A movie box may contain several types of sub-boxes. A sub-box within a movie box may include one or more track boxes. A track box may contain information about individual tracks of the movie. A track box may include a track header box that specifies overall information for a single track. Furthermore, a track box may include a media box containing a media information box. The media information box may include a sample table box containing data indices of media samples in a track. The information in the sample table box can be used to locate the sample in time (and, for each of the samples in the track, by type, size, container, and offset to that container of the sample). Thus, metadata for a track is enclosed in a track box ("trak"), while the media content of the track is enclosed in a media data box ("mdat") or directly in a separate file. The media content for a track includes (e.g., consists of) a sequence of samples, such as an audio or video access unit.

ISOBMFF specifies the following types of tracks: media tracks, which contain elementary media streams; hint tracks, which contain media transmission instructions or represent received packet streams; and timing metadata tracks, which include metadata for time synchronization. The metadata for each track consists of a list of sample description entries, each of which specifies the encoding or encapsulation format used in the track and the initialization data required to process that format. Each sample is associated with one of the sample description entries in the track.

ISOBMFF implementations specify sample-specific metadata through various mechanisms. Certain boxes within the sample table box ("stbl") have been standardized to respond to common needs. For example, the synchronization sample box ("stss") is a box within the sample table frame. The synchronization sample box is used to list random access samples for a playback track. The present invention may refer to the samples listed by the synchronization sample box as synchronization samples. In another example, a sample grouping mechanism implements the mapping of samples into groups of samples that share the same properties specified as sample group description entries in the file based on a four-character grouping type. Several grouping types have been specified in ISOBMFF.

The Sample Table box may include one or more SampleToGroup boxes and one or more Sample Group Description boxes (i.e., SampleGroupDescription boxes). The SampleToGroup box can be used to identify the sample group to which a sample belongs, along with an associated description of the sample group. In other words, the SampleToGroup box may indicate the group to which the sample belongs. The SampleToGroup box may have a box type of "sbgp." The SampleToGroup box may include a grouping type element (e.g., grouping_type). The grouping type element may be an integer that identifies the type of sample grouping (i.e., the criteria used to form the sample group). In addition, the SampleToGroup box may include one or more entries. Each entry in the SampleToGroup box may be associated with a series of different, non-overlapping, consecutive samples in a playback track. Each entry may indicate a sample count element (e.g., sample_count) and a group description index element (e.g., group_description_index). The sample count element of an entry may indicate the number of samples associated with the entry. In other words, the sample count element of an entry may be an integer that specifies the number of consecutive samples with the same sample group descriptor. The GroupDescriptionIndex element may identify a SampleGroupDescription box containing a description of the sample associated with the entry. The GroupDescriptionIndex elements of multiple entries may identify the same SampleGroupDescription box.

The current file format design may have one or more problems. To store video content for a specific video codec based on ISOBMFF, a file format specification for that video codec may be needed. To store video streams containing multiple layers such as MV-HEVC and SHVC, some concepts from the SVC and MVC file formats can be reused. However, many parts cannot be directly used for SHVC and MV-HEVC video streams. Direct application of the HEVC file format has at least the following disadvantages: SHVC and MV-HEVC bitstreams may start with an access unit that contains an IRAP picture in the base layer but may also contain other non-IRAP pictures in other layers, or vice versa. Sync samples currently do not allow indicating this point for random access.

This disclosure describes potential solutions to the above problems, as well as other potential improvements, for efficient and flexible storage of video streams containing multiple layers. The techniques described in this disclosure are potentially applicable to any file format for storing such video content decoded by any video codec, but the description is specific to storing SHVC and MV-HEVC video streams based on the HEVC file format, which is specified in clause 8 of ISO/IEC 14496-15.

The following describes example implementations of some of the techniques of the present invention. The example implementations described below are based on the latest integrated specification of 14496-15 in the MPEG output file W13478. The following includes changes to Appendix A (shown by underlining) and added chapters (Chapter 9 for SHVC and Chapter 10 for MV-HEVC). In other words, specific examples of the present invention may modify Appendix A of ISO/IEC 14496-15, and Chapter 9 and/or Chapter 10 may be added to ISO/IEC 14496-15. Text shown by underlining and double underlining may have specific relevance to the examples of the present invention. Although the term SHVC is used throughout the examples described herein, the design of the present invention will actually support not only SHVC codecs, but all multi-layer codecs including MV-HEVC and 3D-HEVC, unless explicitly mentioned otherwise.

The ISOBMFF specification specifies six types of stream access points (SAPs) for DASH. The first two SAP types (Type 1 and Type 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, and therefore corresponds to a BLA or CRA picture in HEVC. The fourth SAP type (Type 4) corresponds to a GDR random access point.

In the current L-HEVC file format, some high-level information (e.g., information about the layers in the bitstream, bit rate, frame rate, temporal sub-layers, parallelism, operation points, etc.) is signaled in LHEVCSampleEntry, HEVCLHVCSampleEntry, LHVCDecoderConfigurationRecord, TrackContentInfo ('tcon'), and OperationPointsInformationBox ('oinf'). In one example, the syntax of the above boxes is as follows:

Based on the current structure of the above boxes and the information contained therein, to play the content in the file, the player can be configured to first look for the "oinf" box (there is only one in the file) to know which operation points are included, and then select one of the operation points to play. The video player can then check the "tcon" box (one for each track containing L-HEVC video) to know which tracks contain the layers of the selected operation point.

Based on the current structure of the above boxes and the information contained therein, to play the content in the file, the player can be configured to first look for the "oinf" box (there is only one in the file) to know which operation points are included, and then select one of the operation points to play. The video player can then check the "tcon" box (one for each track containing L-HEVC video) to know which tracks contain the layers of the selected operation point.

Keeping in mind the basic usage of the current design, the present invention proposes to include more information (such as the representation format (which includes spatial resolution, bit depth, and color format), bit rate, and frame rate) in the "oinf" box to enable the selection of an operation point. The sample entry in each playback track contains a set of this information, but only for a specific operation point. When multiple operation points are included in a playback track, information for other operation points is omitted.

Another issue relates to the fact that the semantics of many fields in LHEVCDecoderConfigurationRecord are unclear, and some of them are confusing. For example, Profile, Tier, and Level (PTL), chromaFormat, bitDepthLumaMinus8, and bitDepthChromaMinus8 are layer-specific properties, but are currently said to apply to the operation point indicated by operationPointIdx. When the operation point contains more than one layer, the semantics are simply unclear.

