Transporting HEIF formatted images over the Real-time Transport Protocol

Abstract

1. An exemplary device for retrieving media data, the device comprising: a memory configured to store scene data and image data; and one or more processors implemented in circuitry, the one or more processors configured to: receive data for a bitstream indicating that the bitstream includes one or more overlay images; receive one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data that remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence that repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receive scene data including one or more scene images; and present the scene images and the overlay images.

Description

[Technical field]

[0001]

[0001] This application claims priority to U.S. Patent Application No. 17 / 656,159, filed March 23, 2022, and U.S. Provisional Application No. 63 / 168,157, filed March 30, 2021, the entire contents of each of which are incorporated herein by reference. U.S. Patent Application No. 17 / 656,159, filed March 23, 2022, claims the benefit of U.S. Provisional Application No. 63 / 168,157, filed March 30, 2021.

[0002] This disclosure relates to the storage and transport of encoded media data. [Background technology]

[0003] Digital video capabilities may be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, digital cameras, digital recording devices, digital media players, video gaming devices, video game consoles, cellular or satellite radiotelephones, video teleconferencing devices, etc. Digital video devices implement video compression techniques, such as those described in standards defined by MPEG-2, MPEG-4, ITU-T H.263 or ITU-T H.264 / MPEG-4, Part 10, Advanced Video Coding (AVC), ITU-T H.265 (also known as High Efficiency Video Coding (HEVC)), and extensions to such standards, for more efficiently transmitting and receiving digital video information.

[0004] After media data, such as video data, is encoded, the media data may be packetized for transmission or storage and assembled into a media file that conforms to any of a variety of standards, such as the International Organization for Standardization (ISO) Base Media File Format (ISOBMFF) and its extensions, such as AVC. Summary of the Invention

[0005]

[0005] In general, this disclosure describes techniques for supporting the transport and presentation of images as sources for overlays. An overlay, or overlay image, generally corresponds to a static image presented over dynamic video content. That is, a static image overlay remains unchanged when presented over dynamic video content that may change from frame to frame. Alternatively, a series of images may be presented as an overlay, for example in the form of a loop. In such a case, the overlay image sequence may repeat with a regular periodicity, for example according to the number of images included in the overlay image sequence. Overlays are an important aspect of immersive teleconferencing, since they can be used to superimpose a wide variety of content in a scene. For example, overlays may allow slides, logos, and / or information screens to be superimposed on a scene. The overlay texture may be from a video stream, one or more still images, or a sequence of images. The Immersive Teleconferencing and Telepresence for Remote Terminals (ITT4RT) group is working on supporting images as a source for overlays. This disclosure describes the use of the High Efficiency Image File (HEIF) format as a format for containing image overlays.

[0006]

[0006] In one example, a method for retrieving media data includes receiving data for a bitstream indicating that the bitstream includes one or more overlay images; receiving one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data that remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence that repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receiving scene data including one or more scene images; and presenting the scene images and the overlay images.

[0007]

[0007] In another example, a device for retrieving media data includes a memory configured to store scene data and image data and one or more processors implemented in a circuit, the one or more processors configured to: receive data for the bitstream indicating that the bitstream includes one or more overlay images; receive one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data that remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence that repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receive scene data including one or more scene images; and present the scene images and the overlay images.

[0008]

[0008] In another example, a computer-readable storage medium having stored thereon instructions which, when executed, cause a processor to receive data for a bitstream indicating that the bitstream includes one or more overlay images; receive one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data that remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence that repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receive scene data including one or more scene images; and present the scene images and the overlay images.

[0009]

[0009] In another example, a device for receiving media data includes means for receiving data for the bitstream indicating that the bitstream includes one or more overlay images, means for receiving one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented along with the scene data which remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence which repeats with regular periodicity while presented frame-by-frame with the frames of scene data, means for receiving scene data including one or more scene images, and means for presenting the scene images and the overlay images.

[0010]

[0010] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description and drawings, and from the claims. [Brief description of the drawings]

[0011] [Figure 1]

[0011] FIG. 1 is a block diagram illustrating an example system that implements techniques for streaming media data over a network. [Diagram 2]

[0012] 2 is a block diagram illustrating an exemplary set of components of the removal unit 52 of FIG. 1 in greater detail. [Diagram 3]

[0013] FIG. 1 is a conceptual diagram illustrating elements of exemplary multimedia content. [Figure 4]

[0014] 1 is a block diagram showing elements of an exemplary video file that may correspond to segments of a presentation. [Diagram 5]

[0015] 1 is a conceptual diagram illustrating an example structure of a High Efficiency Image File (HEIF) format for containing image data. [Figure 6]

[0016] 1 is a flowchart illustrating an example method for retrieving media data in accordance with techniques of this disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012]

[0017] In general, this disclosure describes techniques for using a particular format, such as the High Efficiency Image File (HEIF) format, to include image overlays. An overlay, or overlay image, generally corresponds to a static image presented over dynamic video content. That is, a static image overlay remains unchanged when presented over dynamic video content that may change from frame to frame. Alternatively, a series of images may be presented as an overlay, for example in the form of a loop. In such a case, the overlay image sequence may repeat with a regular periodicity, for example according to the number of images included in the overlay image sequence. For example, if the overlay image sequence includes N images, the i-th image in the image sequence will be presented every j*N+i frames, where j can range from 0 to infinity and i can range from 0 to N-1. The HEIF format is defined in ISO / IEC 23008-12. ISO / IEC 23008-12 specifies the storage of images and image sequences and their metadata in ISOBMFF-based container files. HEIF defines a general, codec-agnostic structure for storage of images and provides an instantiation based on the H.265 / HEVC (High Efficiency Video Coding) codec.

[0013]

[0018] In various contexts, such as video telephony and video conferencing sessions, it may be desirable to share images between participants. However, some video streaming protocols, such as Real-time Transport Protocol (RTP), do not define the transport of images. HEIF is an image format that allows for the storage of image sets and image sequences, for example, encoded using HEVC or other video codecs. The transport of images over RTP is currently not specified. This disclosure describes techniques for transporting and presenting HEIF image sets and image sequences over RTP. These techniques describe extensions to the RTP payload format, for example, for HEVC, as well as signaling of images in the Session Description Protocol (SDP). In this manner, images and image sequences may be transported during a video conferencing session, for which data may be transported using RTP or other such protocols.

[0014]

[0019] The techniques of this disclosure may be applied to media files, such as video files, that conform to media data encapsulated according to any of the ISO Base Media File Format (ISOBMFF), the Scalable Video Coding (SVC) file format, the Advanced Video Coding (AVC) file format, the 3rd Generation Partnership Project (3GPP®) file format, and / or the Multiview Video Coding (MVC) file format, or other similar video file formats.

[0015]

[0020] 1 is a block diagram illustrating an example system 10 that implements techniques for streaming media data over a network. In this example, the system 10 includes a content creation device 20, a server device 60, and a client device 40. The client device 40 and the server device 60 are communicatively coupled by a network 74, which may comprise the Internet. In some examples, the content creation device 20 and the server device 60 may also be communicatively coupled by the network 74 or another network, or may be communicatively coupled directly. In some examples, the content creation device 20 and the server device 60 may comprise the same device.

[0016]

[0021] 1 example, content creation device 20 comprises audio source 22 and video source 24. Audio source 22 may comprise, for example, a microphone generating electrical signals representative of captured audio data to be encoded by audio encoder 26. Alternatively, audio source 22 may comprise a storage medium storing previously recorded audio data, an audio data generator such as a computerized synthesizer, or any other source of audio data. Video source 24 may comprise a video camera generating video data to be encoded by video encoder 28, a storage medium encoded with previously recorded video data, a video data generation unit such as a computer graphics source, or any other source of video data. Content creation device 20 is not necessarily communicatively coupled to server device 60 in all examples, but may store multimedia content on a separate medium read by server device 60.

[0017]

[0022] The raw audio and video data may comprise analog or digital data. Analog data may be digitized before being encoded by audio encoder 26 and / or video encoder 28. Audio source 22 may obtain audio data from call participants while they are speaking, and video source 24 may simultaneously obtain video data of the call participants. In other examples, audio source 22 may comprise a computer-readable storage medium comprising stored audio data, and video source 24 may comprise a computer-readable storage medium comprising stored video data. In this manner, the techniques described in this disclosure may be applied to live, streaming, real-time audio and video data, or archived, pre-recorded audio and video data.

[0018]

[0023] An audio frame corresponding to a video frame is generally an audio frame that includes audio data captured (or generated) by audio source 22 contemporaneously with the video data captured (or generated) by video source 24 that is included in the video frame. For example, audio source 22 captures audio data while call participants generate audio data generally by speaking, and video source 24 captures video data of the call participants at the same time, i.e., while audio source 22 is capturing audio data. Thus, an audio frame may correspond in time to one or more particular video frames. Thus, an audio frame corresponding to a video frame generally corresponds to situations where audio data and video data were captured contemporaneously, and situations where audio and video frames, respectively, comprise contemporaneously captured audio and video data.

[0019]

[0024] In some examples, audio encoder 26 may encode a timestamp in each encoded audio frame representing the time that audio data for the encoded audio frame was recorded, and similarly, video encoder 28 may encode a timestamp in each encoded video frame representing the time that video data for the encoded video frame was recorded. In such examples, an audio frame corresponding to a video frame may comprise an audio frame with a timestamp and a video frame with the same timestamp. Content creation device 20 may include internal clocks from which audio encoder 26 and / or video encoder 28 may generate timestamps or which audio source 22 and video source 24 may use to associate audio data and video data, respectively, with timestamps.

[0020]

[0025] In some examples, audio source 22 may send data to audio encoder 26 corresponding to the time the audio data was recorded, and video source 24 may send data to video encoder 28 corresponding to the time the video data was recorded. In some examples, audio encoder 26 may encode sequence identifiers in the encoded audio data to indicate the relative temporal order of the encoded audio data without necessarily indicating the absolute time the audio data was recorded, and similarly, video encoder 28 may use sequence identifiers to indicate the relative temporal order of the encoded video data. Similarly, in some examples, the sequence identifiers may be mapped or otherwise correlated with timestamps.

