Abstract:
Systems and methods for combining streaming media content items for streaming to a client computer across a network are described. In one aspect, a playlist is maintained on a server computer. The playlist includes at least one reference to a streaming media content item and at least one placeholder. A request for a requested streaming media content item is received at the server computer from a client computer over a network. The server computer modifies the playlist to create a modified playlist by replacing at least one placeholder with a reference to a streaming media content item. This is accomplished such that the modified playlist includes at least one reference to the requested streaming media content item and at least one reference to at least one further streaming media content item. The streaming media content items referenced by the modified playlist are provided to the client computer over the network.

Description:
RELATED APPLICATION 
   This patent application is a divisional of U.S. patent application Ser. No. 09/892,922, filed on Jun. 26, 2001 now U.S. Pat. No. 7,076,478, titled “Wrapper Playlists on Streaming Media Services”, commonly owned herewith, and hereby incorporated by reference. 

   TECHNICAL FIELD 
   This disclosure relates to networked client/server systems and to methods of delivering requested content in such systems. More particularly, the subject matter relates to systems and methods for delivering client requested content to the client along with additional content. 
   BACKGROUND 
   When a client requests a piece of content such as digital video, audio, or some other content from a server, the client typically provides a global address to the content in the form of a Uniform Resource Locator (URL). The server then accesses the addressed content and sends or “streams” it to the client in the form of a continuous digital data stream. 
   There are various file data formats for streaming digital media content and composite media streams. “Advanced Streaming Format” (ASF) is an example of such a data file format. ASF (sometimes referred to as WINDOWS Container Media Format) specifies a way in which multimedia data content is stored, streamed, and presented by a variety of tools, servers, and clients of a number of different multimedia vendors. ASF provides a storage and transmission data file format that encapsulates multimedia data types (e.g., images, audio, and video) as well as embedded text (e.g., a URL) and also allows for synchronizing these objects within a digital data stream. (Further details about ASF are available from Microsoft Corporation of Redmond, Washington). 
   Regardless of which of a number of different streaming file data formats is used, an individual data stream includes a sequence of digital data sets or units. The units represent an image, sound, or some other stimuli that is perceived by a human to be continuously varying. The client renders the units individually, in sequence, to reproduce the original stimuli. For example, an audio data stream comprises a sequence of sample values that are converted to a pitch and volume to produce continuously varying sound. A video data stream comprises a sequence of digitally specified graphics frames that are rendered in sequence to produce a moving picture. 
   In the simplest case, a client requests a single streaming media content file, to reproduce, or “play” a single piece of content such as a song or a video. Alternatively, the client may request a playlist, or “playlist file” that includes a number of different references to individual streaming media content files. Each playlist file includes information such as information to reference specific pieces of content, an order in which to play the referenced content, and other information (e.g., whether to play certain pieces of referenced content more than one time). In other words, a playlist file not only references media content, but also describe how pieces of media content are combined. 
   Playlists do not normally contain the actual media data, but rather particular references (i.e., a URL) to stored media data. As a result, a playlist file is typically small in size, generally only contains text, and is typically easy and computationally inexpensive to modify. (A reference to a single piece of media content may appear in any number of different playlist files). 
   A playlist is typically created in predetermined format. The Synchronized Multimedia Integration Language (version. 2.0), referred to as “SMIL” is an example of such a predetermined format. SMIL is an extension of the World Wide Web Consortium (W3C) standard Extensible Markup Language (XML). SMIL provides syntax and structure to define both high-level instructions and data corresponding to the content referenced by a playlist. (The specification for SMIL is well understood in the computing industry). 
