System and method for analyzing and transmitting video over a switched network

• US 6,233,226 B1
• Filed: 01/29/1999
• Issued: 05/15/2001
• Est. Priority Date: 12/14/1998
• Status: Expired due to Term

• Current Assignee: Verizon Laboratories Incorporated (Verizon Communications Inc.)
• Original Assignee: Verizon Laboratories Incorporated (Verizon Communications Inc.)
• Inventors: Gringeri, Steven, Shuaib, Khaled Ali, Basch, Evert
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US09/240,484
• Time in Patent Office: 837 Days
• Field of Search: 348/700, 370/230, 370/235, 370/252, 370/253, 709/217-219
• US Class Current: 370/252
• CPC Class Codes: H04L 12/6418 Hybrid transport
• CPC Class Codes: H04L 2012/5636 Monitoring or policing, e.g. compliance with allocated rate, corrective actions
• CPC Class Codes: H04L 2012/5664 Support of Video, e.g. MPEG
• CPC Class Codes: H04L 2012/5681 Buffer or queue management
• CPC Class Codes: H04L 2012/6483 Video, e.g. MPEG
• CPC Class Codes: H04L 2012/6489 Buffer Management, Threshold setting, Scheduling, Shaping
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A system and method are provided for analyzing and transmitting video over a switched network. According to an aspect of the invention, two phases are generally provided: an analysis phase performed before transmission of the video; and a transmission phase performed after analyzing the video stream. During the pre-transmission video analysis phase, the video stream is analyzed in order to determine the needed traffic control parameters, such as the peak cell rate, the sustained cell rate, and the maximum burst size. The goal of the analysis phase is to select a transmission traffic contract for the encoded video stream that will minimize the utilization of network resources and permit the quality of the video to be maintained. After the analysis phase, the transmission phase is performed to transmit the video over the network in accordance with the selected traffic control parameters. During the transmission phase, a model of the decoder buffer is kept at the source and is first pre-filled by transmitting data at the sustained cell rate. Thereafter, the video stream data is transmitted at the peak cell rate or the sustained cell rate depending on the availability of tokens.

Claims

1. A system for analyzing and transmitting an encoded video sequence over a switched network, said system comprising:

an analysis module that analyzes said video sequence to determine a set of traffic control parameters for transmitting said video sequence over the switched network with minimum use of network resources; and

a transmission module that receives the set of traffic control parameters from said analysis module and transmits said video sequence over the network in accordance with the traffic control parameters.

2. A system according to claim 1, wherein said video sequence is transmitted in cells over the network from a source to a destination, and said analysis module includes a model of a decoder buffer and determines the set of traffic control parameters by calculating a transmission rate for each video frame of said video sequence based on a just-in-time scheduling analysis.

3. A system according to claim 2, wherein said analysis module sets the transmission rate for each video frame to a predetermined sustained cell rate provided no underflow or overflow condition of the model decoder buffer is detected.

4. A system according to claim 3, wherein said analysis module calculates in the case of an underflow condition of the model decoder buffer a transmission rate for a video frame that guarantees arrival of the video frame just-in-time for processing.

5. A system according to claim 3, wherein said analysis modules calculates in the case of an overflow condition of the model decoder buffer an adjusted transmission rate to prevent an overflow of the model decoder buffer.

6. A system according to claim 2, wherein said just-in-time scheduling analysis performed by said analysis module includes a look ahead process in which said analysis module calculates a transmission rate for a video frame by looking ahead a predetermined number of video frames and determining a maximum average transmission rate over the predetermined number of video frames.

7. A system according to claim 2, wherein the set of traffic control parameters determined by said analysis module includes a peak cell rate and a maximum burst size.

8. A system according to claim 7, wherein said analysis module sets the peak cell rate to the largest transmission rate calculated for the video frames of said video sequence.

9. A system according to claim 7, wherein said analysis module determines the maximum burst size by analyzing said video sequence and spacing in time between transmitted cells.

10. A system according to claim 7, wherein said transmission module includes a model of a decoder buffer and transmits said video sequence over the network at a sustained cell rate or the peak cell rate depending on the fullness of the decoder buffer model.