[0021]

[0026] The audio encoder 26 generally produces a stream of encoded audio data, and the video encoder 28 produces a stream of encoded video data. Each individual stream of data (whether audio or video) may be referred to as an elementary stream. An elementary stream is a single digitally coded (possibly compressed) component of a representation. For example, a coded video or audio portion of a representation may be an elementary stream. An elementary stream may be converted into a Packetized Elementary Stream (PES) before being encapsulated within a video file. Within the same representation, a stream ID may be used to distinguish PES packets belonging to one elementary stream from others. The basic data unit of an elementary stream is the Packetized Elementary Stream (PES) packet. Thus, coded video data generally corresponds to an elementary video stream. Similarly, audio data corresponds to one or more respective elementary streams.

[0022]

[0027] Many video coding standards, such as ITU-T H.264 / AVC, ITU-T H.265 / High Efficiency Video Coding (HEVC), and the upcoming ITU-T H.266 / Generic Video Coding (VVC) standard, define syntax, semantics, and decoding processes for error-free bitstreams, any of which conform to a certain profile or level. Video coding standards generally do not specify an encoder, but an encoder is given the task of ensuring that the generated bitstream conforms to the standard for a decoder. In the context of video coding standards, a "profile" corresponds to a subset of algorithms, features, or tools, and the constraints applied to them. For example, the "profile" defined by the H.264 standard is a subset of the entire bitstream syntax specified by the H.264 standard. A "level" corresponds to a limit on decoder resource consumption, such as, for example, decoder memory and computation related to picture resolution, bitrate, and block processing rate. The profile may be signaled with a profile_idc (profile indicator) value, while the level may be signaled with a level_idc (level indicator) value.

[0023]

[0028] The H.264 standard recognizes that, within the limits imposed by the syntax of a given profile, it may still require large variations in encoder and decoder performance depending on the values ​​taken by syntax elements in the bitstream, such as the specified size of a decoded picture. The H.264 standard further recognizes that in many applications, it is neither practical nor economical to implement a decoder capable of handling all hypothetical uses of the syntax within a particular profile. Thus, the H.264 standard defines a "level" as a specified set of constraints imposed on the values ​​of syntax elements in the bitstream. These constraints may be simple restrictions on the values. Alternatively, these constraints may take the form of constraints on arithmetic combinations of values ​​(e.g., picture width x picture height x number of pictures decoded per second). The H.264 standard further specifies that individual implementations may support different levels for each supported profile.

[0024]

[0029] A decoder conforming to a profile typically supports all features defined in the profile. For example, as a coding feature, B-picture coding is not supported in the baseline profile of H.264 / AVC, but is supported in other profiles of H.264 / AVC. A decoder conforming to a level should be able to decode any bitstream that does not require resources beyond the limits defined in the level. The definition of the profile and the level may be useful for explainability. For example, during video transmission, a pair of profile definition and level definition may be negotiated and agreed upon for the entire transmission session. More specifically, in H.264 / AVC, a level may define the limits on the number of macroblocks that need to be processed, the decoded picture buffer (DPB) size, the coded picture buffer (CPB) size, the vertical motion vector range, the maximum number of motion vectors per two consecutive MBs, and whether a B block can have a sub-macroblock partition of less than 8×8 pixels. In this way, the decoder may determine whether it is capable of properly decoding the bitstream.

[0025]

[0030] In the example of Figure 1, encapsulation unit 30 of content creation device 20 receives an elementary stream comprising coded video data from video encoder 28 and an elementary stream comprising coded audio data from audio encoder 26. In some examples, video encoder 28 and audio encoder 26 may each include a packetizer for forming PES packets from the coded data. In other examples, video encoder 28 and audio encoder 26 may each interface with a respective packetizer for forming PES packets from the coded data. In yet other examples, encapsulation unit 30 may include packetizers for forming PES packets from the coded audio data and the coded video data.

[0026]

[0031] Video encoder 28 may encode the video data of the multimedia content in various ways to generate different representations of the multimedia content at various bit rates and with various characteristics, such as pixel resolutions, frame rates, compliance with various coding standards, compliance with various profiles and / or levels of profiles for various coding standards, representations having one or more views (e.g., for two-dimensional or three-dimensional playback), or other such characteristics. As used in this disclosure, a representation may comprise one of audio data, video data, text data (e.g., for subtitles), or other such data. A representation may include an elementary stream, such as an audio elementary stream or a video elementary stream. Each PES packet may include a stream_id that identifies the elementary stream to which the PES packet belongs. Encapsulation unit 30 is responsible for assembling the elementary streams into video files (e.g., segments) of the various representations.

[0027]

[0032] Encapsulation unit 30 receives PES packets for the elementary streams of the representation from audio encoder 26 and video encoder 28 and forms corresponding network abstraction layer (NAL) units from the PES packets. Coded video segments may be organized into NAL units that provide a "network friendly" video representation that addresses applications such as video telephony, storage, broadcast, or streaming. NAL units may be classified into video coding layer (VCL) NAL units and non-VCL NAL units. VCL units may contain the core compression engine and may include block, macroblock, and / or slice level data. Other NAL units may be non-VCL NAL units. In some examples, a coded picture in one time instance, typically presented as a primary coded picture, may be included in an access unit that may include one or more NAL units.

[0028]

[0033] Non-VCL NAL units may include, among others, parameter set NAL units and SEI NAL units. Parameter sets may include sequence-level header information (in sequence parameter sets (SPS)) and infrequently changing picture-level header information (in picture parameter sets (PPS)). With parameter sets (e.g., PPS and SPS), infrequently changing information does not need to be repeated for each sequence or picture, and thus coding efficiency may be improved. Furthermore, the use of parameter sets may enable out-of-band transmission of important header information, avoiding the need for redundant transmission for error resilience. In an example of out-of-band transmission, parameter set NAL units may be transmitted on a different channel than other NAL units, such as SEI NAL units.

[0029]

[0034] Supplemental enhancement information (SEI) may contain information that is not necessary for decoding coded picture samples from VCL NAL units, but may assist processes related to decoding, display, error resilience, and other purposes. SEI messages may be included in non-VCL NAL units. SEI messages are normative parts of some standard specifications and therefore are not always mandatory for a decoder implementation that conforms to the standard. The SEI messages may be sequence level SEI messages or picture level SEI messages. Some sequence level information may be included in SEI messages, such as the scalability information SEI message in the SVC example and the view scalability information SEI message in MVC. These exemplary SEI messages may convey information, for example, regarding the extraction of operation points and characteristics of those operation points. Additionally, the encapsulation unit 30 may form a manifest file, such as a media presentation descriptor (MPD) that describes characteristics of the representation. The encapsulation unit 30 may format the MPD according to the extensible markup language (XML).

[0030]

[0035] The encapsulation unit 30 may provide data for one or more representations of the multimedia content along with a manifest file (e.g., MPD) to the output interface 32. The output interface 32 may comprise a network interface or interface for writing to a storage medium, such as a universal serial bus (USB) interface, a CD or DVD writer or burner, an interface to a magnetic or flash storage medium, or other interface for storing or transmitting media data. The encapsulation unit 30 may provide data for each of the representations of the multimedia content to the output interface 32, which may send the data to the server device 60 via network transmission or a storage medium. In the example of FIG. 1, the server device 60 includes a storage medium 62 that stores various multimedia content 64, each including a respective manifest file 66 and one or more representations 68A-68N (representations 68). In some examples, the output interface 32 may also send data directly to a network 74.

[0031]

[0036] In some examples, representations 68 may be separated into adaptation sets, i.e., various subsets of representations 68 may include respective common sets of characteristics, such as codec, profile and level, resolution, number of views, file format for segments, text type information that may identify language or other characteristics of text to be displayed with the representation and / or audio data to be decoded and presented, e.g., by a speaker, camera angle information that may describe a camera angle or real-world camera perspective of a scene for the representations in the adaptation set, rating information that describes content suitability for a particular viewer, etc.

[0032]

[0037] The manifest file 66 may include data indicating a subset of representations 68 that correspond to a particular adaptation set, as well as common characteristics for the adaptation set. The manifest file 66 may also include data representing individual characteristics for each representation in the adaptation set, such as bit rate. In this manner, the adaptation set may enable simplified network bandwidth adaptation. The representations in an adaptation set may be indicated using child elements of the adaptation set element in the manifest file 66.

[0033]

[0038] Server device 60 includes a request processing unit 70 and a network interface 72. In some examples, server device 60 may include multiple network interfaces. Additionally, any or all of the features of server device 60 may be implemented on other devices of the content delivery network, such as routers, bridges, proxy devices, switches, or other devices. In some examples, intermediate devices of the content delivery network may cache data of multimedia content 64 and include components substantially conforming to those of server device 60. In general, network interface 72 is configured to send and receive data over network 74.

[0034]

[0039] The request processing unit 70 is configured to receive network requests for data of the storage medium 62 from a client device, such as the client device 40. For example, the request processing unit 70 may implement the Hypertext Transfer Protocol (HTTP) version 1.1, as described in RFC 2616, "Hypertext Transfer Protocol - HTTP / 1.1," by R. Fielding et al., Network Working Group, IETF, June 1999. That is, the request processing unit 70 may be configured to receive HTTP GET requests or partial GET requests and provide data of the multimedia content 64 in response to these requests. The request may specify a segment of one of the representations 68, for example, using the URL of the segment. In some examples, the request may also specify one or more byte ranges of the segment and thus comprise a partial GET request. The request processing unit 70 may further be configured to service an HTTP HEAD request to provide header data of a segment of one of the representations 68. In either case, the request processing unit 70 may be configured to process the request to provide the requested data to a requesting device, such as the client device 40.

[0035]

[0040] Additionally or alternatively, the request processing unit 70 may be configured to deliver the media data via a broadcast or multicast protocol, such as eMBMS. Although the content creation device 20 may create DASH segments and / or subsegments in substantially the same manner as described, the server device 60 may deliver these segments or subsegments using eMBMS or another broadcast or multicast network transport protocol. For example, the request processing unit 70 may be configured to receive a multicast group join request from the client device 40. That is, the server device 60 may advertise an Internet Protocol (IP) address associated with the multicast group to client devices associated with the particular media content (e.g., a broadcast of a live event), including the client device 40. The client device 40 may submit a request to join the multicast group. The request may be propagated throughout the network 74, e.g., the routers that make up the network 74, such that the routers are caused to direct traffic destined for the IP address associated with the multicast group to the subscribing client devices, such as the client device 40.

[0036]

[0041] 1, multimedia content 64 includes a manifest file 66, which may correspond to a media presentation description (MPD). Manifest file 66 may contain descriptions of different alternative representations 68 (e.g., video services with different qualities), which may include, for example, codec information, profile values, level values, bit rates, and other descriptive characteristics of representations 68. Client device 40 may retrieve the MPD of a media presentation to determine how to access segments of representation 68.