   A playlist can be implemented on a client computer or on a server computer. When a client implements a playlist, the playlist is typically downloaded from a server. The client interprets the downloaded playlist file to present a series of requests to the server, for every piece of content represented in the playlist. A server, upon receipt of a media content request from a client, is generally not aware that the client is requesting media content that is referenced in a client implemented, or “client-side” playlist file. This is because use of a client-side playlist is indistinguishable from a client requesting a server to play one or more respective pieces of media content one-after-the-other. 
   A server implemented playlist, or “server-side” playlist is maintained by a server and is not downloaded to a client. To access media content represented in a server-side playlist, a client typically selects a URL that identifies both a server and a particular playlist file. Responsive to receiving a request from the selection of such a URL, the identified server accesses the requested playlist and streams, or “plays” the media content referenced by the playlist to the requesting client, one piece of media content at a time. 
   Regardless of whether a playlist is implemented on a server or on a client, a playlist can play a substantially important role in building a business based on advertising, source branding, service branding, and/or other revenue basis. For example, a playlist file can allow a content provider (e.g., an Internet radio station) to embed, or combine an advertisement, a brand name, and/or other content such as multimedia content previews, radio-station identifiers and/or the like with scheduled media content. Every time that a content provider chooses to modify an advertisement, branding information, and/the like, that is embodied in a playlist, the content provider must typically modify the playlist to excise the old content to incorporate the new content. Or, the content provider can remove the old playlist and create a completely new playlist to reflect the change(s). Such playlist modifications and may be brought about for any number of reasons such as changes in business methods, regulatory constraints, audience demographics, and/or the like. It can be appreciated that a content provider such as a radio or television station may have any number of playlists (e.g., one playlist, one-hundred playlists, one thousand playlists, or more) that need to be modified, and or created to reflect such changes. Thus such playlist media content changes typically require a substantial amount of administrative overhead. 
   SUMMARY 
   Systems and methods for combining streaming media content items for streaming to a client computer across a network are described. In one aspect, a playlist is maintained on a server computer. The playlist includes at least one reference to a streaming media content item and at least one placeholder. A request for a requested streaming media content item is received at the server computer from a client computer over a network. The server computer modifies the playlist to create a modified playlist by replacing at least one placeholder with a reference to a streaming media content item. This is accomplished such that the modified playlist includes at least one reference to the requested streaming media content item and at least one reference to at least one further streaming media content item. The streaming media content items referenced by the modified playlist are provided to the client computer over the network. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram that illustrates aspects of an exemplary system to deliver additional content along with requested content from a server to a client. 
       FIG. 2  is a block diagram that illustrates aspects of an exemplary playlist wrapper data structure that refers to one or more content items. 
       FIG. 3  is a block diagram that illustrates aspects of an exemplary playlist wrapper data structure or playlist that refers to one or more content items. 
       FIG. 4  is a block diagram that illustrates aspects of an exemplary copy of a playlist wrapper data structure, or playlist that refers to one or more content items. 
       FIG. 5  is a block diagram that illustrates aspects of a modified playlist wrapper data structure or playlist that refers to one or more content items along with a client requested content item. 
       FIG. 6  is a flowchart that illustrates aspects of an exemplary methodology for a server to stream content items to a client. 
       FIG. 7  is a block diagram that illustrates aspects of an exemplary server computer to deliver additional content along with requested content to a client. 
   

