Patent Description:
Session-based DASH operation is an important approach to customize the MPD per session and possibly per client. Current design allows one or more SBD documents to be applied to uniform resource locator (URL) parts or queries of various requests. However, current design fails to allow SBD documents to be applied to queries that request SBD documents. That is, current design does not allow customization of the SBD document URL that may be used in an SBD descriptor. There is a need for being able to customize SBD document URLs in a same manifest.

<CIT> discloses a method comprises receiving a request for a Dynamic Adaptive Streaming over Hypertext Transfer Protocol (DASH) media presentation description (MPD), and transmitting the MPD. In particular the MPD comprises a mechanism for specifying a client's behavior, and the mechanism conditions the client's ability to download content on the client's ability to support a feature.

The present invention is as defined by the appended independent claims, which find support in <FIG> and <FIG> and their corresponding parts of the description. The remaining embodiments described in the description are to be construed within the limitations of the independent claims.

Features, advantages, and significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements.

The proposed features discussed below may be used separately or combined in any order. Further, the embodiments may be implemented by processing circuitry (e.g., one or more processors or one or more integrated circuits). In one example, the one or more processors execute a program that is stored in a non-transitory computer-readable medium.

<FIG> illustrates a simplified block diagram of a communication system <NUM> according to an embodiment of the present disclosure. The communication system <NUM> may include at least two terminals <NUM> and <NUM> interconnected via a network <NUM>. For unidirectional transmission of data, a first terminal <NUM> may code video data at a local location for transmission to the other terminal <NUM> via the network <NUM>. The second terminal <NUM> may receive the coded video data of the other terminal from the network <NUM>, decode the coded data and display the recovered video data.

<FIG> illustrates a second pair of terminals <NUM> and <NUM> provided to support bidirectional transmission of coded video that may occur, for example, during videoconferencing. For bidirectional transmission of data, each terminal <NUM> and <NUM> may code video data captured at a local location for transmission to the other terminal via the network <NUM>. Each terminal <NUM> and <NUM> also may receive the coded video data transmitted by the other terminal, may decode the coded data and may display the recovered video data at a local display device.

In <FIG>, the terminals <NUM>, <NUM>, <NUM> and <NUM> may be illustrated as servers, personal computers and smart phones but the principles of the present disclosure are not so limited. The network <NUM> represents any number of networks that convey coded video data among the terminals <NUM>, <NUM>, <NUM> and <NUM>, including for example wireline and/or wireless communication networks. The communication network <NUM> may exchange data in circuit-switched and/or packet-switched channels. For the purposes of the present discussion, the architecture and topology of the network <NUM> may be immaterial to the operation of the present disclosure unless explained herein below.

<FIG> illustrates, as an example for an application for the disclosed subject matter, the placement of a video encoder and decoder in a streaming environment. The disclosed subject matter may be equally applicable to other video enabled applications, including, for example, video conferencing, digital TV, storing of compressed video on digital media including CD, DVD, memory stick and the like, and so on.

A streaming system may include a capture subsystem <NUM>, that may include a video source <NUM>, for example a digital camera, creating, for example, an uncompressed video sample stream <NUM>. That sample stream <NUM> may be emphasized as a high data volume when compared to encoded video bitstreams and may be processed by an encoder <NUM> coupled to the camera <NUM>. The encoder <NUM> may include hardware, software, or a combination thereof to enable or implement aspects of the disclosed subject matter as described in more detail below. The encoded video bitstream <NUM>, which may be emphasized as a lower data volume when compared to the sample stream, may be stored on a streaming server <NUM> for future use. One or more streaming clients <NUM> and <NUM> may access the streaming server <NUM> to retrieve copies <NUM> and <NUM> of the encoded video bitstream <NUM>. A client <NUM> may include a video decoder <NUM> which decodes the incoming copy of the encoded video bitstream <NUM> and creates an outgoing video sample stream <NUM> that may be rendered on a display <NUM> or other rendering device (not depicted). In some streaming systems, the video bitstreams <NUM>, <NUM> and <NUM> may be encoded according to certain video coding/compression standards. Examples of those standards are noted above and described further herein.

<FIG> may be a functional block diagram of a video decoder <NUM> according to an embodiment of the present invention.

