Abstract:
An apparatus comprises a processor configured to create a Dynamic Adaptive Streaming over Hypertext Transfer Protocol (DASH) media presentation description (MPD), wherein the MPD comprises an AssetIdentifier element associated with a period, wherein the AssetIdentifier element specifies that the period belongs to a certain asset, and wherein the asset is content including media and metadata together with the rights to use the content by a content provider, and a transmitter configured to transmit the MPD. An apparatus comprises a receiver configured to receive a Dynamic Adaptive Streaming over Hypertext Transfer Protocol (DASH) media presentation description (MPD), wherein the MPD comprises an AssetIdentifier element associated with a period, wherein the AssetIdentifier element specifies that the period belongs to a certain asset, and wherein the asset is content including media and metadata together with the rights to use the content by a content provider, and a processor configured to process the MPD.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/669,510 filed Jul. 9, 2012 by Alexander Giladi and titled “Content-Specific Identification and Timing Behavior in DASH,” which is incorporated in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO A MICROFICHE APPENDIX 
       [0003]    Not applicable. 
       BACKGROUND 
       [0004]    Many television and movie viewers now desire on-demand access to video and other media content. As a first example, a television viewer may desire to watch a television show that he or she missed during the show&#39;s regular air time on television. The viewer may download the show on demand over the Internet via a web browser or other application on a notebook computer, tablet computer, desktop computer, mobile telephone, or other device, then view that show in the browser or other application. As a second example, a viewer may download a movie on demand. As a third example, a viewer may participate in a videoconference with other viewers. 
         [0005]    Dynamic Adaptive Streaming over Hypertext Transfer Protocol (DASH) is a standard developed to provide such media content and is partially described in International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) 23009-1, First Edition, 2012 (“23009-1”), which is incorporated in its entirety. In addition, ISO/IEC 23009-1, Technical Corrigendum 1, 2013 is incorporated in its entirety. In DASH, there are two main devices, the Hypertext Transfer Protocol (HTTP) server or servers that provide the content and the DASH client that downloads the content and is associated with the viewer, or user. DASH leaves control with the client, which can request content using the HTTP protocol. DASH is dynamic and adaptive because the client may choose from among multiple forms of content, or data, based on a variety of factors such as network conditions, device capability, and user choice. For example, the HTTP server may inform the client of different download bit rates, the client may choose one of the bit rates, and the client may begin downloading segments of data at the chosen bit rate. If for some reason network conditions deteriorate, then the client may change to a lower bit rate and begin downloading segments of data at the new bit rate. DASH&#39;s adaptability therefore ensures that the client consumes less than the available bandwidth. 
         [0006]    The television show, movie, video conference, or other media content that the client desires to view may be referred to as the main content. The provider of the main content may desire to earn revenue for providing the main content. One way to earn revenue is to include advertisements with the main content. The advertisements may be referred to as ads or ad content. Accordingly, the HTTP server may direct the client to download ads from an ad server. The client may not be able to download or view the main content or portions of the main content until it downloads and views the ad content. Furthermore, certain restrictions may be placed on the browser or other application that the content is viewed through so that the ad content cannot be skipped while viewing. Once the client downloads and views the ads, then the provider of the ad content may pay the provider of the main content. 
       SUMMARY 
       [0007]    In one embodiment, the disclosure includes an apparatus comprising a processor configured to create a Dynamic Adaptive Streaming over Hypertext Transfer Protocol (DASH) media presentation description (MPD), wherein the MPD comprises an AssetIdentifier element associated with a period, wherein the AssetIdentifier element specifies that the period belongs to a certain asset, and wherein the asset is content including media and metadata together with the rights to use the content by a content provider, and a transmitter configured to transmit the MPD. 
         [0008]    In another embodiment, the disclosure includes an apparatus comprising a receiver configured to receive a Dynamic Adaptive Streaming over Hypertext Transfer Protocol (DASH) media presentation description (MPD), wherein the MPD comprises an AssetIdentifier element associated with a period, wherein the AssetIdentifier element specifies that the period belongs to a certain asset, and wherein the asset is content including media and metadata together with the rights to use the content by a content provider, and a processor configured to process the MPD. 
         [0009]    In yet another embodiment, the disclosure includes a method comprising receiving a Dynamic Adaptive Streaming over Hypertext Transfer Protocol (DASH) media presentation description (MPD), wherein the MPD comprises an AssetIdentifier element associated with a period, wherein the AssetIdentifier element specifies that the period belongs to a certain asset, and wherein the asset is content including media and metadata together with the rights to use the content by a content provider, and processing the MPD. 
         [0010]    These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. 
           [0012]      FIG. 1  is a schematic diagram of a DASH system according to an embodiment of the disclosure. 
           [0013]      FIG. 2  is a schematic diagram of a network device according to an embodiment of the disclosure. 
           [0014]      FIG. 3  is a protocol diagram for the DASH system according to an embodiment of the disclosure. 
           [0015]      FIG. 4  is a diagram of a media presentation description (MPD) according to an embodiment of the disclosure. 
           [0016]      FIG. 5  is a diagram of a media presentation according to an embodiment of the disclosure. 
           [0017]      FIG. 6  is a flowchart illustrating a method according to an embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    It should be understood at the outset that, although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents. 
         [0019]    HTTP is a stateless protocol, meaning that it treats each request for data as an independent transaction unrelated to any previous request. As a result, an HTTP server cannot directly know which client downloaded which content. Furthermore, the client cannot directly know whether data it is downloading is main content or ad content. Rather, if the client is downloading from multiple HTTP servers, then the client knows only which HTTP server it is downloading from. In addition, DASH currently does not distinguish between main content and ad content. 