[0037]

[0042] In particular, the retrieval unit 52 may retrieve configuration data (not shown) of the client device 40 to determine the decoding capabilities of the video decoder 48 and the rendering capabilities of the video output 44. The configuration data may also include any or all of a language preference selected by a user of the client device 40, one or more camera perspectives corresponding to a depth preference set by the user of the client device 40, and / or a rating preference selected by the user of the client device 40. The retrieval unit 52 may comprise, for example, a web browser or a media client configured to submit HTTP GET requests and partial GET requests. The retrieval unit 52 may correspond to software instructions executed by one or more processors or processing units (not shown) of the client device 40. In some examples, all or part of the functionality described with respect to the retrieval unit 52 may be implemented in hardware or a combination of hardware, software, and / or firmware, and the requisite hardware may be provided to execute instructions for the software or firmware.

[0038]

[0043] The retrieval unit 52 may compare the decoding and rendering capabilities of the client device 40 with the characteristics of the representations 68 indicated by the information in the manifest file 66. The retrieval unit 52 may first retrieve at least a portion of the manifest file 66 to determine the characteristics of the representations 68. For example, the retrieval unit 52 may request a portion of the manifest file 66 that describes the characteristics of one or more adaptation sets. The retrieval unit 52 may select a subset (e.g., an adaptation set) of the representations 68 that have characteristics that can be satisfied by the coding and rendering capabilities of the client device 40. The retrieval unit 52 may then determine bit rates for the representations in the adaptation set, determine a currently available amount of network bandwidth, and retrieve a segment from one of the representations that has a bit rate that can be satisfied by the network bandwidth.

[0039]

[0044] Generally, a higher bit rate representation may result in higher quality video playback, and a lower bit rate representation may provide sufficient quality video playback when available network bandwidth decreases. Thus, when available network bandwidth is relatively high, retrieval unit 52 may retrieve data from a relatively high bit rate representation, but when available network bandwidth is low, retrieval unit 52 may retrieve data from a relatively low bit rate representation. In this manner, client device 40 may adapt to changing network bandwidth availability of network 74 while streaming multimedia data over network 74.

[0040]

[0045] Additionally or alternatively, retrieval unit 52 may be configured to receive data according to a broadcast or multicast network protocol, such as eMBMS or IP multicast. In such an example, retrieval unit 52 may submit a request to join a multicast network group associated with a particular media content. After joining the multicast group, retrieval unit 52 may receive the data of the multicast group without a further request being issued to server device 60 or content creation device 20. Retrieval unit 52 may submit a request to leave the multicast group when the data of the multicast group is no longer needed, e.g., to stop playback or to change the channel to a different multicast group.

[0041]

[0046] Network interface 54 may receive data for a segment of a selected representation and provide it to retrieval unit 52, which may provide the segment to de-encapsulation unit 50. De-encapsulation unit 50 may de-encapsulate elements of the video file into constituent PES streams, de-packetize the PES streams to retrieve the encoded data, and send the encoded data to either audio decoder 46 or video decoder 48, depending on whether the encoded data is part of an audio or video stream, e.g., as indicated by the stream's PES packet headers. Audio decoder 46 decodes the encoded audio data and sends the decoded audio data to audio output 42, and video decoder 48 decodes the encoded video data and sends decoded video data, which may include multiple views of the stream, to video output 44.

[0042]

[0047] Each of the video encoder 28, the video decoder 48, the audio encoder 26, the audio decoder 46, the encapsulation unit 30, the decapsulation unit 52, and the decapsulation unit 50 may be implemented as any of a variety of suitable processing circuits, such as, when applicable, one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic circuits, software, hardware, firmware, or any combination thereof. Each of the video encoder 28 and the video decoder 48 may be included in one or more encoders or decoders, any of which may be integrated as part of a composite video encoder / decoder (codec). Similarly, each of the audio encoder 26 and the audio decoder 46 may be included in one or more encoders or decoders, any of which may be integrated as part of a composite codec. An apparatus including the video encoder 28, the video decoder 48, the audio encoder 26, the audio decoder 46, the encapsulation unit 30, the decapsulation unit 52, and / or the decapsulation unit 50 may comprise an integrated circuit, a microprocessor, and / or a wireless communication device, such as a cellular telephone.

[0043]

[0048] Client device 40, server device 60, and / or content creation device 20 may be configured to operate in accordance with the techniques of this disclosure. By way of example, this disclosure describes these techniques with respect to client device 40 and server device 60. However, it should be understood that content creation device 20 may be configured to implement these techniques in place of (or in addition to) server device 60.

[0044]

[0049] Encapsulation unit 30 may form NAL units that comprise a header that identifies the program to which the NAL unit belongs, as well as a payload, e.g., audio data, video data, or data that describes the transport or program stream to which the NAL unit corresponds. For example, in H.264 / AVC, a NAL unit includes a one-byte header and a variable-sized payload. A NAL unit that includes video data in its payload may comprise video data of various granularity levels. For example, a NAL unit may comprise a block of video data, multiple blocks, a slice of video data, or an entire picture of video data. Encapsulation unit 30 may receive encoded video data from video encoder 28 in the form of PES packets of elementary streams. Encapsulation unit 30 may associate each elementary stream with a corresponding program.

[0045]

[0050] Encapsulation unit 30 may also assemble an access unit from multiple NAL units. In general, an access unit may comprise a frame of video data, as well as one or more NAL units for representing audio data corresponding to the frame, when such audio data is available. An access unit generally includes all NAL units for one output time instance, e.g., all audio and video data for one time instance. For example, if each view has a frame rate of 20 frames per second (fps), each time instance may correspond to a time interval of 0.05 seconds. During this time interval, certain frames of all views of the same access unit (same time instance) may be rendered simultaneously. In one example, an access unit may comprise a coded picture in one time instance, which may be presented as a primary coded picture.

[0046]

[0051] Thus, an access unit may comprise all audio and video frames of a common temporal instance, e.g., all views corresponding to time X. This disclosure also refers to the coded pictures of a particular view as "view components." That is, a view component may comprise coded pictures (or frames) for a particular view at a particular time. Thus, an access unit may be defined as comprising all view components of a common temporal instance. The decoding order of the access units does not necessarily have to be the same as the output or display order.

[0047]

[0052] A media presentation may include a Media Presentation Description (MPD), which may contain descriptions of different alternative representations (e.g., video services with different qualities), which may include, for example, codec information, profile values, and level values. An MPD is an example of a manifest file, such as manifest file 66. Client device 40 may retrieve the MPD of a media presentation to determine how to access movie fragments of various presentations. The movie fragments may be in a movie fragment box (moof box) of a video file.

[0048]

[0053] Manifest file 66 (which may comprise, for example, an MPD) may advertise the availability of segments of representations 68. That is, the MPD may include information indicating a wall-clock time at which a first segment of one of representations 68 becomes available, as well as information indicating the duration of the segment within representation 68. In this manner, retrieval unit 52 of client device 40 may determine when each segment is available based on the start time, as well as the duration of the segment preceding the particular segment.

[0049]

[0054] After encapsulation unit 30 assembles NAL units and / or access units into a video file based on the received data, encapsulation unit 30 passes the video file to output interface 32 for output. In some examples, encapsulation unit 30 may store the video file locally or send the video file to a remote server via output interface 32 rather than directly to client device 40. Output interface 32 may comprise, for example, a transmitter, a transceiver, a device for writing data to a computer-readable medium, such as, for example, an optical drive, a magnetic media drive (e.g., a floppy drive), a universal serial bus (USB) port, a network interface, or other output interface. Output interface 32 outputs the video file to a computer-readable medium, such as, for example, a transmission signal, a magnetic medium, an optical medium, a memory, a flash drive, or other computer-readable medium.

[0050]

[0055] Network interface 54 may receive NAL units or access units via network 74 and provide the NAL units or access units to de-encapsulation unit 50 via retrieval unit 52. De-encapsulation unit 50 may de-encapsulate elements of the video file into constituent PES streams, de-packetize the PES streams to retrieve the encoded data, and send the encoded data to either audio decoder 46 or video decoder 48 depending on whether the encoded data is part of an audio or video stream, e.g., as indicated by the stream's PES packet headers. Audio decoder 46 decodes the encoded audio data and sends the decoded audio data to audio output 42, and video decoder 48 decodes the encoded video data and sends the decoded video data, which may include multiple views of the stream, to video output 44.

[0051]

[0056] The example of Fig. 1 describes the use of DASH and HTTP-based streaming as an example. However, it should be understood that other types of protocols can be used to transport media data. For example, the request processing unit 70 and the retrieval unit 52 can be configured to operate according to the Real-time Transport Protocol (RTP), the Real-time Streaming Protocol (RTSP), etc., and to use a supporting protocol, such as the Session Description Protocol (SDP) or the Session Initiation Protocol (SIP).

[0052]

[0057] Figure 2 is a block diagram illustrating in more detail an exemplary set of components of retrieval unit 52 of Figure 1. In this example, retrieval unit 52 includes an eMBMS middleware unit 100, a DASH client 110, and a media application 112.

[0053]

[0058] In this example, the eMBMS middleware unit 100 further includes an eMBMS receiving unit 106, a cache 104, and a proxy server unit 102. In this example, the eMBMS receiving unit 106 is configured to receive data via eMBMS in accordance with File Delivery over Unidirectional Transport (FLUTE), e.g., as described in T. Paila et al., “FLUTE - File Delivery over Unidirectional Transport,” Network Working Group, RFC6726, November 2012, available at tools.ietf.org / html / rfc6726. That is, the eMBMS receiving unit 106 may receive files via broadcast from a server device 60, which may act as, for example, a Broadcast / Multicast Service Center (BM-SC).

[0054]

[0059] When the eMBMS middleware unit 100 receives data for a file, the eMBMS middleware unit may store the received data in the cache 104. The cache 104 may comprise a computer-readable storage medium, such as a flash memory, a hard disk, a RAM, or any other suitable storage medium.