A receiver <NUM> may receive one or more codec video sequences to be decoded by the decoder <NUM>; in the same or another embodiment, one coded video sequence at a time, where the decoding of each coded video sequence is independent from other coded video sequences. The coded video sequence may be received from a channel <NUM>, which may be a hardware/software link to a storage device which stores the encoded video data. The receiver <NUM> may receive the encoded video data with other data, for example, coded audio data and/or ancillary data streams that may be forwarded to their respective using entities (not depicted). The receiver <NUM> may separate the coded video sequence from the other data. To combat network jitter, a buffer memory <NUM> may be coupled in between receiver <NUM> and entropy decoder / parser <NUM> ("parser" henceforth). When receiver <NUM> is receiving data from a store/forward device of sufficient bandwidth and controllability, or from an isosychronous network, the buffer <NUM> may not be needed, or may be small. For use on best effort packet networks such as the Internet, the buffer <NUM> may be required, may be comparatively large and may advantageously of adaptive size.

The video decoder <NUM> may include a parser <NUM> to reconstruct symbols <NUM> from the entropy coded video sequence. Categories of those symbols include information used to manage operation of the decoder <NUM>, and potentially information to control a rendering device such as a display <NUM> that is not an integral part of the decoder but may be coupled to it. The control information for the rendering device(s) may be in the form of Supplementary Enhancement Information (SEI messages) or Video Usability Information parameter set fragments (not depicted). The parser <NUM> may parse / entropy-decode the coded video sequence received. The coding of the coded video sequence may be in accordance with a video coding technology or standard, and may follow principles well known to a person skilled in the art, including variable length coding, Huffman coding, arithmetic coding with or without context sensitivity, and so forth. The parser <NUM> may extract from the coded video sequence, a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder, based upon at least one parameters corresponding to the group. Subgroups may include Groups of Pictures (GOPs), pictures, tiles, slices, macroblocks, Coding Units (CUs), blocks, Transform Units (TUs), Prediction Units (PUs) and so forth. The entropy decoder / parser may also extract from the coded video sequence information such as transform coefficients, quantizer parameter values, motion vectors, and so forth.

The parser <NUM> may perform entropy decoding / parsing operation on the video sequence received from the buffer <NUM>, so to create symbols <NUM>. The parser <NUM> may receive encoded data, and selectively decode particular symbols <NUM>. Further, the parser <NUM> may determine whether the particular symbols <NUM> are to be provided to a Motion Compensation Prediction unit <NUM>, a scaler / inverse transform unit <NUM>, an Intra Prediction Unit <NUM>, or a loop filter <NUM>.

Reconstruction of the symbols <NUM> may involve multiple different units depending on the type of the coded video picture or parts thereof (such as: inter and intra picture, inter and intra block), and other factors. Which units are involved, and how, may be controlled by the subgroup control information that was parsed from the coded video sequence by the parser <NUM>. The flow of such subgroup control information between the parser <NUM> and the multiple units below is not depicted for clarity.

Beyond the functional blocks already mentioned, decoder <NUM> may be conceptually subdivided into a number of functional units as described below. In a practical implementation operating under commercial constraints, many of these units interact closely with each other and may, at least partly, be integrated into each other.

A first unit is the scaler / inverse transform unit <NUM>. The scaler / inverse transform unit <NUM> receives quantized transform coefficient as well as control information, including which transform to use, block size, quantization factor, and quantization scaling matrices, etc. as symbol <NUM> from the parser <NUM>. It may output blocks comprising sample values that may be input into aggregator <NUM>.

In some cases, the output samples of the scaler / inverse transform <NUM> may pertain to an intra coded block; that is: a block that is not using predictive information from previously reconstructed pictures, but may use predictive information from previously reconstructed parts of the current picture. Such predictive information may be provided by an intra picture prediction unit <NUM>. In some cases, the intra picture prediction unit <NUM> generates a block of the same size and shape of the block under reconstruction, using surrounding already reconstructed information fetched from the current (partly reconstructed) picture <NUM>. The aggregator <NUM>, in some cases, adds, on a per sample basis, the prediction information the intra prediction unit <NUM> has generated to the output sample information as provided by the scaler / inverse transform unit <NUM>.