         [0020]    The lack of a distinction between main content and ad content may cause at least five issues. First, the client may not be able to properly implement a main content progress bar. A progress bar may refer to a graphical indication of a user&#39;s temporal progress in viewing content. The progress bar may be viewable to the user in the client&#39;s web browser or other application. The issue may be best understood using an example. If a client is downloading a media presentation comprising one minute of ad content followed by five minutes of main content, then the client may implement a progress bar indicating that the fourth minute of the main content is downloading and being viewed when, in reality, only the third minute of the main content is downloading and being viewed because the client may include the first minute of the ad content in calculating the progress of the main content. Second, for the same reason as the first issue, the client may not be able to implement random access functionality, for instance properly seeking to a specific time to view the main content. For example, the user may be in the fourth minute of the main content but desire to return to the third minute of the main content. Without a distinction between the main content and the ad content, a return to the third minute of the main content may be difficult. Third, there may be no way to report that the client downloaded ad content. Without such reporting, the provider of the main content may not receive all of its revenue due from the provider of the ad content. Fourth, without being able to distinguish between main content and ad content, the HTTP server may not be able to associate additional information, such as a movie title, with the main content. Fifth, the HTTP server may not be able to properly implement trick modes. Trick modes may refer to rewind, fast forward, slow motion, pause, and other modes of playing or viewing content other than at normal speed. Trick mode restrictions are often used, especially for ad content. For example, the ad provider may desire for such trick modes to be restricted or completely unavailable in order to ensure that the client downloads, and the user views, the ad content. Workarounds may exist for at least the first two issues, but those workarounds may be complicated and unreliable. A way to distinguish between main content and ad content is therefore desired. 
         [0021]    Disclosed herein are systems and methods for improved DASH implementation. The disclosed technique may provide a way for DASH to uniquely identify content. The disclosed technique may therefore address each of the issues above. The disclosed technique may also apply to other standards and be implemented by other standards developing organizations (SDOs). In other words, the disclosed technique is not limited to 23009-1 or even to other DASH standards. Furthermore, the disclosed technique is not limited to video on demand or videoconferencing, but may apply to other forms of media content as well. 
         [0022]      FIG. 1  is a schematic diagram of a DASH system  100  according to an embodiment of the disclosure. The system  100  may comprise a plurality of n HTTP servers  110 , an ad server  140 , a DASH client  150 , and a network  180 . The HTTP servers  110 , ad server  140 , and client  150  may be communicatively coupled to each other via the network  180  and other network components such as HTTP caches (not shown). 
         [0023]    The HTTP servers  110  may be any hardware computer servers configured to send and receive data via HTTP. The HTTP servers  110  may comprise server DASH modules (DMs)  120  configured to send and receive data via HTTP and according to the DASH standard. The HTTP servers may form a content delivery network (CDN)  130 , which may refer to a distributed system of servers deployed in multiple data centers over multiple backbones for the purpose of delivering content. The CDN  130  may comprise any number of HTTP servers  110  so that n may be any number. Typically, a CDN may comprise thousands of servers. 
         [0024]    The ad server  140  may be any hardware computer server configured to send and receive data via HTTP. In particular, the ad server  140  may receive requests for ads and send the requested ads to other network components. There may be any number of ad servers  140  across the system  100 . If there are multiple ad servers  140 , then the ad servers  140  may or may not be associated with each other. 
         [0025]    The client  150  may be any hardware device configured to send and receive data via HTTP. For example, the client  150  may be a notebook computer, a tablet computer, a desktop computer, a mobile telephone, or another device. The client  150  may comprise a client DM  155 , an application  170 , and a graphical user interface (GUI)  175 . 
         [0026]    The client DM  155  may be configured to send and receive data via HTTP and according to the DASH standard. The client DM  155  may comprise a DASH access engine (DAE)  160  and a media output (ME)  165 . The DAE  160  may be the primary component for receiving raw data from the HTTP servers  110  and constructing that data in a format for viewing. For example, the DAE  160  may format the data in Moving Picture Experts Group (MPEG) container formats along with timing data, then output the formatted data to the ME  165 . The ME  165  may be responsible for initialization, playback, and other functions associated with content and may output that content to the application  170 . 
         [0027]    The application  170  may be a web browser or other application with an interface configured to download and present content. The application  170  may be coupled to the GUI  175  so that a user associated with the client  150  may view the various functions of the application  170 . The application  170  may comprise a search function so that the user can search for content. For example, if the application  170  is a media player, then the application  170  may comprise a search bar so that the user may input a string of words to search for a movie. The application  170  may present a list of search hits, and the user may select the desired movie from among the hits. Upon selection, the application  170  may send instructions to the client DM  155  for downloading the movie. The DM  155  may download the movie and process the movie for outputting to the application  170 . The application  170  may provide instructions to the GUI  175  for the GUI  175  to display the movie for viewing by the user. The application  170  may further provide instructions to the GUI  175  for the GUI  175  to display a progress bar showing the temporal progress of the movie. 
         [0028]    The GUI  175  may be any GUI configured to display functions of the application  170  so that the user may operate the application. As described above, the GUI  175  may display the various functions of the application  170  so that the user may select content to download. The GUI  175  may then display the content for viewing by the user. 