In practice, based on the steps of conventional basic use of the design, some of the information in the sample entries is not actually useful, especially when there is enough information in the "oinf" box for operating point selection.

Another problem is that in SHVC and MV-HEVC, PTL is signaled only for each essential layer (i.e., a layer that is an output layer or a layer directly or indirectly referenced by an output layer in an operation point, or both), and not for any unnecessary layer (a layer that is not an essential layer). Therefore, in file format design, signaling PTL for unnecessary layers may not be necessary.

The following is an overview of the methods and techniques described in the present invention. Detailed examples are provided in later sections. The methods and techniques of the present invention can be applied independently or in combination.

The first technique of this disclosure includes removing the signaling of MPEG4BitRateBox() after LHEVCConfigurationBox in LHEVC sample entries and HEVC LHVC sample entries. Instead, the bit rate information is signaled for each operation point in the "oinf" box.

A second technique of this disclosure includes signaling information about the representation format (which includes spatial resolution, bit depth, and color format) for each operation point in the "oinf" box.

A third technique of the present disclosure includes removing the PTL information, representation format information, and frame rate information that has been provided in the "oinf" box or proposed to be added to the "oinf" box from the LHEVCDecoderConfigurationRecord. The remaining information in the LHEVCDecoderConfigurationRecord applies to all layers contained in the playback track. In another example of the third technique, the design of the LHEVCDecoderConfigurationRecord is restructured so that the representation format information and frame rate information and possibly additional parameters/information (e.g., parallelism information) are signaled for each layer. The syntax element unsigned int(2)parallelismType in the LHEVCDecoderConfigurationRecord may indicate what type of parallel decoding feature may be used for pictures in the decoding layer. Image blocks, wavefronts, and slices are examples of picture segment mechanisms that can be used to facilitate parallel processing.

The fourth technique of this disclosure includes removing operationPointIdx from LHEVCDecoderConfigurationRecord. In another example of the fourth technique, a list of operation point indices associated with a track is signaled in LHEVCDecoderConfigurationRecord.

A fifth technique of this disclosure involves changing the semantics of the layer_count field in the "oinf" box to count only the necessary layers for the operation point.

The following describes an example implementation of the methods and techniques of this disclosure. In the following example, text changes relative to the HEVC and LHEVC file formats are shown. Added text is shown between the identifiers [START INSERTION] and [END INSERTION]. Deleted text is shown between the identifiers [START DELETION] and [END DELETION].

The first implementation is described below.

This section describes detailed modifications to the signaling of LHEVCSampleEntry, HEVCLHVCSampleEntry, LHVCDecoderConfigurationRecord, and OperationPointsInformationBox ('oinf') of techniques 1, 2, 3 (excluding example a. thereof), 4 (excluding example a. thereof), and 5 of this disclosure.

layer_count: This field indicates the number of necessary layers that are part of the [START INSERTION] to [END INSERTION] to [START DELETION] to [END DELETION] operation points.

…

[START INSERTION]

minPicWidth specifies the minimum value of the luma width indicator as defined by the pic_width_in_luma_samples parameter in ISO/IEC 23008-2 for streaming of operation points.

minPicHeight specifies the minimum value of the luma height indicator as defined by the pic_height_in_luma_samples parameter in ISO/IEC 23008-2 for streaming of operation points.

maxPicWidth specifies the maximum value of the luma width indicator as defined by the pic_width_in_luma_samples parameter in ISO/IEC 23008-2 for streaming of operation points.

maxPicHeight specifies the maximum value of the luma height indicator as defined by the pic_height_in_luma_samples parameter in ISO/IEC 23008-2 for streaming of operation points.

maxChromaFormat specifies the maximum value of the chroma_format indicator as defined by the chroma_format_idc parameter in ISO/IEC 23008-2 for the stream of the operation point.

maxBitDepthMinus8 specifies the maximum value of the luma and chroma bit depth indicators as defined by the bit_depth_luma_minus8 and bit_depth_chroma_minus8 parameters, respectively, in ISO/IEC 23008-2 for streaming of the operation point.

A frame_rate_info_flag equal to 0 indicates that no frame rate information is present for the operation point. A value of 1 indicates that frame rate information is present for the operation point.

bit_rate_info_flag equal to 0 indicates that no bit rate information is present for the operation point. A value of 1 indicates that bit rate information is present for the operation point.

avgFrameRate gives the average frame rate in frames/(256 seconds) for the operating point. A value of 0 indicates an unspecified average frame rate.

A constantFrameRate value of 1 indicates that the stream of the operation point has a constant frame rate. A value of 2 indicates that the representation of each temporal layer in the stream of the operation point has a constant frame rate. A value of 0 indicates that the stream of the operation point may or may not have a constant frame rate.

maxBitRate gives the maximum bit rate in bits per second for the stream at the operating point within any window of one second.

avgBitRate gives the average bit rate of the stream in bits per second at the operating point.

…

[END INSERTION]

The second implementation is described below.

This section describes the detailed modifications to the signaling of LHVCDecoderConfigurationRecord of Example 3(a) of the present invention.

num_layers specifies the number of layers in the playback track.

layer_id specifies the layer ID value for which the information in this loop is provided.

[END INSERTION]

The third implementation is described below.

This section describes the detailed modifications to the signaling of LHVCDecoderConfigurationRecord of Example 4(a) of the present invention.

[START INSERTION]numOperationPoints: This field signals the number of operation points available for the playback track. [END INSERTION]

operationPointIdx: This field signals the index of the operation point recorded in the Operation Point Information box. [START DELETION] The values of general_profile_space, general_tier_flag, general_profile_idc, general_profile_compatibility_flags, general_constraint_indicator_flag, and general_level_idc in the LHEVCDecoderConfigurationRecord shall be the same as those for the operationPointIdx-th operation point in the Operation Point Information box. [END DELETION] [START INSERTION] The value of max_temporal_id in the operationPointIdx-th operation point in the Operation Point Information box shall be less than or equal to the value of numTemporalLayers. [END INSERTION]

Note that a track can be associated with one or more output layer sets [START DELETION] and therefore more than one profile [START DELETION]. The player can find out which layers to decode and which layers to output from the profile information in the [START INSERTION]LHEVCDecoderConfigurationRecord corresponding to the selected operation point with index operationPointIdx by examining the information provided for the operationPointIdx-th operation point in the Operation Point Information box.

Note that for each auxiliary picture layer included in a playback track, it is recommended to include a SEI NAL unit within the nalUnit containing a declarative SEI message specifying the characteristics of the auxiliary picture layer (such as a depth representation information SEI message for a depth auxiliary picture layer).

