SYNCHRONIZING REDUNDANT VIDEO STREAMS ENCAPSULATED IN IP/UDP PACKETS

• US 20070237185A1
• Filed: 04/03/2006
• Published: 10/11/2007
• Est. Priority Date: 04/03/2006
• Status: Active Grant

• Current Assignee: Triton US VP Acquisition, Co.
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Pereira, Michael, Toebes, John
• Granted Patent: US 7,796,598 B2
• Time in Patent Office: Days
• US Class Current: 370/503
• CPC Class Codes: H04N 21/2389 Multiplex stream processing, e.g. multiplex stream encrypting
• CPC Class Codes: H04N 21/4385 Multiplex stream processing, e.g. multiplex stream decrypting
• 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 21/631 Multimode Transmission, e.g. transmitting basic layers and enhancement layers of the content over different transmission paths or transmitting with different error corrections, different keys or with different transmission protocols
• CPC Class Codes: H04N 21/6582 Data stored in the client, e.g. viewing habits, hardware capabilities, credit card number arrangements where receivers interact with the broadcast H04H20/38

Abstract

An apparatus, e.g., in a network edge device, a method, and a software program product for synchronizing two or more redundant media streams, e.g., MPEG video streams. The method includes receiving network packets encapsulating redundant media streams representing the same media program, buffering the received streams, learning a program identifier for the media program, searching the packets of the redundant streams for synchronization points defined by a plurality of parameters of stream packets, synchronizing the redundant streams based on the comparison, and providing a single stream as an output stream.

Claims

1. A method in a network at a network device, the method comprising:

receiving network packets encapsulating a plurality of redundant media streams representing the same media program, each stream provided in stream packetized form as stream packets, such that each network packet encapsulates a plurality of stream packets;

buffering the received streams;

learning a program identifier for the media program from the buffered streams;

searching the packets of the buffered redundant streams for synchronization points for the learned program identifier, each synchronization point defined by a plurality of parameters of the stream packets sufficient to uniquely identify a location in the streams;

comparing synchronization points, and synchronizing the redundant streams based on the comparison; and

providing a single stream as an output stream, the providing of each packet containing the output stream being from one of the received buffered streams.

2. A method as recited in claim 1, further comprising:

ascertaining whether at least one stream failure condition from a set of possible failure conditions has occurred; and

taking corrective action based on what failure condition was ascertained to have occurred.

3. A method as recited in claim 2, further comprising:

maintaining of data sufficient to generate statistics on one or more of the stream failure conditions; and

generating statistics on the one or more types of errors.

4. A method as recited in claim 3, further comprising:

reporting the generated statistics to one or more network nodes upstream from the network device at which the network packets are received.

5. A method as recited in claim 2, further comprising:

setting the timing of the output stream.

6. A method as recited in claim 2, wherein setting the timing of the output stream packet depends on the timing of the received stream packet used to source the output stream.

7. A method as recited in claim 2, wherein the streams are multicast streams.

8. A method as recited in claim 2, further comprising:

timestamping each received packet,

wherein in the setting the timing of the output stream, consecutive packets of the output stream are provided with the same relative delay as received consecutive packets according to the timestamping.

9. A method as recited in claim 2, wherein the set of possible failure conditions includes loss of one or more network packets, receiving one or more duplicate network packets, and a failover event, including loss of a stream.

10. A method as recited in claim 2, wherein each stream packet includes a continuity counter, wherein the set of possible failure conditions includes loss of one or more network packets or receiving one or more duplicate network packets, and wherein the ascertaining includes comparing the program identifier and stream packet continuity counter for the streams.

11. A method as recited in claim 10, wherein the ascertaining further includes verifying that the next unique synchronization point is received as expected in each stream.

12. A method as recited in claim 2, wherein the set of possible failure conditions includes loss of stream or other failover event, and wherein ascertaining if there has been loss of stream or other failover event includes ascertaining whether there has been a lack of network packets being received on one of the streams for a pre-defined number of network packets.

13. A method as recited in claim 2, wherein the set of possible failure conditions includes loss of one or more network packets or receiving one or more duplicate network packets, and wherein the taking corrective action includes sourcing a missing packet for the output from one of the other streams for which the missing packet was received.

14. A method as recited in claim 2, wherein the set of possible failure conditions includes loss of stream or other failover event, and wherein the taking corrective action includes synchronously switching the output stream from the source stream in which the failover was ascertained to have occurred to another source stream.

15. A method as recited in claim 1, wherein each stream includes compressed video packetized into packetized compressed pictures, the packetized compressed pictures further packetized into the stream packets, and wherein the synchronization points are defined by a plurality of parameters of the stream packets and of the compressed picture packets.

16. A method as recited in claim 15, wherein each stream further includes a compressed audio stream packetized into compressed audio packets, and wherein the synchronization points for the compressed audio stream are defined by a plurality of parameters of the compressed audio packets.

17. A method as recited in claim 15, wherein each stream includes an MPEG stream according to one of the MPEG standards, the compressed picture packets are PES packets, and the stream packets are TS packets.

18. A method as recited in claim 15, wherein each stream includes a stream compressed according to one of the ITU standards/recommendations for media compression.

19. A method as recited in claim 15, wherein each stream includes a stream compressed according to the VC-1 standard for media compression.

20. A method as recited in claim 17, wherein each synchronization point is defined as the combination of the PID, payload_unit_start_indicator, continuity_counter, packet_start_code_prefix, stream_id, and PES_packet_length.

