Patent Application
20090178096
As computing and communication networks continue to evolve, media is increasingly being stored, shared, and played over these networks. However, network-based media players can be adversely impacted by network constraints. For example, a wireless network may not have sufficient bandwidth for glitch-free playback of streamed media.
Some network-based media players enable a user to stream PC-based TV and media content to network-connected consumer electronics devices elsewhere in the home. When connected via a wireless network, such media players may experience packet loss during media streaming. When confronted with packet loss, a media player has two choices. First, the media player may skip the lost packets and play what content it has. This may result in image corruption onscreen. Second, the media player may request retransmission of the lost packets and delay playback until those packets are received. This may result in the video playback pausing during retransmission.
One approach to such issues involves sending duplicate copies of every packet (“multi-sending”). This approach decreases the probability that a packet will not be received, but may overload wireless networks and may therefore generate more packet loss. Another approach may comprise multi-sending only key frame data when a network is congested. However, hard-coded approaches are ultimately of limited use due to the dynamic nature of wireless networks.
Accordingly, various embodiments for predictive multi-sending of media data segments are described below in the Detailed Description. For example, one embodiment comprises monitoring one or more variable data transmission parameters, detecting one or more invariant media data segment parameters, assigning a value to the media data segment based upon the one or more invariant media data segment parameters and the one or more variable data transmission parameters, comparing the value to a threshold, and sending multiple copies of the media data segment over a network link to a media receiver if the value is above the threshold.
This Summary is provided to introduce concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.
Prior to discussing embodiments for predictive multi-sending of data stream segments, an example streaming media use environment is described.
Instead of a conventional PC, the media server 106 may comprise a variety of other devices capable of storing and distributing media data, including, for example, a notebook or portable computer, a tablet PC, a workstation, a server, an Internet appliance, a DVR, or combinations thereof. The media server 106 may also be a set-top box capable of delivering media data to a computer where it may be streamed, or the set-top box itself could stream the media data. As the media server 106 may be a full function computer running an operating system, the user may also have the option to run standard computer programs (e.g., word processing and spreadsheets), send and receive e-mails, browse the Internet, or perform other functions.
In addition to storing media data, the media server 106 may be connected with a variety of media sources, for example, a cable connection 114, a satellite receiver 116, an antenna (not shown), and/or a network such as the Internet 118. A user may thus control a live stream of media data (e.g., TV content) received, for example, via the cable connection 114, the satellite receiver 116, or antenna. This capability may be enabled by one or more tuners residing in the media server 106. The one or more tuners may alternatively be located remote from the media server 106. In either case, the user may choose a tuner to fit any particular preferences. For example, a user wishing to watch both standard definition (SD) and high definition (HD) content may employ a tuner configured for both types of content. Alternately, the user may employ an SD tuner for SD content and an HD tuner for HD content separately.
The TV content may be received as an analog (i.e., radio frequency) signal or a digital signal (e.g., digital cable). The received TV content may include discrete content packets, where each content packet includes actual TV content (i.e., audio and video data. If TV content is received as an analog signal, discrete content packets may be created from the analog signal.
The entertainment environment 100 may also include one or more network devices functioning as media receivers 122, 126 placed in communication with the media server 106 through a network 128, for example, a local area network (LAN). In an exemplary embodiment, each media receiver 122, 126 may be a Media Center Extender device, for example, an Xbox 360™ (Microsoft Corporation, Redmond, Wash.). The media receivers 122, 126 may also be implemented as any of a variety of conventional media rendering or computing devices, including, for example, a set-top box, a television, a video gaming console, a desktop PC, a notebook or portable computer, a workstation, an Internet appliance, a handheld PC, a cellular telephone or other wireless communications device, a personal digital assistant (PDA), a network capable device, or combinations thereof. Furthermore, the media receivers 122, 126 may include a tuner as described above.