In other cases, the output samples of the scaler / inverse transform unit <NUM> may pertain to an inter coded, and potentially motion compensated block. In such a case, a Motion Compensation Prediction unit <NUM> may access reference picture memory <NUM> to fetch samples used for prediction. After motion compensating the fetched samples in accordance with the symbols <NUM> pertaining to the block, these samples may be added by the aggregator <NUM> to the output of the scaler / inverse transform unit (in this case called the residual samples or residual signal) so to generate output sample information. The addresses within the reference picture memory form where the motion compensation unit fetches prediction samples may be controlled by motion vectors, available to the motion compensation unit in the form of symbols <NUM> that may have, for example X, Y, and reference picture components. Motion compensation also may include interpolation of sample values as fetched from the reference picture memory when sub-sample exact motion vectors are in use, motion vector prediction mechanisms, and so forth.

The output samples of the aggregator <NUM> may be subject to various loop filtering techniques in the loop filter unit <NUM>. Video compression technologies may include in-loop filter technologies that are controlled by parameters included in the coded video bitstream and made available to the loop filter unit <NUM> as symbols <NUM> from the parser <NUM>, but may also be responsive to meta-information obtained during the decoding of previous (in decoding order) parts of the coded picture or coded video sequence, as well as responsive to previously reconstructed and loop-filtered sample values.

The output of the loop filter unit <NUM> may be a sample stream that may be output to the render device <NUM> as well as stored in the reference picture memory <NUM> for use in future inter-picture prediction.

Certain coded pictures, once fully reconstructed, may be used as reference pictures for future prediction. Once a coded picture is fully reconstructed and the coded picture has been identified as a reference picture (by, for example, parser <NUM>), the current reference picture <NUM> may become part of the reference picture buffer <NUM>, and a fresh current picture memory may be reallocated before commencing the reconstruction of the following coded picture.

The video decoder <NUM> may perform decoding operations according to a predetermined video compression technology that may be documented in a standard, such as ITU-T Rec. The coded video sequence may conform to a syntax specified by the video compression technology or standard being used, in the sense that it adheres to the syntax of the video compression technology or standard, as specified in the video compression technology document or standard and specifically in the profiles document therein. Also necessary for compliance may be that the complexity of the coded video sequence is within bounds as defined by the level of the video compression technology or standard. Limits set by levels may, in some cases, be further restricted through Hypothetical Reference Decoder (HRD) specifications and metadata for HRD buffer management signaled in the coded video sequence.

In an embodiment, the receiver <NUM> may receive additional (redundant) data with the encoded video. The additional data may be used by the video decoder <NUM> to properly decode the data and/or to more accurately reconstruct the original video data. Additional data may be in the form of, for example, temporal, spatial, or signal-to-noise ratio (SNR) enhancement layers, redundant slices, redundant pictures, forward error correction codes, and so on.

<FIG> may be a functional block diagram of a video encoder <NUM> according to an embodiment of the present disclosure.

The encoder <NUM> may receive video samples from a video source <NUM> (that is not part of the encoder) that may capture video image(s) to be coded by the encoder <NUM>.

The video source <NUM> may provide the source video sequence to be coded by the encoder (<NUM>) in the form of a digital video sample stream that may be of any suitable bit depth (for example: <NUM> bit, <NUM> bit, <NUM> bit,. <NUM> Y CrCB, RGB,. ) and any suitable sampling structure (for example Y CrCb <NUM>:<NUM>:<NUM>, Y CrCb <NUM>:<NUM>:<NUM>). In a media serving system, the video source <NUM> may be a storage device storing previously prepared video. In a videoconferencing system, the video source <NUM> may be a camera that captures local image information as a video sequence. The pictures themselves may be organized as a spatial array of pixels, wherein each pixel may include one or more samples depending on the sampling structure, color space, etc. in use. A person skilled in the art may readily understand the relationship between pixels and samples.

According to an embodiment, the encoder <NUM> may code and compress the pictures of the source video sequence into a coded video sequence <NUM> in real time or under any other time constraints as required by the application. Enforcing appropriate coding speed is one function of Controller <NUM>. Controller controls other functional units as described below and is functionally coupled to these units. Parameters set by controller may include rate control related parameters (picture skip, quantizer, lambda value of rate-distortion optimization techniques. A person skilled in the art may readily identify other functions of controller <NUM> as they may pertain to video encoder <NUM> optimized for a certain system design.

