Background data traffic delivery of media data

Abstract

An exemplary device for retrieving media data includes a memory configured to store the media data and one or more processors implemented in circuitry, the one or more processors configured to send a request to a media streaming application function (AF) to retrieve the media data via background data transfer, in response to the request, receive an indication of a background data transfer opportunity from the media streaming AF, in response to the indication of the background data transfer opportunity, retrieve the media data via background data transfer, and store the retrieved media data in the memory.

Description

[Technical field]

[0001] This application claims priority to U.S. Patent Application No. 17 / 648,886, filed January 25, 2022, and U.S. Provisional Patent Application No. 63 / 141,580, filed January 26, 2021, the entire contents of which are incorporated herein by reference. U.S. Patent Application No. 17 / 648,886, filed January 25, 2022, claims the benefit of U.S. Provisional Patent Application No. 63 / 141,580, filed January 26, 2021.

[0002] TECHNICAL FIELD This disclosure relates to the 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 game devices, video game consoles, cellular or satellite radiotelephones, video conferencing devices, etc. Digital video devices implement video compression techniques, such as those described in standards set forth 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, in order to more efficiently transmit and receive digital video information.

[0004] After media data, such as video data, is encoded, the media data may be packetized for transmission or storage. The media data may be 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, such as AVC, and its extensions. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] R. Fielding et al., RFC 2616, "Hypertext Transfer Protocol-HTTP / 1.1", Network Working Group, IETF, June 1999. [Non-Patent Document 2] T. Paila et al., “FLUTE-File Delivery over Unidirectional Transport”, Network Working Group, RFC 6726, November 2012 Summary of the Invention [Means for solving the problem]

[0006] Generally, this disclosure describes techniques for streaming media data using background data transfer. In some cases, background data transfer may be used to efficiently deliver content to customers. That is, media data may be sent to client devices during off-peak hours (e.g., when many users are asleep or otherwise not using their devices). Users of the client devices may then play the media data transferred by background data transfer at a later time. Mobile network operators (MNOs) may offer charging discounts for traffic during off-peak hours. Application providers may make predictions about what content will be consumed by various customers and then push appropriate content to corresponding client devices (also called "user equipment" or "UE") during specified time windows, e.g., during off-peak hours.

[0007] This disclosure describes various techniques related to transferring media data using background data transfer. For example, this disclosure describes techniques related to managing the download process on a client device and a network, how downloads can be triggered, and how cache space on a client device can be managed.

[0008] In one example, a method for retrieving media data includes sending, by one or more processors of a client device, a request to a media streaming application function (AF) to retrieve media data via background data transfer; receiving, by the one or more processors of the client device, an indication of a background data transfer opportunity from the media streaming AF in response to the request; retrieving, by the one or more processors, the media data via background data transfer in response to the indication of the background data transfer opportunity; and storing, by the one or more processors, the retrieved media data.

[0009] In another example, a device for retrieving media data comprises a memory configured to store the media data and one or more processors implemented in circuitry, the one or more processors configured to send a request to a media streaming application function (AF) to retrieve the media data by background data transfer, in response to the request, receive an indication of a background data transfer opportunity from the media streaming AF, in response to the indication of the background data transfer opportunity, retrieve the media data by background data transfer, and store the retrieved media data in the memory.

[0010] In another example, a computer-readable storage medium stores instructions that, when executed, cause one or more processors of a client device to send a request to a media streaming application function (AF) to retrieve media data via background data transfer; in response to the request, receive an indication of a background data transfer opportunity from the media streaming AF; in response to the indication of the background data transfer opportunity, retrieve the media data via background data transfer; and store the retrieved media data in memory.

[0011] In another example, a device for retrieving media data includes means for sending a request to retrieve media data via background data transfer, means for receiving an indication of a background data transfer opportunity in response to the request, means for retrieving the media data via background data transfer in response to the indication of the background data transfer opportunity, and means for storing the retrieved media data.

[0012] 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]

[0013] [Figure 1] 1 is a block diagram illustrating an example system that implements techniques for streaming media data over a network. [Diagram 2] FIG. 2 is a block diagram illustrating an exemplary set of components of a removal unit. [Diagram 3] FIG. 2 is a conceptual diagram illustrating exemplary multimedia content elements. [Figure 4] 1 is a block diagram illustrating elements of an exemplary video file that may correspond to segments of a presentation. [Diagram 5]FIG. 1 is a block diagram illustrating an example system in which techniques of this disclosure may be implemented. [Figure 6] 1 is a flowchart illustrating an example method for transporting media data using background data transfer, consistent with techniques of this disclosure. [Figure 7] 1 is a flowchart illustrating an example method for retrieving media data in accordance with techniques of this disclosure. [Figure 8] 10 is a flowchart illustrating another example method for retrieving media data in accordance with techniques of this disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Generally, this disclosure describes techniques for streaming media data using background data transfer. In some cases, background data transfer may be used to efficiently deliver content to customers. That is, media data may be sent to client devices during off-peak hours (e.g., when many users are asleep or otherwise not using their devices). Users of the client devices may then play the media data transferred by background data transfer at a later time. Mobile network operators (MNOs) may offer charging discounts for traffic during off-peak hours. Application providers may make predictions about what content will be consumed by various customers and then push appropriate content to corresponding client devices (also called "user equipment" or "UE") during specified time windows, e.g., during off-peak hours, based on the predictions.

[0015] This disclosure describes various techniques related to transferring media data using background data transfer. For example, this disclosure describes techniques related to managing the download process on a client device and a network, how downloads can be triggered, and how cache space on a client device can be managed.

[0016] The techniques of this disclosure may be applied to video files that conform to video data encapsulated according to any of the ISO Base Media File Format, 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.

[0017] In HTTP streaming, frequently used operations include HEAD, GET, and partial GET. The HEAD operation retrieves the header of a file associated with a given Uniform Resource Locator (URL) or Uniform Resource Name (URN) without retrieving the payload associated with the URL or URN. The GET operation retrieves the entire file associated with a given URL or URN. The partial GET operation receives a byte range as an input parameter and retrieves a consecutive number of bytes of a file, where the number of bytes corresponds to the byte range received. Thus, a movie fragment may be provided for HTTP streaming, since a partial GET operation can retrieve one or more individual movie fragments. In a movie fragment, there may be several track fragments of different tracks. In HTTP streaming, a media presentation may be a structured collection of data accessible to a client. A client can request and download media data information to present a streaming service to a user.

[0018] In an example of streaming 3GPP data using HTTP streaming, multiple representations may exist for video and / or audio data of the multimedia content. As described below, the different representations may correspond to different coding characteristics (e.g., different profiles or levels of a video coding standard), different coding standards or extensions of a coding standard (such as multiview and / or scalable extensions), or different bit rates. A manifestation of such representations may be defined in a Media Presentation Description (MPD) data structure. A media presentation may correspond to a structured collection of data accessible to an HTTP streaming client device. An HTTP streaming client device can request and download media data information to present a streaming service to a user of the client device. A media presentation may be described in an MPD data structure, which may include updates to the MPD.

[0019] A media presentation may include a sequence of one or more periods. Each period may extend until the start of the next period or, in the case of the last period, until the end of the media presentation. Each period may include one or more representations for the same media content. A representation may be one of several alternatively encoded versions of audio, video, timed text, or other such data. The representations may vary by type of encoding, e.g., bit rate, resolution, and / or codec for video data, and bit rate, language, and / or codec for audio data. The term representation may be used to refer to a section of encoded audio or video data that corresponds to a particular period of multimedia content and that has been encoded in a particular way.

[0020] Representations for a particular time period may be assigned to a group indicated by an attribute in the MPD indicating the adaptation set to which the representation belongs. Representations in the same adaptation set are generally considered as alternatives to each other in that a client device may dynamically and seamlessly switch between these representations, for example to perform bandwidth adaptation. For example, each representation of video data for a particular time period may be assigned to the same adaptation set, so that any of the representations may be selected for decoding to present media data, such as video data or audio data, of the multimedia content for the corresponding time period. In some examples, the media content within a time period may be represented by either one representation from group 0, if present, or a combination of at most one representation from each non-zero group. Timing data for each representation for a time period may be represented relative to a start time of the time period.

