Method for reducing channel change startup delays for multicast digital video streams

• US 20070214490A1
• Filed: 03/08/2006
• Published: 09/13/2007
• Est. Priority Date: 03/08/2006
• Status: Active Grant

• Current Assignee: Synamedia Limited
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Li, Ping, Shen, Charles, Cham, Jack, Cheng, Gary
• Granted Patent: US 8,218,654 B2
• Time in Patent Office: Days
• US Class Current: 725/135
• CPC Class Codes: H04N 21/235 Processing of additional data, e.g. scrambling of additional data or processing content descriptors
• CPC Class Codes: H04N 21/23614 Multiplexing of additional data and video streams arrangements for simultaneous broadcast of plural pieces of information H04H20/28
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/435 Processing of additional data, e.g. decrypting of additional data, reconstructing software from modules extracted from the transport stream
• 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 21/6405 Multicasting data broadcast and multicast in packet switching networks H04L12/18

Abstract

Methods and systems for reducing channel change startup delays for multicast digital video streams are described. Packets of a multicast digital video transport stream having a plurality of normal Group of Pictures are received. Further, a channel change request is received and a speed-up Group of Pictures is inserted in the stream in response to the channel change request. In one embodiment, video stream specific information is also inserted in the stream. The packets are processed and transmitted.

Claims

1. A channel change method comprising:

receiving packets of a multicast digital video transport stream having a plurality of normal Group of Pictures;

receiving a channel change request inserting a speed-up Group of Pictures in said stream in response to said channel change request; and

transmitting said packets.

2. The method of claim 1, further comprising inserting video stream specific information.

3. The method of claim 2, wherein said video stream specific information includes a recalculated Program Clock Reference value.

4. The method of claim 1, wherein said speed-up Group of Pictures (GOP) is a Group of Pictures of minimum lengths and comprises of a single Intra-frame.

5. The method of claim 1, wherein said multicast digital video transport stream is in Motion Picture Experts Group 2 (MPEG-2) format.

6. The method of claim 1, wherein said multicast digital video transport stream is in Motion Picture Experts Group 4 (MPEG-4) format.

7. The method of claim 1, wherein said inserting is implemented by a fast start transmitter (FST).

8. A channel change system comprising:

a means for receiving packets of a multicast digital video transport stream having a plurality of normal Group of Pictures;

a means for receiving a channel change request;

a means for injecting video stream specific information and an accelerating Group of Pictures in said stream in response to said channel change request; and

a means for processing said packets.

9. A channel change system comprising:

a receiver for receiving packets of a multicast digital video transport stream having a plurality of normal Group of Pictures and a channel change request;

an injector for injecting an accelerating Group of Pictures and video stream specific information in said stream in response to said channel change request; and

a processor for processing said packets.

10. The channel change system of claim 9, wherein said accelerating Group of Pictures is generated by a fast start transmitter.

11. The channel change system of claim 9, wherein said channel change request is an Internet Group Management Protocol (IGMP) report.

12. The channel change system of claim 9, wherein said accelerating Group of Pictures (GOP) is a Group of Pictures comprises of a single Intra-frame.

13. The channel change system of claim 12, wherein said accelerating Group of Pictures of minimum length comprises a single blank Intra-frame.

14. The channel change system of claim 12, wherein the content of said single Intra-frame is identical to a subsequent Intra-frame.

15. The channel change system of claim 9, wherein said multicast digital video transport stream is in Motion Picture Experts Group 2 (MPEG-2) format.

16. The channel change system of claim 9, wherein said multicast digital video transport stream is in Motion Picture Experts Group 4 (MPEG-4) format.

17. The channel change system of claim 9, wherein said injector comprises a fast start transmitter (FST).

18. The channel change system of claim 9, wherein said receiver is an input port of a router.

19. The channel change system of claim 9, wherein said process is a central processing unit (CPU).

20. The channel change system of claim 9, wherein said system further comprises a plurality of memory buffers to serve as buffers for different channels of said multicast digital video transport stream.