         [0029]    The network  180  may be any network configured to provide for communication among the HTTP servers  110 , ad server  140 , and client  150 . For example, the network  180  may be the Internet, a mobile telephone network, or another network. The network  180  may allow communication along wired or wireless channels. 
         [0030]      FIG. 2  is a schematic diagram of a network device  200  according to an embodiment of the disclosure. The device  200  may comprise a plurality of ingress ports  210  and/or receiver units (Rx)  220  for receiving data, a logic unit or processor  230  to process signals, a plurality of egress ports  240  and/or transmitter units (Tx)  250  for transmitting data to other components, and a memory  260 . The device  200  may be suitable for implementing any of the disclosed features, methods, and devices. For example, the device  200  may be suitable for implementing the HTTP servers  110 , the ad server  140 , and the client  150 . 
         [0031]    The logic unit  230 , which may be referred to as a central processing unit (CPU), may be in communication with the ingress ports  210 , receiver units  220 , egress ports  240 , transmitter units  250 , and memory  260 . The logic unit  230  may be implemented as one or more CPU chips, cores (e.g., as a multi-core processor), field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), and/or digital signal processors (DSPs), and/or may be part of one or more ASICs. 
         [0032]    The memory  260  may be comprised of one or more disks, tape drives, optical disc drives, or solid-state drives; may be used for non-volatile storage of data and as an over-flow data storage device; may be used to store programs when such programs are selected for execution; and may be used to store instructions and data that are read during program execution. The memory  260  may be volatile and/or non-volatile and may be read-only memory (ROM), random-access memory (RAM), ternary content-addressable memory (TCAM), static random-access memory (SRAM), another suitable type of memory, or any combination thereof. The memory  260  may comprise a DM  270 , which may be suitable for implementing the server DMs  120  or the client DM  155 . While the memory  260  is shown as comprising the DM  270 , the logic unit  230  or any combination of the logic unit  230  and the memory  260  may alternatively comprise the DM  270 . 
         [0033]      FIG. 3  is a protocol diagram  300  for the DASH system  100  according to an embodiment of the disclosure. The client  150  may desire to download main content. In that case, at step  310 , the client  150  may send to the HTTP server 1    110   1  a request for an MPD, which may comprise instructions for downloading segments of the main content from any combination of HTTP servers  110 . In addition to instructions for downloading segments of the main content, the MPD may require, and comprise instructions for, downloading segments of ad content from the ad server  140 . MPDs are described more fully below. At step  320 , the HTTP server 1    110   1  may send to the client  150  an MPD. The client  150  may receive the MPD via the DAE  160 , and the DAE  160  may process the MPD in order to construct and issue requests from the HTTP servers  110  for segments of the main content and ad content. 
         [0034]    At step  330 , as instructed by the MPD, the client  150  may send to the HTTP server 1    110   1  via the DAE  160  a first segment request for a first segment of the main content. At step  340 , the HTTP server 1    110   1  may send to the client  150  via the server DM  120  the first segment of the main content. The DAE  160  may receive, process, and format the first segment, then output the formatted data to the ME  165 , which may perform various functions and output the data to the application  170 . After a buffering period, the application  170  may present the data for viewing via the GUI  175 . 
         [0035]    At step  350 , as instructed by the MPD, the client  150  may send to the ad server  140  via the DAE  160  an ad content request. At step  360 , the ad server  140  may send to the client  150  the ad content. The MPD may require that the client  150  download and present the ad content before the client  150  proceeds with downloading additional segments of the main content. 
         [0036]    Subsequently, as instructed by the MPD, the client  150  may send requests for, and receive, additional segments of the main content as well as ad content until, at step  370 , the client  150  may send to the HTTP server 2    110   2  via the DAE  160  a last segment request for a last segment of the main content. Finally, at step  380 , the HTTP server 2    110   2  may send to the client  150  via the server DM  120  the last segment of the main content. After receiving each segment, the DAE  160  may process and format that segment, then output the formatted data to the ME  165 . The ME  165  may perform various functions and output the data to the application  170 . After a buffering period, the application  170  may present the data for viewing via the GUI  175 . 
         [0037]    The main content and ad content may be downloaded in any order as instructed by the MPD. The client  150  may download content while simultaneously displaying the content for viewing. The simultaneous downloading and displaying may be why the process is referred to as streaming. The process of requesting and receiving the MPD may be reiterative. For example, the client  150  may request, or be instructed to request, an updated MPD for a variety of reasons. 
         [0038]      FIG. 4  is a diagram of an MPD  400  according to an embodiment of the disclosure. The MPD  400  may comprise Period  410 , Adaptation Set  420 , Representation  430 , Segment  440 , Sub-Representation  450 , and Sub-Segment  460  elements. The elements may be distinguished by uppercase first letters or camel-casing, as well as bold face, though bold face is removed herein. For example, the Segment  440  may be an element of the MPD  400  that is associated with a segment, the latter of which may be a unit of data as described more fully below. Similarly, the Period  410  may be associated with a period of data. In 23009-1, the MPD  400  may be referred to as a “formalized description for a [m]edia [p]resentation for the purpose of providing a streaming service.” A media presentation, in turn, may be referred to as a “collection of data that establishes a . . . presentation of media content.” In particular, the MPD  400  may define formats to announce HTTP uniform resource locators (URLs), or network addresses, for downloading segments of data. A segment may be referred to as a unit of data associated with a URL. In other words, a segment may generally be the largest unit of data that can be retrieved with a single HTTP request using a single URL. The MPD  400  may be an Extensible Markup Language (XML) document. 
