Patent Publication Number: US-2022217440-A1

Title: Method and apparatus for media scene description

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from U.S. Provisional Application No. 63/134,568, filed on Jan. 6, 2021, the disclosures of which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     Embodiments of the present disclosure relate to system design to support media objects using a three-dimensional (3D) modeling syntax, implement media syntax to support various media codecs, containers, and formats, manage media storage and delivery method through predefined programming interfaces, and provide media buffer control and rendering functions. 
     BACKGROUND 
     ISO/IEC 23009-1 Dynamic Adaptive Streaming over Hypertext Transfer Protocol (DASH) standard is an adaptive bitrate streaming technique that enables high quality using HTTP as transport level protocol. 
     The Graphics Language Transmission Format (glTF) is an API-neutral runtime asset 3D modeling delivery format. Compared with traditional 3D modeling tools, glTF provides a more efficient, extensible, interoperable format for the transmission and loading of 3D content. glTF2.0 is the most recent version of the glTF specification written by the Khronos 3D Group. This format supports a simple scene graph format that is generally capable of supporting static (untimed) objects in scenes, including “png” and “jpeg” image formats. glTF2.0 supports simple animations, including support for translate, rotate, and scale, of basic shapes described using the glTF primitives, i.e. for geometric objects. glTF2.0 does not support timed media, and hence does not support video nor audio. 
     “Information technology—Coding of audiovisual objects—Part 12: ISO base media file format”, ISO/IEC 14496-12 (December 2015), “Draft of FDIS of ISO/IEC 23000-19 Common Media Application Format for Segmented Media”, ISO/IEC JTC1/SC29/WG11 MPEG117/16819 (April 2017); and “Text of ISO/IEC FDIS 23009-1 4th edition”, ISO/IEC JTC 1/SC 29/WG 11 N18609 (August 2019), and the glTF2.0 specification are incorporated herein by reference in their entirety. 
     SUMMARY 
     According to an embodiment, a method of managing media storage and delivery includes obtaining information about a three-dimensional (3D) scene; obtaining, from the information, a parameter indicating that viewport adaptation is enabled; rendering the 3D scene, wherein the 3D scene includes at least one two-dimensional (2D) video to be reproduced within the 3D scene; obtaining a current viewport of a user; determining whether the at least one 2D video is inside of a range of the current viewport; and adjusting a bitrate of the at least one 2D video based on a result of the determining. 
     According to an embodiment, a device for managing media storage and delivery, the device includes at least one memory configured to store program code; and at least one processor configured to read the program code and operate as instructed by the program code, the program code including: first obtaining code configured to cause the at least one processor to obtain information about a three-dimensional (3D) scene; second obtaining code configured to cause the at least one processor to obtain, from the information, a parameter indicating that viewport adaptation is enabled; rendering code configured to cause the at least one processor to render the 3D scene, wherein the 3D scene includes at least one two-dimensional (2D) video to be reproduced within the 3D scene; third obtaining code configured to cause the at least one processor to obtain a current viewport of a user; second determining code configured to cause the at least one processor to determine whether the at least one 2D video is inside of a range of the current viewport; and adjusting code configured to cause the at least one processor to adjust a bitrate of the at least one 2D video based on a result of the determining. 
     According to an embodiment, a non-transitory computer-readable medium stores instructions, the instructions including: one or more instructions that, when executed by at least one processor of a device for managing media storage and delivery, cause the at least one processor to: obtain information about a three-dimensional (3D) scene; obtain, from the information, a parameter indicating that viewport adaptation is enabled; render the 3D scene, wherein the 3D scene includes at least one two-dimensional (2D) video to be reproduced within the 3D scene; obtain a current viewport of a user; determine whether the at least one 2D video is inside of a range of the current viewport; and adjust a bitrate of the at least one 2D video based on a result of the determining. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features, the nature, and various advantages of the disclosed subject matter will be more apparent from the following detailed description and the accompanying drawings in which: 