[0055]

[0060] The proxy server unit 102 may act as a server for the DASH client 110. For example, the proxy server unit 102 may provide the DASH client 110 with an MPD file or other manifest file. The proxy server unit 102 may advertise availability times for the segments in the MPD file, as well as hyperlinks from which the segments may be retrieved. These hyperlinks may include a local host address prefix (e.g., 127.0.0.1 for IPv4) corresponding to the client device 40. In this manner, the DASH client 110 may request the segments from the proxy server unit 102 using an HTTP GET request or a partial GET request. For example, for a segment available from the link http: / / 127.0.0.1 / rep1 / seg3, the DASH client 110 may construct an HTTP GET request that includes a request for http: / / 127.0.0.1 / rep1 / seg3 and submit the request to the proxy server unit 102. The proxy server unit 102 may retrieve requested data from the cache 104 and provide the data to the DASH client 110 in response to such a request.

[0056]

[0061] Client device 40 represents an example of a device for retrieving media data, the device including a memory configured to store scene data and image data, and one or more processors implemented in circuitry, the one or more processors configured to: receive data for a bitstream indicating that the bitstream includes one or more overlay images; receive one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data that remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence that repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receive scene data including one or more scene images; and present the scene images and the overlay images.

[0057]

[0062] FIG. 3 is a conceptual diagram illustrating elements of an exemplary multimedia content 120. The multimedia content 120 may correspond to the multimedia content 64 (FIG. 1) or another multimedia content stored in the storage medium 62. In the example of FIG. 3, the multimedia content 120 includes a media presentation description (MPD) 122 and a number of representations 124A-124N (representations 124). Representation 124A includes optional header data 126 and segments 128A-128N (segments 128), and representation 124N includes optional header data 130 and segments 132A-132N (segments 132). The letter N is used for convenience to designate the last movie fragment in each of the representations 124. In some examples, there may be different numbers of movie fragments among the representations 124.

[0058]

[0063] MPD 122 may comprise a data structure separate from representation 124. MPD 122 may correspond to manifest file 66 of Figure 1. Similarly, representation 124 may correspond to representation 68 of Figure 1. In general, MPD 122 may include data that generally describes characteristics of representation 124, such as coding and rendering characteristics, adaptation sets, profiles to which MPD 122 supports, text type information, camera angle information, rating information, trick mode information (e.g., information indicative of a representation that includes a time subsequence), and / or information for retrieving a remote period (e.g., for targeted advertisement insertion into the media content being played).

[0059]

[0064] Header data 126, when present, may describe characteristics of segment 128, such as the time location of a random access point (RAP, also called a stream access point (SAP)) of segment 128, including the random access point, a byte offset to the random access point within segment 128, a uniform resource locator (URL) for segment 128, or other aspects of segment 128. Header data 130, when present, may describe similar characteristics for segment 132. Additionally or alternatively, such characteristics may be contained entirely within MPD 122.

[0060]

[0065] The segments 128, 132 include one or more coded video samples, each of which may include a frame or slice of video data. Each of the coded video samples of the segment 128 may have similar characteristics, e.g., height, width, and bandwidth requirements. Such characteristics may be described by data in the MPD 122, although such data is not shown in the example of FIG. 3. The MPD 122 may include characteristics described by the 3GPP specifications with the addition of any or all of the signaled information described in this disclosure.

[0061]

[0066] Each of the segments 128, 132 may be associated with a unique Uniform Resource Locator (URL). Thus, each of the segments 128, 132 may be independently retrievable using a streaming network protocol such as DASH. In this manner, a destination device, such as the client device 40, may use an HTTP GET request to retrieve a segment 128 or 132. In some examples, the client device 40 may use an HTTP partial GET request to retrieve a particular byte range of the segment 128 or 132.

[0062]

[0067] FIG. 4 is a block diagram illustrating elements of an exemplary video file 150 that may correspond to a segment of a representation, such as one of the segments 128, 132 of FIG. 3. Each of the segments 128, 132 may include data that substantially conforms to the arrangement of data shown in the example of FIG. 4. The video file 150 may be said to encapsulate a segment. As explained above, video files according to the ISO Base Media File Format and extensions thereof store data in a series of objects called "boxes." In the example of FIG. 4, the video file 150 includes a file type (FTYP) box 152, a movie (MOOV) box 154, a segment index (sidx) box 162, a movie fragment (MOOF) box 164, and a movie fragment random access (MFRA) box 166. Although FIG. 4 represents an example of a video file, it should be understood that other media files may include other types of media data (e.g., audio data, timed text data, etc.) structured similarly to the data of the video file 150 according to the ISO Base Media File Format and extensions thereof.

[0063]

[0068] The File Type (FTYP) box 152 generally describes the file type for the video file 150. The File Type box 152 may contain data identifying specifications that describe the best use of the video file 150. The File Type box 152 may alternatively be placed before the MOOV box 154, the Movie Fragment box 164, and / or the MFRA box 166.

[0064]

[0069] In some examples, a segment, such as video file 150, may include an MPD update box (not shown) before FTYP box 152. The MPD update box may include information indicating that the MPD corresponding to a representation that includes video file 150 should be updated, along with information for updating the MPD. For example, the MPD update box may provide a URI or URL for a resource to be used to update the MPD. As another example, the MPD update box may include data for updating the MPD. In some examples, the MPD update box may immediately follow a segment type (STYP) box (not shown) of video file 150, where the STYP box may define a segment type for video file 150.

[0065]

[0070] 4, the MOOV box 154 includes a Movie Header (MVHD) box 156, a Track (TRAK) box 158, and one or more Movie Extension (MVEX) boxes 160. Generally, the MVHD box 156 may describe general characteristics of the video file 150. For example, the MVHD box 156 may include data describing when the video file 150 was originally created, when the video file 150 was last modified, a time scale for the video file 150, a duration of playback for the video file 150, or other data that generally describes the video file 150.

[0066]

[0071] The TRAK box 158 may contain data about a track of the video file 150. The TRAK box 158 may contain a Track Header (TKHD) box that describes characteristics of the track that corresponds to the TRAK box 158. In some examples, the TRAK box 158 may contain coded video pictures, and in other examples, the coded video pictures of the track may be contained in a movie fragment 164 that may be referenced by data in the TRAK box 158 and / or the sidx box 162.

[0067]

[0072] In some examples, video file 150 may include more than one track. Thus, MOOV box 154 may include a number of TRAK boxes equal to the number of tracks in video file 150. TRAK box 158 may describe characteristics of the corresponding track of video file 150. For example, TRAK box 158 may describe time and / or spatial information for the corresponding track. When encapsulation unit 30 (FIG. 1) includes a parameter set track in a video file, such as video file 150, a TRAK box similar to TRAK box 158 of MOOV box 154 may describe characteristics of the parameter set track. Encapsulation unit 30 may signal the presence of a sequence level SEI message in the parameter set track in a TRAK box that describes the parameter set track.

[0068]

[0073] MVEX box 160 may, for example, describe characteristics of the corresponding movie fragment 164, to signal that video file 150 includes movie fragment 164 in addition to the video data contained in MOOV box 154, if any. In the context of streaming video data, coded video pictures may be included in movie fragment 164 rather than in MOOV box 154. Thus, all coded video samples may be included in movie fragment 164 rather than in MOOV box 154.

[0069]

[0074] The MOOV box 154 may contain a number of MVEX boxes 160 equal to the number of movie fragments 164 in the video file 150. Each of the MVEX boxes 160 may describe the characteristics of a corresponding one of the movie fragments 164. For example, each MVEX box may include a Movie Extension Header Box (MEHD) box that describes the duration for the corresponding one of the movie fragments 164.

[0070]

[0075] As mentioned above, encapsulation unit 30 may store the sequence data set in a video sample that does not contain actual coded video data. A video sample may generally correspond to an access unit, which is a representation of a coded picture at a particular time instance. In the context of AVC, a coded picture includes one or more VCL NAL units that contain information for constructing all pixels of the access unit, and other associated non-VCL NAL units, such as SEI messages. Thus, encapsulation unit 30 may include a sequence data set, which may include a sequence level SEI message, in one of the movie fragments 164. Encapsulation unit 30 may further signal the presence of the sequence data set and / or the sequence level SEI message as present in one of the movie fragments 164 in one of the MVEX boxes 160 that corresponds to one of the movie fragments 164.

[0071]

[0076] The SIDX box 162 is an optional element of the video file 150; that is, a video file conforming to the 3GPP file format, or other such file formats, does not necessarily include the SIDX box 162. According to an example of a 3GPP file format, the SIDX box may be used to identify a sub-segment of a segment (e.g., a segment contained within the video file 150). The 3GPP file format defines a sub-segment as "a self-contained set of one or more consecutive Movie Fragment boxes with corresponding Media Data box(es) and the Media Data box containing the data referenced by the Movie Fragment box must follow the Movie Fragment box and precede the next Movie Fragment box containing information about the same track." The 3GPP file format also indicates that the SIDX box "contains a sequence of references to sub-segments of the (sub)segment documented by the box. The referenced sub-segments are contiguous in presentation time. Similarly, the bytes referenced by a Segment Index box are always contiguous within the segment. The referenced size gives a count of the number of bytes in the referenced material."

[0072]

[0077] The SIDX box 162 generally provides information describing one or more subsegments of a segment contained in the video file 150. For example, such information may include a playback time at which the subsegment begins and / or ends, a byte offset for the subsegment, whether the subsegment contains (e.g., starts at) a Stream Access Point (SAP), a type for the SAP (e.g., whether the SAP is an Instantaneous Decoder Refresh (IDR) picture, a Clean Random Access (CRA) picture, a Cut Link Access (BLA) picture, etc.), the location of the SAP (with respect to playback time and / or byte offset) within the subsegment, etc.

[0073]

[0078] A movie fragment 164 may include one or more coded video pictures. In some examples, a movie fragment 164 may include one or more groups of pictures (GOPs), each of which may include several coded video pictures, e.g., frames or pictures. Additionally, as described above, a movie fragment 164 may include a sequence data set in some examples. Each of the movie fragments 164 may include a Movie Fragment Header Box (MFHD, not shown in FIG. 4). The MFHD box may describe characteristics of the corresponding movie fragment, such as a sequence number for the movie fragment. The movie fragments 164 may be included in the video file 150 in order of sequence number.

[0074]

[0079] The MFRA box 166 may describe random access points within the movie fragments 164 of the video file 150. This may assist in implementing trick modes, such as implementing a seek to a particular time location (i.e., play time) within a segment encapsulated by the video file 150. The MFRA box 166 is generally optional, and in some examples, need not be included in the video file. Similarly, a client device, such as the client device 40, does not necessarily need to reference the MFRA box 166 to correctly decode and display the video data of the video file 150. The MFRA box 166 may include a number of track fragment random access (TFRA) boxes (not shown) equal to the number of tracks of the video file 150, or, in some examples, equal to the number of media tracks (e.g., non-hint tracks) of the video file 150.