FIG2 is a block diagram illustrating an example video encoder 20 that may implement the techniques described in this disclosure. Video encoder 20 may be configured to output single-view, multi-view, scalable, 3D, and other types of video data. Video encoder 20 may be configured to output video to a post-processing entity 27. Post-processing entity 27 is intended to represent an example of a video entity, such as a MANE or splicing/editing device, that may process the encoded video data from video encoder 20. In some cases, the post-processing entity may be an example of a network entity. In some video coding 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. Post-processing entity 27 may be a video device. In some examples, post-processing entity 27 may be the same as file generation device 34 of FIG1 .

Video encoder 20 may perform intra- and inter-coding of 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 unidirectional prediction (P-mode) or bidirectional prediction (B-mode), may refer to any of several temporal-based compression modes.

2 , video encoder 20 includes partitioning unit 37, prediction processing unit 41, filter unit 63, reference picture memory 64, summer 50, transform processing unit 52, quantization unit 54, and entropy encoding unit 56. Prediction processing unit 41 includes motion estimation unit 42, motion compensation unit 44, and intra-prediction processing unit 46. To perform video block reconstruction, video encoder 20 also includes inverse quantization unit 58, inverse transform processing unit 60, and summer 62. 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 filter unit 63 is shown in FIG2 as a loop filter, in other configurations, filter unit 63 may be implemented as a post-loop filter.

Video data memory 35 of video encoder 20 may store video data to be encoded by the components of video encoder 20. The video data stored in video data memory 35 may be obtained, for example, from video source 18. Reference picture memory 64 may be a reference picture memory that stores reference video data for use by video encoder 20 when encoding video data (e.g., in intra- or inter-coding modes). Video data memory 35 and reference picture memory 64 may be formed from any of a variety of memory devices, such as dynamic random access memory (DRAM) (including synchronous DRAM (SDRAM)), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. Video data memory 35 and reference picture memory 64 may be provided by the same memory device or separate memory devices. In various examples, video data memory 35 may be on-chip with other components of video encoder 20, or off-chip relative to those components.

As shown in FIG2 , video encoder 20 receives video data, and partitioning unit 37 partitions the data into video blocks. This partitioning may also include partitioning into slices, tiles, or other larger units, as well as, for example, video block partitioning according to a quadtree structure of LCUs and CUs. Video encoder 20 generally illustrates 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 encoded block for use as a reference picture.

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 predictive blocks in one or more reference pictures to provide temporal compression.

Motion estimation unit 42 may be configured to determine the inter-prediction mode for a video slice based on a predetermined pattern for a video sequence. The predetermined pattern may designate a video slice in the sequence as a P slice, a B slice, or a GPB 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 predictive block within a reference picture.

A predictive 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 motion searches with respect to full-pixel positions and fractional pixel positions and output motion vectors with fractional pixel precision.

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 predictive 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.

Motion compensation performed by motion compensation unit 44 may involve extracting or generating a predictive block based on the motion vector determined by motion estimation, possibly performing interpolation to sub-pixel accuracy. Upon receiving the motion vector for the PU of the current video block, motion compensation unit 44 may locate the predictive block pointed to by the motion vector in one of the reference picture lists. Video encoder 20 may form a residual video block by subtracting the pixel values of the predictive block from the pixel values of the current video block being coded, thereby forming pixel difference values. The pixel difference values form residual data for the block and may include both luma difference components and chroma difference components. Summer 50 represents the 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.

As described above, as an alternative to the inter-prediction performed by motion estimation unit 42 and motion compensation unit 44, intra-prediction processing unit 46 may intra-predict the current block. In other words, intra-prediction processing unit 46 may determine an intra-prediction mode to use to encode the current block. In some examples, intra-prediction processing unit 46 may encode the current block using various intra-prediction modes, for example, during separate encoding passes, and intra-prediction unit 46 (or, in some examples, mode selection unit 40) may select an appropriate intra-prediction mode to use from the tested modes. For example, intra-prediction processing unit 46 may calculate rate-distortion values using a rate-distortion analysis for the various tested intra-prediction modes and select the intra-prediction mode with the best rate-distortion characteristics among the tested modes. Rate-distortion analysis generally determines the amount of distortion (or error) between the encoded block and the original, unencoded block (which was encoded to produce the encoded block), as well as the bit rate (i.e., the number of bits) used to produce the encoded block. Intra-prediction processing unit 46 may calculate ratios from the distortions and rates for the various encoded blocks to determine which intra-prediction mode exhibits the best rate-distortion value for the block.

In any case, after selecting an intra-prediction mode for a block, intra-prediction processing 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 the following in the transmitted bitstream: configuration data, which may include multiple intra-prediction mode index tables and multiple modified intra-prediction mode index tables (also called codeword mapping tables); definitions of encoding 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 to be used for each of the content contexts.

After prediction processing unit 41 generates a predictive block for the current video block via inter-prediction or intra-prediction, video encoder 20 may form a residual video block by subtracting the predictive block from the current video block. The residual video data in the residual block may be included 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.

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 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.

[0066] After quantization, the entropy encoding unit may entropy encode syntax elements representing 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 encoding method or technique. After entropy encoding by entropy encoding unit 56, the encoded bitstream may be transmitted to video decoder 30 or saved for later transmission or retrieval by video decoder 30. Entropy encoding unit 56 may also entropy encode motion vectors and other syntax elements for the current video slice being coded.

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 of a reference picture. Motion compensation unit 44 may calculate a reference block by adding the residual block to a predictive block of one of the reference pictures within 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 use in 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 to inter-predict a block in a subsequent video frame or picture.

Video encoder 20 represents an example of a video coder configured to generate video data that may be stored using the file format techniques described in this disclosure.

FIG3 is a block diagram illustrating an example video decoder 30 that may implement the techniques described in this disclosure. Video decoder 30 may be configured to decode single-view, multi-view, scalable, 3D, and other types of video data. In the example of FIG3 , video decoder 30 includes an entropy decoding unit 80, a prediction processing unit 81, an inverse quantization unit 86, an inverse transform processing unit 88, a summer 90, a filter unit 91, and a reference picture memory 92. Prediction processing unit 81 includes a motion compensation unit 82 and an intra-prediction processing unit 84. In some examples, video decoder 30 may perform a decoding operation that is generally the inverse of the encoding operation described with respect to video encoder 20 from FIG2 .