         [0039]    In short, the MPD  400  may comprise a plurality of URLs, or metadata used by the client  150  to construct a plurality of URLs, pointing to one or more HTTP servers  110  for downloading segments of data. For example, referring to  FIG. 3 , the client  150  may receive a plurality of URLs in the MPD at step  320 . A first URL may be associated with the first segment and point to the HTTP server 1    110   1  so that the client  150  requests and receives the first segment from the HTTP server 1    110   1 . A second URL may be associated with the ad content and point to the ad server  140  so that the client  150  requests and receives the ad content from the ad server  140 . The process may continue until the client  150  requests and receives content from the HTTP server  110  associated with the last URL. 
         [0040]    Referring back to  FIG. 4 , it can be seen that the MPD  400  is a hierarchical data model. In 23009-1, the Period  410  may typically represent “a media content period during which a consistent set of encoded versions of the media content is available.” In other words, the “set of available bitrates, languages, captions, subtitles, etc. does not change during a [p]eriod.” The Representation  430  may describe “a deliverable encoded version of one or several media content components.” The client  150  “may switch from Representation to Representation . . . in order to adapt to network conditions or other factors.” The adaptability of DASH therefore lies among a set of mutually interchangeable Representations  430 . The client  150  may determine if it can support a specific Representation  430 . If not, then the client  150  may select a different Representation  430  that it can support. The client  150  may then begin downloading each segment within the selected Representation until the client  150  ceases downloading or until the client  150  selects another Representation  430 . 
         [0041]    The Period  410 , Adaptation Set  420 , Representation  430 , Segment  440 , Sub-Representation  450 , and Sub-Segment  460  elements describe data. Each element may comprise one or more attributes, which are like properties of the element in that they provide further definition about the element. Elements and attributes are defined in Extensible Markup Language (XML) 1.0, Fifth Edition, 2008, which is incorporated in its entirety. In this text, attributes may be prefixed with the @ symbol. For example, the Period  410  may comprise an @start attribute that may specify when on a presentation timeline a period associated with the Period  410  begins. In addition, the Period  410  may comprise an @duration attribute that may specify the duration of a period associated with the Period  410 . The Adaptation Set  420 , Segment  440 , Sub-Representation  450 , and Sub-Segment  460  elements are described in 23009-1 and do not need further explanation herein. 
         [0042]      FIG. 5  is a diagram  500  of a media presentation  510  according to an embodiment of the disclosure. The media presentation  510  may comprise nine periods, which may be described in nine Periods  410  in the MPD  400 . Periods 1, 5, and 9 may be associated with a movie, or main content. Periods 2-4 and 6-8 may be associated with ads, or ad content. The diagram  500  is one example of a media presentation. In other examples, a media presentation may include pre-roll, mid-roll, and post-roll ad content, meaning that ad content may be included before, in the middle of, and after main content, respectively. Ads may typically be associated with a single period, though a series of ads, for instance ads 1-3, may be associated with a single period. 
         [0043]    As described above, the Period  410  may comprise @start and @duration attributes. When the client  150  receives the MPD  400  with @start and @duration attributes for the Period  410 , the client  150  may be able to calculate the presentation timeline  510 . The presentation timeline, however, contemplates both the main content and the ad content because the MPD  400  does not uniquely identify content. Consequently, when the client  150  downloads and presents the media presentation  510 , the movie may be at time 00:20:00 (i.e., the 20th minute of the movie), though a progress bar may show time 00:35:00. In addition, the client  150  may not be able to, for instance, properly seek to time 00:20:00 in the movie. 
         [0044]    Accordingly, the concept of an asset may be introduced. An asset may refer to media content, for instance a movie. Alternatively, an asset may refer to content including media and metadata together with the rights to use the content by the content provider. An asset may be uniquely identified by an element. In a first embodiment, the element may be an XML element named, for instance, AssetIdentification or AssetIdentifier. The AssetIdentifier element may be used to identify an asset on the period level and specify that a period belongs to a certain asset. In other words, if two different Periods contain equivalent AssetIdentifiers, then the two associated periods may belong to the same asset. Alternatively, the AssetIdentifier element may be used to identify an asset at other levels as well. If the client  150  does not recognize the AssetIdentifier element, then the client  150  may ignore the AssetIdentifier element. The AssetIdentifier element may be unique for each asset, not for each MPD. The AssetIdentifier element may comprise the attributes shown in Table 1. 
         [0000]                                  TABLE 1                   AssetIdentifier element and corresponding attributes            Element or               Attribute Name   Use   Description               AssetIdentifier               @assetId   M   Unique identifier for the asset. This value               corresponds to unique content (e.g. movie asset,               ad spot). Use of standardized and resolvable               identifiers is recommended (see examples below).       @start   O   If provided, specifies the time on the asset               timeline which corresponds to the start time of               the period.       @type   OD   Defines the type of content. Options may be               “main” (main content), “ad-spot” (inserted ad),               etc. If absent, “main” is the default value.               Legend:       For attributes: M = Mandatory; O = Optional; OD = Optional with Default Value; CM = Conditionally Mandatory.       For elements: &lt;minOccurs&gt; . . . &lt;maxOccurs&gt; (N = unbounded).       Elements have uppercase first letters or camel-casing; attributes have a preceding @ symbol.            
As shown in Table 1, the AssetIdentifier element may comprise @assetId, @start, and @type attributes. The @assetId attribute may uniquely identify an asset. The @assetId attribute may be, for instance, an International Standard Audiovisual Number (ISAN), an Entertainment Identifier Registry (EIDR), or a Digital Object Identifier (DOI). The @start attribute may specify the time on an asset timeline which corresponds to the start time of the Period. Asset timelines are described more fully below. The @type attribute may define the type of content, for instance main content or ad content, associated with the asset. The XML syntax corresponding to the AssetIdentifier element may be as follows:
 