[0075]

[0080] In some examples, the movie fragment 164 may include one or more stream access points (SAPs), such as IDR pictures. Similarly, the MFRA box 166 may provide an indication of the location within the video file 150 of the SAPs. Thus, a temporal subsequence of the video file 150 may be formed from the SAPs of the video file 150. The temporal subsequence may also include other pictures, such as P-frames and / or B-frames, that are dependent on the SAPs. The frames and / or slices of the temporal subsequence may be organized into segments such that frames / slices of the temporal subsequence that depend on other frames / slices of the subsequence may be properly decoded. For example, in a hierarchical organization of data, data used for prediction of other data may also be included in the temporal subsequence.

[0076]

[0081] FIG. 5 is a conceptual diagram illustrating an example structure of a High Efficiency Image File (HEIF) format for including image data in a media file 200. The HEIF format is defined in ISO / IEC 23008-12. HEIF specifies the storage of images and image sequences and their metadata in an ISOBMFF-based container file. HEIF not only defines a general codec-agnostic structure for the storage of images, but also provides an instantiation based on the H.265 / HEVC codec. The segments 128, 132 of FIG. 3 may conform to the HEIF format of FIG. 5 in some examples.

[0077]

[0082] HEIF follows the ISOBMFF design rules for media storage: image sequences are thus stored in tracks and still images are stored as metadata items. In the former, images are coded together, and therefore the coded images have some decoding dependencies. In the latter, images are coded independently of each other.

[0078]

[0083] As shown in FIG. 5, a HEIF formatted media file 200 includes an FTYP box 202, a MOOV box 204 which may include a TRAK box 206 containing zero or more images in an image sequence 208, an Image Location (ILOC) box 216 which contains zero or more image items 218 and an Item Properties (IPRP) box 220, an MDAT box 210 which contains zero or more images 212, and an Item Data (IDAT) box 222 which contains zero or more images 224.

[0079]

[0084] ISOBMFF container files that store images with HEVC encoding can be correspondingly identified by the "heic" or "hevc" branding found in the first FTYP box 202 of the ISOBMFF box. The MIME type of these files can be set to "image / heic" for still images or "image / heic-sequence" for image sequences.

[0080]

[0085] Images in a container can be assigned different roles. The following roles are examples that can be assigned to images, such as images 212, 224:

[0081] Cover Image: A default image to be shown in the absence of other information about display preferences. Only one cover image may be defined in HEIF.

[0082] · Thumbnail Image: A smaller resolution image that corresponds to the master image.

[0083] Auxiliary Image: An image that complements the master image, e.g. containing a depth map.

[0084] · Master Image: The primary image in the container file, in full resolution.

[0085] · Hidden Images: Images that are not intended to be displayed.

[0086] · Precomputed derived images: coded images derived from other images.

[0087] · Coded Image: A coded representation of an image.

[0088] Derived Image: An image that must be derived using some operations and references to other images in the container file. Defined operations include cropping, rotating, mirroring and compositing.

[0089]

[0086] An image sequence can serve as a master, auxiliary, or thumbnail image sequence role.

[0090]

[0087] Images 212, 224 may be stored in a container file with their own metadata. Initialization information may be stored in the sample entry as part of the sample description box for image sequences. For still images, initialization information may be stored as part of the IPRP container box 220 as item properties. This metadata may include information such as image dimensions, codec initialization information, etc.

[0091]

[0088] Additional metadata, such as pixel aspect ratio, color information, and bit depth, are present in the item property container box, and the actual image can be referenced using the "cdsc" reference type in the item reference box.

[0092]

[0089] For an image sequence, such as image sequence 208, the specification may define playback control features to describe, for example, any or all of the following:

[0093] Images that should not be displayed Slideshows vs. image collections Playback timings for slideshows Slideshow Looping Image conversion

[0090] To facilitate access to a particular image in an image sequence, sample groupings may be used to indicate the decoding dependency of that image: a decoder does not need to decode all images 212 of an image sequence 208.

[0094]

[0091] The Real-time Transport Protocol (RTP) payload format for HEVC is defined in IETF RFC7798, RTP Payload Format for High Efficiency Video Coding (HEVC). RFC7798 is currently supported by MTSI for transport of video streams. The payload format defines the use of RTP headers when carrying HEVC payloads, packetization of HEVC coded NAL units into RTP packets, SDP description, and payload header extension mechanisms.

[0095]

[0092] In the context of ITT4RT, both images and image sequences can be used as overlays. The HEIF format can be used as a source for overlays. The transmission can be HEVC compliant, i.e. image items and image sequences can be extracted from a HEIF source and transmitted using the HEVC payload format.

[0096]

[0093] The ITT4RT-tx client may indicate the following information to the receiver:

[0097] The stream is an image overlay stream.

[0098] · Whether the stream carries image sequences or still images or both.

[0099] · Number of still image items.

[0100] · The number of images in the image sequence.

[0101] · A transmission mode for still images or image sequences. The transmission mode may be set to "coupled" to indicate coupling of transmission and display, in which case the display time is always determined by the RTP timestamp. Alternatively, the transmission mode may be "decoupled" to indicate that the transmission is independent of the presentation, so that the presentation timing is provided separately to support use cases such as storage and looping.

[0102] · The display order of images in a still image collection or image sequence when the transmission mode is set to "Separate".

[0103] Image metadata for each image item or sample, including image dimensions, image role, etc.

[0104] To support this signaling, the "image" SDP attribute may be used to identify that a stream carries one or more overlay images, including still images and / or image sequences. The "image" attribute may have the following Augmented Backus-Naur Form (ABNF) syntax:

[0105] · image_attribute=“a=image:” pt SP transmission_mode SP item_count · transmission_mode=“tmode=” (“combined” / “separated” [“;” store] [“;” loop]) · item_count=“count=” 1*DIGIT · metadata_index=“meta=” 1*DIGIT · store=“store=” (“0” / ”1”) · loop=“loop=” (“0” / ”1”)

[0095] The semantics for the above syntax elements can be defined as follows:

[0106]

[0096] pt: the payload type used for carrying this image set or image sequence. In the presence of multiple image sequences or a mixture of image sets and image sequences, different payload types shall be used for the different sequences or image sets.

[0107]

[0097] transmission_mode: transmission mode, combined indicates that the overlay image will be continuously streamed (retransmitted) as long as the overlay is to be rendered. The RTP timestamp can be used to determine the presentation time of the overlay image. The image does not need to be stored and no looping needs to be performed. The image can be the master image in this case. In the case of "separate" transmission mode, the presentation of the image can be overwritten by image metadata. The RTP timestamp can be used to determine the index of the image.

[0108] item_count: Gives the number of images in the corresponding image set or image sequence.

[0109]

[0099] store: In separate transmission mode, the store flag tells the receiver whether or not to store the image for continued presentation. This allows the transmission session to be much shorter than the actual presentation. In particular, still image overlays are typically stored for presentation for the entire lifetime of the overlay.

[0110]

[0100] loop: In separate transmission mode, the loop flag indicates whether the image set or image sequence shall be looped, or whether the last image item in the set or image sequence should remain displayed.

[0111]

[0101] Carrying metadata for image items in an image set or image sequence is accomplished using the "image-metadata" attribute, which may be defined as follows: image-metadata=”a=image-metadata:” pt SP coded-metadata

[0102] In the above examples, coded-metadata is the base64 encoded image metadata for the corresponding image set or image sequence.

[0112]

[0103] Image metadata may have the following format:

[0113] [Table 1]

[0114]

[0104] All image properties may be formatted according to their respective definitions, for example as defined in ISO / IEC 23008-12, MPEG systems Technologies-Part 12: Image file formats.

[0115]

[0105] The display_info element may give information about the display order of each image in a set of images or a sequence. An order of 0 means that the image should not be rendered. This may be the case in the case of auxiliary or hidden images. The duration indicates how long the image should be rendered in units of the 90 kHz clock.

[0116]

[0106] Metadata information can be base64 encoded and given as part of the image-metadata attribute independently for each image set or image sequence.

[0117]

[0107] The combined transmission mode may be suitable for live overlay streams, for example live slide presentations. The separate transmission mode may be suitable for pre-set content, such as timed slide shows.

[0118]

[0108] The following table gives an exemplary set of SDP data for the conveyance of image sets and image sequences. . . . m=video 49170 RTP / AVP 98,99 a=rtpmap:98 H265 / 90000 a=fmtp:98 profile-id=1;sprop-vps=<Video Parameter Set Data> a=image:98 tmode=Combined count=14 a=image-metadata:98 coded-metadata=<Base64 Encoded Metadata> a=rtpmap:99 H265 / 90000 a=fmtp:99 profile-id=1;sprop-vps=<Video Parameter Set Data> a=image:99 tmode=Separate;store=1;loop=1 count=6 a=image-metadata:99 coded-metadata=<Base64 Encoded Metadata> . . .

[0109] FIG. 6 is a flowchart showing an exemplary method of retrieving media data according to the techniques of the present disclosure. The method of FIG. 6 is described with respect to the client device 40 and the extraction unit 52 of FIGS. 1 and 2. Other devices may be configured to implement this method or a similar method.

[0119]

[0110] As explained above, the bitstream may include data indicating that the bitstream includes one or more overlay images. In particular, the overlay images may include either static images or image sequences or both. A static image may be an image to be presented along with the scene data (e.g., video data, extended reality (XR) content, augmented reality (AR) content, virtual reality (VR) content, etc.) that remains unchanged while being presented frame-by-frame along with the frames of the scene data. Additionally or alternatively, an image sequence may be a sequence of images that repeat with a regular periodicity while being presented frame-by-frame along with the frames of the scene data.

[0120]

[0111] An overlay image may occupy a smaller area of ​​the complete viewport presentation than the scene data as a whole. That is, while the scene data may generally occupy the entire viewport (i.e., the entire screen, lens, or other display device), an overlay image may occupy a relatively small portion of the viewport and be presented over (in front of) the scene data, such that the overlay image occupies a small portion of the scene data.

[0121]

[0112] The data in the bitstream may include SDP image attributes or other data indicating a payload type, for example, indicating whether the overlay image includes a static image, an image sequence, or both. The data may also indicate a transmission mode, for example, "combined" or "separate." A transmission mode of "combined" indicates that the overlay image is transmitted continuously in the bitstream. A transmission mode of "separate" indicates that the overlay image is not retransmitted. In some examples, the data may further indicate whether the overlay image should be stored (buffered) and / or whether the overlay image should be played in a loop.

