Low-delay video encoding method for concealing the effects of packet loss in multi-channel packet switched networks

• US 20020126668A1
• Filed: 03/12/2002
• Published: 09/12/2002
• Est. Priority Date: 03/12/2001
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Polycom Incorporated (HP Inc.)
• Inventors: Flott, Rick, Horowitz, Michael, Shah, Athar, Raper, Kevin
• Granted Patent: US 7,136,394 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/30 Routing of multiclass traffic
• CPC Class Codes: H04L 45/3065 for real time traffic
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 69/14 Multichannel or multilink protocols
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/114 Adapting the group of pictures [GOP] structure, e.g. number of B-frames between two anchor frames H04N19/107 takes precedence
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder
• 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 21/234327 by decomposing into layers, e.g. base layer and one or more enhancement layers
• CPC Class Codes: H04N 21/234381 by altering the temporal resolution, e.g. decreasing the frame rate by frame skipping
• CPC Class Codes: H04N 21/2402 Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• 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 21/631 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

Abstract

A method for encoding digital video with low delay for transport on a multi-channel QoS packet-switched network using multiple reference pictures with specially designated “key frames” to minimize the undesired effects of packet loss on video quality.

Claims

1. A method of encoding and transporting interactive video, comprising the steps of:

receiving a video sequence;

encoding the video sequence into key frames represented by key frame bit sequences and non-key frames represented by non-key frame bit sequences;

packetizing and transporting the key frame bit sequences over a high quality network channel; and

packetizing and transporting the non-key frame bit sequences over a lower quality network channel.

2. The method of claim 1, wherein the non-key frames exclude bi-directionally predicted frames.

3. The method of claim 1, wherein the non-key frames include predicted frames.

4. The method of claim 1, wherein the key frames are inter-frames.

5. The method of claim 1, wherein the key frames are intra-frames.

6. The method of claim 1, wherein a number of bits used to encode a frame is a function of an integral distance between the frame and a nearest preceding key frame.

7. The method of claim 1, wherein a number of bits used to encode a key frame is a function of bandwidth available on the high quality network channel.

8. The method of claim 1, wherein a number of bits used to encode a non-key frame is a function of bandwidth available on the lower quality network channel.

9. The method of claim 1, wherein spacing between key frames in the sequence of key frames is a function of bandwidth available on the high quality network channel.

10. The method of claim 7, wherein the function is redefined with each change in network status.

11. The method of claim 9, wherein the function is redefined with each change in network status.

12. The method of claim 1, wherein the high quality network channel is a Quality of Service channel.

14. The system of claim 13, wherein the non-key frames exclude bi-directionally predicted frames.

15. The system of claim 13, wherein the non-key frames include predicted frames.

16. The system of claim 13, wherein the key frames are inter-frames.

17. The system of claim 13, wherein the key frames are intra-frames.

18. The system of claim 13, wherein a number of bits used to encode a frame is a function of an integral distance between the frame and a nearest preceding key frame.

19. The system of claim 13, wherein a number of bits used to encode a key frame is a function of bandwidth available on the high quality network channel.

20. The system of claim 13, wherein a number of bits used to encode a non-key frame is a function of bandwidth available on the lower quality network channel.

21. The system of claim 13, wherein spacing between key frames in the sequence of key frames is a function of bandwidth available on the high quality network channel.

22. The system of claim 19, wherein the function is redefined with each change in network status.

23. The system of claim 21, wherein the function is redefined with each change in network status.

24. The system of claim 13, wherein the high quality network channel is a Quality of Service channel.

13. A system for encoding and transporting interactive video, comprising:

a system encoder for encoding a video stream into key frames represented by key frame bit sequences and non-key frames represented by non-key frame bit sequences;

a system packetizer coupled to the system encoder for packetizing the key frame bit sequences and the non-key frame bit sequences;

a high quality network channel coupled to the system packetizer for transporting the packetized key frame bit sequences; and

a lower quality network channel coupled to the system packetizer for transporting the packetized non-key frame bit sequences.

25. A system for encoding and transporting interactive video on multiple-network channels, comprising:

a system encoder for encoding a video stream into key frames and non-key frames, spacing between consecutive key frames based on bandwidth available on the multiple-network channels, and a number of bits used to encode any given frame based on an integral distance between the given frame and a nearest preceding key frame and the bandwidth available on the multiple-network channels;

a system packetizer for packetizing key bits representing the key frames and non-key bits representing the non-key frames, coupled to the system encoder;

a high quality network channel for transporting the packetized key bits, coupled to the system packetizer; and

a network channel of the multiple-network channels for transporting the packetized non-key bits, coupled to the system packetizer.

26. A system for encoding and transporting interactive video on multiple-network channels, comprising:

a means for encoding a video stream into key frames and non-key frames, the spacing between consecutive key frames based on bandwidth available on the multiple-network channels, and a number of bits used to encode any given frame based on an integral distance between the given frame and a nearest preceding key frame and the bandwidth available on the multiple-network channels;

a means for packetizing key bits representing the key frames and the non-key bits representing the non-key frames, coupled to the means for encoding;

a first means for providing high quality transportation of the packetized key bits, coupled to the means for packetizing; and

a second means for providing lower quality transportation of the packetized non-key bits, coupled to the means for packetizing.

27. A system for encoding and transporting interactive video, comprising:

means for receiving a video stream;

means for encoding the video stream into a sequence of key bits representing key frames and a sequence of non-key bits representing non-key frames;

means for packetizing and transporting the sequence of key bits over a high quality network channel; and

means for packetizing and transporting the sequence of non-key bits over a lower quality network channel.