   DETAILED DESCRIPTION 
   The following description sets forth a specific embodiment of a server component and methodology that incorporates elements recited in the appended claims. The embodiment is described with specificity in order to meet statutory requirements. However, the description itself is not intended to limit the scope of this patent. Rather, the inventors have contemplated that the claimed subject matter might also be embodied in other ways, to include different elements or combinations of elements similar to the ones described in this document, in conjunction with other present or future technologies. 
   Exemplary System Environment 
     FIG. 1  shows a client/server network system  100  and environment. Generally, the system includes one or more network server computers  102  and multiple network client computers  104 . The computers communicate with each other over a data communications network  106  such as the Internet. The data communications network might also comprise intranets, local-area networks and private wide-area networks. The system has associated data storage media  106 . 
   In one embodiment, server  102  is a streaming media content server that receives URLs or other references that indicate streaming media content, files, and/or sources. For example, the URL might identify an ASF (.asf) file. A variety of requests from the client are typically received by server  102 , and might identify requested content in a variety of different forms other than the URL form. Furthermore, some requests might not be processed in accordance with the technique described below. However, at least one subset of the received requests includes requests to one or more different content items that will be processed in accordance with the described technique. 
   In response to receiving the content request, the server  102  identifies or creates a data structure, or content template that refers to one or more other content items. In the described embodiment, the content template comprises a playlist. The playlist or other type of data structure can be created in a number of different data formats. SMIL provides an example of a suitable format. 
   The data structure acts as a wrapper or content template because the data structure specifies content that will wrap or frame at least a subset of the content sent by a server  102  to a client  104 . 
   After identifying the appropriate base data structure, the server  102  modifies the data structure to reference the requested content item by inserting the requested URL into the playlist&#39;s sequence of URLs. In most cases, this modification will be performed on a copy of the base data structure. A copy of the base data structure is a duplicate playlist. After the base playlist has been modified in this manner, server  102  provides the content items referenced by the modified data structure or playlist to the client  104 . 
     FIG. 2  shows an exemplary data structure  200  to reference one or more items of content. The data structure includes a sequence of one or more references  202  to content items. In the described implementation, the references are URLs. Additionally, the data structure includes a placeholder  204 , or flag that identifies a particular point in a sequence where the reference to the client requested content is to be placed. The placeholder  204  can be located at any position with respect to the references  202 . 
   There can be any number of placeholders  204  in the data structure  200 , each placeholder identifying a particular point in a sequence where the reference to the client-requested content is to be placed. If there is more than one placeholder, the total number of placeholders is analogous to a repeat count of how may times the client requested content will be referenced in the data structure. Optionally, the number and position of each placeholder is indicated in the client&#39;s request for the content item. 
   Although the implementation that is described above has been applied to playlists and streaming media, there are other types of content that might benefit from this approach. For example, the client&#39;s request might be for any other type of a document or file such as a Web page (e.g., an HTML document). In this case, the data structure  200  can be represented in the file/document/Web page specification with a placeholder indicating where the requested content, or reference to the content is to be inserted. 
   It can be appreciated that other types and combinations of content besides streaming media files are also possible such as bitmaps, JPEGs, MPEGs, and/or the like. 
     FIG. 3  is a block diagram that shows an exemplary base playlist  206  that references one or more items of streaming media content. The playlist is one example of a data structure  200  of  FIG. 2 . In this implementation, the playlist references streaming media content items by identifying the content items with respective URLs  208 . The playlist also includes a placeholder  210 , or flag to identify a particular point in a sequence where a reference to client requested content is placed. The placeholder can be located at any position with respect to the one or more references or URLs. 
     FIG. 4  is a block diagram that shows an exemplary copy  212  of a base data structure  206  or playlist. A copy of a base data structure  206  or playlist is a duplicate data structure or playlist. The copy/duplicate is modified to reference client requested content item(s). Because playlist  212  is a copy of playlist  206 , playlist  212  includes streaming media content references  208  and placeholder  210 . 
   A client plays a temporary copy  212  of the wrapper playlist file  206 , so modifying the temporary copy for one client request will not affect any other concurrent or future client requests. Thus, a server is able to apply a same wrapper playlist to any number of different clients that request any number of different original URL&#39;s. This is because each requesting client will play their own requested URL in a private copy of the wrapper playlist. 
   A URL  214  represents an item of content requested by a client. In this example, the client&#39;s content request refers to streaming media content file “newstuff.asf”. Server  102  modifies playlist  212  to reference the requested content item. This modification is illustrated in  FIG. 5 . 
     FIG. 5  is a block diagram that shows an exemplary playlist  212  after it has been modified. Specifically, the server  102  has inserted a URL  214  into the playlist  212  at the location identified by a placeholder  210 . A server can use this technique to “wrap” other content items around a client-requested content item. The client  104  does is not required to do anything special to receive the other content items. This is because the server automatically translates the client&#39;s request for a particular content item into a request for the particular content item and the other content items. 
   To illustrate this, consider a playlist that includes the HTML instruction sequence shown in Table 1. 
   