Coded picture buffer (CPB) 79 may receive and store encoded video data (e.g., NAL units) of a bitstream. The video data stored in CPB 79 may be obtained, for example, from link 16, from a local video source such as a camera, via a wired or wireless network for communicating video data, or by accessing physical data storage media. CPB 79 may form a video data memory that stores encoded video data from an encoded video bitstream. CPB 79 may be a reference picture memory that stores reference video data for use by video decoder 30 when decoding the video data (e.g., in intra- or inter-coding modes). CPB 79 and reference picture memory 92 may be formed from any of a variety of memory devices, such as dynamic random access memory (DRAM) (including synchronous DRAM (SDRAM)), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. CPB 79 and reference picture memory 92 may be provided by the same memory device or separate memory devices. In various examples, CPB 79 may be on-chip with other components of video decoder 30 , or off-chip relative to those components.

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. Video decoder 30 may receive the encoded video bitstream from network entity 29. Network entity 29 may, for example, be a server, a MANE, a video editor/splicer, or other such device configured to implement one or more of the techniques described above. Network entity 29 may or may not include a video encoder, such as video encoder 20. Some of the techniques described in this disclosure may be implemented by network entity 29 before network entity 29 transmits the encoded video bitstream to video decoder 30. In some video decoding systems, network entity 29 and video decoder 30 may be parts of separate devices, while in other cases, the functionality described with respect to network entity 29 may be performed by the same device that includes video decoder 30. Network entity 29 may be considered a video device. Furthermore, in some examples, network entity 29 is file generation device 34 of FIG.

Entropy decoding unit 80 of video decoder 30 entropy decodes specific syntax elements of the bitstream to generate 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.

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, P, or GPB) slice, motion compensation unit 82 of prediction processing unit 81 generates predictive blocks for the video block of the current video slice based on motion vectors and other syntax elements received from entropy decoding unit 80. The predictive blocks 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.

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 produce a predictive block for the current video block being decoded. For example, motion compensation unit 82 uses some of the received syntax elements to determine a prediction mode (e.g., intra-prediction or inter-prediction) used to code the video block of the video slice, an inter-prediction slice type (e.g., a B slice, a P slice, or a GPB slice), construction information for one or more of the slice's reference picture lists, a motion vector for each inter-coded video block of the slice, an inter-prediction state for each inter-coded video block of the slice, and other information used to decode the video blocks in the current video slice.

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

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 the video slice to determine the degree of quantization and, likewise, 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 to produce residual blocks in the pixel domain.

After motion compensation unit 82 generates a predictive 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 predictive block generated by motion compensation unit 82. Summer 90 represents one or more components that perform this summing operation. If desired, loop filters (either in the coding loop or after the coding loop) may also be used 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 filter unit 91 is shown in FIG3 as a loop filter, 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, such as display device 32 of FIG1 .

Video decoder 30 of FIG. 3 represents an example of a video decoder configured to decode video data that may be stored using the file format techniques described in this disclosure.

4 is a block diagram illustrating an example set of devices that form part of network 100. In this example, network 100 includes routing devices 104A, 104B (routing devices 104) and transcoding device 106. Routing devices 104 and transcoding device 106 are intended to represent a small number of the devices that may form part of network 100. Other network devices, such as switches, hubs, gateways, firewalls, bridges, and other such devices, may also be included within network 100. Furthermore, additional network devices may be provided along the network path between server device 102 and client device 108. In some examples, server device 102 may correspond to source device 12 (FIG. 1), while client device 108 may correspond to destination device 14 (FIG. 1).

Generally speaking, routing device 104 implements one or more routing protocols to exchange network data via network 100. In some instances, routing device 104 may be configured to perform proxy or caching operations. Therefore, in some instances, routing device 104 may be referred to as a proxy device. Generally speaking, routing device 104 executes routing protocols to discover routes through network 100. By executing such routing protocols, routing device 104B may discover a network route from itself via routing device 104A to server device 102.

The techniques of this disclosure may be implemented by network devices such as routing device 104 and transcoding device 106, but may also be implemented by client device 108. In this manner, routing device 104, transcoding device 106, and client device 108 represent examples of devices configured to perform the techniques of this disclosure. Furthermore, the devices of FIG. 1 , as well as encoder 20 illustrated in FIG. 2 and decoder 30 illustrated in FIG. 3 , are also examples of devices that may be configured to perform one or more of the techniques of this disclosure.

FIG5A is a conceptual diagram illustrating an example structure of a file 300 in accordance with one or more techniques of this disclosure. In the example of FIG5A , file 300 includes a movie box 302 and a plurality of media data boxes 304. Although illustrated in the example of FIG5A as being in the same file, in other examples, movie box 302 and media data boxes 304 may be in separate files. As indicated above, a box may be an object-oriented building block defined by a unique type identifier and length. For example, a box may be a basic syntactic structure in ISOBMFF, including a four-character encoding of the box type, the box's byte count, and the payload.

Movie block 302 may contain metadata for a track of file 300. Each track of file 300 may comprise a continuous stream of media data. Each of media data blocks 304 may include one or more samples 305. Each of samples 305 may comprise an audio or video access unit. As described elsewhere in this disclosure, in multi-view coding (e.g., MV-HEVC and 3D-HEVC) and scalable video coding (e.g., SHVC), each access unit may comprise multiple coded pictures. For example, an access unit may include one or more coded pictures for each layer.

Furthermore, in the example of FIG5A , movie box 302 includes track box 306. Track box 306 may enclose metadata for a track of file 300. In other examples, movie box 302 may include multiple track boxes for different tracks of file 300. Track box 306 includes media box 307. Media box 307 may contain all objects that declare information about the media data within the track. Media box 307 includes media information box 308. Media information box 308 may contain all objects that declare information about the characteristics of the media of the track. Media information box 308 includes sample table box 309. Sample table box 309 may specify sample-specific metadata.

In the example of FIG5A , sample table box 309 includes a SampleToGroup box 310 and a SampleGroupDescription box 312, and SampleGroupDescription box 312 includes an oinf box 316. In other examples, sample table box 309 may include additional boxes in addition to SampleToGroup box 310 and SampleGroupDescription box 312, and/or may include multiple SampleToGroup boxes and SampleGroupDescription boxes. SampleToGroup box 310 may map a sample (e.g., a particular one of sample 305) to a group of samples. SampleGroupDescription box 312 may specify properties shared by samples in the group of samples (i.e., a sample group). Furthermore, sample table box 309 may include multiple SampleEntry boxes 311. Each of the SampleEntry boxes 311 may correspond to a sample in the group of samples. In some examples, the SampleEntry boxes 311 are instances of a randomly accessible SampleEntry class that extends the basic SampleGroupDescription class.