[0021] A representation may include one or more segments. Each representation may include an initialization segment, or each segment of a representation may be self-initializing. An initialization segment, if present, may include initialization information for accessing a representation. In general, an initialization segment does not include media data. A segment may be uniquely referenced by an identifier, such as a Uniform Resource Locator (URL), Uniform Resource Name (URN), or Uniform Resource Identifier (URI). The MPD may provide an identifier for each segment. In some examples, the MPD may also provide a byte range in the form of a range attribute, which may correspond to data for a segment within a file accessible by a URL, URN, or URI.

[0022] Different representations may be selected for retrieval substantially simultaneously for different types of media data. For example, a client device may select an audio representation, a video representation, and a timed text representation from which to retrieve segments. In some examples, a client device may select a particular adaptation set to perform bandwidth adaptation. That is, the client device may select an adaptation set including a video representation, an adaptation set including an audio representation, and / or an adaptation set including timed text. Alternatively, a client device may select an adaptation set for one type of media (e.g., video) and directly select a representation for another type of media (e.g., audio and / or timed text).

[0023] 1 is a block diagram illustrating an example system 10 that implements techniques for streaming media data over a network. In this example, system 10 includes a content preparation device 20, a server device 60, and a client device 40. Client device 40 and server device 60 are communicatively coupled by a network 74, which may include the Internet. In some examples, content preparation device 20 and server device 60 may also be coupled by network 74 or another network, or may be communicatively coupled directly. In some examples, content preparation device 20 and server device 60 may include the same device.

[0024] In the example of FIG. 1, content preparation device 20 includes audio source 22 and video source 24. Audio source 22 may comprise, for example, a microphone that generates electrical signals representative of captured audio data to be encoded by audio encoder 26. Alternatively, audio source 22 may comprise a storage medium that stores 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 that generates 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 preparation device 20 is not necessarily communicatively coupled to server device 60 in all examples, although it may store multimedia content on a separate medium that is read by server device 60.

[0025] The raw audio and video data may include 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 a speaking participant while the speaking participant is speaking, and video source 24 may simultaneously obtain video data of the speaking participant. In other examples, audio source 22 may comprise a computer-readable storage medium containing stored audio data, and video source 24 may comprise a computer-readable storage medium containing stored video data. Thus, the techniques described in this disclosure may be applied to live, streaming, real-time audio and video data, or to archived, pre-recorded audio and video data.

[0026] 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 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 a speaking participant is generally generating audio data by speaking, and video source 24 captures video data of the speaking participant contemporaneously, 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 a situation in which audio data and video data were captured contemporaneously, for which the audio frame and video frame, respectively, include contemporaneously captured audio data and video data.

[0027] In some examples, audio encoder 26 may encode in each encoded audio frame a timestamp representing the time the audio data for the encoded audio frame was recorded, and similarly, video encoder 28 may encode in each encoded video frame a timestamp representing the time the video data for the encoded video frame was recorded. In such examples, audio frames corresponding to a video frame may include an audio frame that includes a timestamp and a video frame that includes the same timestamp. Content preparation 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 and video data, respectively, with timestamps.

[0028] 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 a sequence identifier in the encoded audio data to indicate the relative time order of the encoded audio data, although not necessarily indicating the absolute time the audio data was recorded, and similarly, video encoder 28 may use the sequence identifier to indicate the relative time order of the encoded video data. Similarly, in some examples, the sequence identifier may be mapped with or correlated to a timestamp.

[0029] The audio encoder 26 generally generates a stream of encoded audio data, and the video encoder 28 generates 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, the 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 PES packets belonging to other elementary streams. The basic unit of data 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.

[0030] Many video coding standards, such as the ITU-T H.264 / AVC and ITU-T H.265 High Efficiency Video Coding (HEVC) standards, and the ITU-T H.266 Versatile Video Coding (VVC) standard, define syntax, semantics, and decoding processes for error-free bitstreams, all of which conform to a certain profile or level. Video coding standards do not generally prescribe an encoder, but an encoder is tasked with ensuring that the generated bitstream conforms to the standard for a decoder. In the context of a video coding standard, a "profile" corresponds to a subset of algorithms, features, or tools, and the constraints that apply to these. As defined by the H.264 standard, for example, a "profile" is a subset of the entire bitstream syntax specified by the H.264 standard. A "level" corresponds to a constraint on the decoder's resource consumption, such as, for example, decoder memory and computation, which is related to picture resolution, bitrate, and block processing speed. The profile may be signaled by a profile_idc (profile indicator) value, while the level may be signaled by a level_idc (level indicator) value.

[0031] For example, the H.264 standard acknowledges that within the range imposed by the syntax of a given profile, it is still possible to require large variations in the performance of encoders and decoders depending on the values ​​taken by syntax elements in the bitstream, such as the specified size of the decoded picture. The H.264 standard further acknowledges that in many applications, it is neither practical nor economical to implement a decoder capable of handling all hypothetical uses of the syntax in 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 limitations on values. Alternatively, these constraints may take the form of constraints on arithmetic combinations of values ​​(e.g., the product of the number of pictures decoded per second, the picture height, and the picture width). The H.264 standard further specifies that individual implementations may support different levels for each supported profile.

[0032] A decoder conforming to a profile usually 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 limit defined in the level. Profile and level definitions may be useful for explainability. For example, during video transmission, a pair of profile and level definitions may be negotiated and agreed upon for the entire transmission session. More specifically, in H.264 / AVC, a level may define the number of macroblocks that need to be processed, the size of the decoded picture buffer (DPB), the size of the coded picture buffer (CPB), the range of motion vectors in the vertical direction, the limit on the maximum number of motion vectors per two consecutive MBs, and whether B blocks may have sub-macroblock partitions smaller than 8×8 pixels. In this way, a decoder can determine whether it is capable of properly decoding a bitstream.

[0033] In the example of Figure 1, encapsulation unit 30 of content preparation device 20 receives an elementary stream including coded video data from video encoder 28 and an elementary stream including 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.

[0034] The video encoder 28 may encode the video data of the multimedia content in various ways to generate various representations of the multimedia content at various bit rates with various characteristics, such as pixel resolution, frame rate, compliance with various coding standards, compliance with various profiles and / or levels of profiles for various coding standards, representations with one or more views (e.g., for two-dimensional or three-dimensional playback), or other such characteristics. A representation as used in this disclosure may include one of audio data, video data, text data (e.g., for closed captioning), or other such data. The 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. The encapsulation unit 30 is responsible for assembling the elementary streams into video files (e.g., segments) of the various representations.

[0035] 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, which realize addressing applications of the video representation that are "network friendly," 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 contain block, macroblock, and / or slice level data. Other NAL units may be non-VCL NAL units. In some examples, a coded picture at one time instance may be contained within an access unit, which is typically presented as a primary coded picture and may contain one or more NAL units.

[0036] Non-VCL NAL units may include parameter set NAL units and SEI NAL units, among others. Parameter sets may contain sequence level header information (in sequence parameter sets (SPS)) and picture level header information that does not change frequently (in picture parameter sets (PPS)). With parameter sets (e.g., PPS and SPS), this infrequently changing information does not need to be repeated for each sequence or picture, thus improving coding efficiency. Furthermore, the use of parameter sets may enable out-of-band transmission of important header information, eliminating the need for redundant transmission for error recovery. 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.

[0037] Supplemental Enhancement Information (SEI) may include information that is not necessary for decoding coded picture samples from VCL NAL units, but may assist processes related to decoding, display, error recovery, 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 in the implementation of a decoder 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 within SEI messages, such as the Scalability Information SEI message in the example of SVC and the View Scalability Information SEI message in MVC. These exemplary SEI messages may convey information, for example, regarding extraction of operation points and characteristics of the operation points. In addition, 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).