Some video encoders operate in what a person skilled in the art readily recognizes as a "coding loop. " As an oversimplified description, a coding loop may consist of the encoding part of an encoder <NUM> ("source coder" henceforth) (responsible for creating symbols based on an input picture to be coded, and a reference picture(s)), and a (local) decoder <NUM> embedded in the encoder <NUM> that reconstructs the symbols to create the sample data that a (remote) decoder also would create (as any compression between symbols and coded video bitstream is lossless in the video compression technologies considered in the disclosed subject matter). That reconstructed sample stream is input to the reference picture memory <NUM>. As the decoding of a symbol stream leads to bit-exact results independent of decoder location (local or remote), the reference picture buffer content is also bit exact between local encoder and remote encoder. This fundamental principle of reference picture synchronicity (and resulting drift, if synchronicity cannot be maintained, for example because of channel errors) is well known to a person skilled in the art.

The operation of the "local" decoder <NUM> may be the same as of a "remote" decoder <NUM>, which has already been described in detail above in conjunction with <FIG>. Briefly referring also to <FIG>, however, as symbols are available and en/decoding of symbols to a coded video sequence by entropy coder <NUM> and parser <NUM> may be lossless, the entropy decoding parts of decoder <NUM>, including channel <NUM>, receiver <NUM>, buffer <NUM>, and parser <NUM> may not be fully implemented in local decoder <NUM>.

An observation that may be made at this point is that any decoder technology except the parsing/entropy decoding that is present in a decoder also necessarily needs to be present, in substantially identical functional form, in a corresponding encoder. The description of encoder technologies may be abbreviated as they are the inverse of the comprehensively described decoder technologies.

As part of its operation, the source coder <NUM> may perform motion compensated predictive coding, which codes an input frame predictively with reference to one or more previously-coded frames from the video sequence that were designated as "reference frames. " In this manner, the coding engine <NUM> codes differences between pixel blocks of an input frame and pixel blocks of reference frame(s) that may be selected as prediction reference(s) to the input frame.

The local video decoder <NUM> may decode coded video data of frames that may be designated as reference frames, based on symbols created by the source coder <NUM>. Operations of the coding engine <NUM> may advantageously be lossy processes. When the coded video data may be decoded at a video decoder (not shown in <FIG>), the reconstructed video sequence typically may be a replica of the source video sequence with some errors. The local video decoder <NUM> replicates decoding processes that may be performed by the video decoder on reference frames and may cause reconstructed reference frames to be stored in the reference picture cache <NUM>. In this manner, the encoder <NUM> may store copies of reconstructed reference frames locally that have common content as the reconstructed reference frames that will be obtained by a far-end video decoder (absent transmission errors).

The predictor <NUM> may perform prediction searches for the coding engine <NUM>. That is, for a new frame to be coded, the predictor <NUM> may search the reference picture memory <NUM> for sample data (as candidate reference pixel blocks) or certain metadata such as reference picture motion vectors, block shapes, and so on, that may serve as an appropriate prediction reference for the new pictures. The predictor <NUM> may operate on a sample block-by-pixel block basis to find appropriate prediction references. In some cases, as determined by search results obtained by the predictor <NUM>, an input picture may have prediction references drawn from multiple reference pictures stored in the reference picture memory <NUM>.

The controller <NUM> may manage coding operations of the video coder <NUM>, including, for example, setting of parameters and subgroup parameters used for encoding the video data.

Output of all aforementioned functional units may be subjected to entropy coding in the entropy coder <NUM>. The entropy coder translates the symbols as generated by the various functional units into a coded video sequence, by loss-less compressing the symbols according to technologies known to a person skilled in the art as, for example Huffman coding, variable length coding, arithmetic coding, and so forth.

The transmitter <NUM> may buffer the coded video sequence(s) as created by the entropy coder <NUM> to prepare it for transmission via a communication channel <NUM>, which may be a hardware/software link to a storage device which would store the encoded video data. The transmitter <NUM> may merge coded video data from the video coder <NUM> with other data to be transmitted, for example, coded audio data and/or ancillary data streams (sources not shown).

The controller <NUM> may manage operation of the encoder <NUM>. During coding, the controller <NUM> may assign to each coded picture a certain coded picture type, which may affect the coding techniques that may be applied to the respective picture. For example, pictures often may be assigned as one of the following frame types:.

Similarly, multiple-predictive pictures may use more than two reference pictures and associated metadata for the reconstruction of a single block.