[0122]

[0113] Thus, retrieval unit 52 of client device 40 of FIG. 1 may, for example, receive data of the bitstream indicating that one or more overlay images are included in the bitstream (250). Retrieval unit 52 may then use this data to determine the overlay image type (252). For example, retrieval unit 52 may determine whether the overlay image includes a static image and / or an image sequence.

[0123]

[0114] The retrieval unit 52 may also determine a transmission mode for the overlay image (254). For example, the retrieval unit 52 may determine whether the overlay image is continuously retransmitted or sent once (or on demand, e.g., via unicast instead of broadcast or multicast). Thus, the retrieval unit 52 may determine when and how to extract the overlay image, whether to buffer the overlay image, how to present the overlay image (e.g., over a loop or as a single presentation), etc. The retrieval unit 52 may provide data representing the extraction of the overlay image to the decapsulation unit 50 and provide a presentation of the overlay image to, e.g., the video output 44.

[0124]

[0115] Retrieval unit 52 receives scene data for the scene (256), as well as the overlay image itself (258). The overlay image may be included in a media file, such as media file 200 of FIG. 5. Assuming that the received data indicates that the overlay image should be buffered, retrieval unit 52 may buffer the overlay image, for example, in cache 104 (FIG. 2).

[0125]

[0116] The media application 112 (FIG. 2) of the retrieval unit 52 may then present the overlay image with the scene data (260). For example, the media application 112 may be configured to present the overlay image on the scene data while presenting the scene data frame by frame via the video output 44. For example, the media application 112 may be configured to present a single, static overlay image on the scene data presented frame by frame. Alternatively, if the overlay image includes an image sequence that is to be looped, the media application 112 may present the overlay image repeatedly in order. That is, if a video sequence includes N images, where N is a positive integer, for loop j, where j is a non-negative integer, the media application 112 may present image i at time j*N+i. The received data may indicate a presentation time for the overlay image, and the media application 112 may accordingly present the overlay image at the indicated presentation time.

[0126]

[0117] The DASH client 110 may be configured to retrieve overlay images either from a separate server device using unicast or from the proxy server 102. In particular, if the images are to be stored locally in the cache 104, the DASH client 110 may repeatedly retrieve the overlay images from the cache 104 (i.e., local memory) via the proxy server 102. Alternatively, the media application 112 may be allocated memory in a storage device separate from the cache 104 and buffer the overlay images in the allocated memory.

[0127]

[0118] Thus, the method of Figure 6 represents one example of a method that includes receiving data for a bitstream indicating that the bitstream includes one or more overlay images, receiving one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data that remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence that repeats with regular periodicity while presented frame-by-frame with the frames of scene data, receiving scene data including one or more scene images, and presenting the scene images and the overlay images.

[0128]

[0119] Various examples of the techniques of the present disclosure are summarized in the following paragraphs.

[0129]

[0120] Clause 1: A method for extracting media data, the method comprising: receiving data for a bitstream indicating that the bitstream includes one or more overlay images; receiving one or more overlay images from the bitstream; receiving scene data including one or more scene images; and presenting the scene images and the overlay images.

[0130]

[0121] Clause 2: The method of clause 1, further comprising receiving data for the bitstream indicating whether the one or more overlay images include one or more image sequences and whether the one or more overlay images include one or more still images.

[0131]

[0122] Clause 3: The method of clause 2, further comprising, when the data indicates that the one or more overlay images include one or more image sequences, a number of images in each of the image sequences.

[0132]

[0123] Clause 4: The method of any of clauses 2 and 3, further comprising a number of still images when the data indicates that the one or more overlay images include one or more still images.

[0133]

[0124] Clause 5: The method of any of clauses 2 to 4, further comprising receiving data indicating a transmission mode for the image sequence and the still image.

[0134]

[0125] Clause 6: The method of clause 5, further comprising determining a display time for the overlay image from timestamp data in the bitstream when one of the transmission modes is "combined."

[0135]

[0126] Clause 7: The method of clause 6, wherein the time stamp data comprises Real-time Transport Protocol (RTP) time stamp data.

[0136]

[0127] Clause 8: A method as described in any of clauses 5 to 7, further comprising separately receiving data representing a display time for the overlay image when one of the transmission modes is "separate", and determining the display time for the overlay image from the separately received data.

[0137]

[0128] Clause 9: The method of any of clauses 1 to 8, further comprising receiving data representing a display order of the overlay images when the one or more overlay images include two or more overlay images.

[0138]

[0129] Clause 10: A method according to any of clauses 1 to 9, further comprising receiving image metadata for each of the overlay images from the bitstream, the metadata indicating one or more of image dimensions or image roles.

[0139]

[0130] Clause 11: The method of clause 10, wherein the image role comprises at least one of a cover image, a thumbnail image, an auxiliary image, a master image, a hidden image, a pre-computed derived image, a coded image, or a derived image.

[0140]

[0131] Clause 12: A method according to any of clauses 10 and 11, wherein the metadata includes one or more of an image_properties() element, a display_info() element, or an extension_info() element.

[0141]

[0132] Clause 13: The method described in clause 12, wherein the image_properties() element includes one or more of: ispe_present_flag, pasp_present_flag, colr_present_flag, pixi_present_flag, clap_present_flag, irot_present_flag, imir_present_flag, other_properties() element, ImageSpatialExtentsProperty() element, PixelAspectRatioBox() element, ColourInformationBox() element, PixelInformationProperty() element, CleanApertureBox() element, or ImageRotation() element.

[0142]

[0133] Clause 14: A method according to any of clauses 12 and 13, wherein the display_info() element includes one or more of an order element indicating the order of presentation of the overlay images, or a duration element indicating the amount of time a corresponding one of the overlay images should be displayed.

[0143]

[0134] Clause 15: The method of any one of clauses 1 to 14, further comprising receiving a Session Description Protocol (SDP) picture attribute that identifies the bitstream.

[0144]

[0135] Clause 16: The method described in clause 15, wherein the SDP image attributes include one or more syntax elements including image_attribute, transmission_mode, item_count, metadata_index, store, or loop.

[0145]

[0136] Clause 17: The method of clause 1, further comprising receiving data for the bitstream indicating whether the one or more overlay images include one or more image sequences and whether the one or more overlay images include one or more still images.

[0146]

[0137] Clause 18: The method of clause 17, further comprising, when the data indicates that the one or more overlay images include one or more image sequences, the number of images in each of the image sequences.

[0147]

[0138] Clause 19: The method of clause 18, further comprising a number of still images when the data indicates that the one or more overlay images include one or more still images.

[0148]

[0139] Clause 20: The method of clause 18, further comprising receiving data indicating a transmission mode for the image sequence and the still image.

[0149]

[0140] Clause 21: The method of clause 20, further comprising determining a display time for the overlay image from timestamp data of the bitstream when one of the transmission modes is "combined."

[0150]

[0141] Clause 22: The method of clause 21, wherein the timestamp data comprises Real-time Transport Protocol (RTP) timestamp data.

[0151]

[0142] Clause 23: The method described in clause 20, further comprising separately receiving data representing a display time for the overlay image when one of the transmission modes is "separate", and determining the display time for the overlay image from the separately received data.

[0152]

[0143] Clause 24: The method of clause 1, further comprising receiving data indicating a display order of the overlay images when the one or more overlay images include two or more overlay images.

[0153]

[0144] Clause 25: The method of clause 1, further comprising receiving image metadata for each of the overlay images from the bitstream, the metadata indicating one or more of image dimensions or image roles.

[0154]

[0145] Clause 26: The method of clause 25, wherein the image role comprises at least one of a cover image, a thumbnail image, an auxiliary image, a master image, a hidden image, a pre-computed derived image, a coded image, or a derived image.

[0155]

[0146] Clause 27: The method of clause 26, wherein the metadata includes one or more of an image_properties() element, a display_info() element, or an extension_info() element.

[0156]

[0147] Clause 28: The method described in clause 27, wherein the image_properties() element includes one or more of: ispe_present_flag, pasp_present_flag, colr_present_flag, pixi_present_flag, clap_present_flag, irot_present_flag, imir_present_flag, other_properties() element, ImageSpatialExtentsProperty() element, PixelAspectRatioBox() element, ColourInformationBox() element, PixelInformationProperty() element, CleanApertureBox() element, or ImageRotation() element.

[0157]

[0148] Clause 29: The method described in clause 27, wherein the display_info() element includes one or more of an order element indicating the order of presentation of the overlay images, or a duration element indicating the amount of time a corresponding one of the overlay images should be displayed.

[0158]

[0149] Clause 30: The method of clause 1, further comprising receiving a Session Description Protocol (SDP) picture attribute that identifies the bitstream.

[0159]

[0150] Clause 31: The method described in clause 30, wherein the SDP image attributes include one or more syntax elements including image_attribute, transmission_mode, item_count, metadata_index, store, or loop.

[0160]

[0151] Clause 32: A device for retrieving media data, the device comprising one or more means for implementing the methods of any of clauses 1 to 31.

[0161]

[0152] Clause 33: A device as described in clause 32, wherein the one or more means comprise one or more processors implemented in circuitry.

[0162]

[0153] Clause 34: The device of clause 32, wherein the device comprises at least one of an integrated circuit, a microprocessor, or a wireless communication device.

[0163]

[0154] Clause 35: A computer-readable storage medium having stored thereon instructions which, when executed, cause a processor to perform a method according to any one of clauses 1 to 31.

[0164]

[0155] Clause 36: A device for receiving media data, the device comprising: means for receiving data for a bitstream indicating that the bitstream includes one or more overlay images; means for receiving one or more overlay images from the bitstream; means for receiving scene data including one or more scene images; and means for presenting the scene images and the overlay images.

[0165]

[0156] Clause 37: A method of retrieving media data, the method comprising: receiving data for a bitstream indicating that the bitstream includes one or more overlay images; receiving one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data which remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence which repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receiving scene data including one or more scene images; and presenting the scene images and the overlay images.

[0166]

[0157] Clause 38: The method of clause 37, further comprising receiving a Session Description Protocol (SDP) picture attribute that identifies the bitstream.

[0167]

[0158] Clause 39: The method of clause 38, wherein the SDP image attribute includes an image attribute indicating a payload type indicating whether the one or more overlay images include a single static image or an image sequence.

[0168]

[0159] Clause 40: The method of clause 39, wherein when the payload type indicates that the one or more images include a single static image, presenting the scene image and the overlay image comprises repeatedly presenting the single static image when presenting the scene image for each image.