         [0000]                                                              &lt;!-- Asset Identifier --&gt;                &lt;xs:complexType name=“AssetIdentifier”&gt;                &lt;xs:attribute name=“assetId” type=“xs:anyUri”           use=“required”/&gt;           &lt;xs:attribute name=“start” type=“xs:duration”/&gt;           &lt;xs:attribute name=“type” type=“AssetType” default=“main”/&gt;           &lt;xs:anyAttribute namespace=“##other” processContents=“lax”/&gt;                &lt;/xs:complexType&gt;                        
An example XML document incorporating the AssetIdentifier element may be as follows:
 
         [0000]    
       
         
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
           
               
                   
               
             
             
               
                 &lt;Period id=“pre-roll” duration=“PT60S”&gt; 
               
             
          
           
               
                   
                 &lt;BaseURL&gt;http://cdn1.example.com/&lt;/BaseURL&gt; 
               
               
                   
                 &lt;BaseURL&gt;http://cdn2.example.com/&lt;/BaseURL&gt; 
               
               
                   
                 &lt;AssetIdentifier 
               
               
                   
                  assetId=“urn:org:provider:ad-id:528573CD-1485-13A6- 
               
               
                   
                  56B778222E2B2936” type=“ad-spot”/&gt; 
               
             
          
           
               
                   
                 &lt;AdaptationSet 
               
             
          
           
               
                   
                 mimeType=“video/mp2t” 
               
               
                   
                 codecs=“avc1.4D401F,mp4a” 
               
               
                   
                 frameRate=“24000/1001” 
               
               
                   
                 segmentAlignment=“true” 
               
               
                   
                 subsegmentAlignment=“true” 
               
               
                   
                 bitstreamSwitching=“true” 
               
               
                   
                 startWithSAP=“2” 
               
               
                   
                 subsegmentStartsWithSAP=“2”&gt; 
               
               
                   
                 &lt;ContentComponent contentType=“video” id=“481”/&gt; 
               
               
                   
                 &lt;ContentComponent contentType=“audio” id=“482” lang=“en”/&gt; 
               
               
                   
                 &lt;BaseURL&gt;PreRoll_&lt;/BaseURL&gt; 
               
               
                   
                 &lt;SegmentTemplate 
               
             
          
           
               
                   
                 media=“$RepresentationID$_$Number%05$.ts” 
               
               
                   
                 initialization=“$RepresentationID$-init.ts” 
               
               
                   
                 bitstreamSwitching=“$RepresentationID$-bssw.ts” 
               
               
                   
                 duration=“4” 
               
               
                   
                 startNumber=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;Representation id=“720kbps” bandwidth=“792000” width=“640” 
               
               
                   
                 height=“368”/&gt; 
               
               
                   
                 &lt;Representation id=“1130kbps” bandwidth=“1243000” width=“704” 
               
               
                   
                 height=“400”/&gt; 
               
               
                   
                 &lt;Representation id=“1400kbps” bandwidth=“1540000” width=“960” 
               
               
                   
                 height=“544”/&gt; 
               
               
                   
                 Representation id=“2100kbps” bandwidth=“2310000” width=“1120” 
               
               
                   
                 height=“640”/&gt; 
               
               
                   
                 &lt;Representation id=“2700kbps” bandwidth=“2970000” width=“1280” 
               
               
                   
                 height=“720”/&gt; 
               
               
                   
                 &lt;Representation id=“3400kbps” bandwidth=“3740000” width=“1280” 
               
               
                   
                 height=“720”/&gt; 
               
             
          
           
               
                   
                 &lt;/AdaptationSet&gt; 
               
             
          
           
               
                   
                 &lt;/Period&gt; 
               
               
                   
                 &lt;Period id=“movie1” duration=“PT900S”&gt; 
               
             
          
           
               
                   
                 &lt;AssetIdentifier 
               
               
                   
                  assetId=“http://dx.doi.org/10.1000/182” type=“asset”/&gt; 
               
               
                   
                 &lt;AdaptationSet 
               
             
          
           
               
                   
                 mimeType=“video/mp2t” 
               
               
                   
                 codecs=“avc1.4D401F,mp4a” 
               
               
                   
                 frameRate=“24000/1001” 
               
               
                   
                 segmentAlignment=“true” 
               
               
                   
                 subsegmentAlignment=“true” 
               
               
                   
                 bitstreamSwitching=“true” 
               
               
                   
                 startWithSAP=“2” 
               
               
                   
                 subsegmentStartsWithSAP=“2”&gt; 
               
               
                   
                 &lt;ContentComponent contentType=“video” id=“481”/&gt; 
               
               
                   
                 &lt;ContentComponent contentType=“audio” id=“482” lang=“en”/&gt; 
               
               
                   
                 &lt;ContentComponent contentType=“audio” id=“483” lang=“es”/&gt; 
               
               
                   
                 &lt;BaseURL&gt;SomeMovie_&lt;/BaseURL&gt; 
               
               
                   
                 &lt;SegmentTemplate 
               
             
          
           
               
                   
                 media=“$RepresentationID$_$Number%05$.ts” 
               
               
                   
                 index=“$RepresentationID$.sidx” 
               
               
                   
                 initialization=“$RepresentationID$-init.ts” 
               
               
                   
                 bitstreamSwitching=“$RepresentationID$-bssw.ts” 
               
               
                   
                 duration=“4” 
               
               
                   
                 startNumber=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;Representation id=“720kbps” bandwidth=“792000” width=“640” 
               
               
                   
                 height=“368” &gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
               
                   
                 &lt;SegmentBase timescale=“90000” 
               
               
                   
                 presentationTimeOffset=“162000000” /&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 &lt;Representation id=“1130kbps” bandwidth=“1243000” width=“704” 
               
               
                   
                 height=“400”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 &lt;Representation id=“1400kbps” bandwidth=“1540000” width=“960” 
               
               
                   
                 height=“544”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 &lt;Representation id=“2100kbps” bandwidth=“2310000” width=“1120” 
               
               
                   
                 height=“640”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 &lt;Representation id=“2700kbps” bandwidth=“2970000” width=“1280” 
               
               
                   
                 height=“720”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 &lt;Representation id=“3400kbps” bandwidth=“3740000” width=“1280” 
               