According to one or more techniques of this disclosure, the SampleGroupDescription box 312 may specify that each sample in the sample group contains at least one IRAP picture. In this manner, the file generation device 34 may generate a file including a Track box 306 containing metadata for a track in the file 300. The media data for the track includes a series of samples 305. Each of the samples may be a video access unit of multi-layer video data (e.g., SHVC, MV-HEVC, or 3D-HEVC video data). Furthermore, as part of generating the file 300, the file generation device 34 may generate an additional box (i.e., a Sample Table box 309) in the file 300 that lists all samples 305 that contain at least one IRAP picture. In other words, the additional box identifies all samples 305 that contain at least one IRAP picture. In the example of FIG. 5A , the additional box defines a sample group that lists (e.g., identifies) all samples 305 that contain at least one IRAP picture. In other words, the additional box specifies that the samples 305 that contain at least one IRAP picture belong to the sample group.

According to the techniques of this disclosure, SampleGroupDescription box 312 may include oinf box 316. The oinf box may store representation format information for each operation point of the video data. The representation format information may include one or more of spatial resolution, bit depth, or color format. In addition, the oinf box may store a layer count indicating the number of necessary layers for the operation point of the video data. The oinf box may also store bit rate information for each operation point of the video data. Therefore, due to the bit rate information signaled in the oinf box, there may be no need to signal a bit rate box after the configuration box.

In addition, there may not be a need to store configuration files, hierarchy and level (PTL) information, representation format information, and frame rate information in the decoder configuration record of the file format. All other information in the decoder configuration record can be associated with all layers of video data in the playback track. The decoder configuration record for each layer of video data can store representation format information and frame rate information. The decoder configuration record can store parallelism information for each layer of video data. A file typically contains only one decoder configuration record for a playback track, but a playback track can contain one or more layers and one or more operation points. PTL information, representation format information, and frame rate information can be associated with each layer or each OP. Therefore, unlike the HEVC file format that supports only one layer, the decoder configuration record may not be able to properly facilitate this association for the LHEVC file format that supports multiple layers.

A decoder configuration record may not store an operation point index in the decoder configuration record, where the operation point index refers to the index of the operation point recorded in the operation point information box. Storing the operation point index in the decoder configuration record may cause a device playing the track (i.e., associated with the decoder configuration record) to play the operation point referenced by that operation point index. However, there may be more operation points available. Removing the operation point index may better enable the playback device to identify all operation points supported by the file. The decoder configuration record may store a list of operation point indices associated with the track of video data. The decoder configuration record may be derived, for example, from the information in sample entry box 311 of FIG. 5A .

The decoder configuration record stores information such as the size of the length field used in each sample to indicate the length of the NAL unit it contains, and the parameter set (if stored in the sample entry). The decoder configuration record can, for example, be externally framed (e.g., its size must be provided by the structure containing it). The decoder configuration record may also contain a version field to identify the version of the specification being followed, where an incompatible change to the record is indicated by a change in the version number. In contrast, compatible extensions of this record may not require a change in the configuration version code. The decoder configuration record may also include values for several HEVC syntax elements defined in HEVC, such as general_profile_space, general_tier_flag, general_profile_idc, general_profile_compatibility_flags, general_constraint_indicator_flags, general_level_idc, min_spatial_segmentation_idc, chroma_format_idc, bit_depth_luma_minus8, and bit_depth_chroma_minus8. The decoder configuration record may contain general information associated with a track including configuration records, number of temporal sub-layers, fragment information, supported parallelism types, and parameter set NAL units (e.g., VPS, SPS, PPS, SEI, etc.).

Furthermore, in accordance with one or more techniques of this disclosure, each of the sample entry boxes 311 may include a value (e.g., all_pics_are_IRAP) indicating whether all coded pictures in the corresponding sample are IRAP pictures. In some examples, a value equal to 1 specifies that not all coded pictures in the sample are IRAP pictures. A value equal to 0 specifies that not every coded picture in every sample in the sample group is an IRAP picture.

In some examples, when not all coded pictures in a particular sample are IRAP pictures, file generation device 34 may include a value indicating the number of IRAP pictures in the particular sample (e.g., num_IRAP_pics) in one of sample entry blocks 311 for the particular sample. Additionally, file generation device 34 may include a value indicating the layer identifier of the IRAP pictures in the particular sample in the sample entry for the particular sample. File generation device 34 may also include a value indicating the NAL unit type of the VCL NAL units in the IRAP pictures of the particular sample in the sample entry for the particular sample.

Furthermore, in the example of FIG5A , sample table box 309 includes a subsample information box 314. Although the example of FIG5A shows only one subsample information box, sample table box 309 may include multiple subsample information boxes. Generally, the subsample information box is designed to contain subsample information. A subsample is a series of contiguous bytes of a sample. ISO/IEC 14496-12 specifies that a specific definition of subsamples should be provided for a given coding system, such as H.264/AVC or HEVC.

Section 8.4.8 of ISO/IEC 14496-15 specifies the definition of subsamples for HEVC. Specifically, Section 8.4.8 of ISO/IEC 14496-15 specifies that, for use of the subsample information box (8.7.7 of ISO/IEC 14496-12) in an HEVC stream, subsamples are defined based on the value of the flags field of the subsample information box. According to one or more techniques of this disclosure, if the flags field in the subsample information box 314 is equal to 5, then the subsample corresponding to the subsample information box 314 contains one coded picture and associated non-VCL NAL units. The associated non-VCL NAL units may include NAL units containing SEI messages applicable to the coded picture and NAL units containing parameter sets (e.g., VPS, SPS, PPS, etc.) applicable to the coded picture.

Thus, in one example, file generation device 34 may generate a file (e.g., file 300) that includes a track box (e.g., track box 306) containing metadata for a track in the file. In this example, the media data for the track includes a series of samples, each of which is a video access unit of multi-layer video data (e.g., SHVC, MV-HEVC, or 3D-HEVC video data). Furthermore, in this example, as part of generating the file, file generation device 34 may generate a subsample information box (e.g., subsample information box 314) in the file that contains a flag that specifies the type of subsample information given in the subsample information box. When the flag has a particular value, the subsample corresponding to the subsample information box contains exactly one coded picture and zero or more non-VCL NAL units associated with the coded picture.