     
       
             
           
             
             
           
         
             
               TABLE 1 
             
             
                 
             
             
               EXAMPLE OF A PLACEHOLDER IN A WRAPPER PLAYLIST 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
                 
               &lt;HTML&gt; 
             
             
                 
               &lt;SEQ&gt; 
             
             
                 
                &lt;MEDIA src=“http://advertisements/ advertisement1.asf“/&gt; 
             
             
                 
                &lt;MEDIA src=“%url%”/&gt; 
             
             
                 
                &lt;MEDIA src=“http://advertisements/advertisement2.asf“/&gt; 
             
             
                 
               &lt;/SEQ&gt; 
             
             
                 
               &lt;/HTML&gt; 
             
             
                 
                 
             
           
        
       
     
   
   A placeholder  214  in the above HTML sequence is identified by “% url %”. The server replaces every occurrence of the string “% url %” with a URL requested by the client. For example, consider a playlist that includes the HTML sequence shown in Table 2. 
   
     
       
             
           
             
             
           
         
             
               TABLE 2 
             
             
                 
             
             
               EXAMPLE OF WRAPPING OTHER URLS AROUND A 
             
             
               A CLIENT REQUESTED URL 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
                 
                 &lt;HTML&gt; 
             
             
                 
                 &lt;SEQ&gt; 
             
             
                 
                  &lt;MEDIA src=“http://advertisements/ advertisement1.asf”/&gt; 
             
             
                 
                  &lt;MEDIA 
             
             
                 
               src=“http://serverName/FeatureMovies/BigActionMovie.asf”/&gt; 
             
             
                 
                  &lt;MEDIA src=“http://advertisements/advertisement2.asf“/&gt; 
             
             
                 
                 &lt;/SEQ&gt; 
             
             
                 
                 &lt;/HTML&gt; 
             
             
                 
                 
             
           
        
       
     