               
                   
                 height=“720”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
             
          
           
               
                   
                 &lt;/AdaptationSet&gt; 
               
             
          
           
               
                   
                 &lt;/Period&gt; 
               
               
                   
                 &lt;Period id=“mid-roll #1” duration=“PT240S”&gt; 
               
             
          
           
               
                   
                 &lt;AdaptationSet 
               
             
          
           
               
                   
                 mimeType=“video/mp2t” 
               
               
                   
                 codecs=“avc1.4D401F,mp4a” 
               
               
                   
                 frameRate=“24000/1001” 
               
               
                   
                 segmentAlignment=“true” 
               
               
                   
                 subsegmentAlignment=“true” 
               
               
                   
                 bitstreamSwitching=“true” 
               
               
                   
                 startWithSAP=“2” 
               
               
                   
                 subsegmentStartsWithSAP=“2”&gt; 
               
               
                   
                 &lt;AssetIdentifier 
               
               
                   
                  assetId=“urn:org:provider:ad-id:89ac2cf2-0a0e-4e27-8493- 
               
               
                   
                  e8e7106a6646” type=“ad-spot”/&gt; 
               
             
          
           
               
                   
                 &lt;ContentComponent contentType=“video” id=“481”/&gt; 
               
               
                   
                 &lt;ContentComponent contentType=“audio” id=“482” lang=“en”/&gt; 
               
               
                   
                 &lt;BaseURL&gt;MidRoll_&lt;/BaseURL&gt; 
               
               
                   
                 &lt;SegmentTemplate 
               
             
          
           
               
                   
                 media=“$RepresentationID$_$Number%05$.ts?cid=480ccc41e6b7&amp;am 
               
               
                   
                 p;sid=99b2&amp;amp;d=3” 
               
             
          
           
               
                   
                 initialization=“$RepresentationID$-init.ts” 
               
               
                   
                 bitstreamSwitching=“$RepresentationID$-bssw.ts” 
               
               
                   
                 duration=“4” 
               
               
                   
                 startNumber=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;Representation id=“720kbps” bandwidth=“792000” width=“640” 
               
               
                   
                 height=“368”/&gt; 
               
               
                   
                 &lt;Representation id=“1130kbps” bandwidth=“1243000” width=“704” 
               
               
                   
                 height=“400”/&gt; 
               
               
                   
                 &lt;Representation id=“1400kbps” bandwidth=“1540000” width=“960” 
               
               
                   
                 height=“544”/&gt; 
               
               
                   
                 &lt;Representation id=“2100kbps” bandwidth=“2310000” width=“1120” 
               
               
                   
                 height=“640”/&gt; 
               
               
                   
                 &lt;Representation id=“2700kbps” bandwidth=“2970000” width=“1280” 
               
               
                   
                 height=“720”/&gt; 
               
               
                   
                 &lt;Representation id=“3400kbps” bandwidth=“3740000” width=“1280” 
               
               
                   
                 height=“720”/&gt; 
               
             
          
           
               
                   
                 &lt;/AdaptationSet&gt; 
               
             
          
           
               
                   
                 &lt;/Period&gt; 
               
               
                   
                 &lt;Period id=“movie2” duration=“PT900S”&gt; 
               
             
          
           
               
                   
                 &lt;AssetIdentifier assetId=“http://dx.doi.org/10.1000/182” start=“PT900S” 
               
               
                   
                 type=“asset”/&gt; 
               
               
                   
                 &lt;AdaptationSet 
               
             
          
           
               
                   
                 mimeType=“video/mp2t” 
               
               
                   
                 codecs=“avc1.4D401F,mp4a” 
               
               
                   
                 frameRate=“24000/1001” 
               
               
                   
                 segmentAlignment=“true” 
               
               
                   
                 subsegmentAlignment=“true” 
               
               
                   
                 bitstreamSwitching=“true” 
               
               
                   
                 startWithSAP=“2” 
               
               
                   
                 subsegmentStartsWithSAP=“2”&gt; 
               
               
                   
                 &lt;ContentComponent contentType=“video” id=“481”/&gt; 
               
               
                   
                 &lt;ContentComponent contentType=“audio” id=“482” lang=“en”/&gt; 
               
               
                   
                 &lt;ContentComponent contentType=“audio” id=“483” lang=“es”/&gt; 
               
               
                   
                 &lt;BaseURL&gt;SomeMovie_&lt;/BaseURL&gt; 
               
               
                   
                 &lt;SegmentTemplate 
               
             
          
           
               
                   
                 media=“$RepresentationID$_$Number%05$.ts?cid=480ccc41e6b7&amp;amp;si 
               
               
                   
                 d=99b2&amp;amp;d=3” 
               
             
          
           
               
                   
                 index=“$RepresentationID$.sidx” 
               
               
                   
                 initialization=“$RepresentationID$-init.ts” 
               
               
                   
                 bitstreamSwitching=“$RepresentationID$-bssw.ts” 
               
               
                   
                 duration=“4” 
               
               
                   
                 startNumber=“1”/&gt; 
               
               
                   
                 &lt;Representation id=“720kbps” bandwidth=“792000” width=“640” 
               
               
                   
                 height=“368” &gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
               
                   
                 &lt;SegmentBase timescale=“90000” 
               
               
                   
                 presentationTimeOffset=“162000000” /&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 &lt;Representation id=“1130kbps” bandwidth=“1243000” width=“704” 
               
               
                   
                 height=“400”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 &lt;Representation id=“1400kbps” bandwidth=“1540000” width=“960” 
               
               
                   
                 height=“544”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 &lt;Representation id=“2100kbps” bandwidth=“2310000” width=“1120” 
               
               
                   
                 height=“640”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 Representation id=“2700kbps” bandwidth=“2970000” width=“1280” 
               
               
                   
                 height=“720”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
               
                   
                 &lt;Representation id=“3400kbps” bandwidth=“3740000” width=“1280” 
               
               
                   
                 height=“720”&gt; 
               
             
          
           
               
                   
                 &lt;SubRepresentation level=“1” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“32”/&gt; 
               
               
                   
                 &lt;SubRepresentation level=“2” contentComponent=“481” 
               
               
                   
                 maxPlayoutRate=“4” dependencyLevel=“1”/&gt; 
               
             
          
           
               
                   
                 &lt;/Representation&gt; 
               
             
          
           
               
                   
                 &lt;/AdaptationSet&gt; 
               
             
          
           
               
                   
                 &lt;/Period&gt;. 
               