The network 128 may comprise a wired and/or wireless network, for example, cable, Ethernet, WiFi, a wireless access point (WAP), or any other electronic, radio frequency or optical coupling means, including the Internet. The network 128 may enable communication between the media server 106, the media receivers 122 and 126, and any other connected device through packet-based communication protocols, such as Transmission Control Protocol (TCP), Internet Protocol (IP), Real-time Transport Protocol (RTP), User Datagram Protocol (UDP) and Real-time Transport Control Protocol (RTCP), or other packet based communication protocols, as examples. Communications may be transmitted directly between devices over a LAN, or they may be carried over a wide area network (WAN), for example, the Internet 118.
Entertainment environment 100 may include one or more video display devices, for example a main TV 120 in the living room 102, a secondary TV 124 in the bedroom 104, and a video monitor 112 in the entertainment environment 100. These video display devices may be connected with the media server 106 via the network 128 either directly or via the media receivers 122, 126. As shown in the example of
The media receivers 122, 126 may be configured to receive streamed media data, including video and TV content, from the media server 106. Media data, and particularly video and TV content, may be transmitted from the media server 106 to the media receivers 122, 126 as streaming media comprised of discrete content packets via the network protocols described above, or even other network protocols. The streamed media data may comprise IPTV (television content delivered over the Internet), SD, and HD content, including video, audio, and image files, decoded on the media receivers 122, 126 for presentation on the connected TVs 120, 124 or monitor 112. The media data may further be “mixed” with additional content, for example, an EPG, presentation content related to the media data, a web browser window, and other user interface environments transmitted from the media server for output on the TVs 120, 124 or the monitor 112. Such additional media data may be delivered in a variety of ways using different protocols, including, for example, standard Remote Desktop Protocol (RDP), Graphics Device Interface (GDI), Hypertext Markup Language (HTML), or other protocols providing similar functionality.
In addition to the media receivers 122, 126 and the video display devices 112, 120, 124, the media server 106 may be connected with other peripheral devices, including components such as a DVR, cable or satellite set-top boxes, speakers, a printer (not shown), etc. The media server 106 and/or media receivers 122, 126 may also enable multi-channel output for speakers. This may be accomplished through the use of digital interconnect outputs, such as Sony-Philips Digital Interface Format (S/PDIF) or TOSLINK®, enabling the delivery of Dolby Digital, Digital Theater Sound (DTS), or Pulse Code Modulation (PCM).
It will be appreciated that the embodiments described herein may be implemented, for example, via computer-executable instructions or code, such as programs, stored on a computer-readable storage medium and executed by a computing device. Generally, programs include routines, objects, components, data structures, and the like that perform particular tasks or implement particular abstract data types. As used herein, the term “program” may connote a single program or multiple programs acting in concert, and may be used to denote applications, services, or any other type or class of program. Likewise, the terms “computer” and “computing device” as used herein include any device that electronically executes one or more programs, including, but not limited to, media server 106, media receivers 122, 126, and any other suitable device such as personal computers, servers, laptop computers, hand-held devices, cellular phones, microprocessor-based programmable consumer electronics and/or appliances, routers, gateways, hubs and other computer networking devices.
Continuing with the Figures,
Media server 106 includes an audio/video (A/V) source 210 coupled to an A/V network sender 212 to transmit media data over a network link to media receiver 122 for playback. Media server 106 also comprises a transmission control module 214 that includes over-transmission logic. The term “over-transmission”, as used herein, refers to the multiple sending of a segment of data to reduce the probability that the segment of data will not be received by media receiver 122. The over-transmission logic is configured to decide whether any selected segment of data is to be over-transmitted. In this manner, the over-transmission of data may be tailored to the specific application-layer characteristics of the data being sent, as well as to real-time network constraints. By operating at an application layer, or any other layer above a transport layer, the over-transmission of segments may allow over-transmission of segments of a different size than a transport layer packet, including large application layer segments that span multiple transport packet layer packets, as well as multiple small segments that fit inside a single transport layer packet. This may allow some embodiments to control transport or network packet size to manage network bandwidth while also providing a more robust delivery of the data. While the over-transmission logic is depicted as residing on the media server 106, in other embodiments the over-transmission logic may reside on another device in communication with media server 106. The over-transmission logic is described in more detail below.