   
   Note that the “% url %” placeholder has been replaced with a client requested URL  214  (http://serverName/FeatureMovies/BigActionMovie.asf). 
   In these examples, the playlists of Tables 1 and 2 are illustrated using the SMIL data format. However, the SMIL format is used for illustration purposes only, and a wrapper playlist can be generated and/or modified using instructions and/or data represented in one of a number of other multimedia integration formats. 
   Using a playlist structure and technique as described, allows a server to add advertisements, previews of coming attractions, or other content to a playlist sequence without having to modify an original playlist, or change a URL that corresponds to the original playlist. A data structure or playlist is not restricted to placing advertisements before a requested URL. Such playlists can be used to specify that a client will receive any stream of content that can be described by the playlist language, and that the original requested URL may appear anywhere and any number of times in this sequence of content. Moreover, as discussed above, any other playlist attributes that can be applied to content, such as repeat count and/or the like, can also be applied to the original requested content reference (e.g., a URL). 
   Furthermore, a data structure such as this allows an administrator to specify an advertising policy by editing the content of the playlist. The policy can easily be changed, by simply editing the base playlist. As a result, the discussed problem of configuring an advertising policy is turned into a much simpler problem of authoring an advertising template or playlist to frame or wrap all content. Authoring content is a well-understood problem and many existing tools for authoring Web content can help with this task. 
   In some cases, a server may store a standard playlist that is applied to all incoming client requests for content items. In other implementations, a collection of base playlists can be stored for use with different types of requests. Requests can be distinguished, for example, by a storage location of the referenced content, by a file name or extension indicated in the request, and/or by a variety of other distinguishing factors. 
   As discussed above, base data structures or wrappers can be useful for other types of servers besides streaming media servers. For example, a Web server typically serves Web pages that contain multiple references or URLs specified in a format such as HTML (hypertext markup language). A document such as this can be used as a template or wrapper according to the novel procedures discussed above, by including a placeholder indicating where embedded content should be located. When a client requests a Web page specification by supplying a URL reference, the server inserts this URL reference into the wrapper, in place of the placeholder, and then serves the resulting Web page. 
   To illustrate this, consider that a client requests a URL, for example, “http://server/doc1.htm”. The Web server responds by making a temporary copy of a “wrapper” HTML document. The Web server then modifies the temporary copy by inserting the originally requested URL (“http://server/doc1.htm”) into the contents of the wrapper document. 
   The “wrapper” HTML document may place banner advertisements and other helpful links around the originally requested content. When the modified temporary copy of the wrapper html document is presented to the user, the contents of the original URL “http://server/doc1.htm” might then appear in the middle of the wrapper document. 
   Exemplary Procedure 
     FIG. 6  is a flowchart diagram that shows an exemplary procedure  600  to stream data from a server to a client. At block  610 , the procedure receives a request from a client for one or more content items. At block  612 , the procedure identifies a data structure that refers to one or more further content items. At block  614 , the procedure modifies the data structure to reference the requested content items. At block  616 , the procedure provides the requested content items (block  610 ) referenced by the modified data structure (block  614 ) to the requesting client (block  610 ). 
   Exemplary Computer Environment 
     FIG. 7  shows components of computer  700  that forms a suitable environment for a server computer  102  of  FIG. 1 . The components shown in  FIG. 7  are only examples, and are not intended to suggest any limitation as to the scope of the functionality of the subject matter; the subject matter is not necessarily dependent on the features shown in  FIG. 7 . 
   Generally, various different general purpose or special purpose computing system configurations can be used. Examples of well known computing systems, environments, and/or configurations that may be suitable for use with the subject matter include, but are not limited to, personal computers, server computers, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like. 
   The functionality of a computer is embodied in many cases by computer-executable instructions, such as program modules that are executed by the computer. Generally, a program module includes routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Tasks might also be performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media. 
   The instructions and/or program modules are stored at different times in the various computer-readable media that are either part of the computer or that can be read by the computer. Programs are typically distributed, for example, on floppy disks, CD-ROMs, DVD, or some form of communication media such as a modulated signal. From there, they are installed or loaded into the secondary memory of a computer. At execution, they are loaded at least partially into the computer&#39;s primary electronic memory. The subject matter described herein includes these and other various types of computer-readable media when such media contain instructions programs, and/or modules for implementing the steps described below in conjunction with a microprocessor or other data processors. The subject matter also includes the computer itself when programmed according to the methods and techniques described below. 
   For purposes of illustration, programs and other executable program components such as the operating system are illustrated herein as discrete blocks, although it is recognized that such programs and components reside at various times in different storage components of the computer, and are executed by the data processor(s) of the computer. 