[0038] The encapsulation unit 30 may provide data for one or more representations of the multimedia content to the output interface 32 along with a manifest file (e.g., MPD). The output interface 32 may include an interface for writing to a storage medium, such as a network interface or 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 a 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 of which includes a respective manifest file 66 and one or more representations 68A-68N (representations 68). In some examples, the output interface 32 may also send the data directly to a network 74.

[0039] 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 of the segments, text type information that may identify, e.g., by speaker, language or other characteristics of the text to be displayed along with the representation and / or audio data to be decoded and presented, camera angle information that may represent the camera angle or field of view of a real-world camera of the scene of the representation in the adaptation set, rating information that represents the suitability of the content for a particular viewer, etc.

[0040] 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 of the adaptation set. The manifest file 66 may also include data representing individual characteristics, such as bit rates, for each representation of the adaptation set. 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 of the manifest file 66.

[0041] 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 transmit and receive data over network 74.

[0042] The request processing unit 70 is configured to receive network requests for data on 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 or partial GET requests and provide data for the multimedia content 64 in response to those 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, thus comprising a partial GET request. The request processing unit 70 may further be configured to respond to an HTTP HEAD request to provide header data for 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.

[0043] 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. Content preparation device 20 may create DASH segments and / or subsegments in substantially the same manner as described, but 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 client device 40. That is, server device 60 may advertise to client devices, including client device 40, an Internet Protocol (IP) address associated with a multicast group associated with a particular multimedia content (e.g., a broadcast of a live event). Client device 40 may then submit a request to join the multicast group. This request may be propagated throughout network 74, e.g., to routers constituting network 74, such that the routers direct traffic destined for the IP address associated with the multicast group to subscribing client devices, such as client device 40.

[0044] 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 various alternative representations 68 (e.g., video services of 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.

[0045] 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 the user of the client device 40, one or more camera fields of view 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 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 a portion 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, in which case the requisite hardware may be provided to execute instructions for the software or firmware.

[0046] 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 of the representations 68 (e.g., an adaptation set) that has 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.

[0047] Generally, a higher bit rate of the representation may provide higher quality video playback, while a lower bit rate of the representation may provide sufficient quality video playback when the available network bandwidth is reduced. Thus, when the available network bandwidth is relatively high, retrieval unit 52 may retrieve data from a representation with a relatively high bit rate, and when the available network bandwidth is low, retrieval unit 52 may retrieve data from a representation with a relatively low bit rate. In this manner, client device 40 may stream multimedia data over network 74 while also adapting to the changing network bandwidth availability of network 74.

[0048] 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 issuing a further request to server device 60 or content preparation device 20. Retrieval unit 52 may submit a request to exit 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.

[0049] Network interface 54 may receive and provide data for segments of a selected representation to retrieval unit 52, which may then provide the segments to de-encapsulation unit 50. De-encapsulation unit 50 may de-encapsulate elements of the video file into constituent PES streams and de-packetize the PES streams to retrieve the encoded data and pass it 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 passes the decoded audio data to audio output 42, while video decoder 48 decodes the encoded video data and passes the decoded video data, which may include multiple views of the stream, to video output 44.

[0050] 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 circuitry, such as, where applicable, one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), discrete logic circuitry, software, hardware, firmware, or any combination thereof. Each of the video encoder 28 and the video decoder 48 may be included within 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 within 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 include an integrated circuit, a microprocessor, and / or a wireless communication device, such as a cellular telephone.

[0051] Client device 40, server device 60, and / or content preparation 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 preparation device 20 may be configured to implement these techniques in place of (or in addition to) server device 60.

[0052] Encapsulation unit 30 may form NAL units that include 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 within its payload may include various levels of granularity of the video data. For example, a NAL unit may include 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.

[0053] Encapsulation unit 30 may also assemble an access unit from multiple NAL units. In general, an access unit may include one or more NAL units to represent a frame of video data, as well as 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 data 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, a particular frame for all views of the same access unit (same time instance) may be rendered simultaneously. In one example, an access unit may include a coded picture in one time instance, which may be presented as a primary coded picture.

[0054] Thus, an access unit may include all audio and video frames of a common time instance, e.g., all views corresponding to time X. This disclosure also refers to the coded pictures of a particular view as a "view component." That is, a view component may include coded pictures (or frames) for a particular view at a particular time. Thus, an access unit may be defined as including all view components of a common time instance. The decoding order of the access units is not necessarily the same as the output or display order.

[0055] A media presentation may include a media presentation description (MPD) that may contain descriptions of different alternative representations (e.g., video services with different qualities), and the description 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 the various presentations. The movie fragments may be placed within a movie fragment box (moof box) of a video file.

[0056] Manifest file 66 (which may include, for example, an MPD) may advertise the availability of segments of representations 68. That is, the MPD may include information indicating the 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 can determine when each segment is available based on the start time as well as the duration of the segment preceding a particular segment.

[0057] After the encapsulation unit 30 assembles the NAL units and / or access units into a video file based on the received data, the encapsulation unit 30 passes the video file to the output interface 32 for output. In some examples, the encapsulation unit 30 may store the video file locally or send the video file to a remote server via the output interface 32 instead of sending the video file directly to the client device 40. The output interface 32 may include, 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. The 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.

[0058] Network interface 54 may receive NAL units or access units over network 74 and provide the NAL units or access units to decapsulation unit 50 via retrieval unit 52. Decapsulation unit 50 may decapsulate elements of the video file into constituent PES streams, depacketize 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, while 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.

[0059] The content preparation device 20 and / or the server device 60 may represent application provider devices, and the client device 40 may represent user equipment (UE). The network 74 may represent a fifth generation (5G) mobile network. In general, the content preparation device 20 and / or the server device 60 may create a background data transfer (BDT) configuration, and the client device 40 may determine to download media data using the background data transfer. The client device 40 (e.g., the retrieval unit 52) ​​may execute a media session handler (MSH) and a media player application or a streaming application (e.g., a DASH application or a plug-in to a web browser). According to techniques of this disclosure, the retrieval unit 52 may, for example, request to perform a background data transfer to retrieve media data from the server device 60, receive data representing a BDT opportunity for a particular time, and then perform the background data transfer at the time indicated for the BDT opportunity.

[0060] Figure 2 is a block diagram illustrating in greater detail an exemplary set of components of retrieval unit 52 of Figure 1. In this example, retrieval unit 52 includes a media session handler (MSH) unit 100 and a media application 112.

[0061] In this example, the MSH unit 100 further includes a receiving unit 106, a cache 104, and a proxy server unit 102. In this example, the receiving unit 106 is configured to receive data according to a communication standard such as 3GPP, 5G, etc. In some examples, the receiving unit 106 may receive media data according to a file delivery protocol, for example, according to File Delivery over Unidirectional Transport (FLUTE) as described in T. Paila et al., “FLUTE - File Delivery over Unidirectional Transport,” Network Working Group, RFC 6726, November 2012, available at tools.ietf.org / html / rfc6726. That is, the receiving unit 106 may receive a file by broadcast from a server device 60, which may act as, for example, a Broadcast / Multicast Service Center (BM-SC).

[0062] When MSH unit 100 receives data for media data (e.g., a file), MSH unit 100 may store the received data in cache 104. Cache 104 may include a computer-readable storage medium, such as flash memory, a hard disk, RAM, or any other suitable storage medium.

[0063] The proxy server unit 102 may act as a server to provide media data from the cache 104 to the media application 112. For example, the proxy server unit 102 may provide an MPD file or other manifest file to the media application 112 or an intermediate application such as a DASH client. The proxy server unit 102 may advertise availability times for the segments in the MPD file as well as in hyperlinks from which the segments can be retrieved. These hyperlinks may include a local host address prefix (e.g., 127.0.0.1 for IPv4) that corresponds to the client device 40. In this manner, the media application 112 or the intermediate application may request the segments from the proxy server unit 102, for example, using an HTTP GET or partial GET request. For example, for a segment available from the link http: / / 127.0.0.1 / rep1 / seg3, the media application 112 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 media data from the cache 104 and provide the data to the media application 112 in response to such a request.