         FIG. 1  is a diagram of an environment in which methods, apparatuses and systems described herein may be implemented, according to embodiments. 
         FIG. 2  is a block diagram of example components of one or more devices of  FIG. 1 , according to embodiments. 
         FIG. 3  is a schematic illustration of glTF scene description objects, according to embodiments. 
         FIG. 4  is a schematic illustration of the media scene description system reference architecture, according to embodiments. 
         FIG. 5  is an example of glTF JavaScript Object Notation (JSON) format representation, according to embodiments. 
         FIG. 6A  is an example of MPEG glTF extension, according to embodiments. 
         FIG. 6B  is an example of timed media JSON representation, according to embodiments. 
         FIG. 7  is a schematic illustration of two or more-timed media playback in an immersive scene scenario, according to embodiments. 
         FIG. 8  is a schematic illustration of DASH viewport adaptation top-level syntax, according to embodiments. 
         FIG. 9  is a schematic illustration of an example of MPEG_dash_viewport_adaptation usage, according to embodiments. 
         FIGS. 10A-10B  are diagrams of example processes for managing media storage and delivery according to embodiments. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a diagram of an environment  100  in which methods, apparatuses, and systems described herein may be implemented, according to embodiments. As shown in  FIG. 1 , the environment  100  may include a user device  110 , a platform  120 , and a network  130 . Devices of the environment  100  may interconnect via wired connections, wireless connections, or a combination of wired and wireless connections. 
     The user device  110  includes one or more devices capable of receiving, generating, storing, processing, and/or providing information associated with platform  120 . For example, the user device  110  may include a computing device (e.g., a desktop computer, a laptop computer, a tablet computer, a handheld computer, a smart speaker, a server, etc.), a mobile phone (e.g., a smart phone, a radiotelephone, etc.), a wearable device (e.g., a pair of smart glasses or a smart watch), or a similar device. In some implementations, the user device  110  may receive information from and/or transmit information to the platform  120 . 
     The platform  120  includes one or more devices as described elsewhere herein. In some implementations, the platform  120  may include a cloud server or a group of cloud servers. In some implementations, the platform  120  may be designed to be modular such that software components may be swapped in or out depending on a particular need. As such, the platform  120  may be easily and/or quickly reconfigured for different uses. 
     In some implementations, as shown, the platform  120  may be hosted in a cloud computing environment  122 . Notably, while implementations described herein describe the platform  120  as being hosted in the cloud computing environment  122 , in some implementations, the platform  120  may not be cloud-based (i.e., may be implemented outside of a cloud computing environment) or may be partially cloud-based. 
     The cloud computing environment  122  includes an environment that hosts the platform  120 . The cloud computing environment  122  may provide computation, software, data access, storage, etc. services that do not require end-user (e.g., the user device  110 ) knowledge of a physical location and configuration of system(s) and/or device(s) that hosts the platform  120 . As shown, the cloud computing environment  122  may include a group of computing resources  124  (referred to collectively as “computing resources  124 ” and individually as “computing resource  124 ”). 
     The computing resource  124  includes one or more personal computers, workstation computers, server devices, or other types of computation and/or communication devices. In some implementations, the computing resource  124  may host the platform  120 . The cloud resources may include compute instances executing in the computing resource  124 , storage devices provided in the computing resource  124 , data transfer devices provided by the computing resource  124 , etc. In some implementations, the computing resource  124  may communicate with other computing resources  124  via wired connections, wireless connections, or a combination of wired and wireless connections. 
     As further shown in  FIG. 1 , the computing resource  124  includes a group of cloud resources, such as one or more applications (“APPs”)  124 - 1 , one or more virtual machines (“VMs”)  124 - 2 , virtualized storage (“VSs”)  124 - 3 , one or more hypervisors (“HYPs”)  124 - 4 , or the like. 