   With reference to  FIG. 7 , the components of computer  700  may include, but are not limited to, a processing unit  720 , a system memory  730 , and a system bus  721  that couples various system components including the system memory to the processing unit  720 . The system bus  721  may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISAA) bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnect (PCI) bus also known as the Mezzanine bus. 
   Computer  700  typically includes a variety of computer-readable media. Computer-readable media can be any available media that can be accessed by computer  700  and includes both volatile and nonvolatile media, removable and non-removable media. By way of example, and not limitation, computer-readable media may comprise computer storage media and communication media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computer  710 . 
   Communication media typically embodies computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more if its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of any of the above should also be included within the scope of computer readable media. 
   The system memory  730  includes computer storage media in the form of volatile and/or nonvolatile memory such as read only memory (ROM)  731  and random access memory (RAM)  732 . A basic input/output system  733  (BIOS), containing the basic routines that help to transfer information between elements within computer  700 , such as during start-up, is typically stored in ROM  731 . RAM  732  typically contains data and/or program modules that are immediately accessible to and/or presently being operated on by processing unit  720 . By way of example, and not limitation,  FIG. 7  illustrates operating system  734 , application programs  735 , other program modules  736 , and program data  737 . 
   Such application programs  735  include server component  738 , which responds to client requests for content by providing the requested content and additional content to the client. Aspects of an exemplary methodology of server component  738  were described above in reference to  FIGS. 7-6 . 
   The computer  700  may also include other removable/non-removable, volatile/nonvolatile computer storage media. By way of example only,  FIG. 7  illustrates a hard disk drive  741  that reads from or writes to non-removable, nonvolatile magnetic media, a magnetic disk drive  751  that reads from or writes to a removable, nonvolatile magnetic disk  752 , and an optical disk drive  755  that reads from or writes to a removable, nonvolatile optical disk  756  such as a CD ROM or other optical media. Other removable/non-removable, volatile/nonvolatile computer storage media that can be used in the exemplary operating environment include, but are not limited to, magnetic tape cassettes, flash memory cards, digital versatile disks, digital video tape, solid state RAM, solid state ROM, and the like. The hard disk drive  741  is typically connected to the system bus  721  through an non-removable memory interface such as interface  740 , and magnetic disk drive  751  and optical disk drive  755  are typically connected to the system bus  721  by a removable memory interface such as interface  750 . 
   The drives and their associated computer storage media discussed above and illustrated in  FIG. 7  provide storage of computer-readable instructions, data structures, program modules, and other data for computer  700 . In  FIG. 7 , for example, hard disk drive  741  is illustrated as storing operating system  744 , application programs  745 , other program modules  746 , and program data  747 . Note that these components can either be the same as or different from operating system  734 , application programs  735 , other program modules  736 , and program data  737 . Operating system  744 , application programs  745 , other program modules  746 , and program data  747  are given different numbers here to illustrate that, at a minimum, they are different copies. A user may enter commands and information into the computer  700  through input devices such as a keyboard  762  and pointing device  761 , commonly referred to as a mouse, trackball, or touch pad. Other input devices (not shown) may include a microphone, joystick, game pad, satellite dish, scanner, or the like. These and other input devices are often connected to the processing unit  720  through a user input interface  760  that is coupled to the system bus, but may be connected by other interface and bus structures, such as a parallel port, game port, or a universal serial bus (USB). A monitor  791  or other type of display device is also connected to the system bus  721  via an interface, such as a video interface  790 . In addition to the monitor, computers may also include other peripheral output devices such as speakers  797  and printer  796 , which may be connected through an output peripheral interface  795 . 
   The computer may operate in a networked environment using logical connections to one or more remote computers, such as a remote computer  780 . The remote computer  780  may be a personal computer, a server, a router, a network PC, a peer device or other common network node, and typically includes many or all of the elements described above relative to computer  700 , although only a memory storage device  781  has been illustrated in  FIG. 7 . The logical connections depicted in  FIG. 7  include a local area network (LAN)  771  and a wide area network (WAN)  773 , but may also include other networks. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets, and the Internet. 
   When used in a LAN networking environment, the computer  700  is connected to the LAN  771  through a network interface or adapter  770 . When used in a WAN networking environment, the computer  700  typically includes a modem  772  or other means for establishing communications over the WAN  773 , such as the Internet. The modem  772 , which may be internal or external, may be connected to the system bus  721  via the user input interface  760 , or other appropriate mechanism. In a networked environment, program modules depicted relative to the computer  700 , or portions thereof, may be stored in the remote memory storage device. By way of example, and not limitation,  FIG. 7  illustrates remote application programs  785  as residing on memory device  781 . It will be appreciated that the network connections shown are exemplary and other means of establishing a communications link between the computers may be used. 
   CONCLUSION 
   Although various implementations of the described subject matter have been described in language specific to structural features and/or methodological operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or steps described. Rather, the specific features and operations are disclosed as exemplary forms of implementing the claimed subject matter.