Continuing with
As depicted in the embodiment in
As mentioned above, the over-transmission logic on transmission control module 214 is configured to intelligently decide whether or not to over-transmit media data from media server 106 to media receiver 122 based upon various inputs. This allows the over-transmission logic to adjust the over-transmission behavior of transmission control module 214 in response to characteristics of the network, the transmitted media data, the media receiver 122, retransmission requests received, and/or any other suitable factor. For example, over-transmission may be reduced or temporarily disabled if the bandwidth of the network link decreases, or may be increased if the bandwidth of the network link increases.
The decision of whether to over-transmit a media data segment may be made on any suitable factor. For example, in some embodiments, the decision of whether to over-transmit a media data segment may be based upon a determined consequence of the omission of the media data segment on playback performance, and/or a determined consequence of over-transmission on network performance as well as playback performance. In light of such factors, over-transmission of the media data may be utilized when it would improve media playback, and not utilized when it would degrade media playback.
Various inputs may be used to decide whether over-transmission is a net benefit or detriment to media playback performance. Such parameters include, but are not limited to, invariant media data segment parameters, and/or variable data transmission parameters. Invariant media data segment parameters that may be considered include, but are not limited to, a characteristic of the media data segment being sent (i.e. key frame or predictive frame); a type of media file format (e.g. Windows Media Video (WMV) data, MPEG-2 (Motion Picture Experts Group), etc.), a type of media data (audio or video); a distance between key frames in a data stream; a distance from a current predictive frame to a next key frame, etc. Variable data transmission parameters that may be considered include, but are not limited to, a relative fullness of a network receiver/buffer 220, a network capacity, a network latency, a current network utilization, a capability of the media receiver 122, etc.
Any suitable number of different parameters may be used to make a determination of whether to over-transmit data. For example, in some embodiments, a combination of network bandwidth limitations and data type/frame type parameters may be taken into consideration. As a specific example, if a transmitted media data segment contains WMV key frame data, the loss of the media data segment may result in video image corruption that persists until the next key frame is played. However, WMV data key frames may be spaced relatively far apart (e.g. on the order of seconds). Therefore, where bandwidth limitations exist, any pause in playback due to lag introduced by the over-transmission of the media data segment on a bandwidth-limited network link may be less noticeable than a seconds-long glitch caused by the loss of data. On the other hand, if the media data segment contains media data from a WMV bi-directionally predicted frame, loss of the data may cause a glitch that is no longer noticeable within milliseconds. In this case, a pause in playback due to lag caused by the over-transmission may be more disruptive than the glitch caused by the loss of data. Therefore, where network bandwidth is too low to over-transmit data without introducing a pause in playback, a decision on whether to over-transmit data may be made based upon the relative disruption of over-transmission compared to a data loss in light of the data format type and data frame type.
Further, an over-transmission behavior of transmission control module 214 may be modified depending upon changes in bandwidth availability. For example, at times when a network bandwidth is approximately equal to a media data stream bit-rate, over-transmission may be disabled, as in this case over-transmission may saturate the network and induce packet loss. Likewise, if network capacity is greater than or equal to a media data stream bit-rate in combination with a bit-rate of sending a stream of key frames in the absence of any predictive frames, then the key frames in the media data may be over-transmitted while the predictive frames are sent only once. In this case, the number of copies over-transmitted frames may depend upon the amount of additional bandwidth present. Additionally, if it is determined that network capacity is between the above two cases, over-transmission may be enabled whereby a subset of key frames, such as a copy of every nth key frame for example, is over-transmitted such that the available bandwidth is utilized without saturating the network.
In some embodiments, the media server 106 may encode media data at an application layer using media frames such as WMV frames, MPEG-2 frames, etc. When these frames are sent over a network link, they may be sent using transport layer protocols such as User Datagram Protocol (UDP), other transport layer protocols, or even protocols from other layers. The media data frames are often a different size than the transport layer protocol packets. For example, a WMV key frame may be substantially larger than 64 Kilobytes (KB) while a UDP packet may be 1460 bytes. Therefore, instead of a 1:1 mapping between media frames and transport packets, media frames are distributed over multiple packets.