[0064] In accordance with the techniques of this disclosure, media application 112 may correspond to a media or streaming application that interacts with MSH unit 100 to retrieve media data through background data transfer. In the example shown in FIG. 2, MSH unit 100 may retrieve the media data through background data transfer, e.g., for storage in cache 104.

[0065] In another example, the MSH unit 100 may alert the media application 112 to a BDT opportunity, and the media application 112 may retrieve the media data via background data transfer.

[0066] For purposes of illustration, assuming that MSH unit 100 retrieves media data from server device 60, e.g., via background data transfer, MSH unit 100 may generally determine the time to retrieve the media data. For example, MSH unit 100 may receive data representing an off-peak designated time window for retrieving the media data. For example, media application 112 may first send a request to MSH unit 100 indicating that particular media data is required and should be transferred via background data transfer. MSH unit 100 may then send the data of the request to, e.g., a 5G media streaming downlink (5G MSd) application function (AF) or other media streaming application function executed by server device 60 or another unit of network 74.

[0067] The 5GMSd AF may respond to the MSH unit 100 with a notification of a background data transfer opportunity. The notification may include data defining an off-peak designated time window. Thus, the MSH unit 100 (or in some examples, the media application 112) may retrieve the media data during the off-peak designated time window. In examples where the media application 112 is to retrieve the media data, the MSH unit 100 may send the data from the notification defining the off-peak designated time window to the media application 112.

[0068] In the example of FIG. 2, MSH unit 100 may store in cache 104 media data retrieved by a background data transfer. MSH unit 100 may store this media data in cache 104 until a later time, for example, a time when a user desires to watch the media data play. In some examples, the media data may be locked until a later time such that MSH unit 100 may prevent access to the media data until a subsequent time. For example, the media data may correspond to an unreleased movie. Thus, MSH unit 100 may retrieve the media data prior to the release date of the media data and prevent access to the retrieved media data until the release date and time. The release date and time may be specified in the instruction of the background data transfer opportunity, in some examples.

[0069] 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), while 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 between the representations 124.

[0070] MPD 122 may include 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 generally representative of 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 temporal subsequence), and / or information for retrieving discrete time periods (e.g., for insertion of targeted advertisements into the media content being played).

[0071] Header data 126, when present, may describe characteristics of segment 128, such as the temporal location of a random access point (RAP, also called a stream access point (SAP)), which of segments 128 contain a 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 of segment 132. Additionally or alternatively, such characteristics may be contained entirely within MPD 122.

[0072] 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 segment 128 may have similar characteristics, e.g., height, width, and bandwidth requirements. Such characteristics may be described by data in MPD 122, although such data is not shown in the example of FIG. 3. MPD 122 may include characteristics as described by 3GPP specifications, plus any or all of the signaled information described in this disclosure.

[0073] 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 separately retrievable using a streaming network protocol such as DASH. In this manner, a destination device such as the client device 40 may retrieve a segment 128 or 132 using an HTTP GET request. In some examples, the client device 40 may retrieve a particular byte range of the segment 128 or 132 using an HTTP partial GET request.

[0074] 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 its extensions 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 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.) that are similarly arranged to the data of the video file 150 according to the ISO base media file format and its extensions.

[0075] The file type (FTYP) box 152 generally represents the file type of the video file 150. The file type box 152 may contain data that identifies specifications that represent 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.

[0076] 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 of a resource 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, which may define the segment type of video file 150.

[0077] 4, MOOV box 154 includes a Movie Header (MVHD) box 156, a Track (TRAK) box 158, and one or more Movie Extension (MVEX) boxes 160. In general, MVHD box 156 may describe general characteristics of video file 150. For example, MVHD box 156 may include data representing when video file 150 was originally created, data representing when video file 150 was last modified, data representing a timescale of video file 150, data representing the playback length of video file 150, or other data generally describing video file 150.

[0078] The TRAK box 158 may contain data for a track of the video file 150. The TRAK box 158 may contain a Track Header (TKHD) box that describes characteristics of the track that corresponds to the TRAK box 158. In some examples, the TRAK box 158 may contain coded video pictures, while in other examples, the coded video pictures for the track may be contained within a Movie Fragment box 164 that may be referenced by data in the TRAK box 158 and / or data in the sidx box 162.

[0079] 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 temporal and / or spatial information of the corresponding track. A TRAK box similar to TRAK box 158 of MOOV box 154 may describe characteristics of a parameter set track when encapsulation unit 30 (FIG. 3) includes the parameter set track in a video file such as video file 150. Encapsulation unit 30 may signal the presence of a sequence level SEI message for a parameter set track within a TRAK box describing the parameter set track.

[0080] An MVEX box 160 may describe characteristics of a corresponding movie fragment box 164, for example, to signal that the video file 150 includes a movie fragment box 164 in addition to the video data, if any, contained in the MOOV box 154. In the context of streaming video data, coded video pictures may be contained in the movie fragment box 164 but not in the MOOV box 154. Thus, all coded video samples may be contained in the movie fragment box 164 but not in the MOOV box 154.

[0081] The MOOV box 154 may contain a number of MVEX boxes 160 equal to the number of movie fragment boxes 164 in the video file 150. Each of the MVEX boxes 160 may describe the characteristics of a corresponding one of the movie fragment boxes 164. For example, each MVEX box may include a Movie Extension Header Box (MEHD) box that describes the duration of the corresponding one of the movie fragment boxes 164.

[0082] As mentioned above, encapsulation unit 30 may store a sequence data set in a video sample that does not include 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 fragment boxes 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 fragment boxes 164 in one of the MVEX boxes 160 that corresponds to one of the movie fragment boxes 164.

[0083] 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 subsegment of a segment (e.g., a segment contained within the video file 150). The 3GPP file format defines a subsegment as "a self-contained set of one or more consecutive Movie Fragment boxes with corresponding Media Data boxes, where the Media Data box containing the data referenced by a Movie Fragment box must follow that 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 series of references to subsegments of the (sub)segment documented by the box. The referenced subsegments 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."

[0084] SIDX box 162 generally provides information describing one or more subsegments of a segment contained within 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., begins with) a Stream Access Point (SAP), the type of SAP (e.g., whether the SAP is an Instantaneous Decoder Refresh (IDR) picture, a Clean Random Access (CRA) picture, a Broken Link Access (BLA) picture, etc.), the location of the SAP (in terms of playback time and / or byte offset) within the subsegment, etc.

[0085] The movie fragment box 164 may include one or more coded video pictures. In some examples, the movie fragment box 164 may include one or more groups of pictures (GOPs), each of which may include multiple coded video pictures, e.g., frames or pictures. In addition, as described above, the movie fragment box 164 may include a sequence data set in some examples. Each of the movie fragment boxes 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 the sequence number of the movie fragment. The movie fragment boxes 164 may be included in the video file 150 in sequence number order.

[0086] The MFRA box 166 may describe random access points within the movie fragment box 164 of the video file 150. This may assist in implementing trick modes, such as implementing a search for a particular temporal location (i.e., play time) within a segment encapsulated by the video file 150. The MFRA box 166 is generally optional and need not be included in the video file, in some examples. 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 may include a number of TFRA boxes equal to the number of media tracks (e.g., non-hint tracks) of the video file 150.

[0087] In some examples, the movie fragment box 164 may include one or more stream access points (SAPs), such as an IDR picture. Similarly, the MFRA box 166 may provide an indication of the location of the SAPs within the video file 150. Thus, a temporal subsequence of the video file 150 may be formed from the SAPs of the video file 150. The temporal subsequence may also include other pictures, such as P-frames and / or B-frames, that are dependent on the SAPs. The frames and / or slices of the temporal subsequence may be ordered within 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 for other data may also be included within the temporal subsequence.

[0088] 5 is a block diagram illustrating an example system 180 that may implement techniques of the present disclosure. In this example, the system 180 includes a content service provider 182 (which may correspond to the content preparation device 20 of FIG. 1), a content delivery network 184 (which may include the server device 60 of FIG. 1), a mobile network operator (MNO) 190 (which may be included in the network 74 of FIG. 1), and a client device 200 (which may correspond to the client device 40 of FIG. 1). In the example of FIG. 5, the MNO 190 includes a cache management unit 192 and an access network unit 194, and the client device 200 includes a native application or browser 202 (which may include a web browser, a web browser plug-in, and / or other media player application or media streaming application) and a 3GPP standard unit 204 that includes a UE-based cache and management unit 206 and a connectivity unit 208.