     The application  124 - 1  includes one or more software applications that may be provided to or accessed by the user device  110  and/or the platform  120 . The application  124 - 1  may eliminate a need to install and execute the software applications on the user device  110 . For example, the application  124 - 1  may include software associated with the platform  120  and/or any other software capable of being provided via the cloud computing environment  122 . In some implementations, one application  124 - 1  may send/receive information to/from one or more other applications  124 - 1 , via the virtual machine  124 - 2 . 
     The virtual machine  124 - 2  includes a software implementation of a machine (e.g., a computer) that executes programs like a physical machine. The virtual machine  124 - 2  may be either a system virtual machine or a process virtual machine, depending upon use and degree of correspondence to any real machine by the virtual machine  124 - 2 . A system virtual machine may provide a complete system platform that supports execution of a complete operating system (“OS”). A process virtual machine may execute a single program, and may support a single process. In some implementations, the virtual machine  124 - 2  may execute on behalf of a user (e.g., the user device  110 ), and may manage infrastructure of the cloud computing environment  122 , such as data management, synchronization, or long-duration data transfers. 
     The virtualized storage  124 - 3  includes one or more storage systems and/or one or more devices that use virtualization techniques within the storage systems or devices of the computing resource  124 . In some implementations, within the context of a storage system, types of virtualizations may include block virtualization and file virtualization. Block virtualization may refer to abstraction (or separation) of logical storage from physical storage so that the storage system may be accessed without regard to physical storage or heterogeneous structure. The separation may permit administrators of the storage system flexibility in how the administrators manage storage for end users. File virtualization may eliminate dependencies between data accessed at a file level and a location where files are physically stored. This may enable optimization of storage use, server consolidation, and/or performance of non-disruptive file migrations. 
     The hypervisor  124 - 4  may provide hardware virtualization techniques that allow multiple operating systems (e.g., “guest operating systems”) to execute concurrently on a host computer, such as the computing resource  124 . The hypervisor  124 - 4  may present a virtual operating platform to the guest operating systems, and may manage the execution of the guest operating systems. Multiple instances of a variety of operating systems may share virtualized hardware resources. 
     The network  130  includes one or more wired and/or wireless networks. For example, the network  130  may include a cellular network (e.g., a fifth generation (5G) network, a long-term evolution (LTE) network, a third generation (3G) network, a code division multiple access (CDMA) network, etc.), a public land mobile network (PLMN), a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), a telephone network (e.g., the Public Switched Telephone Network (PSTN)), a private network, an ad hoc network, an intranet, the Internet, a fiber optic-based network, or the like, and/or a combination of these or other types of networks. 
     The number and arrangement of devices and networks shown in  FIG. 1  are provided as an example. In practice, there may be additional devices and/or networks, fewer devices and/or networks, different devices and/or networks, or differently arranged devices and/or networks than those shown in  FIG. 1 . Furthermore, two or more devices shown in  FIG. 1  may be implemented within a single device, or a single device shown in  FIG. 1  may be implemented as multiple, distributed devices. Additionally, or alternatively, a set of devices (e.g., one or more devices) of the environment  100  may perform one or more functions described as being performed by another set of devices of the environment  100 . 
       FIG. 2  is a block diagram of example components of one or more devices of  FIG. 1 . The device  200  may correspond to the user device  110  and/or the platform  120 . As shown in  FIG. 2 , device  200  may include a bus  210 , a processor  220 , a memory  230 , a storage component  240 , an input component  250 , an output component  260 , and a communication interface  270 . 
     The bus  210  includes a component that permits communication among the components of the device  200 . The processor  220  is implemented in hardware, firmware, or a combination of hardware and software. The processor  220  is a central processing unit (CPU), a graphics processing unit (GPU), an accelerated processing unit (APU), a microprocessor, a microcontroller, a digital signal processor (DSP), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), or another type of processing component. In some implementations, the processor  220  includes one or more processors capable of being programmed to perform a function. The memory  230  includes a random access memory (RAM), a read only memory (ROM), and/or another type of dynamic or static storage device (e.g., a flash memory, a magnetic memory, and/or an optical memory) that stores information and/or instructions for use by the processor  220 . 