[0169]

[0160] Clause 41: The method of clause 39, when the payload type indicates that one or more images include an image sequence, presenting the scene image and the overlay image comprises presenting images of the image sequence in order together with corresponding images of the scene image.

[0170]

[0161] Clause 42: The method according to clause 38, wherein the SDP image attributes include a transmission mode attribute that indicates whether the overlay image is to be continuously retransmitted as long as the overlay image is to be presented with the frame of scene data.

[0171]

[0162] Clause 43: The method of clause 38, wherein the SDP image attributes include data indicating whether the overlay image should be presented repeatedly in a loop.

[0172]

[0163] Clause 44: The method of clause 43, when the data indicates that the overlay image should be repeatedly presented in a loop, presenting the scene image and the overlay image comprises determining that the overlay image includes N images in the image sequence, and presenting image i of the image sequence of the overlay image at time j*N+i for a loop number j, where N is a positive integer and j is a non-negative integer, where i corresponds to the i-th image of the image sequence of the overlay image.

[0173]

[0164] Clause 45: The method of clause 38, wherein the SDP image attribute includes data indicating whether the overlay image should be stored locally after reception.

[0174]

[0165] Clause 46: The method of clause 45, wherein when the data indicates that the overlay image should be stored locally after reception, the method further comprises storing the overlay image in local memory, wherein presenting the scene image and the overlay image comprises retrieving the overlay image from the local memory and presenting the retrieved overlay image.

[0175]

[0166] Clause 47: The method of clause 45, wherein when the data indicates that the overlay image is to be retransmitted, presenting the scene image and the overlay image comprises receiving a retransmitted version of the overlay image and presenting the retransmitted version of the overlay image.

[0176]

[0167] Clause 48: The method of clause 38, wherein the SDP image attribute includes data indicating the number of images included in the overlay image.

[0177]

[0168] Clause 49: The method of clause 37, further comprising receiving data for the bitstream indicating whether the one or more overlay images include one or more image sequences and whether the one or more overlay images include one or more still images.

[0178]

[0169] Clause 50: The method of clause 49, further comprising receiving data for the bitstream indicating the number of images in each of the image sequences when the data indicates that the one or more overlay images include one or more image sequences.

[0179]

[0170] Clause 51: The method of clause 49, further comprising receiving data for the bitstream indicating the number of still images when the data indicates that the one or more overlay images include one or more still images.

[0180]

[0171] Clause 52: The method of clause 49, further comprising receiving data indicating a transmission mode for the image sequence and the still image.

[0181]

[0172] Clause 53: The method of clause 52, further comprising determining a display time for the overlay image from timestamp data in the bitstream when one of the transmission modes is "combined".

[0182]

[0173] Clause 54: The method of clause 53, wherein the timestamp data comprises Real-time Transport Protocol (RTP) timestamp data.

[0183]

[0174] Clause 55: The method described in clause 52, further comprising separately receiving data representing a display time for the overlay image when one of the transmission modes is "separate", and determining the display time for the overlay image from the separately received data.

[0184]

[0175] Clause 56: The method of clause 37, further comprising receiving data representing a display order of the overlay images when the one or more overlay images include two or more overlay images.

[0185]

[0176] Clause 57: The method of clause 37, further comprising receiving image metadata for each of the overlay images from the bitstream, the metadata indicating one or more of image dimensions or image roles.

[0186]

[0177] Clause 58: The method of clause 57, wherein the image role comprises at least one of a cover image, a thumbnail image, an auxiliary image, a master image, a hidden image, a pre-computed derived image, a coded image, or a derived image.

[0187]

[0178] Clause 59: The method of clause 57, wherein the metadata includes one or more of an order element indicating an order of presentation of the overlay images, or a duration element indicating the amount of time a corresponding one of the overlay images should be displayed.

[0188]

[0179] Clause 60: A device for retrieving media data, the device comprising: a memory configured to store scene data and image data; and one or more processors implemented in circuitry, the one or more processors configured to: receive data for a bitstream indicating that the bitstream includes one or more overlay images; receive one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data which remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence that repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receive scene data including one or more scene images; and present the scene images and the overlay images.

[0189]

[0180] Clause 61: The device of clause 60, wherein the one or more processors are further configured to receive a Session Description Protocol (SDP) image attribute that identifies the bitstream.

[0190]

[0181] Clause 62: The device of clause 61, wherein the SDP image attribute includes an image attribute indicating a payload type indicating whether the one or more overlay images include a single static image or an image sequence.

[0191]

[0182] Clause 63: A device as described in Clause 62, wherein, to present a scene image and an overlay image, the one or more processors are configured to, when the payload type indicates that the one or more images include a single static image, repeatedly present the single static image when presenting the scene image image by image.

[0192]

[0183] Clause 64: To present the scene image and the overlay image, the one or more processors are configured to present images of the image sequence in order together with corresponding images of the scene image when the payload type indicates that one or more images include an image sequence.

[0193]

[0184] Clause 65: A device as described in clause 61, wherein the SDP image attributes include a transmission mode attribute indicating whether the overlay image is to be continuously retransmitted as long as the overlay image is to be presented with the frame of scene data.

[0194]

[0185] Clause 66: The device of clause 61, wherein the SDP image attribute includes data indicating whether the overlay image should be presented repeatedly in a loop.

[0195]

[0186] Clause 67: The device described in Clause 66, wherein to present the scene image and the overlay image, the one or more processors are configured to: when the data indicates that the overlay image should be repeatedly presented in a loop, determine that the overlay image includes N images in the image sequence, and for a loop number j, where N is a positive integer and j is a non-negative integer, present image i of the image sequence of the overlay image at time j*N+i, where i corresponds to the i-th image of the image sequence of the overlay image.

[0196]

[0187] Clause 68: The device of clause 61, wherein the SDP image attribute includes data indicating whether the overlay image should be stored locally after receipt.

[0197]

[0188] Clause 69: The device described in Clause 68, wherein the one or more processors are further configured to store the overlay image in memory when the data indicates that the overlay image should be stored locally after reception, and wherein to present the scene image and the overlay image, the one or more processors are configured to retrieve the overlay image from the memory and present the retrieved overlay image.

[0198]

[0189] Clause 70: To present a scene image and an overlay image, the device described in Clause 68, wherein the one or more processors are configured to receive a retransmitted version of the overlay image when the data indicates that the overlay image is to be retransmitted, and to present the retransmitted version of the overlay image.

[0199]

[0190] Clause 71: A computer-readable storage medium storing instructions which, when executed, cause a processor to receive data for a bitstream indicating that the bitstream includes one or more overlay images; receive one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data which remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence that repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receive scene data including one or more scene images; and present the scene images and the overlay images.

[0200]

[0191] Clause 72: A device for receiving media data, the device comprising: means for receiving data for the bitstream indicating that the bitstream includes one or more overlay images; means for receiving one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented along with the scene data which remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence which repeats with regular periodicity while presented frame-by-frame with the frames of scene data; means for receiving scene data including one or more scene images; and means for presenting the scene images and the overlay images.

[0201]

[0192] Clause 73: A method of retrieving media data, the method comprising: receiving data for a bitstream indicating that the bitstream includes one or more overlay images; receiving one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data which remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence which repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receiving scene data including one or more scene images; and presenting the scene images and the overlay images.

[0202]

[0193] Clause 74: The method of clause 73, further comprising receiving a Session Description Protocol (SDP) picture attribute that identifies the bitstream.

[0203]

[0194] Clause 75: The method according to clause 74, wherein the SDP image attribute includes an image attribute indicating a payload type indicating whether the one or more overlay images include a single static image or an image sequence.

[0204]

[0195] Clause 76: The method of clause 75, when the payload type indicates that the one or more images include a single static image, presenting the scene image and the overlay image comprises repeatedly presenting the single static image when presenting the scene image for each image.

[0205]

[0196] Clause 77: The method of clause 75, when the payload type indicates that the one or more images include an image sequence, presenting the scene image and the overlay image comprises presenting images of the image sequence in order together with corresponding images of the scene image.

[0206]

[0197] Clause 78: A method according to any of clauses 74 to 77, wherein the SDP image attributes include a transmission mode attribute indicating whether the overlay image is to be continuously retransmitted as long as the overlay image is to be presented with the frame of scene data.

[0207]

[0198] Clause 79: A method according to any of clauses 74 to 78, wherein the SDP image attributes include data indicating whether the overlay image should be presented repeatedly in a loop.

[0208]

[0199] Clause 80: When the data indicates that the overlay image should be repeatedly presented in a loop, presenting the scene image and the overlay image comprises determining that the overlay image includes N images in the image sequence, and presenting image i of the image sequence of the overlay image at time j*N+i for a loop number j, where N is a positive integer and j is a non-negative integer, where i corresponds to the i-th image of the image sequence of the overlay image.

[0209]

[0200] Clause 81: A method according to any one of clauses 74 to 80, wherein the SDP image attribute includes data indicating whether the overlay image should be stored locally after reception.

[0210]

[0201] Clause 82: The method of clause 81, wherein when the data indicates that the overlay image should be stored locally after reception, the method further comprises storing the overlay image in local memory, wherein presenting the scene image and the overlay image comprises retrieving the overlay image from the local memory and presenting the retrieved overlay image.

[0211]

[0202] Clause 83: The method of clause 81, when the data indicates that the overlay image is to be retransmitted, presenting the scene image and the overlay image comprises receiving a retransmitted version of the overlay image and presenting the retransmitted version of the overlay image.

[0212]

[0203] Clause 84: A method according to any one of clauses 74 to 83, wherein the SDP image attributes include data indicating the number of images included in the overlay image.

[0213]

[0204] Clause 85: A method according to any of clauses 73 to 84, further comprising receiving data for the bitstream indicating whether the one or more overlay images include one or more image sequences and whether the one or more overlay images include one or more still images.

[0214]

[0205] Clause 86: The method of clause 85, further comprising receiving data for the bitstream indicating the number of images in each of the image sequences when the data indicates that the one or more overlay images include one or more image sequences.

[0215]

[0206] Clause 87: A method as described in any of clauses 85 and 86, further comprising receiving data for the bitstream indicating the number of still images when the data indicates that the one or more overlay images include one or more still images.

[0216]

[0207] Clause 88: The method of any of clauses 85 to 87, further comprising receiving data indicating a transmission mode for the image sequence and the still image.