[0089] In this example, the native application or browser 202 may act as a streaming application or media player application (e.g., corresponding to the media application 112 of FIG. 2 and may further include a DASH client), and the 3GPP standard unit 204 may act as a media session handler (MSH). The client device 200 may include an application programming interface (API), such as the M6 ​​API, between the native application or browser 202 and the 3GPP standard unit 204. The M6 ​​API may be extended to include new components that represent background data transfer, such as "_backgroundTraffic" or "_backgroundDownload". The API may cover both downlink and uplink commands and data transfers. The M6 ​​API may include API calls registerBDT() or registerDownload() and registerUplink(), which register requests for downlink / uplink background data transfers. Parameters may include a list of files, file size, desired time, and / or a flag indicating whether the MSH or the application is performing the download.

[0090] The M6 ​​API may also include a notifyBDTOpportunity() API call. The MSH (e.g., in the 3GPP standard unit 204) may use this callback function to notify a native application or the media player application of the browser 202 of an opportunity to perform a download. Parameters may include the total traffic volume allocated to this session, the bit rate allocated to the session, and the time window for performing the download.

[0091] The M6 ​​API may further include a notifyBDTComplete() API call. If the registration request indicates that the MSH should perform the download, the MSH may use this call to notify the media player application that the download is complete. Parameters may include the location of the downloaded content, the size of the downloaded content, and the cache duration for the content.

[0092] In some examples, the MSH may receive a special link to perform the download for added security. Also for security, the content may undergo an additional encryption step with a special key available only to the media player application. Additionally, for extra security, the application provider may distribute a group key to all applications that perform the BDT download.

[0093] The MSH may, in some examples, allow for the rental of cache space. An application provider may rent a certain amount of disk space on a UE for caching BDT download content. The amount of space may vary between UEs, but the amount may be discoverable by the media player application.

[0094] There may also be various BDT policy features. For example, an application provider may define multiple policies and tag them with one or more feature tags. The feature tags may be used to differentiate media quality, e.g., 4K vs. FHD vs. HD. The 5G Media Streaming Downlink (5GMSd) application function (AF) may track consumption quotas and degrade to a lower policy if the quota is exceeded.

[0095] 6 is a flow chart illustrating an example method for transporting media data using background data transfer in accordance with the techniques of this disclosure. The method of FIG. 6 is described with respect to elements of FIG. 1 and FIG. 2, but it should be understood that other devices, such as the device of FIG. 5, may be configured to implement the techniques of this disclosure.

[0096] In some examples according to techniques of this disclosure, content preparation device 20 and / or server device 60 may provision a background data transfer (BDT) configuration with a 5G media streaming downlink (5GMSd) application function (AF). Provisioning such a configuration may include providing the 5GMSd AF with information about an overall data volume for media data, a list of user equipment (UE), a data budget per UE, one or more geographic areas, etc. (220). The 5GMSd AF may contact a device providing policy and charging functions (PCF) to create a new BDT policy (222). The PCF device may reply to a unified data repository (UDR) with a BDT reference ID for the policy (224). The 5GMSd AF may then confirm to the application provider that a successful BDT policy was created (226).

[0097] The client device 40 may run a media player application and a media session handler (MSH). The media player application may provide the MSH with data about the need for background data transfer and register a background data transfer request (228). For example, the media player application may provide the MSH with a list of files, their corresponding sizes, and desired availability times. The media player application may, in various examples, request that the MSH perform the download using background data transfer, or the media player application may request notification of download opportunities and perform the download itself. If the MSH performs the download itself, the MSH may provide the media player application with the location of the download after the MSH performs the download.

[0098] The MSH may register with the 5GMSd AF a request for a BDT download opportunity (230). The MSH may then provide an application provider identifier or domain name and a UE identifier (such as a General Public Subscription Identifier (GPSI)). The 5GMSd AF may inform the MSH when a BDT download opportunity is available (232). The 5GMSd AF may also verify the existence of an appropriate BDT policy for that application provider and UE. The 5GMSd AF may directly query the Unified Data Repository (UDR) to verify the existence of a BDT policy (234). If a BDT policy is found, the 5GMSd AF may identify the BDT reference ID, time window, data limits per UE, aggregate data, etc. The MSH may then perform the download or trigger a media player application to perform the download. The MSH may also receive data representing the remaining quota for download.

[0099] In particular, in one example, the MSH sends a notification to the media player application that a background data transfer opportunity is available (236A). In response, the media player application retrieves the media data content directly from the application provider (238A). In another example, the MSH itself retrieves the media data and then sends a notification to the media player application when the media data retrieval is complete (fully or partially) (236B). In response, the media player application retrieves the media data from the MSH (238B).

[0100] Thus, the method of FIG. 6 represents an example of a method including the steps of sending, by one or more processors of the client device, a request to a media streaming application function (AF) to retrieve media data via background data transfer; receiving, by the one or more processors of the client device, an indication of a background data transfer opportunity from the media streaming AF in response to the request; retrieving, by the one or more processors, the media data via background data transfer in response to the indication of the background data transfer opportunity; and storing, by the one or more processors, the retrieved media data.

[0101] As mentioned above, this disclosure describes a framework that can be used to implement background data transfer for 5G media delivery, for example. This framework can seamlessly integrate with existing 5G media streaming architecture. These techniques also allow MNOs to maintain control over data volumes and download windows. These techniques can also be secure and provide opportunistic retrieval of media content.

[0102] Application providers and MNOs may be likely to encourage the use of these techniques to reduce costs and offload traffic to less congested time windows. These techniques may be implemented as part of a media session handler service, which may be part of the modem's protocol stack. These techniques may be incorporated into the 5G standard.

[0103] FIG. 7 is a flow chart illustrating an example method of retrieving media data in accordance with techniques of this disclosure. The method of FIG. 7 is described with respect to client device 40 of FIG. 1. Other devices, such as client device 200 of FIG. 5, may be configured to implement this or a similar method. Retrieval unit 52 of client device 40 of FIG. 1 may include both a media application and a media session handler (MSH), for example, as shown in FIG. 2. The media application and MSH of retrieval unit 52 of client device 40 of FIG. 1 may implement various elements of FIG. 7 discussed below.

[0104] Initially, a media application may request a background data transfer, for example for a particular media presentation (250). The media application may send a request to the MSH. In response, the MSH may register the background data transfer request with the 5GMSd AF (252). The MSH may then receive a notification of a background data transfer opportunity from the 5GMSd AF (254). The notification may include data representing the time when media data for the media presentation may be available for retrieval via background data transfer.

[0105] In the example of Figure 7, the MSH may send data about background data transfer opportunities to the media application (256). The data may indicate, for example, times when media data for a media presentation may be retrieved via background data transfer. The media application may receive the background data transfer opportunity data (258) and then retrieve the media data via background data transfer (260). For example, the media application may retrieve the media data at a designated time. The designated time may correspond to an off-peak designated time window.

[0106] Thus, the method of FIG. 7 represents an example of a method including the steps of sending, by one or more processors of the client device, a request to a media streaming application function (AF) to retrieve media data via background data transfer; receiving, by the one or more processors of the client device, an indication of a background data transfer opportunity from the media streaming AF in response to the request; retrieving, by the one or more processors, the media data via background data transfer in response to the indication of the background data transfer opportunity; and storing, by the one or more processors, the retrieved media data.

[0107] FIG. 8 is a flow chart illustrating another example method of retrieving media data in accordance with techniques of this disclosure. The method of FIG. 8 is described with respect to client device 40 of FIG. 1. Other devices, such as client device 200 of FIG. 5, may be configured to implement this or a similar method. Retrieval unit 52 of client device 40 of FIG. 1 may include both a media application and a media session handler (MSH), for example, as shown in FIG. 2. The media application and MSH of retrieval unit 52 of client device 40 of FIG. 1 may implement various elements of FIG. 8 discussed below.