     The storage component  240  stores information and/or software related to the operation and use of the device  200 . For example, the storage component  240  may include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, and/or a solid state disk), a compact disc (CD), a digital versatile disc (DVD), a floppy disk, a cartridge, a magnetic tape, and/or another type of non-transitory computer-readable medium, along with a corresponding drive. 
     The input component  250  includes a component that permits the device  200  to receive information, such as via user input (e.g., a touch screen display, a keyboard, a keypad, a mouse, a button, a switch, and/or a microphone). Additionally, or alternatively, the input component  250  may include a sensor for sensing information (e.g., a global positioning system (GPS) component, an accelerometer, a gyroscope, and/or an actuator). The output component  260  includes a component that provides output information from the device  200  (e.g., a display, a speaker, and/or one or more light-emitting diodes (LEDs)). 
     The communication interface  270  includes a transceiver-like component (e.g., a transceiver and/or a separate receiver and transmitter) that enables the device  200  to communicate with other devices, such as via a wired connection, a wireless connection, or a combination of wired and wireless connections. The communication interface  270  may permit the device  200  to receive information from another device and/or provide information to another device. For example, the communication interface  270  may include an Ethernet interface, an optical interface, a coaxial interface, an infrared interface, a radio frequency (RF) interface, a universal serial bus (USB) interface, a Wi-Fi interface, a cellular network interface, or the like. 
     The device  200  may perform one or more processes described herein. The device  200  may perform these processes in response to the processor  220  executing software instructions stored by a non-transitory computer-readable medium, such as the memory  230  and/or the storage component  240 . A computer-readable medium is defined herein as a non-transitory memory device. A memory device includes memory space within a single physical storage device or memory space spread across multiple physical storage devices. 
     Software instructions may be read into the memory  230  and/or the storage component  240  from another computer-readable medium or from another device via the communication interface  270 . When executed, software instructions stored in the memory  230  and/or the storage component  240  may cause the processor  220  to perform one or more processes described herein. Additionally, or alternatively, hardwired circuitry may be used in place of or in combination with software instructions to perform one or more processes described herein. Thus, implementations described herein are not limited to any specific combination of hardware circuitry and software. 
     The number and arrangement of components shown in  FIG. 2  are provided as an example. In practice, the device  200  may include additional components, fewer components, different components, or differently arranged components than those shown in  FIG. 2 . Additionally, or alternatively, a set of components (e.g. one or more components) of the device  200  may perform one or more functions described as being performed by another set of components of the device  200 . 
     Referring to  FIG. 3 , the Graphics Language Transmission Format (glTF) is an application programming interface (API)-neutral runtime asset 3D modeling delivery format. Compared with traditional 3D modeling tools, glTF provides a more efficient, extensible, interoperable format for the transmission and loading of 3D content. 
     A glTF scene may be a combination of multiple glTF assets. The glTF assets may be JavaScript Object Notation (JSON)-formatted files containing a full scene description which may include, for example, a scene object  301 , node  302 , camera  303 , mesh  304 , light  305 , animation  306 , accessor  307 , material  308 , skin  309 , bufferview  310 , technique  311 , texture  312 , buffer  313 , program  314 , image  315 , sampler  316 , shader  317 , plus supporting external data. 
     glTF also supports external data sources which may be referenced in any above-mentioned scene objects. In embodiments, a binary file may be used for animation  306  or other buffer-based data  313 . An image file may be used for object textures  312 . 