[0217]

[0208] Clause 89: The method of clause 88, further comprising determining a display time for the overlay image from timestamp data in the bitstream when one of the transmission modes is "combined".

[0218]

[0209] Clause 90: The method of clause 89, wherein the timestamp data comprises Real-time Transport Protocol (RTP) timestamp data.

[0219]

[0210] Clause 91: The method described in clause 88, further comprising separately receiving data representing a display time for the overlay image when one of the transmission modes is "separate", and determining the display time for the overlay image from the separately received data.

[0220]

[0211] Clause 92: The method of any of clauses 73 to 91, further comprising receiving data representing a display order of the overlay images when the one or more overlay images include two or more overlay images.

[0221]

[0212] Clause 93: A method according to any of clauses 73 to 92, further comprising receiving image metadata for each of the overlay images from the bitstream, the metadata indicating one or more of image dimensions or image roles.

[0222]

[0213] Clause 94: The method of clause 93, wherein the image role comprises at least one of a cover image, a thumbnail image, an auxiliary image, a master image, a hidden image, a pre-computed derived image, a coded image, or a derived image.

[0223]

[0214] Clause 95: A method as described in any of clauses 93 and 94, wherein the metadata includes one or more of an order element indicating an order of presentation of the overlay images, or a duration element indicating the amount of time a corresponding one of the overlay images should be displayed.

[0224]

[0215] Clause 96: A device for retrieving media data, the device comprising: a memory configured to store scene data and image data; and one or more processors implemented in circuitry, the one or more processors configured to: receive data for a bitstream indicating that the bitstream includes one or more overlay images; receive one or more overlay images from the bitstream, the overlay image comprising either a single static image to be presented with the scene data which remains unchanged while presented frame-by-frame with the frames of scene data, or an image sequence that repeats with regular periodicity while presented frame-by-frame with the frames of scene data; receive scene data including one or more scene images; and present the scene images and the overlay images.

[0225]

[0216] Clause 97: The device of clause 96, wherein the one or more processors are further configured to receive a Session Description Protocol (SDP) image attribute that identifies the bitstream.

[0226]

[0217] Clause 98: The device of clause 97, wherein the SDP image attribute includes an image attribute indicating a payload type indicating whether the one or more overlay images include a single static image or an image sequence.

[0227]

[0218] Clause 99: The device described in Clause 98, wherein, to present a scene image and an overlay image, the one or more processors are configured to, when the payload type indicates that the one or more images include a single static image, repeatedly present the single static image when presenting the scene image for each image.

[0228]

[0219] Clause 100: The device described in Clause 98, wherein to present the scene image and the overlay image, the one or more processors are configured to, when the payload type indicates that one or more images include an image sequence, present images of the image sequence in order together with corresponding images of the scene image.

[0229]

[0220] Clause 101: A device described in any of clauses 97 to 100, wherein the SDP image attributes include a transmission mode attribute indicating whether the overlay image is to be continuously retransmitted as long as the overlay image is to be presented with the frame of scene data.

[0230]

[0221] Clause 102: The device of clause 101, wherein the SDP image attribute includes data indicating whether the overlay image should be presented repeatedly in a loop.

[0231]

[0222] Clause 103: The device described in Clause 102, wherein to present the scene image and the overlay image, the one or more processors are configured to: when the data indicates that the overlay image should be repeatedly presented in a loop, determine that the overlay image includes N images in the image sequence, and present image i of the image sequence of the overlay image at time j*N+i for a loop number j, where N is a positive integer and j is a non-negative integer, where i corresponds to the i-th image of the image sequence of the overlay image.

[0232]

[0223] Clause 104: A device described in any of clauses 97 to 103, wherein the SDP image attribute includes data indicating whether the overlay image should be stored locally after reception.

[0233]

[0224] Clause 105: The device described in clause 104, wherein the one or more processors are further configured to store the overlay image in memory when the data indicates that the overlay image should be stored locally after reception, and wherein to present the scene image and the overlay image, the one or more processors are configured to retrieve the overlay image from the memory and present the retrieved overlay image.

[0234]

[0225] Clause 106: A device described in any of clauses 104 and 105, wherein to present a scene image and an overlay image, the one or more processors are configured to receive a retransmitted version of the overlay image when the data indicates that the overlay image is to be retransmitted, and to present the retransmitted version of the overlay image.

[0235]

[0226] 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 code and executed by a hardware-based processing unit. A computer-readable medium may include a computer-readable storage medium, which corresponds to a tangible medium, such as a data storage medium, or may include a communication medium, which includes any medium that facilitates transfer of a computer program from one place to another, for example according to a communication protocol. In this manner, a computer-readable medium may generally correspond to (1) a tangible computer-readable storage medium that is non-transitory, or (2) a communication medium, such as a signal or carrier wave. A data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, code, and / or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer-readable medium.

[0236]

[0227] By way of example and not limitation, such computer-readable storage media may comprise 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 may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Also, any connection is properly referred to as a computer-readable medium. For example, if the instructions are transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of the 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 instead cover 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 and discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer readable media.

[0237]

[0228] The instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated circuits or discrete logic circuitry. Thus, the term "processor" as used herein may refer to any of the above structures, or any other structure suitable for implementing the techniques described herein. Furthermore, in some aspects, the functionality described herein may be provided in dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into a composite codec. Also, the techniques may be fully implemented in one or more circuits or logic elements.

[0238]

[0229] The techniques of the present disclosure may be implemented in a wide variety of devices or apparatuses, including wireless handsets, integrated circuits (ICs) or sets of ICs (e.g., chipsets). In this disclosure, various components, modules, or units have been described to highlight functional aspects of devices configured to implement the disclosed techniques, but those components, modules, or units do not necessarily require realization by different hardware units. Rather, as described above, the various units may be combined in a codec hardware unit or provided by a collection of interoperable hardware units, including one or more processors described above, along with suitable software and / or firmware.

[0239]

[0230] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. 1. A method for retrieving media data, the method comprising: receiving data for a Real-time Transport Protocol (RTP) bitstream; an attribute indicating that the RTP bitstream includes one or more overlay images, the one or more overlay images comprising either a single static image to be presented along with the frames of scene data that remains unchanged while being presented frame-by-frame with the frames of scene data, or a sequence of images that repeat with a regular periodicity while being presented frame-by-frame with the frames of the scene data; a payload type syntax element that specifies a payload type to be used for the transport of the one or more overlay images in the RTP bitstream; Session Description Protocol (SDP) image attributes including: receiving the one or more overlay images from the RTP bitstream; receiving the scene data including one or more scene images; presenting the scene image and the overlay image; A method comprising:

2. 2. The method of claim 1, wherein the SDP image attribute includes a transmission mode syntax element that indicates whether the overlay image is to be continuously retransmitted for as long as the overlay image is to be presented with the frame of the scene data.

3. the SDP image attributes include a loop syntax element that indicates whether the overlay image should be presented repeatedly in a loop; Optionally, when the loop syntax element indicates that the overlay image should be repeatedly presented in the loop, presenting the scene image and the overlay image comprises: determining that the overlay image comprises N images in an image sequence, N being a positive integer; presenting an image i of the image sequence of the overlay images at a time j*N+i for a loop number j, where j is a non-negative integer, where i corresponds to the i-th image of the image sequence of the overlay images; The method of claim 1 , comprising:

4. The method of claim 1 , wherein the SDP image attributes include a store syntax element that indicates whether the overlay image should be stored locally after receipt.

5. When the store syntax element indicates that the overlay image should be stored locally after receiving, the method further comprises storing the overlay image in a local memory, wherein presenting the scene image and the overlay image comprises: retrieving the overlay image from the local memory; presenting the retrieved overlay image; and The method of claim 4 comprising:

6. presenting the scene image and the overlay image when the store syntax element indicates that the overlay image is to be retransmitted; receiving a retransmitted version of the overlay image; presenting the retransmitted version of the overlay image; and The method of claim 4 comprising:

7. The method of claim 1 , wherein the SDP image attributes include data indicating a number of images included in the overlay image.

8. 2. The method of claim 1, further comprising receiving data for the RTP bitstream indicating whether the one or more overlay images include one or more image sequences and whether the one or more overlay images include one or more still images.

9. receiving data for the RTP bitstream indicating a number of images in each of the image sequences when the data indicates that the one or more overlay images include the one or more image sequences; or receiving data for the RTP bitstream indicating a number of the still images when the data indicates that the one or more overlay images include the one or more still images; The method of claim 8 further comprising:

10. The method of claim 8 , further comprising receiving data representative of a transmission mode for the image sequence and the still image.

11. determining a display time for the overlay image from timestamp data of the RTP bitstream when one of the transmission modes is "combined"; Optionally, the timestamp data comprises Real-time Transport Protocol (RTP) timestamp data. The method of claim 10.

12. When one of the transmission modes is "separate", separately receiving data representing a display time for the overlay image; determining the display time for the overlay image from the separately received data; and The method of claim 10 further comprising:

13. The method of claim 1 , further comprising receiving data representing a display order of the one or more overlay images when the one or more overlay images include two or more overlay images.

14. receiving image metadata for each of the overlay images from the RTP bitstream, the metadata indicating one or more of an image dimension or an image role; Optionally, the image role comprises at least one of a cover image, a thumbnail image, an auxiliary image, a master image, a hidden image, a pre-computed derived image, a coded image, or a derived image; or the metadata includes one or more of an order element indicating an order of presentation of the overlay images, or a duration element indicating an amount of time a corresponding one of the overlay images should be displayed; The method of claim 1.

15. 1. A device for retrieving media data, said device comprising: a memory configured to store scene data and image data; and one or more processors implemented in a circuit, the one or more processors comprising: receiving data for a Real-time Transport Protocol (RTP) bitstream; an attribute indicating that the RTP bitstream includes one or more overlay images, the one or more overlay images comprising either a single static image to be presented with the scene data, which remains unchanged while being presented frame-by-frame with the frames of the scene data, or a sequence of images which repeat with a regular periodicity while being presented frame-by-frame with the frames of the scene data; a payload type syntax element that specifies a payload type to be used for the transport of the one or more overlay images in the RTP bitstream; Session Description Protocol (SDP) image attributes including: receiving the one or more overlay images from the bitstream; receiving the scene data including one or more scene images; presenting the scene image and the overlay image; A device configured to:

16. The device of claim 15, further configured to perform a method according to any one of claims 2 to 14.

17. A computer readable storage medium having instructions stored thereon which, when executed, cause a processor to perform the method of any one of claims 1 to 14.

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