Source pictures commonly may be subdivided spatially into a plurality of sample blocks (for example, blocks of <NUM> x <NUM>, <NUM> x <NUM>, <NUM> x <NUM>, or <NUM> x <NUM> samples each) and coded on a block-by-block basis. Pixel blocks of P pictures may be coded non-predictively, via spatial prediction or via temporal prediction with reference to one previously coded reference pictures. Blocks of B pictures may be coded non-predictively, via spatial prediction or via temporal prediction with reference to one or two previously coded reference pictures.

The video coder <NUM> may perform coding operations according to a predetermined video coding technology or standard, such as ITU-T Rec. In its operation, the video coder <NUM> may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancies in the input video sequence.

In an embodiment, the transmitter <NUM> may transmit additional data with the encoded video. The source coder <NUM> may include such data as part of the coded video sequence. Additional data may comprise temporal/spatial/SNR enhancement layers, other forms of redundant data such as redundant pictures and slices, Supplementary Enhancement Information (SEI) messages, Visual Usability Information (VUI) parameter set fragments, and so on.

<FIG> illustrates a simplified block diagram of an exemplary architecture <NUM> for session-based DASH operations, according to embodiments.

Streaming media or video content may originate at origin <NUM> and be provided to a content delivery network (CDN) <NUM> which may provide MPD/segments to a DASH access client <NUM>. A session client <NUM> may be controlled to request a value, by the DASH access client <NUM> value may be provided to the DASH Access Client <NUM> from the session client <NUM>. As an example, a value such as by getValue (key, time) may be requested by the DASH access client <NUM> value may be provided to the DASH Access Client <NUM> from the session client <NUM>. The session client <NUM> may provide the value to the DASH access client <NUM> in conjunction with control from the session controllers <NUM> and <NUM> and their respective SBD data, such as SBD[<NUM>] n SBD [<NUM>] as in the example embodiments of <FIG> and <FIG>.

As an example, there is introduced an element in the SBD descriptor for URL templating, and, more specifically according to embodiments, SBD operations (e.g., query or URL customization) should be such that a session client <NUM> may apply its processing to the segment URL generated by the DASH access client <NUM>, after retrieving enough information from the MPD in the DASH access client <NUM>. However, the SBD operations shall not intercept the DASH access client <NUM> operation in example embodiments, and, while example implementations may combine MPD and SBD processing, other embodiments hold that such features may be done consequently. In this light, an advantage thereof may be that the SBD operation may be added to any DASH access client as an application rather than integrated with the DASH client logic. As such, embodiments may change a URL to a new value may be added.

According to embodiments of the present disclosure, the session-based DASH operation standards related to SBD (e.g., ISO/IEC <NUM>-<NUM>) may be extended to allow customization of SBD document URLs or SBD URLs. That is, SBD standard that allows for multiple documents to be applied to URLs or queries of various requests, may be extended to request and apply other SBD URL requests.

An MPD element may have one or more SBD descriptors. However, as stated above, while URLS and requests may be modified using SBD descriptors, SBD document URLs for SBD descriptors may not be modified using available standards. Thus, to solve this technical problem and provide more flexibility in customization, embodiments of the present disclosure add a SBD descriptor called pre-session-description (PreSBD), and PreSBD may be used for customizing other SBD URL requests.

A PreSBD descriptor has have the same syntax as that of "regular" SBD descriptors, with a value of "sbd" assigned to its @urlclass attribute. The @urlclass attribute specifies which HPPT GET requests are subjected to SBD processing. Since @urlclass attribute specifies which HPPT GET requests are subjected to SBD processing, a value of "sbd" indicates that the PreSBD descriptor information includes a type of hypertext transfer protocol (HTTP) get request that is subject to customized SBD document URL generation.

The value associated with the @urlclass may be a list of concatenated list of allowable keys. For a PreSBD descriptor, the @urlclass attribute value may be a concatenated list including at least "sbd". Other possible values that may be included in the concatenated list are "segment," "xlink," "mpd," "callback," "chaining," and "fallback.

Attributes of a PreSBD descriptor may not be limited to the @urlclass attribute. Table <NUM>, illustrates an example of MPD EssentialProperty Descriptor attributes for session-based DASH processing using a PreSBD descriptor.

According to embodiments of the present disclosure, including PreSBD Descriptor in MPD processing may have one or more restrictions.