     Referring to  FIG. 5 , as mentioned above, a glTF scene may be organized in JSON format. A glTF asset may include zero or more scenes  503 , which may be the set of visual objects to render. Scenes may be defined in a scene array. In example illustrated in  FIG. 5 , there is a single scene  506  with a single node  501 , although embodiments are not limited thereto. Various parameters that may be associated with each node object. For example, name  502  may specify the name of the node object, and scene name  504  may specify the name of the single scene. 
     The glTF scene assets may be consumed by a presentation engine for rendering a 3D or immersive scene to users. The existing glTF syntax only supports 3D objects including static or computer-generated animations. There is no support for media types such as video or audio, let alone rendering those video/audio media types. 
     Meanwhile, existing glTF can not describe a scene using geographical coordinate systems, which in some media presentation scenarios, such a feature is desired. 
     Therefore, there is a need to extend the glTF to support media types includes traditional 2D flat video, immersive media content such as virtual reality (VR), augmented reality (AR), extended reality (XR), and spatial audios. This may require an extension to support video/audio syntax and a system for media deliveries and render 
     Moving Picture Experts Group (MPEG) defines some extensions on top of the glTF specification to support immersive media content. Referring to  FIG. 3 , new extensions are MPEG_media  330 , MPEG_scene_dynamic  331 , MPEG_texture_video  333 , MEPG_animation_timing  332 , MPEG_audio_spatial  334 , MPEG_accessor_timed  335 , MPEG_buffer_circular  336 . In  FIG. 3  generally, elements with rounded outlines, for example elements  301 - 317 , may be glTF elements, and elements with square outlines, for example elements  330 - 336 , may correspond to MPEG-based extensions of the glTF specification, although embodiments are not limited thereto. 
     If MPEG_media  330  as a root identifier, if specified, then MPEG_media may be supported. Referring to  FIG. 6 , the syntax to support MPEG media may be declared as the top-level JSON syntax. Syntax from  601  to  604  may be presented exactly as shown if supported. 
     Scene Updates may be expressed using the JSON Patch protocol and MPEG_scene_dynamic  331  may be used to support JSON patch protocol. 
     MPEG texture video extension, identified by MPEG_texture_video  333 , may provide the possibility to link a glTF texture object to MPEG media and its respective track, listed by an MPEG_media object. MPEG texture video extension may also provide a reference to the MPEG_accessor_timed  335 , where the decoded timed texture will be made available. 
     The MPEG_audio_spatial  334  extension may support multiple audio types. 
     In order to support timed data access, the buffer element may be extended to provide circular buffer functionality. The extension is named MPEG_buffer_circular  336  and may be included as part of the glTF “buffers” objects, for example buffer  313 . 
     Above MEPG extensions may allow for the creation of immersive experiences using glTF. Eventually the glTF assets with MPEG extension may be used to be load into a rendering engine for visualization. 
     Referring to  FIG. 4 , a reference media scene description architecture  400  illustrates an example of how MPEG extensions may be used to support media type such as audio/video. The media contents may be retrieved using a Media Retrieval Engine and Media Access Functions (MAF)  402  from external sources such as a media cloud  401 , processed using video decoder  403 , audio decoder  404 , and other data compressor  405 , buffered in video buffer  406 , audio buffer  407 , and other buffer  408 , and rendered by a presentation engine  409 . In some cases, media content may be stored in local storage  410 . 
     Referring to  FIG. 4 , the MPEG scene description extensions may decouple the Presentation Engine  409  from the Media Retrieval Engine  402 . Presentation Engine  409  and Media Retrieval Engine  402  may communicate through the predefined programming interfaces, which allows the Presentation Engine  409  to request media data required for the rendering of the scene. The Media Retrieval Engine  402  may retrieve the requested media and make it available in a timely manner and in a format that can be immediately processed by the Presentation Engine  409 . For instance, a requested media asset may be compressed and residing in the network, so the Media Retrieval Engine  402  will retrieve and decode the asset and pass the resulting media data to the Presentation Engine  409  for rendering. The media data may be passed in form of buffers from the Media Retrieval Engine  402  to the Presentation Engine  409 . The requests for media data may be passed through a Media Retrieval API from the Presentation Engine  409  to the Media Retrieval Engine  402 . For flexible use of video decoding resource, the Video Decoder  403  may be used. When the Video Decoder  403  is used, the Presentation Engine  409  may provide information for input formatting and output formatting to the Video Decoder  403  through Application Configuration APIs. 
