Methods and apparatus for efficient scheduling and multiplexing

• US 6,795,506 B1
• Filed: 10/05/2000
• Issued: 09/21/2004
• Est. Priority Date: 10/05/1999
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Liu, Humphrey, Zhang, Ji
• Primary Examiner(s): PHILIPPE, GIMS S
• Application Number:
  US09/684,623
• Time in Patent Office: 1,447 Days
• Field of Search: 375/240.03, 375/240.01, 375/240.08, 375/240.02, 375/240.26, 370/395.1, 370/394, 370/468, 370/252, 348/700, 348/467, 348/423.1, 348/405.1, 348/385.1, 348/387.1, 348/390.1
• US Class Current: 375/240.26
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/50 Queue scheduling
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04N 21/2343 involving reformatting operations of video signals for distribution or compliance with end-user requests or end-user device requirements video transcoding H04N19/40; media packet handling at the source H04L65/762
• CPC Class Codes: H04N 21/235 Processing of additional data, e.g. scrambling of additional data or processing content descriptors
• CPC Class Codes: H04N 21/23608 Remultiplexing multiplex streams, e.g. involving modifying time stamps or remapping the packet identifiers
• CPC Class Codes: H04N 21/2365 Multiplexing of several video streams
• CPC Class Codes: H04N 21/23655 Statistical multiplexing, e.g. by controlling the encoder to alter its bitrate to optimize the bandwidth utilization
• CPC Class Codes: H04N 21/2662 Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities
• CPC Class Codes: H04N 21/4347 Demultiplexing of several video streams
• 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

Abstract

Techniques and mechanisms are provided for scheduling and multiplexing compressed bitstreams. A compressed bitstream includes bit rate information describing the bit rate of video data. The bit rate information is used to improve the scheduling and multiplexing efficiency of compressed bitstreams. Compressed video data can be transmitted over communication channels at bit rates that comply with available channel bandwidth.

Claims

1. A network device for providing a compressed bitstream including video data, the network device comprising:

an encoder apparatus that receives video data and outputs the compressed bitstream including the video data;

a processor apparatus that outputs bit rate information describing the bit rate of the video data; and

a network interface that transmits an output compressed bitstream comprising the compressed bitstream including the video data and transmits the bit rate information.

2. The system of claim 1 wherein the processor apparatus generates and outputs the bit rate information based on the video data before the encoder apparatus receives the video data.

3. The network device of claim 2 further comprising a combiner that combines the bit rate information with the compressed bitstream.

4. The system of claim 3 wherein the combiner embeds the bit rate information in a user data portion of the compressed bitstream including the video data.

5. The system of claim 3 wherein the compressed bitstream is an MPEG-2 compressed bitstream and the combiner embeds the bit rate information in one of the transport stream, the PES layer, and the private data in elementary stream layer of the MPEG-2 bitstream.

6. The network device of claim 1 wherein the bit rate information includes information describing compression of the video data by the encoder apparatus.

7. The network device of claim 6 wherein the bit rate information describes the bit rate profile of a variable bit rate profile compressed bitstream.

8. The network device of claim 1 wherein the encoder apparatus comprises two or more encoder portions.

9. The network device of claim 8 wherein a first encoder portion receives the video data and outputs the compressed bitstream including the video data.

10. The network device of claim 9 wherein a second encoder portion receives second video data and outputs a second compressed bitstream including the second video data.

11. The network device of claim 10 further comprising a multiplexer configured to receive the first compressed bitstream, the second compressed bitstream and the bit rate information, and further configured to output the output compressed bitstream comprising the first video data, the second video data and the bit rate information.

12. The network device of claim 10 wherein the processor apparatus comprises first and second processor portions, the first processor portion responsible for outputting the bit rate information describing the bit rate of the compressed first video data and the second processor portion responsible for outputting the second bit rate information describing the bit rate of the compressed second video data.

13. The network device of claim 1 wherein the bit rate information comprises one of video pre-compression coding information and coding statistics.

14. A method for providing compressed video data, the method comprising:

encoding video data to provide a compressed bitstream including the compressed video data;

obtaining bit rate information describing the bit rate of the video data; and

transmitting an output compressed bitstream comprising the video data and transmitting the bit rate information.

15. The method of claim 14 further including embedding the bit rate information within the compressed video stream to provide the output compressed bitstream.

16. The method of claim 14 further including multiplexing the first compressed bitstream with a second compressed bitstream.

17. The method of claim 14 wherein the bit rate information is obtained in non real-time.

18. The method of claim 17 further including storing the output compressed bitstream comprising the video data and storing the bit rate information.

19. The method of claim 14 wherein the bit rate information includes coding statistics obtained during compression of the video data.

20. The method of claim 14 wherein the bit rate information comprises pre-compression coding information.

21. A network device for transmitting a first compressed bitstream including first video data and a second compressed bitstream including second video data onto a network, the network device comprising:

an extractor apparatus that obtains bit rate information describing the bit rate of the first video data; and

a scheduler coupled to the extractor apparatus, the scheduler configured to receive the first compressed bitstream and receive the second compressed bitstream, the scheduler configured to use the bit rate information describing the bit rate of the first video data to schedule the first compressed bitstream and the second compressed bitstream, the scheduler configured to output a compressed bitstream including the first video data and the second video data.

