METHODS AND APPARATUS FOR SUPPORTING VOD REQUESTS IN A SYSTEM WITH HIERARCHICAL CONTENT STORES

• US 20110131618A1
• Filed: 11/30/2009
• Published: 06/02/2011
• Est. Priority Date: 11/30/2009
• Status: Active Grant

• Current Assignee: Time Warner Cable Enterprises LLC (Charter Communications Incorporated)
• Original Assignee: Time Warner Cable Enterprises LLC (Charter Communications Incorporated)
• Inventors: Hasek, Charles
• Granted Patent: US 8,539,535 B2
• Time in Patent Office: Days
• US Class Current: 725/89
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04N 21/2183 Cache memory caches in web servers or browsers G06F16/9574; intermediate storage and caching in data networks H04L67/568
• CPC Class Codes: H04N 21/2225 Local VOD servers
• CPC Class Codes: H04N 21/26616 for merging a unicast channel into a multicast channel, e.g. in a VOD application, when a client served by unicast channel catches up a multicast channel to save bandwidth data multicast over packet-switching network H04L12/18
• CPC Class Codes: H04N 21/47202 for requesting content on demand, e.g. video on demand
• CPC Class Codes: H04N 21/47217 for controlling playback functions for recorded or on-demand content, e.g. using progress bars, mode or play-point indicators or bookmarks specific graphical features in visual interfaces H04N21/4312
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends

Abstract

Methods and apparatus for supporting video on demand requests in a system supporting hierarchical content stores, e.g., program caches, is described. Requested content is requested by a local streaming device from a remote cache when it is not available in a local cache. Content, e.g., I, P and B frames, supplied by the remote cache is tracked and content delivery is initiated prior to receipt of the full program from the remote content store. Trick play content is requested as needed from the remote content store to respond to trick play commands. Frames which are received as part of the trick play content stream are tracked and not included in normal play data subsequently obtained from the remote cache. The storage of the trick play data along with subsequent normal play data results in a full set of the program content being received and stored in a local cache for streaming in response to a VOD request.

Claims

1. A method of operating an apparatus to provide video content representing a program, the method comprising:

determining if sufficient data is locally available to support a trick playback operation corresponding to a received trick play command;

when it is determined that sufficient data is not locally available to support the trick playback operation, requesting trick play data from a remote cache;

tracking which frames are received as part of the trick play data from the remote cache; and

updating a set of locally stored normal playback data as a function of the received trick play data and additional frames received from said remote cache which are included in said normal play data but not said trick play data.

2. The method of claim 1, further comprising

receiving at least some additional data including said additional frames, required to complete the set of normal playback data corresponding to said program while receiving trick play data from said remote cache required to support said trick playback operation.

3. The method of claim 1, further comprising:

prior to receiving said trick play command, receiving frame data corresponding to said program from said remote cache at a rate sufficient to support the normal playback rate.

4. The method of claim 1, further comprising:

generating from received frame data, a set of normal playback rate data and a plurality of different sets of trick play data corresponding to different trick play data rates, each set of trick play data being a subset of said normal playback rate data; and

storing the generated set of normal playback data and said plurality of different sets of trick play data in a local storage device.

5. The method of claim 4, further comprising:

in response to receiving trick play data, updating said plurality of different sets of trick play data and said set of normal playback rate data with trick play data received from said remote cache.

6. The method of claim 5, wherein said received trick play data includes I-frames but not P-frames or B-frames.

7. The method of claim 5, further comprising:

keeping track of frames included in the received trick play data and normal play data.

8. The method of claim 7, further comprising:

while receiving trick play data from said remote cache at a rate lower than said rate sufficient to support a normal playback rate, receiving from said remote cache frames which are missing from a portion of said normal play data set for which at least some frames have already been stored. (e.g., missing P or B frames corresponding to a portion of the program for which at least some I frames are stored).

9. The method of claim 8, wherein keeping track of frames included in the received trick play data and normal play data includes keeping a list of received frames, the method further comprising:

prior to receiving missing frames while receiving trick play data, requesting from said remote cache frames which are missing from a portion of said normal play data includes sending a message to said cache identifying frames corresponding to a portion of said program for which at least some trick play data has been received but a complete set of normal play data has not yet been stored.

10. The method of claim 9, wherein said message to said remote cache identifying frames which are missing provides frame identifiers (frame numbers) which are being supplied to allow said remote cache to supply missing frames to said set of normal playback data.

11. The method of claim 9, wherein missing I-frames are requested prior to missing P-frames.

12. The method of claim 11, wherein missing P-frames are requested prior to missing B-frames.

13. The method of claim 8, further comprising:

receiving missing I-frames corresponding to a portion of a program for which trick play data has been received but not a full set of normal play data, while receiving additional trick play data corresponding to another portion of said program.

14. The method of claim 13, wherein missing I-frames are received prior to missing P-frames.

15. The method of claim 14, wherein missing P-frames are received prior to missing B-frames.

16. The method of claim 1, further comprising:

receiving a command to resume normal playback operation;

supplying frames from the normal playback set of data stored on the local storage device from a location in the program indicated in the command to resume normal playback operation if the required frame data has been locally stored; and

requesting the required normal playback data from the remote cache if the required frame data has not already been locally stored.

17. The method of claim 1, wherein said trick play command is one of a fast forward and reverse command.

18. The method of claim 17, wherein said trick play command is received in a message from a set top box, said message indicating a trick play speed and direction of playback being requested and indicating (e.g., by frame number) a frame location in the program from which the command is to begin being implemented.

19. The method of claim 1, further comprising:

receiving an additional trick play command;

determining if sufficient frame data has already been received from said remote cache to support the additional trick playback operation corresponding to said received trick play command;

when it is determined that sufficient data has been received to support an additional trick playback corresponding to said received additional trick play command, supplying said frame data from said local storage device; and

when it is determined that sufficient data has not already been received to support an additional trick playback operation corresponding to said received additional trick play command, requesting additional trick play data from said remote cache, said requested data not including frame data which has already been received from said cache; and

while receiving additional trick play data from said remote cache, receiving at least some additional data, omitted from received trick play data, required to complete a set of normal playback data corresponding to said program.

20. An apparatus for providing video content representing a program, comprising:

a determination module for determining if sufficient data is locally available to support a trick playback operation corresponding to a received trick play command;

a request module configured to request trick play data from a remote cache, when it is determined by said determination module that sufficient data is not locally available to support the trick playback operation;

a frame tracking module for tracking which frames are received as part of the trick play data from the remote cache; and

an update module for updating a set of locally stored normal playback data as a function of the received trick play data and additional frames received from said remote cache which are included in said normal play data but not said trick play data.

21. The apparatus of claim 20, further comprising

a receiver module for receiving at least some additional data including said additional frames, required to complete the set of normal playback data corresponding to said program while receiving trick play data from said remote cache required to support said trick playback operation.

22. The apparatus of claim 20,

wherein said receiver module is configure to receive, prior to receiving said trick play command, frame data corresponding to said program from said remote cache at a rate sufficient to support the normal playback rate.

23. The apparatus of claim 20, further comprising:

a generation module for generating from received frame data, a set of normal playback rate data and a plurality of different sets of trick play data corresponding to different trick play data rates, each set of trick play data being a subset of said normal playback rate data; and

a memory for storing the generated set of normal playback data and said plurality of different sets of trick play data in a local storage device.

24. The apparatus of claim 23, wherein said update module is configured to update said plurality of different sets of trick play data and said set of normal playback rate data with trick play data received from said remote cache, in response to receiving trick play data.