11. A system according to claim 10, wherein said transmission module stops transmitting cells if the decoder buffer model is full.

12. A system according to claim 1, wherein said analysis module and said transmission module are provided at the source of the transmission, and the encoded video sequence is a variable bit rate encoded video sequence.

13. A system according to claim 1, wherein said switched network comprises an Asynchronous Transfer Mode (ATM) network.

14. A system according to claim 1, further comprising a traffic contract analyzer that determines an optimum traffic contract from a plurality of traffic contracts provided as output to said traffic contract analyzer from said analysis module, said traffic contract analyzer including an effective bandwidth metric for determining the optimum traffic contract that will require minimum use of network resources.

15. A method for transporting a variable bit rate encoded video sequence over a switched network, said video sequence being transported in cells over the network from a source to a destination, said method comprising:

analyzing said video sequence, prior to transmission over the network, to determine a set of traffic control parameters that will minimize the network resources that are required for transmitting said video sequence; and

transmitting said video sequence in cells over the network based on the determined set of traffic control parameters.

16. A method according to claim 15, wherein said method further comprises providing a model of a decoder buffer and determining the set of traffic control parameters by calculating a transmission rate for each video frame of said video sequence based on a just-in-time scheduling analysis.

17. A method according to claim 16, wherein said method further comprises setting the transmission rate for each video frame to a predetermined sustained cell rate unless underflow or overflow of the model decoder buffer will occur.

18. A method according to claim 17, wherein said method further comprises calculating, in the case of an underflow condition of the model decoder buffer, a transmission rate for a video frame that will guarantee arrival of the video frame just-in-time for processing.

19. A method according to claim 17, wherein said method further comprises calculating, in the case of an overflow condition of the model decoder buffer, an adjusted transmission rate to prevent an overflow of the model decoder buffer.

20. A method according to claim 16, wherein said analyzing comprises calculating a peak cell rate by setting the peak cell rate to the largest transmission rate calculated for the video frames of said video sequence.

21. A method according to claim 20, wherein said transmitting step includes monitoring the fullness of the decoder buffer model and transmitting said video sequence over the network at a predetermined sustained cell rate or the peak cell rate depending on the fullness of the decoder buffer model.

22. A method according to claim 15, wherein said analyzing comprises calculating a maximum burst size by analyzing said video sequence and spacing between transmission cells.

23. A method according to claim 15, wherein said method further comprises calculating a transmission rate for a video frame by looking ahead a predetermined number of video frames and determining a maximum average transmission rate over the predetermined number of video frames.

24. A method according to claim 15, wherein said method further comprises establishing a connection over the network in accordance with the determined set of traffic control parameters, said network comprising an Asynchronous Transfer Mode (ATM) network.

25. A method according to claim 15, wherein said method further comprises providing a model of a decoder buffer and compensating for network jitter to prevent an underflow or overflow condition from occurring in the model decoder buffer.

26. A video distribution system for distributing an encoded video sequence over a switched network, said system comprising:

means for analyzing said video sequence to determine a set of traffic control parameters based on a predetermined sustained cell rate and a just-in-time scheduling analysis of a transmission rate of each frame of said video sequence; and

means for transmitting said video sequence over the network in accordance with the traffic control parameters determined by said analyzing means.

27. A system according to claim 26, said system further comprising means for providing a model of a decoder buffer and monitoring the fullness of the model decoder buffer based on the transmission rate of the each frame, wherein said analyzing means sets the transmission rate for each video frame to the predetermined sustained cell rate unless underflow or overflow of the model decoder buffer will occur.

28. A system according to claim 27, wherein said analyzing means includes means for calculating, in the case of an underflow condition of the model decoder buffer, a transmission rate for a video frame that will guarantee arrival of the video frame just-in-time for processing.

29. A system according to claim 27, wherein said analyzing means includes means for calculating, in the case of an overflow condition of the model decoder buffer, an adjusted transmission rate to prevent an overflow of the model decoder buffer.

30. A system according to claim 26, wherein said analyzing means further comprises means for calculating a transmission rate for a video frame by looking ahead a predetermined number of video frames and determining a maximum average transmission rate over the predetermined number of video frames.