22. The network device of claim 21 wherein the scheduler is included in an open-loop multiplexer.

23. The network device of claim 22 wherein the open-loop multiplexer is a statistical re-multiplexer.

24. The network device of claim 21 wherein the bit rate information is stored in storage location in the first compressed bitstream and the extractor apparatus extracts the bit rate information from the storage location.

25. The network device of claim 24 wherein the bit rate information is stored in a user data portion of the first compressed bitstream.

26. The network device of claim 21 wherein the bit rate information comprises one of video pre-compression coding information and coding statistics.

27. The network device of claim 21 wherein the extractor apparatus comprises a first extractor portion that obtains the bit rate information describing the bit rate of the first video data and a second extractor portion obtains second bit rate information describing the bit rate of the second video data.

28. The network device of claim 21 further including a bit rate converter capable of adapting the bit rate of the first compressed bitstream.

29. The network device of claim 28 further including a bit rate controller that communicates with the bit rate converter to adapt the first compressed bitstream.

30. The network device of claim 21 further including a transmitter coupled to the scheduler and configured to transmit the compressed bitstream including the first video data and the second video data.

31. The network device of claim 21 wherein the network device is configured within a headend.

32. A network device for transmitting a first compressed bitstream including first video data and a second compressed bitstream including second video data onto a network, the network device comprising:

a processor apparatus that parses the first compressed bitstream and obtains bit rate information describing the bit rate of the first video data; and

a scheduler coupled to the processor apparatus, the scheduler configured to receive the first compressed bitstream and receive the second compressed bitstream, the scheduler configured to use the bit rate information describing the bit rate of the first video data to schedule the first compressed bitstream and the second compressed bitstream, the scheduler configured to output a compressed bitstream including the first video data and the second video data.

33. The network device of claim 32 wherein the scheduler is included in an open-loop multiplexer.

34. The network device of claim 32 further including a bit rate converter capable of adapting the bit rate of the first compressed bitstream.

35. The network device of claim 34 wherein the multiplexer comprises a bit rate controller that communicates with the bit rate converter to adapt the bit rate of the first compressed bitstream.

36. The network device of claim 32 further including a transmitter coupled to the scheduler and configured to transmit the compressed bitstream including the first video data and the second video data.

37. The network device of claim 32 wherein the bit rate information comprises one of video pre-compression coding information and coding statistics.

38. A method for transmitting first video data and second video data over a transmission channel, the method comprising:

receiving a first compressed bitstream including the first video data and a second compressed bitstream including the second video data;

obtaining bit rate information from the first compressed bitstream, the bit rate information describing the bit rate of the first video data;

scheduling the first compressed bitstream including the first video data and the second compressed bitstream including the second video data using the bit rate information to provide a compressed bitstream comprising the first video data and the second video data; and

transmitting the compressed bitstream comprising the first video data and the second video data over the transmission channel.

39. The method of claim 38 wherein one of the first compressed bitstream and the second compressed bitstream has a variable bit rate profile.

40. The method of claim 38 wherein the bit rate information is stored in a storage location of the first compressed bitstream and obtaining the bit rate information comprises removing the bit rate information from the storage location.

41. The method of claim 38 further comprising obtaining second bit rate information describing the bit rate of the second video data from the second compressed bitstream.

42. The method of claim 38 wherein obtaining the bit rate information from the first compressed video stream comprises processing a portion of the first compressed bitstream to produce the bit rate information.

43. The method of claim 38 wherein the bit rate information comprises one of video pre-compression coding information and coding statistics at same or different coding conditions.

44. The method of claim 38 further including adapting the bit rate of the compressed bitstream comprising the first video data and the second video data by adapting the bit rate of one of the first compressed bitstream and the second compressed bitstream.

45. A system for providing compressed video data over a transmission channel, the system comprising:

means for receiving a first compressed bitstream including first video data and a second compressed bitstream including second video data;

means for obtaining bit rate information from the first compressed bitstream, the bit rate information describing the bit rate of the first video data;

means for scheduling the first compressed bitstream including the first video data and the second compressed bitstream including the second video data using the bit rate information to provide a compressed bitstream comprising the first video data and the second video data; and

means for transmitting the compressed bitstream comprising the first video data and the second video data over the transmission channel.

46. A computer readable medium including instructions for providing compressed video data over a transmission channel, the instructions comprising:

instructions for receiving a first compressed bitstream including first video data and a second compressed bitstream including second video data;

instructions for obtaining bit rate information from the first compressed bitstream, the bit rate information describing the bit rate of the first video data;

instructions for scheduling the first compressed bitstream including the first video data and the second compressed bitstream including the second video data using the bit rate information to provide a compressed bitstream comprising the first video data and the second video data; and

instructions for transmitting the compressed bitstream comprising the first video data and the second video data over the transmission channel.