Furthermore, according to one or more techniques of this disclosure, if the Flags field of the Subsample Information box 314 is equal to 0, then the Subsample Information box 314 further includes a DiscardableFlag value, a NoInterLayerPredFlag value, a LayerId value, and a TempId value. If the Flags field of the Subsample Information box 314 is equal to 5, then the Subsample Information box 314 may include a DiscardableFlag value, a VclNalUnitType value, a LayerId value, a TempId value, a NoInterLayerPredFlag value, a SubLayerRefNalUnitFlag value, and a Reserved value.

SubLayerRefNalUnitFlag equal to 0 indicates that all NAL units in the subsample are VCL NAL units of sub-layer non-reference pictures, as specified in ISO/IEC 23008-2 (i.e., HEVC). SubLayerRefNalUnitFlag equal to 1 indicates that all NAL units in the subsample are VCL NAL units of sub-layer reference pictures, as specified in ISO/IEC 23008-2 (i.e., HEVC). Therefore, when the file generation device 34 generates the subsample information box 314 and the flag has a specific value (e.g., 5), the file generation device 34 includes an additional flag in the subsample information box 314 that indicates whether all NAL units in the subsample are VCL NAL units of sub-layer non-reference pictures.

The DiscardableFlag value indicates the value of the discardable_flag value of the VCL NAL unit in the subsample. As specified in Chapter A.4 of ISO/IEC 14496-15, the discardable_flag value should be set to 1 if and only if all extracted or aggregated NAL units have the discardable_flag set to 1, and otherwise it should be set to 0. If the bitstream containing the NAL unit can be correctly decoded without the NAL unit, then the NAL unit may have the discardable_flag set to 1. Therefore, if the bitstream containing the NAL unit can be correctly decoded without the NAL unit, then the NAL unit may be "discardable". All VCL NAL units in a subsample should have the same discardable_flag value. Therefore, when the file generation device 34 generates the subsample information box 314 and the flag has a specific value (e.g., 5), the file generation device 34 includes an additional flag (e.g., discardable_flag) in the subsample information box 314 indicating whether all VCL NAL units of the subsample are discardable.

The NoInterLayerPredFlag value indicates the value of the inter_layer_pred_enabled_flag for the VCL NAL units in the subsample. The inter_layer_pred_enabled_flag should be set to 1 if and only if all extracted or aggregated VCL NAL units have the inter_layer_pred_enabled_flag set to 1, and otherwise set to 0. All VCL NAL units in a subsample should have the same inter_layer_pred_enabled_flag value. Therefore, when the file generation device 34 generates the subsample information box 314 and the flag has a specific value (e.g., 5), the file generation device 34 includes an additional value (e.g., inter_layer_pred_enabled_flag) in the subsample information box 314 indicating whether inter-layer prediction is enabled for all VCL NAL units of the subsample.

LayerId indicates the nuh_layer_id value of the NAL unit in the subsample. All NAL units in the subsample should have the same nuh_layer_id value. Therefore, when the file generation device 34 generates the subsample information box 314 and the flag has a specific value (e.g., 5), the file generation device 34 includes an additional value (e.g., LayerId) indicating the layer identifier of each NAL unit of the subsample in the subsample information box 314.

TempId indicates the TemporalId value of the NAL units in the subsample. All NAL units in a subsample should have the same TemporalId value. Therefore, when the file generation device 34 generates the subsample information box 314 and the flag has a specific value (e.g., 5), the file generation device 34 includes an additional value (e.g., TempId) indicating the temporal identifier of each NAL unit of the subsample in the subsample information box 314.

VclNalUnitType indicates the nal_unit_type syntax element of the VCL NAL unit in the subsample. The nal_unit_type syntax element is a syntax element in the NAL unit header of a NAL unit. The nal_unit_type syntax element specifies the type of RBSP contained in the NAL unit. All nal_unit_type VCL NAL units in a subsample should have the same nal_unit_type value. Therefore, when the file generator 34 generates the subsample information box 314 and the flag has a specific value (e.g., 5), the file generator 34 includes an additional value (e.g., VclNalUnitType) in the subsample information box 314 indicating the NAL unit type of the VCL NAL unit of the subsample. All VCL NAL units of a subsample have the same NAL unit type.

FIG5B is a conceptual diagram illustrating an alternative example structure of file 300 in accordance with one or more techniques of this disclosure. In the example of FIG5B , an oinf box 316 is included in media information box 308 as a separate box from sample table box 309, rather than being included in sample group description box 312 as shown in FIG5A . The contents and functions of the various boxes in FIG3B may otherwise be the same as those described with respect to FIG5A .

FIG6 is a conceptual diagram illustrating an example structure of a file 300 in accordance with one or more techniques of this disclosure. As specified in Section 8.4.9 of ISO/IEC 14496-15, HEVC allows file format samples to be used only for reference and not for output. For example, HEVC allows non-display reference pictures in a video.

Furthermore, Section 8.4.9 of ISO/IEC 14496-15 specifies that when any such non-output samples are present in a playback track, the file should be constrained as follows.

1. Non-output samples should be given a composition time outside the time range of the output samples.

2. An edit list that does not include component times for non-output samples should be used.

3. When the playback track contains CompositionOffsetBox (‘ctts’),

a. Version 1 of CompositionOffsetBox should be used,

The value of b.sample_offset should be set equal to -2 ³¹ for each non-output sample,

c.CompositionToDecodeBox(‘cslg’) should be contained in the SampleTableBox(‘stbl’) of the playback track, and

d. When a CompositionToDecodeBox exists for a playback track, the value of the leastDecodeToDisplayDelta field in the box should be equal to the minimum composition offset in the CompositionOffsetBox excluding the sample_offset value of non-output samples.

Note: Therefore, leastDecodeToDisplayDelta is greater than -2 ³¹ .

As specified in ISO/IEC 14496-12, the CompositionOffsetBox provides the offset between the decoding time and the composition time. The CompositionOffsetBox contains a set of sample_offset values. Each sample_offset value is a non-negative integer that gives the offset between the composition time and the decoding time. The composition time is the time at which the sample will be output. The decoding time is the time at which the sample will be decoded.

As indicated above, a coded slice NAL unit may include a slice segment header. The slice segment header may be part of a coded slice segment and may contain data elements related to the first or all CTUs in the slice segment. In HEVC, the slice segment header includes a pic_output_flag syntax element. Generally, the pic_output_flag syntax element is included in the first slice segment header of a slice of a picture. Therefore, this disclosure may refer to the pic_output_flag of the first slice segment header of a slice of a picture as the pic_output_flag of the picture.