     Dynamic Adaptive Streaming over HTTP (DASH) or MPEG-DASH, is an adaptive bitrate streaming technique that enables high quality using HTTP as transport level protocol. The DASH content may be divided into multiple segments and each segment may contain a short interval of playback time of content. The content may be made available at a variety of different bit rates, i.e., alternative segments encoded at different bit rates covering aligned short intervals of playback time. While the content is being played back by an MPEG-DASH client, the client may use a customized bit rate adaptation algorithm to automatically select the segment with the highest bit rate possible based on network condition which resulting in a smooth playback without causing stalls or re-buffering events in the playback 
     A scene description may support MPEG-DASH for playback. Currently, MPEG supports DASH media playback as a timed media identified as MPEG timed media extension. 
     Referring to  FIG. 6B , a DASH-based timed media may be identified by the mimeType ( 613 ) with a IANA value “application/dash+xml”. Each DASH may have one manifest file called a Media Presentation Description (MPD) file to illustrate how media segments are divided and configured. Such MPD file may be identified by a url or uri ( 614 ). The media track information may be identified by a track, and each DASH timed media may have one or more track information, such as shown in ( 615 ). A DASH client may use different track # based on the network condition. Also there may be more than one DASH MPD file in one timed media extension such as shown in extension ( 616 ) which may have one or more tracks for that specific MPD file. 
     In an immersive scene environment, a point of view of a user or camera is not always fixed on a particular object. With the current support of timed media in scene description, there is a desire for an optimal view experience when there is one or more timed media in a scene. Accordingly, embodiments may relate to an extension to enable DASH dynamic bitrate switching along with viewport update. In the glTF concept, this enables DASH-based MPEG timed media to automatically switch bitrate when the camera moving the focus on and off a timed media object. This may a user&#39;s quality of experience, increase network bandwidth efficiency. 
     As discussed above, DASH as an adaptive HTTP-based media streaming method enables a client to automatically adjust bitstream bitrate with predefined small bitstream segments based on network condition or buffer status. The advantage of switching up/down the bitrate quality can reduce re-buffer frequency resulting in a smooth playback experience. 
     As shown in  FIG. 6A , an MPEG media extension, identified as MPEG_media ( 601 ), may enable scene description for playback DASH-based timed media. While the current design of DASH adaptive streaming is implementation-specific, the usage of DASH native switching does not provide optimal networking bandwidth usage in an immersive or 360-degree scene environments. For example, a view of a media play may not be always in the range of the current viewport, which may cause the unnecessary network resource waste. In embodiments, a current viewport may be a portion of an immersive, 3D, VR/AR/XR, or 360-degree scene that is currently being viewed by a camera or a user, or reproduced for a user. To provide a smooth timed media playback experience, it may be important to manage how network bandwidth is consumed. 
     Accordingly, embodiments may enable DASH-based timed media bitrate adaptation along with viewport update. In the glTF concept, this may enable DASH-based media playback to automatically switch bitrate when the camera on and off focus on a timed media object. In turn, this improves a user&#39;s quality of experience, and increase network bandwidth efficiency. 
     Referring to  FIG. 7 , an immersive scene ( 701 ) with one or potentially more media playback is shown. Playback view  1  ( 703 ) and view  2  ( 702 ) may be rendered by presentation engine  409  and being allocated with positions shown in  FIG. 7 . 
     It is reasonable to assume that not all of the 360 view are in the range of the user&#39;s viewport or a camera&#39;s coverage area. That being said, not all view  1  and view  2  are currently being watched at the same time. 
     To explain further the use cases, the following scene objects are used for explanation of potential use cases. Refer back to  FIG. 7 , assuming video-1 is playing under view  1  ( 703 ) and video-2 is playing in view  2  ( 704 ). Table 1 provides information about the scene shown in  FIG. 7 . 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Asset 
                 Description 
               