21. A method as recited in claim 15, wherein the network packets are UDP packets.

22. A method as recited in claim 1, wherein the method is carried out in a network edge device.

23. An apparatus comprising:

a set of input buffers coupled to network interfaces that are each coupled to a corresponding network and configured to receive network packets encapsulating a plurality of redundant media streams representing the same media program, each stream provided in stream packetized form as stream packets, such that each network packet encapsulates a plurality of stream packets;

redundancy logic coupled to the input buffers and configured, in operation, to learn a program identifier for the media program, to search the packets of the redundant streams for synchronization points for the learned program identifier, each synchronization point defined by a plurality of parameters of the stream packets sufficient to uniquely identify a location in the streams, to compare synchronization points, to synchronizing the redundant streams based on the comparison; and

to providing a single stream as an output stream, the providing of each packet containing the output stream being from one of the received buffered streams.

24. An apparatus as recited in claim 23, wherein the redundancy logic is further configured, in operation, to ascertain whether at least one stream failure condition from a set of possible failure conditions has occurred, and to take corrective action based on the what failure condition was ascertained to have occurred.

25. An apparatus as recited in claim 24, wherein the set of possible failure conditions includes loss of one or more network packets, receiving one or more duplicate network packets, and a failover event, including loss of a stream.

26. An apparatus as recited in claim 23, wherein each stream includes an MPEG stream, the compressed picture packets are PES packets, and the stream packets are TS packets.

27. An apparatus as recited in claim 23, wherein the network packets are UDP packets.

28. An apparatus as recited in claim 23, wherein the apparatus is in a network edge device.

29. An apparatus as recited in claim 23, comprising a processor, wherein the redundancy logic is implemented in the processor.

30. An apparatus comprising:

means for receiving network packets encapsulating a plurality of redundant media streams representing the same media program, each stream provided in stream packetized form as stream packets, such that each network packet encapsulates a plurality of stream packets;

means for buffering the received streams;

means for learning a program identifier for the media program;

means for searching, the packets of the redundant streams for synchronization points for the learned program identifier, each synchronization point defined by a plurality of parameters of the stream packets sufficient to uniquely identify a location in the streams;

means for comparing synchronization points and synchronizing the redundant streams based on the comparison; and

means for providing a single stream as an output stream, wherein each packet containing the output stream is from one of the received buffered streams.

31. An apparatus as recited in claim 30, further comprising:

means for ascertaining whether at least one stream failure condition from a set of possible failure conditions has occurred; and

means for taking corrective action based on what failure condition was ascertained to have occurred.

32. An apparatus as recited in claim 31, further comprising:

means for setting the timing of the output stream.

33. An apparatus as recited in claim 30, wherein each stream includes compressed video packetized into packetized compressed pictures, the packetized compressed pictures further packetized into the stream packets, and wherein the synchronization points are defined by a plurality of parameters of the stream packets and of the compressed picture packets.

34. An apparatus as recited in claim 33, wherein each stream includes an MPEG stream, the compressed picture packets are PES packets, and the stream packets are TS packets.

35. An apparatus as recited in claim 33, wherein the network packets are UDP packets.

46. A carrier medium as recited in claim 30, wherein the processing system is in a network edge device.

36. A computer-readable carrier medium carrying a set of instructions that when executed by at least one processor of a processing system, causes the processing system to carry out a method comprising:

receiving network packets encapsulating a plurality of redundant media streams representing the same media program, each stream provided in stream packetized form as stream packets, such that each network packet encapsulates a plurality of stream packets;

buffering the received streams;

learning a program identifier for the media program from the buffered streams;

searching the packets of the buffered redundant streams for synchronization points for the learned program identifier, each synchronization point defined by a plurality of parameters of the stream packets sufficient to uniquely identify a location in the streams;

comparing synchronization points, and synchronizing the redundant streams based on the comparison; and

providing a single stream as an output stream, the providing of each packet containing the output stream being from one of the received buffered streams.

37. A carrier medium as recited in claim 36, wherein the method further comprises:

ascertaining whether at least one stream failure condition from a set of possible failure conditions has occurred; and

taking corrective action based on what failure condition was ascertained to have occurred.

38. A carrier medium as recited in claim 37, wherein the method further comprises:

setting the timing of the output stream.

39. A carrier medium as recited in claim 37, wherein the set of possible failure conditions includes loss of one or more network packets, receiving one or more duplicate network packets, and a failover event, including loss of a stream.

40. A carrier medium as recited in claim 37, wherein each stream packet includes a continuity counter, wherein the set of possible failure conditions includes loss of one or more network packets or receiving one or more duplicate network packets, and wherein the ascertaining includes comparing the program identifier and stream packet continuity counter for the streams.

41. A carrier medium as recited in claim 40, wherein the ascertaining further includes verifying that the next unique synchronization point is received as expected in each stream.

42. A carrier medium as recited in claim 37, wherein the set of possible failure conditions includes loss of stream or other failover event, and wherein ascertaining if there has been loss of stream or other failover event includes ascertaining whether there has been a lack of network packets being received on one of the streams for a pre-defined number of network packets.

43. A carrier medium as recited in claim 36, wherein each stream includes compressed video packetized into packetized compressed pictures, the packetized compressed pictures further packetized into the stream packets, and wherein the synchronization points are defined by a plurality of parameters of the stream packets and of the compressed picture packets.

44. A carrier medium as recited in claim 43, wherein each stream includes an MPEG stream, the compressed picture packets are PES packets, and the stream packets are TS packets.

45. A carrier medium as recited in claim 43, wherein the network packets are UDP packets.