               
                   
                   
               
             
          
         
       
     
         [0045]    With the addition of the AssetIdentifier element, the client  150  may properly calculate an asset timeline. For example, if an asset is the movie in periods 1, 5, and 9 in  FIG. 5 , then an asset timeline may correspond to the movie timeline in  FIG. 5 . An asset timeline may therefore be equivalent to a presentation timeline of the movie. The asset timeline may be identical to the presentation timeline in a single period. While the presentation timeline may span across all periods, the asset timeline may correlate to all periods related to the movie. The AssetIdentifier may therefore allow the client  150  to translate between the presentation timeline and the asset timeline. 
         [0046]    The client  150  may calculate the asset timeline in at least three ways. First, the MPD  400  may comprise an AssetIdentifier element for Period 1 that uniquely identifies period 1 as comprising the movie. An @duration attribute for Period 1 may identify that period 1 lasts for 10 minutes. The client  150  may therefore determine that the asset timeline for the movie should include 10 minutes for period 1. The AssetIdentifier elements for Periods 2-4 may identify that periods 2-4 comprise assets different from the movie and the @duration attributes for Periods 2-4 may identify that periods 2-4 last for 15 minutes, so the client  150  may determine that the asset timeline for the movie should not include the 15 minutes for periods 2-4. The AssetIdentifier element for Period 5 may identify that period 5 comprises the movie and the @duration attribute for Period 5 may identify that period 5 lasts for 10 minutes, so the client  150  may determine that the asset timeline for the movie should include the 10 minutes for Period 5. The AssetIdentifier elements for Periods 6-8 may identify that periods 6-8 comprise assets different from the movie and the @duration attributes for Periods 6-8 may identify that periods 6-8 last for 15 minutes, so the client  150  may determine that the asset timeline for the movie should not include the 15 minutes for periods 6-8. The AssetIdentifier element for Period 9 may identify that period 9 comprises the movie and the @duration attribute for Period 9 may identify that period 9 lasts for 10 minutes, so the client  150  may determine that the asset timeline for the movie should include the 10 minutes for period 9. By adding the 10-minute periods for the movie, the client  150  may determine that the movie lasts for 30 minutes, so the client  150  may be able to determine an asset timeline for the movie. 
         [0047]    Second, the MPD  400  may comprise an AssetIdentifier element for Period 1 that uniquely identifies period 1 as comprising the movie, and an @start attribute for Period 1 may identify that period 1 begins at 0 minutes on the presentation timeline. The AssetIdentifier element for Periods 2-4 may identify that periods 2-4 comprise assets different from the movie, and an @start attribute for Period 2 may identify that period 2 begins at 10 minutes on the presentation timeline, so the client  150  may determine that the asset timeline for the movie should include only 10 minutes for period 1. The AssetIdentifier element for Period 5 may identify that period 5 comprises the movie and the @start attribute for Period 5 may identify that period 5 begins at 25 minutes on the presentation timeline. The AssetIdentifier element for Periods 6-8 may identify that period 6-8 comprise assets different from the movie, and an @start attribute for Period 6 may identify that period 6 begins at 35 minutes on the presentation timeline, so the client  150  may determine that the asset timeline for the movie should include only 10 minutes for period 5. The AssetIdentifier element for Period 9 may identify that period 9 comprises the movie and the @start attribute for Period 9 may identify that period 9 begins at 50 minutes on the presentation timeline. There are no further Periods, so the client  150  may determine that the asset timeline for the movie should include the 10 minutes for Period 9. By adding the 10-minute periods for the movie, the client  150  may determine that the movie lasts for 30 minutes, so the client  150  may be able to determine an asset timeline for the movie. 
         [0048]    Third, the MPD  400  may comprise AssetIdentifier elements for Periods 1, 5, and 9 that uniquely identify periods 1, 5, and 9 as comprising the movie. Furthermore, the AssetIdentifier elements for Periods 1, 5, and 9 may comprise @start attributes that directly specify times on an asset timeline, as opposed to on a presentation timeline, which corresponds to the start times of periods 1, 5, and 9. The client  150  may therefore directly determine an asset timeline for the movie. 
         [0049]    In a second embodiment, the element may be an AssetIdentifier element of the type DescriptorType. Like the first embodiment above, the AssetIdentifier element in the second embodiment may be used to identify an asset on the period level and specify that a period belongs to a certain asset. Alternatively, the AssetIdentifier element may be used to identify an asset at other levels as well. If the client  150  does not recognize the AssetIdentifier element, then the client  150  may ignore the AssetIdentifier element. The AssetIdentifier element may be unique for each asset, not for each MPD. The AssetIdentifier element may comprise an @schemeIdUri attribute and an @value attribute. The @schemeIdUri attribute may specify a uniform resource identifier (URI) to identify a scheme. The @value attribute may be used to indicate whether the asset comprises main content or inserted content. Inserted content may refer to ad content or any other content that is not main content. An example of the XML syntax corresponding to the AssetIdentifier element may be as follows: 
         [0000]                                            &lt;AssetIdentifier schemeIdUri=”urn:org:somelabs:asset-id”           value=”main”&gt;10.5240/           1489-49A2-3956-4B2D-FE16-5&lt;/ AssetIdentifier &gt;.                        
In the example above, the @schemeIdUri attribute may specify a URI to identify a scheme that indicates that the @value attribute and the element content are to be interpreted as described in the second embodiment, the @value attribute may indicate that the asset is main content, and the element content may indicate an EIDR of an associated asset. Because the AssetIdentifier element does not comprise an @start attribute, the client  150  may not use the second or third method for calculating an asset timeline described above. Rather, the client  150  may use the first method for calculating an asset timeline described above.
 