[0108] Initially, a media application may request a background data transfer, for example for a particular media presentation (280). The media application may send a request to the MSH. In response, the MSH may register the background data transfer request with the 5GMSd AF (282). The MSH may then receive a notification of a background data transfer opportunity from the 5GMSd AF (284). The notification may include data representing the time when media data for the media presentation may be available for retrieval via background data transfer.

[0109] In the example of Figure 8, the MSH may then retrieve the media data via background data transfer (286). For example, the MSH may retrieve the media data at a time indicated in the notification. The indicated time may correspond to an off-peak designated time window. After retrieving some or all of the media data for the media presentation, the MSH may send data indicating that the media data has been retrieved and is available to the media application (288).

[0110] The media application may receive an indication from the MSH that media data is available (290). In response, at some future point in time, the media application may retrieve the media data from the MSH (292).

[0111] Thus, the method of FIG. 8 represents an example of a method including the steps of sending, by one or more processors of the client device, a request to a media streaming application function (AF) to retrieve media data via background data transfer; receiving, by the one or more processors of the client device, an indication of a background data transfer opportunity from the media streaming AF in response to the request; retrieving, by the one or more processors, the media data via background data transfer in response to the indication of the background data transfer opportunity; and storing, by the one or more processors, the retrieved media data.

[0112] Various examples of the techniques of this disclosure are summarized in the following paragraphs.

[0113] Clause 1: A method for retrieving media data, comprising the steps of: sending a request to retrieve the media data using background data transfer; receiving an indication of a background data transfer opportunity in response to the request; retrieving the media data using background data transfer in response to the indication of the background data transfer opportunity; and storing the retrieved media data.

[0114] Clause 2: The method of clause 1, wherein using background data transfer, retrieving the media data includes retrieving the media data during an off-peak designated time window.

[0115] Clause 3: The method of clause 2, wherein the indication of background data transfer opportunities includes data defining an off-peak specified time window.

[0116] Clause 4: Any of the methods of clauses 1 to 3, wherein the step of sending a request to retrieve media data using background data transfer includes a step of sending a request to retrieve media data using background data transfer to a 5G media streaming downlink (5GMSd) application function (AF) by a media session handler executed by the client device.

[0117] Clause 5: The method of any one of clauses 1 to 4, wherein the step of receiving an indication of a background data transfer opportunity includes a step of receiving notification of the background data transfer opportunity by a media session handler executed by the client device.

[0118] Clause 6: The method of clause 5, further comprising the step of sending, by the media session handler, data representing the background data transfer to a media player application executed by the client device, and the step of retrieving the media data comprises the step of retrieving the media data using the background data transfer by the media player application.

[0119] Clause 7: The method of clause 5, wherein the step of retrieving the media data using background data transfer includes the step of retrieving the media data using background data transfer by a media session handler, the method further including the step of sending, by the media session handler, data indicating that the media data has been retrieved to a media player application executed by the client device, and the step of sending, by the media session handler, the retrieved data to the media player application.

[0120] Clause 8: Any of the methods of clauses 1 to 7, wherein the step of sending the request includes the step of sending at least one of a list of one or more files of media data to be retrieved, a size of the one or more files, or a desired available time for background data transfer.

[0121] Clause 9: A device for retrieving media data, comprising one or more means for implementing the methods of any of clauses 1 to 8.

[0122] Clause 10: The device of clause 9, wherein the one or more means comprise one or more processors implemented in circuitry.

[0123] Clause 11: A computer-readable storage medium having stored thereon instructions that, when executed, cause a processor to perform any of the methods of clauses 1 to 8.

[0124] Clause 12: A device for retrieving media data, comprising: means for sending a request to retrieve the media data using background data transfer; means for receiving an indication of a background data transfer opportunity in response to the request; means for retrieving the media data using background data transfer in response to the indication of the background data transfer opportunity; and means for storing the retrieved media data.

[0125] Clause 13: A method for retrieving media data, comprising the steps of: sending, by one or more processors of a client device, a request to a media streaming application function (AF) to retrieve media data by background data transfer; receiving, by the one or more processors of the client device in response to the request, an indication of a background data transfer opportunity from the media streaming AF; retrieving, by the one or more processors, the media data by background data transfer in response to the indication of the background data transfer opportunity; and storing, by the one or more processors, the retrieved media data.

[0126] Clause 14: The method of clause 13, wherein retrieving the media data via background data transfer includes determining an off-peak designated time window and retrieving the media data during the off-peak designated time window.

[0127] Clause 15: The method of clause 14, wherein determining the off-peak designated time window includes determining the off-peak designated time window from data defining the off-peak designated time window included in the indication of the background data transfer opportunity.

[0128] Clause 16: The method of clause 13, wherein the step of sending a request to retrieve media data via background data transfer includes a step of sending a request to retrieve media data via background data transfer to a 5G Media Streaming Downlink (5GMSd) Application Function (AF) by a Media Session Handler (MSH) executed by one or more processors of the client device.

[0129] Clause 17: The method of clause 13, wherein receiving an indication of a background data transfer opportunity includes receiving notification of the background data transfer opportunity by a media session handler (MSH) executed by one or more processors of the client device.

[0130] Clause 18: The method of clause 17, further comprising the step of sending, by the MSH, data representing the background data transfer to a media player application executed by one or more processors of the client device, and the step of retrieving the media data comprises the step of retrieving the media data by the media player application executed by the one or more processors of the client device via the background data transfer.

[0131] Clause 19: The method of clause 17, wherein the step of retrieving the media data by background data transfer includes a step of retrieving the media data by background data transfer by an MSH executed by one or more processors of the client device, and the method further includes a step of sending, by the MSH executed by the one or more processors of the client device, data indicating that the media data has been retrieved to a media player application executed by the one or more processors of the client device, and a step of sending, by the MSH executed by the one or more processors of the client device, the retrieved data to the media player application.

[0132] Clause 20: The method of clause 13, further comprising forming the request to include at least one of a list of one or more files of media data to be retrieved, a size of the one or more files, or a desired availability time for background data transfer.

[0133] Clause 21: A device for retrieving media data, comprising: a memory configured to store media data; and one or more processors implemented in circuitry, the one or more processors configured to: send a request to a media streaming application function (AF) to retrieve media data by background data transfer; in response to the request, receive an indication of a background data transfer opportunity from the media streaming AF; and in response to the indication of the background data transfer opportunity, retrieve the media data by background data transfer; and store the retrieved media data in the memory.

[0134] Clause 22: The device of clause 21, wherein to retrieve the media data via background data transfer, the one or more processors are configured to determine an off-peak designated time window and retrieve the media data during the off-peak designated time window.

[0135] Clause 23: The device of clause 22, wherein the one or more processors are configured to determine an off-peak designated time window from data defining the off-peak designated time window included in the indication of the background data transfer opportunity.

[0136] Clause 24: To send a request to retrieve media data via background data transfer, the one or more processors are configured to execute a media session handler (MSH) configured to send a request to retrieve media data via background data transfer to a 5G media streaming downlink (5GMSd) application function (AF).

[0137] Clause 25: The device of clause 21, wherein to receive an indication of a background data transfer opportunity, the one or more processors are configured to execute a media session handler (MSH) configured to receive notification of a background data transfer opportunity.

[0138] Clause 26: The device of clause 25, wherein the MSH is further configured to send data representing the background data transfer to a media player application executed by the one or more processors, to retrieve the media data, and the media player application is configured to retrieve the media data via the background data transfer.

[0139] Clause 27: The device of clause 25, wherein to retrieve the media data via background data transfer, the MSH is configured to retrieve the media data via background data transfer, and the MSH is further configured to send data indicating that the media data has been retrieved to a media player application executed by one or more processors of the client device, and to send the retrieved data to the media player application.

[0140] Clause 28: The device of clause 21, wherein the one or more processors are further configured to formulate the request to include at least one of a list of one or more files of media data to be retrieved, a size of the one or more files, or a desired availability time for background data transfer.