In such cases, the over-transmission logic may either over-transmit an entire application-level data frame, or may be configured to make decisions regarding a size of a segment of media data to over-transmit in order to provide improved playback of a data stream. For example, if a number of packets needed to provide improved playback of a data stream is low as compared to a relative importance of the media frame to playback quality, the over-transmission logic may request over-transmission. On the other hand, if a number of packets needed is high as compared to the relative importance of the media frame, the over-transmission logic may refrain from over-transmission.
Continuing with the Figures,
Method 300 also comprises detecting one or more invariant media data segment parameters to be sent to a media receiver, as indicated in block 320. Such media data segment parameters may include, but are not limited to, a characteristic of the media data segment being sent (i.e. key frame or predictive frame); a type of media file format (e.g. Windows Media Video (WMV) data, MPEG-2 (Motion Picture Experts Group), etc.), a type of media data (audio or video), a distance between key frames in a data stream, a distance from a current predictive frame to a next key frame, etc.
Next, method 300 comprises assigning a value to a media data segment based upon one or more of the variable data transmission parameters and one or more of the invariant media data segment parameters, as indicated at 330. The term “value” as used herein refers generally to a quantification or qualification of a media data segment that allows a determination of whether to request data over-transmission to be made. The term may refer to any suitable data type, for example a string, a digit, an alphanumerical character, etc., or any other suitable representation of value.
The invariant media data characteristics may have any suitable effect on the value assigned. For example, in some embodiments, a higher value may be assigned to key frame data and a lower value may be assigned to predictive frame data. The terms “higher value” and “lower value” as used herein signify a greater or lesser propensity toward over-transmission, respectively, and are not intended to signify an actual magnitude of the values. Likewise, a higher value may be assigned to WMV key frames than to MPEG-2 key frames, as the WMV key frames may be more widely separated than the MPEG-2 key frames.
In some embodiments, a higher value may be assigned to audio data than to video data, as gaps in audio data may be perceived more easily by a user than gaps in video data. In other embodiments, a higher value may be assigned to video data than for audio data, as the loss of a video key frame may cause a disruption of a longer duration than the loss of an audio frame. Whether audio is assigned a higher or lower value than video may depend upon variable parameters, such as a user-set preference for one or the other.
The variable data transmission parameters may also have any suitable effect and/or weighting on the value assigned to a media data segment. For example, a higher value may be assigned where it is determined that a receiving device buffer is relatively empty, while a lower value may be assigned where it is determined that a receiving device buffer is relatively full. Likewise, a higher value may be assigned where it is determined that a relatively larger amount of network bandwidth is available, while a lower value may be assigned where a relatively smaller amount of network bandwidth is available. Similarly, higher values may be assigned for lower network latency, higher network capacity, etc.
Continuing with
Next, if the value meets a preselected condition relative to the threshold (e.g. greater than the threshold, greater than or equal to the threshold, or other suitable condition), as indicated in block 350, method 300 comprises over-transmitting copies of the media data segment. Any suitable number of copies of a media data segment may be over-transmitted. For example, a greater number of copies of a media data segment may be sent for a key frame, while a lesser number of copies may be sent for a frame considered to be of lesser importance to playback quality, such as a predictive frame. A number of copies over-transmitted may also depend upon available bandwidth, where a greater number of copies are sent when more bandwidth is available.
While described herein in the context of a home streaming media environment, it will be appreciated that the concepts disclosed herein may be used in any suitable streaming media environment, including, but not limited to, other client-server-based use environments and peer-to-peer-based use environments. Furthermore, while the media server and media receiver are shown herein as being located on different devices, it will be understood that these components may comprise separate components, modules, programs or other entities running on a single device.
It will further be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated may be performed in the sequence illustrated, in other sequences, in parallel, or in some cases omitted. Likewise, the order of any of the above-described processes is not necessarily required to achieve the features and/or results of the embodiments described herein, but is provided for ease of illustration and description. The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.