               
                   
                   
               
             
            
               
                   
                 A scene 
                 A glTF asset that represents a living room. 
               
               
                   
                 Video-1 
                 DASH-based video files 
               
               
                   
                 Video-2 
                 DASH-based video files 
               
               
                   
                   
               
            
           
         
       
     
     In a simple example use case, there is only one DASH-based timed media played in a scene as shown in  FIG. 3 . The media may be rendered based on the MPEG_media extension with configurable parameters such as autoplay ( 621 ), loop ( 622 ), etc. DASH adaptative streaming in this case may be used within its native mechanism by switching bitrate based on either network condition or buffer status. The key observation in this case is that the video keeps playing even when the viewport is not in focus. In an adequate network environment, DASH switches to the highest bitrate possible without considering the overall bandwidth consumption for a scene as a whole. In a less desirable network condition, with a camera&#39;s focus is on a set of relatively large bandwidth consumption scene objects such as point cloud compressed (PCC) objects, unnecessary bandwidth consumption from the ongoing timed media playback may not be an optimal solution for view quality of the current viewport. 
     When more than one timed media is played at the same time, as shown in  FIG. 7 , network bandwidth usage is similar to the use case like above. However, the situation may get worse when all of the timed media are in a high-resolution setup. The lack of balancing network resources for each of the media play may worsen the view quality. 
     Therefore, providing a client with options for configurable bandwidth usage for each of the DASH-based timed media may become an important feature for scene description. 
     Accordingly, embodiments enable DASH-based MPEG timed media to automatically switch bitrate based on the camera&#39;s focus point. The implementation of how the bitrate level is adjusted can be case-by-case. This provides the opportunity for a client to turn on/off the viewpoint adaptation in certain view configurations to save network bandwidth in a relatively complex scene rendering scenarios. 
     Referring to  FIG. 8 , an MPEG DASH viewport adaptation extension according to embodiments may be identified by MPEG_dash_viewport_adaptation ( 802  and  804 ). It may be included in the extensionsUsed ( 803 ) and extensionsRequired ( 801 ) of the scene description document for scene descriptions that require the use of DASH viewport adaptation. In embodiments, viewport adaptation may refer to the use of adaptive streaming techniques, for example DASH-based timed media bitrate adaptation or any other adaptive streaming techniques, based on or in consideration of a viewport or viewpoint of a user. 
     When the MPEG_dash_viewport_adaptation extension is not supported, a camera object may remain the same parameter set as specified in the glTF. Table 2 list an example of the definition of top-level objects of MPEG_dash_viewport_adaptation extension. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Name 
                 Type 
                 Description 
               
               
                   
               
             
            
               
                 adaptive 
                 Boolean 
                 Specifies to turn on/off DASH adaptive 
               
               
                   
                   
                 viewpoint adaptation. Default is false. 
               
               
                   
               
            
           
         
       
     