[0141] Clause 29: A computer-readable storage medium having instructions stored thereon that, when executed, cause one or more processors of a client device to send a request to a media streaming application function (AF) to retrieve media data via background data transfer, and in response to the request, receive an indication of a background data transfer opportunity from the media streaming AF, and in response to the indication of the background data transfer opportunity, retrieve the media data via background data transfer, and store the retrieved media data in memory.

[0142] Clause 30: The computer-readable storage medium of clause 29, wherein the instructions for causing the processor to retrieve the media data through background data transfer include instructions for causing the processor to determine an off-peak designated time window and retrieve the media data during the off-peak designated time window.

[0143] Clause 31: The computer-readable storage medium of clause 30, wherein the instructions for causing the processor to determine the off-peak designated time window include instructions for causing the processor to determine the off-peak designated time window from data defining the off-peak designated time window that is included in the indication of the background data transfer opportunity.

[0144] Clause 32: The computer-readable storage medium of clause 29, wherein the instructions for causing the processor to send a request to retrieve media data via background data transfer include instructions for causing the processor to execute a media session handler (MSH) to send a request to retrieve media data via background data transfer to a 5G media streaming downlink (5GMSd) application function (AF).

[0145] Clause 33: The computer-readable storage medium of clause 29, wherein the instructions for causing the processor to receive an indication of a background data transfer opportunity include instructions for causing the processor to execute a media session handler (MSH) to receive notification of the background data transfer opportunity.

[0146] Clause 34: The computer-readable storage medium of clause 33, further including instructions for causing the processor to execute the MSH to send data representing the background data transfer to a media player application executed by one or more processors of the client device, wherein the instructions for causing the processor to retrieve the media data include instructions for causing the processor to execute the media player application to retrieve the media data via the background data transfer.

[0147] Clause 35: The computer-readable storage medium of clause 33, wherein the instructions for causing the processor to retrieve media data via background data transfer include instructions for causing the processor to execute the MSH to retrieve the media data via background data transfer, and further include instructions for causing the processor to execute the MSH to send data indicating that the media data has been retrieved to a media player application executed by one or more processors of the client device, and to execute the MSH to send the retrieved data to the media player application.

[0148] Clause 36: The computer-readable storage medium of clause 29, further comprising forming the request to include at least one of a list of one or more files of media data to be retrieved, a size of the one or more files, or a desired availability time for background data transfer.

[0149] Clause 37: A device for retrieving media data, comprising: means for sending a request to retrieve media data by background data transfer; means for receiving an indication of a background data transfer opportunity in response to the request; means for retrieving the media data by background data transfer in response to the indication of the background data transfer opportunity; and means for storing the retrieved media data.

[0150] Clause 38: A method for retrieving media data, comprising the steps of: sending, by one or more processors of a client device, a request to a media streaming application function (AF) to retrieve media data by background data transfer; receiving, by the one or more processors of the client device in response to the request, an indication of a background data transfer opportunity from the media streaming AF; retrieving, by the one or more processors, the media data by background data transfer in response to the indication of the background data transfer opportunity; and storing, by the one or more processors, the retrieved media data.

[0151] Clause 39: The method of clause 38, wherein retrieving the media data via background data transfer includes determining an off-peak designated time window and retrieving the media data during the off-peak designated time window.

[0152] Clause 40: The method of clause 39, wherein determining the off-peak designated time window includes determining the off-peak designated time window from data defining the off-peak designated time window included in the indication of the background data transfer opportunity.

[0153] Clause 41: Any of the methods of clauses 38 to 40, wherein the step of sending a request to retrieve media data via background data transfer includes a step of sending a request to retrieve media data via background data transfer to a 5G Media Streaming Downlink (5GMSd) Application Function (AF) by a Media Session Handler (MSH) executed by one or more processors of the client device.

[0154] Clause 42: Any of the methods of clauses 38 to 41, wherein the step of receiving an indication of a background data transfer opportunity includes a step of receiving notification of the background data transfer opportunity by a media session handler (MSH) executed by one or more processors of the client device.

[0155] Clause 43: The method of clause 42, further comprising the step of sending, by the MSH, data representative of the background data transfer to a media player application executed by one or more processors of the client device, and the step of retrieving the media data comprises the step of retrieving the media data by the media player application executed by the one or more processors of the client device via the background data transfer.

[0156] Clause 44: The method of clause 42, wherein the step of retrieving the media data by background data transfer includes a step of retrieving the media data by background data transfer by an MSH executed by one or more processors of the client device, the method further including a step of sending, by the MSH executed by the one or more processors of the client device, data indicating that the media data has been retrieved to a media player application executed by the one or more processors of the client device, and a step of sending, by the MSH executed by the one or more processors of the client device, the retrieved data to the media player application.

[0157] Clause 45: The method of any of clauses 38-44, further comprising forming the request to include at least one of a list of one or more files of media data to be retrieved, a size of the one or more files, or a desired availability time for background data transfer.

[0158] Clause 46: A device for retrieving media data, comprising: a memory configured to store media data; and one or more processors implemented in circuitry, the one or more processors configured to: send a request to a media streaming application function (AF) to retrieve media data by background data transfer; in response to the request, receive an indication of a background data transfer opportunity from the media streaming AF; and in response to the indication of the background data transfer opportunity, retrieve the media data by background data transfer; and store the retrieved media data in the memory.

[0159] Clause 47: The device of clause 46, wherein to retrieve the media data via background data transfer, the one or more processors are configured to determine an off-peak designated time window and retrieve the media data during the off-peak designated time window.

[0160] Clause 48: The device of clause 47, wherein the one or more processors are configured to determine an off-peak designated time window from data defining the off-peak designated time window included in the indication of the background data transfer opportunity.

[0161] Clause 49: To send a request to retrieve media data via background data transfer, the one or more processors are configured to execute a media session handler (MSH) configured to send a request to retrieve media data via background data transfer to a 5G media streaming downlink (5GMSd) application function (AF).

[0162] Clause 50: To receive an indication of a background data transfer opportunity, the one or more processors are configured to execute a media session handler (MSH) configured to receive notification of a background data transfer opportunity.

[0163] Clause 51: The device of clause 50, wherein the MSH is further configured to send data representing the background data transfer to a media player application executed by the one or more processors, to retrieve the media data, and the media player application is configured to retrieve the media data via the background data transfer.

[0164] Clause 52: The device of clause 50, wherein to retrieve the media data via background data transfer, the MSH is configured to retrieve the media data via background data transfer, and the MSH is further configured to send data indicating that the media data has been retrieved to a media player application executed by one or more processors of the client device, and to send the retrieved data to the media player application.

[0165] Clause 53: The device of any of clauses 38 to 52, wherein the one or more processors are further configured to form the request to include at least one of a list of one or more files of media data to be retrieved, a size of the one or more files, or a desired availability time for background data transfer.

[0166] Clause 54: A computer-readable storage medium having instructions stored thereon that, when executed, cause one or more processors of a client device to send a request to a media streaming application function (AF) to retrieve media data via background data transfer, and in response to the request, receive an indication of a background data transfer opportunity from the media streaming AF, and in response to the indication of the background data transfer opportunity, retrieve the media data via background data transfer, and store the retrieved media data in memory.

[0167] Clause 55: The computer-readable storage medium of clause 54, wherein the instructions for causing the processor to retrieve the media data through background data transfer include instructions for causing the processor to determine an off-peak designated time window and retrieve the media data during the off-peak designated time window.

[0168] Clause 56: The computer-readable storage medium of clause 55, wherein the instructions for causing the processor to determine the off-peak designated time window include instructions for causing the processor to determine the off-peak designated time window from data defining the off-peak designated time window that is included in the indication of the background data transfer opportunity.

[0169] Clause 57: The computer-readable storage medium of any of clauses 54 to 56, wherein the instructions for causing the processor to send a request to retrieve media data via background data transfer include instructions for causing the processor to execute a media session handler (MSH) to send a request to retrieve media data via background data transfer to a 5G media streaming downlink (5GMSd) application function (AF).

