Fast channel change with conditional return to multicasting

• US 7,904,581 B2
• Filed: 02/23/2006
• Issued: 03/08/2011
• Est. Priority Date: 02/23/2005
• Status: Active Grant

• Current Assignee: Synamedia Limited
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Sherer, W. Paul, Pickens, John, Palfreyman, Andrew, Connery, Glenn, Blattman, Kirk
• Primary Examiner(s): Chan; Wing F
• Assistant Examiner(s): WOO, ANDREW M
• Application Number:
  US11/360,078
• Publication Number:
  US 20070107026A1
• Time in Patent Office: 1,839 Days
• Field of Search: 709/231, 709/230
• US Class Current: 709/231
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/1863 comprising mechanisms for improved reliability, e.g. status reports arrangements for detecting or preventing errors by carrying supervisory signal the return channel H04L1/16
• CPC Class Codes: H04L 65/611 for multicast or broadcast systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04L 65/613 for the control of the source by the destination control signals issued by the client directed to the server or network components specially adapted for selective content distribution H04N21/637
• CPC Class Codes: H04L 65/752 adapting media to network capabilities
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/238 Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams hybrid fiber coaxial [HFC] networks for downstream channel allocation for video distribution H04L12/2801; flow control in packet networks H04L47/10; real-time communication protocols in data switching networks H04L65/00; scheduling or organising the servicing of application requests H04L67/60
• CPC Class Codes: H04N 21/23805 Controlling the feeding rate to the network, e.g. by controlling the video pump
• 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 21/2668 Creating a channel for a dedicated end-user group, e.g. insertion of targeted commercials based on end-user profiles information retrieval from the Internet by querying with filtering and personalisation G06F16/9535; arrangements for replacing or switching information during the broadcast H04H20/10; push services over packet-switching network H04L12/1859; adaptation of message content in packet-switching networks H04L51/063
• CPC Class Codes: H04N 21/4384 involving operations to reduce the access time, e.g. fast-tuning for reducing channel switching latency
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip
• CPC Class Codes: H04N 21/6405 Multicasting data broadcast and multicast in packet switching networks H04L12/18
• CPC Class Codes: H04N 21/6408 Unicasting

Abstract

In a digital video network that is capable of distributing digital video content to a client via multicasting and unicasting, servicing a channel change request from a client involves switching from providing the digital video content to the client via multicasting to providing the digital video content to the client via unicasting and continuing to provide digital video content to the client via unicasting until a pre-established condition is met. Continuing to provide digital video content to the client via unicasting until a pre-established condition is met allows the network to opportunistically switch the client from unicasting back to multicasting.

Claims

1. A method for servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the method comprising:

providing digital video content to a client via multicasting, the digital video content being related to a first channel;

detecting a channel change request related to the client, the channel change request requesting a change to a second channel;

providing digital video content related to the second channel to the client via unicasting in response to the channel change request;

continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met, wherein continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met involves unicasting a sequence of consecutive frames of the digital video content related to the second channel to the client, wherein the unicasting starts from an I-frame and progresses to B and P frames of a group of pictures (GOP); and

switching to providing digital video content related to the second channel to the client via multicasting after the pre-established condition is met.

2. The method of claim 1 wherein the pre-established condition comprises the expiration of a time interval.

3. The method of claim 1 wherein the pre-established condition comprises the expiration of a time interval in which no channel change requests are received.

4. The method of claim 1 wherein the pre-established condition comprises an explicit request to rejoin multicasting.

5. The method of claim 1 wherein the pre-established condition comprises a resource threshold.

6. The method of claim 1 wherein the pre-established condition comprises a benefit threshold.

7. The method of claim 1 further comprising joining the client to a multicast group after the pre-established condition is met.

8. The method of claim 1 further comprising providing digital video content related to a third channel to the client via unicasting before switching to multicasting.

9. The method of claim 8 further comprising providing an indication of a channel change boundary between digital video content related to the second channel and digital video content related to the third channel.

10. The method of claim 9 further comprising flushing undecoded frames from a buffer in response to detecting the channel change boundary.

11. The method of claim 9 further comprising resetting a decoder in response to detecting the channel change boundary.

12. The method of claim 8 wherein providing digital video content related to the third channel to the client comprises splicing the third channel into a current unicast session.

13. The method of claim 1 further comprising servicing subsequent channel change requests related to the client via unicasting before switching to multicasting and until the pre-established condition is met.

14. The method of claim 1 further comprising buffering consecutive frames of digital video content related to the second channel and wherein providing digital video content to the client via unicasting comprises unicasting the buffered consecutive frames.

15. The method of claim 14 wherein unicasting the buffered consecutive frames comprises starting the unicasting at the first buffered I-frame.

16. The method of claim 1 wherein switching from unicasting to multicasting comprises:

providing digital video content to a client via unicasting at a first rate;

increasing the rate at which digital video content is provided to the client via unicasting to a second rate; and

after digital video content has been provided to the client via unicasting at the second rate for a first time interval, switching to providing the digital video content to the client via multicasting instead of unicasting.

