ADAPTIVE VIDEO SWITCHING FOR VARIABLE NETWORK CONDITIONS

• US 20090328124A1
• Filed: 06/27/2008
• Published: 12/31/2009
• Est. Priority Date: 06/27/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: ZHANG, Wenbo, KHOUZAM, Gilles, GEORGE, Sam, HARSH, Mike, SCHLIEMANN, Federico, KARLOV, Donald
• Granted Patent: US 8,352,996 B2
• Time in Patent Office: Days
• US Class Current: 725/116
• CPC Class Codes: H04N 21/234354 by altering signal-to-noise ratio parameters, e.g. requantization
• CPC Class Codes: H04N 21/234363 by altering the spatial resolution, e.g. for clients with a lower screen resolution
• CPC Class Codes: H04N 21/234381 by altering the temporal resolution, e.g. decreasing the frame rate by frame skipping
• CPC Class Codes: H04N 21/23439 for generating different versions
• CPC Class Codes: H04N 21/44209 Monitoring of downstream path of the transmission network originating from a server, e.g. bandwidth variations of a wireless network arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896
• CPC Class Codes: H04N 21/4621 Controlling the complexity of the content stream or additional data, e.g. lowering the resolution or bit-rate of the video stream for a mobile client with a small screen arrangements for using the results of monitoring on user's side in broadcast systems H04H60/65; flow control in packet networks H04L47/10
• CPC Class Codes: H04N 21/47202 for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 21/633 Control signals issued by server directed to the network components or client management of faults, events, alarms in data networks H04L41/06
• CPC Class Codes: H04N 21/6373 for rate control , e.g. request to the server to modify its transmission rate flow control in packet networks H04L47/10
• CPC Class Codes: H04N 21/6377 directed to server one-way streaming services wherein the source is controlled by the destination H04L65/613
• CPC Class Codes: H04N 21/64738 Monitoring network characteristics, e.g. bandwidth, congestion level data switched network analysis H04L41/14; monitoring functioning in data switched networks H04L43/0817; flow control in packet networks H04L47/10
• CPC Class Codes: H04N 21/64769 for rate control flow control in packet networks H04L47/10

Abstract

A method for video playback switching in response to changing network conditions. The method includes accessing a server to retrieve respective index files for a low bit rate version and a high bit rate version of the video file, and instantiating a low bit rate media player and a high bit rate media. Playback of the video file is begun by the high bit rate media player streaming the high bit rate version from the server. Upon an indication of impeded network conditions, a transition point is selected, wherein the transition point indicates where downloading of the high bit rate version stops and where downloading of the low bit rate version begins. The low bit rate media player is then positioned to begin playback at the transition point. Playback of the video file is then switched to the low bit rate player upon encountering the transition point.

Claims

1. A method for video playback switching, comprising:

accessing a server to retrieve respective index files for a low bit rate version of a video file and a high bit rate version of the video file;

instantiating a low bit rate media player for the low bit rate version and a high bit rate media player for the high bit rate version;

beginning playback of the video file by the high bit rate media player streaming the high bit rate version from the server;

upon an indication of impeded network conditions, selecting a transition point within the high bit rate version, wherein the transition point indicates where downloading of the high bit rate version stops and where downloading of the low bit rate version begins;

positioning the low bit rate media player to begin playback at the transition point; and

switching playback of the video file from the high bit rate player to the low bit rate player upon encountering the transition point, where after the low bit rate player streams the low bit rate version from the server.

2. The method of claim 1 further comprising:

upon an indication of improved network conditions, selecting a transition point within the low bit rate version, wherein the transition point indicates where downloading of the low bit rate version stops and where downloading of the high bit rate version begins;

positioning the high bit rate media player to begin playback at the transition point; and

switching playback of the video file from the low bit rate player to the high bit rate player upon encountering the transition point, where after the high bit rate player resumes streaming the high bit rate version from the server.