While an MPD may have one or more PreSBD descriptors, according to some embodiments, a MPD element may only have at most one PreSBD descriptor. In some embodiments, the MPD may have more than one PreSBD, no more than one PreSBD descriptor information may be present in one media presentation description (MPD) element. In an embodiment, lower-level elements of an MPD element having a PreSBD may not have a PreSBD Descriptor. Accordingly, the PreSBD descriptor information may be absent in a lower-level element of a media presentation description (MPD) element with the PreSBD descriptor information. Therefore, according to some embodiments, a MPD element may have at most one PreSBD descriptor.

According to embodiments of the present disclosure, for a MPD element, the PreSBD descriptor may be processed prior to any of the "regular" SBD descriptors in that MPD element being processed. This disclosure is directed to customizing SBD document URLs using other SBD URLs. To enable such a hierarchical structure and enable "regular" SBD descriptors to customize their SBD document URLs, the PreSBD descriptor may be processed before any other descriptors in a MPD element. Therefore, a PreSBD client may be instantiated before instantiation of any other SBD clients of the MPD element.

According to embodiments of the present disclosure, the SBD document URL of any SBD descriptor may be sent to the corresponding PreSBD client for customization before a request for the SBD document is made. In some embodiments, the SBD document URL of any SBD descriptor may be sent to the corresponding PreSBD client for customization prior to a request for a SBD document is made and a respective SBD client generates and/or modifies a segment URL for the segment of the video content. Therefore, a respective SBD document URL associated with the plurality of SBD descriptors in the same MPD element for the session may be transmitted to the PreSBD client prior to processing a respective request for the segment of the video content.

Referring now to <FIG> and <FIG>, <FIG> is a flow chart illustrating a process <NUM> for session-based description URL customization; and <FIG> is an exemplary illustration of call flow <NUM> for session-based description URL customization, according to embodiments.

As shown in <FIG>, at operation <NUM>, a pre-session-based description (PreSBD) information of a session is obtained instructing a PreSBD client to generate customized session-based description (SBD) document uniform resource locator (URL) for a plurality of SBD descriptors of the session. A DASH client, such as DASH access client <NUM>, parses the MPD such as from the CDN <NUM>, and obtains a pre-session-based description (PreSBD) information of a session instructing a PreSBD client to generate customized session-based description (SBD) document uniform resource locator (URL) for a plurality of SBD descriptors of the session.

At operation <NUM>, the PreSBD client is instantiated and PreSBD descriptor information is a passed to the PreSBD client. The DASH client, such as DASH client <NUM> performs finding of the PreSBD descriptor which instantiates the PreSBD client, such as PreSBD client <NUM>. The PreSBD descriptor information includes a @urlclass attribute with a value "sbd," which may be used by the DASH client <NUM>. The PreSBD descriptor information includes a type of hypertext transfer protocol (HTTP) GET request that is subject to customized SBD document URL generation.

The PreSBD client is instantiated prior to launching the first SBD client or launching any non-PreSBD client in the MPD element. Referring to <FIG>, at operation <NUM> of the call flow <NUM>, the DASH client <NUM> performs finding of the PreSBD descriptor which instantiates the PreSBD client, such as PreSBD client <NUM>, and passes on the PreSBD descriptor to the PreSBD client <NUM>.

At operation <NUM>, of process <NUM>, generation of a customized SBD document URL associated with a first SBD descriptor from the plurality of SBD descriptors of the session is controlled. At operation <NUM> of the call flow <NUM>, the DASH client <NUM> controls the generation of a customized SBD document URL associated with a first SBD descriptor, such as, SBD1 descriptor. At operation <NUM>, the DASH client <NUM> receives the customized SBD document URL associated with the first SBD descriptor SBD <NUM>. The PreSBD client <NUM> generates the customized SBD document under the direction of DASH client <NUM>.

According to embodiments, the plurality of SBD descriptors of the session for whom the customized SBD document URL may be generated may include SBD descriptors in a same media presentation description (MPD) element with the PreSBD descriptor information or the SBD descriptors in a lower-level MPD element than the MPD element with the PreSBD descriptor information. As stated above, the PreSBD process may have some restrictions including no more than one PreSBD descriptor information may be present in a media presentation description (MPD) element and the PreSBD descriptor information may be absent in a lower-level element of a media presentation description (MPD) element with the PreSBD descriptor information.