As specified in Chapter 7.4.7.1 of the HEVC WD, the pic_output_flag syntax element affects the decoded picture output and removal procedures, as specified in Annex C of the HEVC WD. In general, if the pic_output_flag syntax element of the slice segment header for a slice segment is 1, then the pictures including the slice corresponding to the slice segment header are output. Otherwise, if the pic_output_flag syntax element of the slice segment header for a slice segment is 0, then the pictures including the slice corresponding to the slice segment header may be decoded for use as reference pictures, but the pictures are not output.

According to one or more techniques of this disclosure, references to HEVC in Section 8.4.9 of ISO/IEC 14496-15 may be replaced by corresponding references to SHVC, MV-HEVC, or 3D-HEVC. Furthermore, according to one or more techniques of this disclosure, when an access unit contains some coded pictures with pic_output_flag equal to 1 and some other coded pictures with pic_output_flag equal to 0, at least two tracks must be used to store the stream. For each respective one of the tracks, all coded pictures in each sample of the respective track have the same pic_output_flag value. Thus, all coded pictures in a first one of the tracks have pic_output_flag equal to 0, and all coded pictures in a second one of the tracks have pic_output_flag equal to 1.

6 , the file generation device 34 may generate a file 400. Similar to the file 300 in the example of FIG. 5A , the file 400 includes a movie box 402 and one or more media data boxes 404. Each of the media data boxes 404 may correspond to a different track of the file 400. The movie box 402 may contain metadata for the tracks of the file 400. Each track of the file 400 may include a continuous stream of media data. Each of the media data boxes 404 may include one or more samples 405. Each of the samples 405 may include an audio or video access unit.

As indicated above, in some examples, when an access unit contains some coded pictures with pic_output_flag equal to 1 and some other coded pictures with pic_output_flag equal to 0, at least two tracks must be used to store the stream. Thus, in the example of FIG6 , movie block 402 includes track block 406 and track block 408. Each of track blocks 406 and 408 encloses metadata for a different track of file 400. For example, track block 406 may enclose metadata for a track that has coded pictures with pic_output_flag equal to 0 and no pictures with pic_output_flag equal to 1. Track block 408 may enclose metadata for a track that has coded pictures with pic_output_flag equal to 1 and no pictures with pic_output_flag equal to 0.

Thus, in one example, file generation device 34 may generate a file (e.g., file 400) that includes a media data box (e.g., media data box 404) that encloses (e.g., includes) media content. The media content includes a series of samples (e.g., sample 405). Each of the samples may be an access unit of multi-layer video data. In this example, when file generation device 34 generates a file in response to a determination that at least one access unit of a bitstream includes a coded picture with a picture output flag equal to 1 and a coded picture with a picture output flag equal to 0, file generation device 34 may store the bitstream in the file using at least two tracks. For each respective track from the at least two tracks, all coded pictures in each sample of the respective track have the same picture output flag value. Pictures with a picture output flag equal to 1 are allowed to be output, and pictures with a picture output flag equal to 0 are allowed to be used as reference pictures, but are not allowed to be output.

FIG7 is a flowchart illustrating an example operation of the file generation device 34 according to one or more techniques of this disclosure. The operation of FIG7 , along with the operations illustrated in other flowcharts of this disclosure, is an example. Other example operations according to the techniques of this disclosure may include more, fewer, or different actions.

In the example of FIG. 7 , file generation device 34 generates a file. As part of generating the file, file generation device 34 obtains multi-layer video data (170) and stores the multi-layer video data in a file format (172). File generation device 34 stores representation format information for each operation point of the multi-layer video data in an oinf box of the file format (174). File generation device 34 generates a file (176) of the video data formatted according to the file format. The representation format information may include one or more of a spatial resolution, a bit depth, or a color format. File generation device 34 may additionally or alternatively store bit rate information for each operation point of the multi-layer video data in an oinf box of the file format and/or may not signal the bit rate box after the configuration box of the file format. File generation device 34 may additionally or alternatively not store the configuration file, hierarchy and level (PTL) information, representation format information, and frame rate information in a decoder configuration record of the file format and associate all other information in the decoder configuration record with all layers of the multi-layer video data in the playback track. The file generation device 34 may additionally or alternatively store a layer count in an oinf box of the file format, wherein the layer count indicates the number of necessary layers for an operation point of the multi-layer video data.

The oinf box may be contained in the media information box, and the oinf box may be contained in the sample group description box. The sample group description box may be contained in the sample table box, and the sample table box may be contained in the media information box.

The file generation device 34 may store the presentation format information and the frame rate information in the decoder configuration record for each layer of the multi-layer video data. The file generation device 34 may also or alternatively store the parallelism information in the decoder configuration record for each layer of the multi-layer video data. The file generation device 34 may not store the operation point index in the decoder configuration record of the file format. The file generation device 34 may also or alternatively store a list of operation point indexes associated with the playback tracks of the multi-layer video data in the decoder configuration record of the file format.

FIG8 is a flowchart illustrating an example operation of a file reading device, such as destination device 14, post-processing entity 27, or network entity 29. The operation of FIG8 , along with the operations illustrated in other flowcharts of this disclosure, is an example. Other example operations according to the techniques of this disclosure may include more, fewer, or different actions.

In the example of FIG8 , a file reader obtains a file of multi-layer video data formatted according to a file format (180). The file reader determines, for the file format, representation format information for each operation point of the multi-layer video data in an oinf box of the file format (182). The file reader decodes the multi-layer video data based on the determined representation format information, possibly in conjunction with a video decoder such as the video decoder 30 (184).

In one or more examples, the described functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or program codes and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media (which corresponds to tangible media such as data storage media) or communication media, which includes, for example, any media that facilitates the transfer of a computer program from one place 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 this disclosure. A computer program product may include computer-readable media.

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 devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed 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 microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but rather refer 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.

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 structure suitable for implementing the techniques described herein. Furthermore, 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 components.

The techniques of this disclosure can be implemented in a wide variety of devices or apparatuses, including wireless handsets, integrated circuits (ICs), or collections of ICs (e.g., chipsets). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require implementation by different hardware units. Rather, as described above, the various units can be combined in a codec hardware unit or provided by a collection of interoperable hardware units (including one or more processors as described above) in conjunction with appropriate software and/or firmware.

Various embodiments have been described. These and other embodiments are within the scope of the following claims.