         [0050]    By determining an asset timeline for the movie, the client  150  may be able to properly implement a progress bar for the movie and random access functionality on the asset timeline. Furthermore, by identifying ads by the @type attribute of the AssetIdentifier element, the client  150  may be able to determine when it downloads ads and may therefore report to the HTTP server  110  or the ad server  140  when it does so. Alternatively, by identifying ads by the @type attribute of the AssetIdentifier element, the HTTP server  110  may be able to determine when it uploads the MPD  400  associated with ads and may therefore report to the ad server  140  when it does so. Finally, by uniquely identifying assets by the @assetId attribute of the AssetIdentifier element, the client  150  may access additional information about those assets, for instance a title, a summary, an actor, an actress, a rating, trivia, a review, social media data, and information about a product or service being advertised. 
         [0051]    In addition to the AssetIdentifier element, an element for implementing trick mode restrictions, for instance a TrickModeRestriction element, may be introduced. The TrickModeRestriction element may comprise the attributes shown in Table 2. 
         [0000]                                  TABLE 2                   TrickModeRestriction element and corresponding attributes            Element or               Attribute Name   Use   Description               TrickModeRestriction               @minSpeed   OD   Minimum allowed trick play speed.               Default value is −INF.       @maxSpeed   OD   Maximum allowed trick play speed.               Default value is INF.               Legend:       For attributes: M = Mandatory; O = Optional; OD = Optional with Default Value; CM = Conditionally Mandatory.       For elements: &lt;minOccurs&gt; . . . &lt;maxOccurs&gt; (N = unbounded).       Elements have uppercase first letters or camel-casing; attributes have a preceding @ symbol.            
As shown in Table 2, the TrickModeRestriction element may comprise @minSpeed and @maxSpeed attributes. The @minSpeed attribute may define the minimum allowed trick play speed. The @maxSpeed attribute may define the maximum allowed trick play speed. Speed may be referred to as the factor which the presentation rate is multiplied by for trick mode purposes. Speed may be identical to the Speed header defined in section 12.35 of Internet Engineering Task Force (IETF) Request for Comments (RFC) 2326, Real Time Streaming Protocol (RTSP), 1998, which is incorporated in its entirety. Speeds less than zero may represent rewind speeds, a speed of zero may represent a pause, speeds between zero and one may represent slow-motions speeds, a speed of one may represent normal speed, and speeds greater than one may represent fast forward speeds. These trick mode restrictions may be behavioral restrictions that regulate client  150  behavior and may be unrelated to whether there are, for instance, SubRepresentations that support such trick modes. The trick mode restrictions may be implemented in multiple ways. For example, they may be implemented via a dedicated client  150 -specific descriptor and an element at the Period level. Alternatively, they may be implemented via elements of the SCTE 130-10 schema defined in Society of Cable Telecommunications Engineers (SCTE) Digital Program Insertion—Advertising Systems Interfaces, Part 10, Stream Restriction Data Model (SRDM), 2013, which is incorporated in its entirety. Such alternative implementation may comprise using an element of the type DescriptorType which contains an @schemeIdUri attribute indicating that SRDM elements are contained within it and contains XML elements and attributes defined in SRDM.
 
         [0052]    The MPD  400  may associate a TrickModeRestriction element with a specific Period. For example, because Periods 2-4 and 6-8 are associated with ads, the MPD  400  may provide a TrickModeRestriction element for Periods 2-4 and 6-8. Accordingly, trick modes may be limited or completely unavailable for Periods 2-4 and 6-8 to ensure that the client  150  downloads, and the user views, the ad content associated with those Periods. An ad provider may determine the TrickModeRestriction element, the @minSpeed attribute, and the @maxSpeed attribute. 
         [0053]      FIG. 6  is a flowchart illustrating a method  600  according to an embodiment of the disclosure. The method  600  may be implemented, for instance, in the client  150 . At step  610 , a DASH MPD may be received. The DASH MPD may be the MPD  400 . The MPD may comprise an AssetIdentifier element associated with a period. The AssetIdentifier element may specify that the period belongs to a certain asset. The asset may be content including media and metadata together with the rights to use the content by a content provider. At step  620 , the MPD may be processed. The client  150  may process the MPD  400  and, for instance, implement a progress bar and random access functionality on an asset timeline. 
         [0054]    At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations may be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R l , and an upper limit, R u , is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R l +k*(R u −R l ), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. The use of the term “about” means +/−10% of the subsequent number, unless otherwise stated. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having may be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present disclosure. The discussion of a reference in the disclosure is not an admission that it is prior art, especially any reference that has a publication date after the priority date of this application. The disclosure of all patents, patent applications, and publications cited in the disclosure are hereby incorporated by reference, to the extent that they provide exemplary, procedural, or other details supplementary to the disclosure. 
         [0055]    While several embodiments have been provided in the present disclosure, it may be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented. 
         [0056]    In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and may be made without departing from the spirit and scope disclosed herein.