Since the PreSBD descriptor is needed to instantiate the PreSBD client and generate the customized SBD document URL associated with a SBD descriptor from the plurality of SBD descriptors of the session, The PreSBD client is instantiated prior to launching the first SBD client or launching any non-PreSBD client. Similarly, respective SBD document URL associated with the plurality of SBD descriptors of the session are transmitted to the PreSBD client prior to processing a respective request for the segment of the video content.

At operation <NUM>, of process <NUM>, first SBD client is launched based on the customized SBD document URL and the first SBD descriptor is passed to the first SBD client. At operation <NUM>, of call flow <NUM>, the DASH client <NUM> launches SBD1 client <NUM> based on the customized SBD document URL associated with the first SBD descriptor SBD1 received at operation <NUM>.

At operation <NUM>, of process <NUM>, generation of a segment uniform resource locator (URL) is controlled based on the first SBD descriptor and the customized SBD document URL, and a request for a segment of the video content by at least modifying the segment URL is processed. At operations <NUM> and <NUM>, the DASH client <NUM> controls the generation of a segment uniform resource locator (URL) based on the PreSBD descriptor and SBD <NUM> descriptor. The SBD1 client <NUM> generates a segment uniform resource locator (URL) under the direction of DASH client <NUM>.

Further, at operation <NUM>, a request for a segment of the video content by at least modifying the segment URL is processed. Respective SBD document URLs associated with the plurality of SBD descriptors of the session are transmitted to the PreSBD client prior to processing a respective request for the segment of the video content.

At operation <NUM>, the segment of the video content based on the modified segment URL is provided. The DASH client <NUM>, at operation <NUM> of call flow <NUM> provides the segment of the video content based on the modified segment URL received from SBD1 Client <NUM>. In some embodiments, the DASH client <NUM>, at operation <NUM> of call flow <NUM> may process a request for a segment of the video content by at least modifying the segment URL received from SBD1 Client <NUM>, and provide the segment of the video content based on the modified segment URL.

The techniques described above, may be implemented as computer software using computer-readable instructions and physically stored in one or more computer-readable media or by a specifically configured one or more hardware processors. For example, <FIG> shows a computer system <NUM> suitable for implementing certain embodiments of the disclosed subject matter.

The computer software may be coded using any suitable machine code or computer language, that may be subject to assembly, compilation, linking, or like mechanisms to create code comprising instructions that may be executed directly, or through interpretation, micro-code execution, and the like, by computer central processing units (CPUs), Graphics Processing Units (GPUs), and the like.

The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablet computers, servers, smartphones, gaming devices, internet of things devices, and the like.

The components shown in <FIG> for computer system <NUM> are exemplary in nature and are not intended to suggest any limitation as to the scope of use or functionality of the computer software implementing embodiments of the present disclosure. Neither should the configuration of components be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary embodiment of a computer system <NUM>.

The human interface devices may also be used to capture certain media not necessarily directly related to conscious input by a human, such as audio (such as: speech, music, ambient sound), images (such as: scanned images, photographic images obtain from a still image camera), video (such as two-dimensional video, three-dimensional video including stereoscopic video).

Input human interface devices may include one or more of (only one of each depicted): keyboard <NUM>, mouse <NUM>, trackpad <NUM>, touch screen <NUM>, joystick <NUM>, microphone <NUM>, scanner <NUM>, camera <NUM>.

Computer system <NUM> may also include certain human interface output devices. Such human interface output devices may include tactile output devices (for example tactile feedback by the touch-screen <NUM>, or joystick <NUM>, but there may also be tactile feedback devices that do not serve as input devices), audio output devices (such as: speakers <NUM>, headphones (not depicted)), visual output devices (such as screens <NUM> to include CRT screens, LCD screens, plasma screens, OLED screens, each with or without touch-screen input capability, each with or without tactile feedback capability-some of which may be capable to output two dimensional visual output or more than three dimensional output through means such as stereographic output; virtual-reality glasses (not depicted), holographic displays and smoke tanks (not depicted)), and printers (not depicted).

Computer system <NUM> may also include human accessible storage devices and their associated media such as optical media including CD/DVD ROM/RW <NUM> with CD/DVD <NUM> or the like media, thumb-drive <NUM>, removable hard drive or solid state drive <NUM>, legacy magnetic media such as tape and floppy disc (not depicted), specialized ROM/ASIC/PLD based devices such as security dongles (not depicted), and the like.