Claims (32)

1. A method for processing multi-layer video data, the method comprising: Obtain multi-layer video data including multiple operation points; The multi-layer video data is stored in a file format, wherein the file format includes operation point information oinf boxes, which identify the operation points included in the multi-layer video data; The oinf box stores the configuration file, hierarchy, and indicator of the level PTL information for each layer at each operation point of the multi-layer video data; The oinf box stores representation format information for each operational point of the multi-layer video data, wherein the representation format information includes one or more of spatial resolution, bit depth, or color format; and Generates a file containing video data formatted according to the stated file format. 2. The method of claim 1, wherein the oinf box definition includes sample group operation points in the multi-layer video data. 3. The method according to claim 1, further comprising: The bit rate information for each operation point of the multi-layer video data is stored in the oinf box of the file format; and The signal transmission bit rate box is not used after the configuration box for the file format. 4. The method of claim 1, further comprising: The configuration file, hierarchy and level PTL information, representation format information, and frame rate information are not stored in the decoder configuration record of the file format; and This associates all information from each layer in the decoder configuration record with each layer of the multi-layer video data in the playback track. 5. The method of claim 1, further comprising: The representation format information and frame rate information are stored in the decoder configuration record for each layer of the multi-layer video data. 6. The method of claim 5, further comprising: Parallelism information is stored in the decoder configuration record for each layer of the multi-layer video data. 7. The method of claim 1, further comprising: The operation point index is not stored in the decoder configuration record of the file format. 8. The method of claim 1, further comprising: The decoder configuration record of the file format stores a list of operation point indices associated with the playback track of the multi-layer video data. 9. The method of claim 1, further comprising: The layer count is stored in the oinf box of the file format, wherein the layer count indicates the number of necessary layers for the operation points of the multi-layer video data. 10. The method of claim 1, wherein the oinf box is included in the media information box. 11. The method of claim 10, wherein the oinf box is further included in the sample group description box, wherein the sample group description box is included in the sample table box, and wherein the sample table box is included in the media information box. 12. The method of claim 1, wherein each operation point of the multilayer video data comprises a bitstream, the bitstream being generated from the other stream by means of an operation of a sub-bitstream extraction procedure of the other stream. 13. A video apparatus for processing multi-layer video data, the apparatus comprising: Data storage media configured to store the multi-layer video data; and One or more processors configured to perform the following operations: Obtain multi-layer video data including multiple operation points; The multi-layer video data is stored in a file format, wherein the file format includes operation point information oinf boxes, which identify the operation points included in the multi-layer video data; The oinf box stores the configuration file, hierarchy, and indicator of the level PTL information for each layer at each operation point of the multi-layer video data; The oinf box stores representation format information for each operational point of the multi-layer video data, wherein the representation format information includes one or more of spatial resolution, bit depth, or color format; and Generates a file containing video data formatted according to the stated file format. 14. The apparatus of claim 13, wherein the oinf box definition includes sample group operation points in the multilayer video data. 15. The apparatus of claim 13, wherein the one or more processors are further configured to perform the following operations: The bit rate information for each operation point of the multi-layer video data is stored in the oinf box of the file format; and The signal transmission bit rate box is not used after the configuration box for the file format. 16. The apparatus of claim 13, wherein the one or more processors are further configured to perform the following operations: The configuration file, hierarchy and level PTL information, representation format information, and frame rate information are not stored in the decoder configuration record of the file format; and This associates all information from each layer in the decoder configuration record with each layer of the multi-layer video data in the playback track. 17. The apparatus of claim 13, wherein the one or more processors are further configured to perform the following operations: The representation format information and frame rate information are stored in the decoder configuration record for each layer of the multi-layer video data. 18. The apparatus of claim 17, wherein the one or more processors are further configured to perform the following operations: Parallelism information is stored in the decoder configuration record for each layer of the multi-layer video data. 19. The apparatus of claim 13, wherein the one or more processors are further configured to perform the following operations: The operation point index is not stored in the decoder configuration record of the file format. 20. The apparatus of claim 13, wherein the one or more processors are further configured to perform the following operations: The decoder configuration record of the file format stores a list of operation point indices associated with the playback track of the multi-layer video data. 21. The apparatus of claim 13, wherein the one or more processors are further configured to perform the following operations: The layer count is stored in the oinf box of the file format, wherein the layer count indicates the number of necessary layers for the operation points of the multi-layer video data. 22. The apparatus of claim 13, wherein the oinf box is included in the media information box. 23. The apparatus of claim 22, wherein the oinf box is further included in a sample group description box, wherein the sample group description box is included in a sample table box, and wherein the sample table box is included in the media information box. 24. The apparatus of claim 13, wherein each operation point of the multilayer video data comprises a bitstream, the bitstream being generated from the other stream by operation of a sub-bitstream extraction procedure of the other stream. 25. A video apparatus for processing multi-layer video data, the apparatus comprising: A device for acquiring multi-layer video data including multiple operation points; A means for storing the multi-layer video data in a file format, wherein the file format includes operation point information oinf boxes that identify the operation points included in the multi-layer video data; A means for storing in the oinf box an indicator of the configuration file, hierarchy, and level PTL information for each layer at each point of operation of the multi-layer video data; Means for storing representation format information for each operational point of the multi-layer video data within the oinf frame, wherein the representation format information includes one or more of spatial resolution, bit depth, or color format; and A means for generating a file of video data formatted according to the file format. 26. The apparatus of claim 25, wherein the oinf box definition includes sample group operation points in the multilayer video data. 27. The apparatus of claim 25, wherein the oinf box is included in the media information box. 28. The apparatus of claim 27, wherein the oinf box is further included in a sample group description box, wherein the sample group description box is included in a sample table box, and wherein the sample table box is included in the media information box. 29. A non-transitory computer-readable storage medium storing instructions, which, when executed, cause one or more processors to perform the following operations: Obtain multi-layer video data including multiple operation points; The multi-layer video data is stored in a file format, wherein the file format includes operation point information oinf boxes, which identify the operation points included in the multi-layer video data; The oinf box stores the configuration file, hierarchy, and indicator of the level PTL information for each layer at each operation point of the multi-layer video data; The oinf box stores representation format information for each operational point of the multi-layer video data, wherein the representation format information includes one or more of spatial resolution, bit depth, or color format; and Generates a file containing video data formatted according to the stated file format. 30. The non-transitory computer-readable storage medium of claim 29, wherein the oinf block definition includes sample grouping operation points in the multi-layer video data. 31. The non-transitory computer-readable storage medium of claim 29, wherein the oinf box is included in the media information box. 32. The non-transitory computer-readable storage medium of claim 31, wherein the oinf box is further included in the sample group description box, wherein the sample group description box is included in the sample table box, and wherein the sample table box is included in the media information box.