[0170] Clause 58: A computer-readable storage medium according to any of clauses 54 to 57, wherein the instructions for causing a processor to receive an indication of a background data transfer opportunity include instructions for causing the processor to execute a media session handler (MSH) to receive notification of the background data transfer opportunity.

[0171] Clause 59: The computer-readable storage medium of clause 58, further including instructions for causing the processor to execute the MSH to send data representing the background data transfer to a media player application executed by one or more processors of the client device, wherein the instructions for causing the processor to retrieve the media data include instructions for causing the processor to execute the media player application to retrieve the media data via the background data transfer.

[0172] Clause 60: The computer-readable storage medium of clause 58, wherein the instructions for causing the processor to retrieve media data via background data transfer include instructions for causing the processor to execute the MSH to retrieve the media data via background data transfer, and further include instructions for causing the processor to execute the MSH to send data indicating that the media data has been retrieved to a media player application executed by one or more processors of the client device, and to execute the MSH to send the retrieved data to the media player application.

[0173] Clause 61: The computer-readable storage medium of any of clauses 54-60, further comprising forming the request to include at least one of a list of one or more files of media data to be retrieved, a size of the one or more files, or a desired availability time for background data transfer.

[0174] 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 the transfer of a computer program from one place to another, for example according to a communication protocol. As such, a computer-readable medium may generally correspond to (1) a non-transitory tangible computer-readable storage medium, 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.

[0175] 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 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. Disk and disc, as used herein, include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically and discs reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer readable media.

[0176] The instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic 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. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and / or software modules configured for encoding and decoding, or may be incorporated into a composite codec. Also, the techniques may be fully implemented in one or more circuits or logic elements.

[0177] 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). Various components, modules, or units are described in the present disclosure to highlight functional aspects of devices configured to implement the disclosed techniques, but they 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 as described above, along with suitable software and / or firmware.

[0178] Various examples have been described. These and other examples are within the scope of the following claims. [Explanation of symbols]

[0179] 10. System 20 Content Preparation Devices 22 Audio Sources 24 Video Sources 26 Audio Encoder 28 Video Encoder 30 Encapsulation Units 32 Output Interface 40 client devices 42 Audio Output 44 Video Output 46 Audio Decoder 48 Video Decoder 50 Decapsulation Units 52 Removal unit 54 Network Interface 60 Server Devices 62 Storage medium 64 Multimedia Content 66 Manifest File 68 expression 68A~68N expression 70 Request Processing Unit 72 Network Interface 74 Network 100 Media Session Handler (MSH) units 102 Server unit, proxy server unit 104 Cache 106 Receiving unit 112 Media Applications 120 Multimedia Content 122 Media Presentation Description (MPD) 124 Expression 124A Expression 124N expression 126 Header Data 128 segments 128A~128N Segments 130 Header Data 132 segments 132A~132N Segment 150 Video files 152 File Type (FTYP) Box 154 Movie (MOOV) Box 156 Movie Header (MVHD) Box 158 TRAK BOX 160 Movie Extension (MVEX) Box 162 Segment Index (sidx) Box 164 Movie Fragment (MOOF) Box 166 Movie Fragment Random Access (MFRA) Box 180 System 182 Content Service Providers 184 Content Delivery Network 190 Mobile Network Operators (MNOs) 192 Cache Management Unit 194 Access Network Unit 204 3GPP standard units 206 UE-based cache and management unit 208 Connectivity Unit

Claims

1. 1. A method for retrieving media data, comprising: receiving, from a media player application executed by one or more processors of a client device, a first request to retrieve media data from an application provider by a media session handler (MSH) executed by the one or more processors of the client device, the first request indicating retrieval of the media data via background data transfer; In response to the first request to retrieve the media data, sending, by the MSH of the client device, a second request to a 5G Media Streaming Downlink (5GMSd) Application Function (AF) to retrieve media data by background data transfer; receiving, by the MSH of the client device in response to the second request, an indication of a background data transfer opportunity from the 5G media streaming downlink AF; retrieving, by the one or more processors of the client device in response to the indication of the background data transfer opportunity, the media data from an application provider via the background data transfer; and storing, by the one or more processors, the retrieved media data.

2. The step of retrieving the media data by the background data transfer includes: determining an off-peak designated time window; and retrieving the media data during the off-peak designated time window.

3. 3. The method of claim 2, wherein determining the off-peak designated time window comprises determining the off-peak designated time window from data defining the off-peak designated time window included in the indication of the background data transfer opportunity.

4. 2. The method of claim 1, wherein receiving the indication of the background data transfer opportunity comprises receiving notification of the background data transfer opportunity by the media session handler (MSH) executed by the one or more processors of the client device.

5. 5. The method of claim 4, further comprising the step of sending, by the MSH, data representing the background data transfer to a media player application executed by the one or more processors of the client device, and wherein retrieving the media data comprises retrieving the media data via the background data transfer by the media player application executed by the one or more processors of the client device.

6. The step of retrieving the media data via background data transfer includes a step of retrieving the media data via background data transfer by the MSH executed by the one or more processors of the client device, the method comprising: sending data indicating that the media data has been retrieved by the MSH executed by the one or more processors of the client device to a media player application executed by the one or more processors of the client device; and sending, by the MSH executed by the one or more processors of the client device, the retrieved data to the media player application.

7. 2. The method of claim 1, further comprising forming the request to include at least one of a list of one or more files of the media data to be retrieved, a size of the one or more files, or a desired availability time for the background data transfer.

8. 1. A device for retrieving media data, comprising: a memory configured to store the media data; and one or more processors implemented in circuitry, the one or more processors comprising: receiving, from a media player application executed by the one or more processors, a first request at a media session handler (MSH) executed by the one or more processors to retrieve media data from an application provider, the first request indicating retrieval of the media data via background data transfer; in response to the first request to retrieve the media data of a media presentation, sending, by the MSH, a second request to a 5G Media Streaming Downlink (5GSMd) Application Function (AF) to retrieve media data by background data transfer; receiving an indication of a background data transfer opportunity from the 5G media streaming downlink AF in response to the second request; retrieving the media data from an application provider via the background data transfer in response to the indication of the background data transfer opportunity; and storing the retrieved media data in the memory.

9. To retrieve the media data via the background data transfer, the one or more processors: determining an off-peak designated time window; and retrieving the media data during the off-peak designated time window.

10. 10. The device of claim 9, wherein the one or more processors are configured to determine the off-peak designated time window from data defining the off-peak designated time window included in the indication of the background data transfer opportunity.

11. 10. The device of claim 8, wherein to receive the indication of the background data transfer opportunity, the one or more processors are configured to execute a media session handler (MSH) configured to receive notification of the background data transfer opportunity.

12. 12. The device of claim 11, wherein the MSH is further configured to send data representing the background data transfer to a media player application executed by the one or more processors, wherein the media player application is configured to retrieve the media data via the background data transfer to retrieve the media data.

13. To retrieve the media data via the background data transfer, the MSH is configured to retrieve the media data via the background data transfer, the MSH comprising: sending data to a media player application executed by the one or more processors of a client device indicating that the media data has been retrieved; and sending the retrieved data to the media player application.

14. 10. The device of claim 8, wherein the one or more processors are further configured to form the request to include at least one of a list of one or more files of the media data to be retrieved, a size of the one or more files, or a desired availability time for the background data transfer.

15. A computer-readable storage medium having stored thereon instructions that, when executed, cause one or more processors of a client device to: receiving, from a media player application executed by the one or more processors, a first request at a media session handler (MSH) executed by the one or more processors to retrieve media data from an application provider, the first request indicating retrieval of the media data via background data transfer; In response to the first request to retrieve the media data of a media presentation, sending, by the MSH, a second request to a 5G Media Streaming Downlink (5GMSd) Application Function (AF) to retrieve media data by background data transfer; receiving an indication of a background data transfer opportunity from the 5G media streaming downlink AF in response to the second request; retrieving the media data from an application provider via the background data transfer in response to the indication of the background data transfer opportunity; and storing the retrieved media data in a memory.

Images