17. The method of claim 1 wherein switching from unicasting to multicasting comprises:

providing digital video content to a client via unicasting;

providing digital video content to the client via multicasting such that digital video content is provided simultaneously via multicasting and unicasting; and

once the client begins buffering duplicate frames of digital video content via both unicasting and multicasting, switching to providing the digital video content to the client via multicasting instead of unicasting.

18. A processor accessible non-transitory storage media comprising processor-executable instructions, that when executed, direct a computer system to perform a method for servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the method comprising:

providing digital video content to a client via multicasting, the digital video content being related to a first channel;

detecting a channel change request related to the client, the channel change request requesting a change to a second channel;

providing digital video content related to the second channel to the client via unicasting in response to the channel change request;

continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met, wherein continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met involves unicasting a sequence of consecutive frames of the digital video content related to the second channel to the client, wherein the unicasting starts from an I-frame and progresses to B and P frames of a group of pictures (GOP); and

switching to providing digital video content related to the second channel to the client via multicasting after the pre-established condition is met.

19. A method for servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the method comprising:

providing digital video content to a client via multicasting, the digital video content being related to a first channel;

detecting a channel change request related to the client, the channel change request requesting a change to a second channel;

providing digital video content related to the second channel to the client via unicasting in response to the channel change request, wherein providing digital video content related to the second channel to the client via unicasting in response to the channel change request involves unicasting a sequence of consecutive frames of the digital video content related to the second channel to the client, wherein the unicasting is started from an I-frame and progresses to B and P frames of a group of pictures (GOP); and

detecting a subsequent channel change request related to the client, the channel change request requesting a change to a third channel;

providing digital video content related to the third channel to the client via unicasting in response to the channel change request, wherein providing digital video content related to the third channel to the client via unicasting in response to the channel change request involves splicing the third channel into the unicasting of the second channel and unicasting a sequence of consecutive frames of the digital video content related to the third channel to the client, wherein the unicasting is started from an I-frame and progresses to B and P frames of a group of pictures (GOP);

switching to providing digital video content related to the third channel to the client via multicasting only if a pre-established condition is met.

20. A system for servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the system comprising:

a server system having a processor and processor-accessible non-transitory storage media comprising processor-executable instructions, that when executed, direct the server system to;

provide digital video content to a client via multicasting, the digital video content being related to a first channel;

detect a channel change request related to the client, the channel change request requesting a change to a second channel;

provide digital video content related to the second channel to the client via unicasting in response to the channel change request; and

continue to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met, wherein continuing to provide digital video content related to the second channel to the client via unicasting until a pre-established condition is met involves unicasting a sequence of consecutive frames of the digital video content related to the second channel to the client, wherein the unicasting is started from an I-frame and progresses to B and P frames of a group of pictures (GOP); and

switch to providing digital video content related to the second channel to the client via multicasting after the pre-established condition is met.

21. A system for servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the system comprising:

a server system having a processor and processor-accessible non-transitory storage media comprising processor-executable instructions, that when executed, direct the server system to;

provide digital video content to a client via multicasting, the digital video content being related to a first channel;

detect a channel change request related to the client, the channel change request requesting a change to a second channel;

provide digital video content related to the second channel to the client via unicasting in response to the channel change request, wherein providing digital video content related to the second channel to the client via unicasting in response to the channel change request involves unicasting a sequence of consecutive frames of the digital video content related to the second channel to the client, wherein the unicasting is started from an I-frame and progresses to B and P frames of a group of pictures (GOP); and

switch to providing digital video content related to the second channel to the client via multicasting only if a pre-established condition is met.

22. A method for servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the method comprising:

providing digital video content to a client via multicasting;

identifying the client as being in a surf mode in response to a channel change request;

providing digital video content to the client via unicasting for as long as the client is in the surf mode, wherein providing digital video content to the client via unicasting for as long as the client is in the surf mode involves unicasting a sequence of consecutive frames of digital video content to the client, wherein the unicasting is started from an I-frame and progresses to B and P frames of a group of pictures (GOP); and

switching back to providing digital video content to the client via multicasting once the client exits surf mode.

23. The method of claim 22 further comprising servicing additional channel change requests from the client via unicasting while the client is in surf mode.

24. The method of claim 23 wherein servicing channel change requests via unicasting comprises buffering digital video content related to a requested channel and unicasting the buffered digital video content starting at the first buffered I-frame.

25. The method of claim 22 wherein surf mode is exited in response to one of the expiration of a time period, the expiration of a time period without any channel change requests, and an explicit exit command.

26. A system for servicing channel change requests in a digital video network that is capable of distributing digital video content to clients via multicasting and unicasting, the system comprising:

a server system having a processor and processor-accessible non-transitory storage media comprising processor-executable instructions, that when executed, direct the server system to;

provide digital video content to a client via multicasting;

identify the client as being in a surf mode in response to a channel change request;

provide digital video content to the client via unicasting for as long as the client is in the surf mode, wherein providing digital video content to the client via unicasting for as long as the client is in the surf mode involves unicasting a sequence of consecutive frames of digital video content to the client, wherein the unicasting is started from an I-frame and progresses to B and P frames of a group of pictures (GOP); and

switch back to providing digital video content to the client via multicasting upon the expiration of a pre-established time interval in which no channel change requests are received from the client.