       FIG. 9 , shows an example of one camera object with proposed MPEG_dash_viewport_adaptation extension. The original MPEG_extension with mimeType specifying “application/dash+xml” remains unchanged. 
     When MPEG_dash_viewport_adaptation is in use according to embodiments discussed above, by switching on and off the “adaptative” parameter specified in Table 2, a client can enable the viewport adaptation with “adaptative”=True. The logic of bitrate level or DASH track switching may be implementation specific. 
     Accordingly, embodiments may relate to a new scene description extension to enable DASH-based timed media bitrate adaptation along with viewport update, and to a set of parameters as identification of enabling a proposed extension. 
     Referring to  FIGS. 10A-10B  a processes  1000 A and  1000 B for managing media storage and delivery are described below. 
       FIG. 10A  is a flowchart of an example process  1000 A for managing media storage and delivery. 
     As shown in  FIG. 10A , process  1000 A may include obtaining information about a three-dimensional (3D) scene (block  1011 ). In embodiments, the information may correspond to a glTF scene or a glTF asset. 
     As further shown in  FIG. 10A , process  1000 A may include obtaining, from the information, a parameter indicating that viewport adaptation is enabled (block  1012 ). In embodiments, the parameter may correspond to the “adaptive” parameter of the DASH viewport adaptation extension discussed above. 
     As further shown in  FIG. 10A , process  1000 A may include rendering the 3D scene, wherein the 3D scene includes at least one two-dimensional (2D) video to be reproduced within the 3D scene (block  1013 ). 
     As further shown in  FIG. 10A , process  1000 A may include obtaining a current viewport of a user (block  1014 ). 
     As further shown in  FIG. 10A , process  1000 A may include determining whether the at least one 2D video is inside of a range of the current viewport (block  1015 ). 
     As further shown in  FIG. 10A , process  1000 A may include adjusting a bitrate of the at least one 2D video based on a result of the determining (block  1016 ). 
       FIG. 10B  is a flowchart of an example process  1000 B for managing media storage and delivery. In embodiments, one or more blocks of process  1000 B may correspond to one or more blocks of process  1000 A. For example, in embodiments block  1021  of process  1000 B, may correspond to block  1014  of process  1000 A, and one or both of blocks  1022  and  1023  of process  1000  may correspond to block  1016  of process  1000 A. 
     As shown in  FIG. 10B , process  1000 B may include determining whether the at least one 2D video is inside of the range of the current viewport (block  1021 ). 
     As further shown in  FIG. 10B , process  1000 B may include, based on determining that the at least one 2D video is inside of the range of the current viewport (YES at block  1021 ), increasing the bitrate (block  1022 ). 
     As further shown in  FIG. 10B , process  1000 B may include based on determining that the at least one 2D video is outside of the range of the current viewport (NO at block  1021 ), decreasing the bitrate (block  1023 ). 
     In embodiments, the at least one 2D video may include a first 2D video having a first bitrate and a second 2D video having a second bitrate, and the adjusting may include, based on determining that the first 2D video is inside of the range of the current viewport and that the second 2D video is outside of the range of the current viewport, adjusting the second bitrate to be lower than the first bitrate. 
     In embodiments, the information may include a graphics language transmission format (glTF) asset. 
     In embodiments, the glTF asset may include a JavaScript Object Notation (JSON) object. 
     In embodiments, the parameter may be included in a camera node of the glTF asset. 
     In embodiments, the parameter may be included in a Moving Picture Experts Group (MPEG) media extension specified by the glTF asset. 
     In embodiments, the parameter may relate to streaming of the at least one 2D video using MPEG-Dynamic Adaptive Streaming over Hypertext Transfer Protocol (MPEG-DASH). 
     Although  FIGS. 10A-10B  show example blocks of processes  1000 A and  1000 B, in some implementations, processes  1000 A and  1000 B may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in  FIGS. 10A-10B . Additionally, or alternatively, two or more of the blocks of processes  1000 A and  1000 B may be performed in parallel. In embodiments, any one or more blocks of process  1000 A may be combined with any one or more blocks of process  1000 B in any order, and any one or more of any blocks of processes  1000 A and  1000 B may be split or combined as desired. 
     Further, the proposed methods 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 to perform one or more of the proposed methods. 
     The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the implementations to the precise form disclosed. Modifications and variations are possible in light of the above disclosure or may be acquired from practice of the implementations. 
     It will be apparent that systems and/or methods, described herein, may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the implementations. Thus, it should be understood that software and hardware may be designed to implement the systems and/or methods based on the description herein. 
     Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of possible implementations. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of possible implementations includes each dependent claim in combination with every other claim in the claim set. 
     No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, etc.), and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.