Computer system <NUM> may also include interface <NUM> to one or more communication networks <NUM>. Networks <NUM> may for example be wireless, wireline, optical. Networks <NUM> may further be local, wide-area, metropolitan, vehicular and industrial, real-time, delay-tolerant, and so on. Examples of networks <NUM> include local area networks such as Ethernet, wireless LANs, cellular networks to include GSM, <NUM>, <NUM>, <NUM>, LTE and the like, TV wireline or wireless wide area digital networks to include cable TV, satellite TV, and terrestrial broadcast TV, vehicular and industrial to include CANBus, and so forth. Certain networks <NUM> commonly require external network interface adapters that attached to certain general-purpose data ports or peripheral buses (<NUM> and <NUM>) (such as, for example USB ports of the computer system <NUM>; others are commonly integrated into the core of the computer system <NUM> by attachment to a system bus as described below (for example Ethernet interface into a PC computer system or cellular network interface into a smartphone computer system). Using any of these networks <NUM>, computer system <NUM> may communicate with other entities. Such communication may be uni-directional, receive only (for example, broadcast TV), uni-directional send-only (for example CANbusto certain CANbus devices), or bi-directional, for example to other computer systems using local or wide area digital networks. Certain protocols and protocol stacks may be used on each of those networks and network interfaces as described above.

Aforementioned human interface devices, human-accessible storage devices, and network interfaces may be attached to a core <NUM> of the computer system <NUM>.

The core <NUM> may include one or more Central Processing Units (CPU) <NUM>, Graphics Processing Units (GPU) <NUM>, a graphics adapter <NUM>, specialized programmable processing units in the form of Field Programmable Gate Areas (FPGA) <NUM>, hardware accelerators for certain tasks <NUM>, and so forth. These devices, along with Read-only memory (ROM) <NUM>, Random-access memory <NUM>, internal mass storage such as internal non-user accessible hard drives, SSDs, and the like <NUM>, may be connected through a system bus <NUM>. In some computer systems, the system bus <NUM> may be accessible in the form of one or more physical plugs to enable extensions by additional CPUs, GPU, and the like. The peripheral devices may be attached either directly to the core's system bus <NUM>, or through a peripheral bus <NUM>.

CPUs <NUM>, GPUs <NUM>, FPGAs <NUM>, and accelerators <NUM> may execute certain instructions that, in combination, may make up the aforementioned computer code. That computer code may be stored in ROM <NUM> or RAM <NUM>. Transitional data may be also be stored in RAM <NUM>, whereas permanent data may be stored for example, in the internal mass storage <NUM>. Fast storage and retrieval to any of the memory devices may be enabled through the use of cache memory, that may be closely associated with one or more CPU <NUM>, GPU <NUM>, mass storage <NUM>, ROM <NUM>, RAM <NUM>, and the like.

The computer readable media may have computer code thereon for performing various computer-implemented operations. The media and computer code may be those specially designed and constructed for the purposes of the present disclosure, or they may be of the kind well known and available to those having skill in the computer software arts.

Claim 1:
A method for providing video content in a Dynamic Adaptive Streaming over Hypertext Transfer Protocol, DASH, streaming session, the method being performed by at least one processor, characterized by the method comprising:
obtaining (<NUM>) a pre-session-based description, PreSBD, descriptor information of the DASH streaming session from a media presentation description, MPD, associated with the DASH streaming session instructing a PreSBD client to generate customized session-based description, SBD, document uniform resource locator, URL, for a plurality of SBD descriptors of the DASH streaming session, wherein the PreSBD descriptor information comprises a @urlclass attribute with a value "sbd" indicating that the PreSBD descriptor information includes SBD hypertext transfer protocol (HTTP) GET requests;
instantiating (<NUM>) the PreSBD client and passing (<NUM>) PreSBD descriptor information;
controlling (<NUM>) by a DASH client generation of a customized SBD document URL associated with a first SBD descriptor from the plurality of SBD descriptors of the DASH streaming session;
launching (<NUM>) a first SBD client based on the customized SBD document URL and passing (<NUM>) the first SBD descriptor to the first SBD client;
controlling (<NUM>) generation of a segment URL based on the first SBD descriptor and the customized SBD document URL, and processing (<NUM>) a request for a segment of the video content by at least modifying the segment URL; and
providing (<NUM>) the segment of the video content based on the modified segment URL.