3. The method of claim 1, wherein the video server further includes a plurality of different versions of the video file with each of the plurality of versions having a respective different bit rate, and wherein a corresponding plurality of respective different media players are instantiated to enable switching playback of the video file between the plurality of different versions to dynamically adapt to changing network conditions.

4. The method of claim 1, wherein the indication of impeded network conditions comprises a drainage state of a playback buffer within the high bit rate media player indicating the streaming is being impeded by the network conditions.

5. The method of claim 1, wherein the switching of the playback of the video file is controlled by a player arbiter coupled to the low bit rate media player and the high bit rate media player, and wherein switching appears seamless to a user.

6. The method of claim 1, wherein the low bit rate version of the video file is independently playable and wherein the high bit rate version of the video file is independently playable.

7. The method of claim 1, wherein the transition point is located at a keyframe to facilitate switching to the low bit rate player.

8. The method of claim 1, wherein the transition point is located a number of frames away from a keyframe, and wherein the number of frames and the keyframe are downloaded to position the low bit rate media player to begin playback at the transition point.

9. The method of claim 8, wherein the number of frames and the keyframe are downloaded in the background and the low bit rate media player is positioned to begin playback at the transition point in the background.

10. A method for adaptive video switching to respond to varying conditions, comprising:

receiving a request to playback a video file stored on a server;

in response to the request, accessing the server to determine how many different versions of the video file are stored on the server, where at least two of the different versions have a different bit rate;

instantiating a respective media player for each of the different versions of the video file;

beginning playback of a default one of the different versions using its corresponding media player;

monitoring a contention indicator within the corresponding media player;

when the contention indicator indicates impeded playback, selecting a transition point within default one of the different versions, wherein the transition point indicates where downloading of the default one of the different versions stops and where downloading of a subsequent one of the different versions begins;

positioning a subsequent media player to begin playback of the subsequent one of the different versions at the transition point; and

switching playback of the video file from the default one of the different versions to the subsequent one of the different versions upon encountering the transition point, where after the subsequent media player streams the subsequent one of the different versions from the server.

11. The method of claim 10, wherein the subsequent one of the different versions can be selected based upon its different file format or its different bit rate in comparison to the default one of the different versions.

12. The method of claim 10, wherein the subsequent one of the different versions can be selected based upon its different file format and its different bit rate in comparison to the default one of the different versions.

13. The method of claim 10, wherein the varying conditions comprises variable network transmission bandwidth.

14. The method of claim 10, wherein the varying conditions comprises variable processor availability for video playback.

15. The method of claim 10, wherein the contention indicator comprises a drainage state of a playback buffer within the corresponding media player indicating streaming is being impeded by the varying conditions.

16. The method of claim 10, wherein the switching of the playback of the video file is controlled by a player arbiter coupled to the respective media player for each of the different versions.

17. A computer readable media having computer executable code which, when executed by a processor of a computer system, causes the computer system to implement a method for adaptive video switching, comprising:

instantiating a first media player for a first version of a video file stored on a server;

instantiating a second media player for a second version of the video file stored on the server;

beginning playback of the first version by first media player streaming the first version from the server;

upon an indication of changed network conditions, selecting a transition point within the first version, wherein the transition point indicates where downloading of the first version stops and where downloading of the second version begins;

positioning the second media player to begin playback at the transition point; and

switching playback of the video file from the first player to the second player upon encountering the transition point, where after the second e player streams the second version from the server.

18. The computer readable media of claim 17, wherein the first version is a low bit rate version and the second version is a high bit rate version, and wherein the switching occurs when the changed network conditions indicate increased bandwidth is available.

19. The computer readable media of claim 17, wherein the first version is a high bit rate version and the second version is a low bit rate version, and wherein the switching occurs when the changed network conditions indicate decreased bandwidth is available.

20. The computer readable media of claim 17, wherein the transition point is located a number of frames away from a keyframe, and wherein the number of frames and the keyframe are downloaded to position the second media player to begin playback at the transition point.