31. A system according to claim 26, wherein the set of traffic control parameters determined by said analyzing means includes a peak cell rate, a maximum burst size and a sustainable burst size.

32. A system according to claim 26, further comprising a traffic contract analyzer that determines an optimum traffic contract from a plurality of traffic contracts provided as output to said traffic contract analyzer from said analyzing means, said traffic contract analyzer including an effective bandwidth metric for determining the optimum traffic contract that will minimize use of network resources.

33. A system according to claim 26, further comprising means for providing a model of a decoder buffer and means for compensating for network jitter to prevent an underflow or overflow condition from occurring in the model decoder buffer.

34. A method for analyzing an encoded video sequence to be transmitted over a network from a source location to a destination location, said method comprising:

providing a model of a decoder buffer, said decoder buffer model including parameters indicating the size of a decoder buffer provided at the destination location and a rate at which video frames are removed from the decoder buffer;

pre-filling said decoder buffer model at a predetermined sustained cell rate SCR, said decoder buffer model being pre-filled with a maximum number N of video frames of said video sequence that will fit in the decoder buffer model;

calculating a transmission rate R for the next video frame to be transmitted after the pre-filling of said decoder buffer model, said transmission rate R being calculated based on the size of the next video frame and the maximum number N of video frames that can be pre-filled into said decoder buffer model;

determining if said calculated transmission rate R is less than the sustained cell rate SCR;

setting said transmission rate R to be equal to the sustained cell rate SCR if it is determined that the rate R is less than the sustained cell rate SCR;

determining if the transmission R will cause an overflow of said decoder buffer model;

recalculating the transmission rate R if it is determined that overflow of said decoder buffer model will occur, said transmission rate R being recalculated based on the maximum number N of video frames that can be pre-filled into said decoder buffer model and the difference between the size of the decoder buffer model and the current occupancy of the decoder buffer model; and

determining a new transmission rate for the next frame period after each video frame is removed from said decoder buffer model, said new transmission rate being calculated in accordance with the foregoing steps for calculating the transmission rate R and with the maximum number N being replaced with the number of current frames in the decoder buffer model.

35. A method according to claim 34, wherein said method further comprises determining a set of traffic control parameters based on the transmission rates calculated for each of the video frames of said video sequence, said set of traffic control parameters including a peak cell rate and a maximum burst size.

36. A method according to claim 35, wherein said method further comprises determining the peak rate by setting the peak cell rate to the largest transmission rate calculated for the video frames of said video sequence.

37. A method according to claim 35, wherein said method further comprises determining the maximum burst size by analyzing said video sequence and spacing between transmission cells.

38. A method according to claim 34, wherein said method further comprises calculating a transmission rate for a video frame by looking ahead a predetermined number of video frames and determining a maximum average transmission rate over the predetermined number of video frames.

39. A method according to claim 34, wherein said method further comprises compensating for network jitter to prevent an underflow or overflow condition from occurring in the decoder buffer model.

40. A method for transmitting an encoded video sequence over a switched network from a source location to a destination location, said method comprising:

providing a model of a decoder buffer, said decoder buffer model including parameters indicating the size of a decoder buffer provided at the destination location and a rate at which video frames are removed from the decoder buffer;

establishing a connection over the network in accordance with a predetermined set of traffic control parameters, said predetermined set of traffic control parameters including a sustained cell rate SCR and a peak cell rate PCR;

pre-filling the decoder buffer at the destination location by transmitting video frames of said video sequence over the network in transmission cells at the sustained cell rate SCR;

determining when said decoder buffer is pre-filled with a maximum number N of video frames that will fit in the decoder buffer based on the parameters of the decoder buffer model;

transmitting, after pre-filling the decoder buffer, the next transmission cell at the peak cell rate PCR if a token is available and the decoder buffer is not full; and

transmitting, after pre-filling the decoder buffer, the next transmission cell at the sustained cell rate SCR if no tokens are available and the decoder buffer is not full.

41. A method according to claim 40, wherein said method further comprises decreasing the number of available tokens for every transmission cell transmitted at the peak cell rate PCR.

42. A method according to claim 40, wherein said method further comprises increasing the number of available tokens for each zero transmission period during which no cells were transmitted over the network.