Granted Patent B1

US 7,317,685 · App. 10/305,485 · Granted Jan 8, 2008

Abstract

Claims (26)

1. A method for adjusting a video bit rate (VBR) during transmission of a video data over a packet-switched network, comprising:

reducing the VBR to no less than a minimum video bit rate threshold (VBRmin), if a packet loss (PL) over a time interval is greater that a PL threshold;

increasing the reduced VBR by a bit rate enhancement factor (BREF) to obtain a second VBR, if the PL over a maximum integer number of time intervals (ntMax) is less than or equal to the PL threshold;

increasing the ntMax if the PL at the second VBR is greater than the PL threshold; and

increasing the second VBR by the BREF for each consecutive time interval until a VBRmax is reached, if the PL for each previous time interval is less than or equal to the PL threshold.

2. The method of claim 1 , wherein reducing the VBR further comprises reducing the VBR by a bit rate reduction factor (BRRF).

3. The method of claim 2 , wherein the VBR is reduced by the BRRF, if the VBR is equal to or less than a previous VBR.

4. The method of claim 2 wherein the BRRF=1.0−PL−C 1 , where 0≦C 1 ≦1.0.

5. The method of claim 1 , wherein the PL=(VBR−a received VBR at the remote endpoint)/(VBR).

6. The method of claim 1 , wherein reducing the VBR further comprises reducing the VBR to a last good VBR (LVBR).

7. The method of claim 6 , wherein the VBR is reducing to the LVBR, if the VBR is greater than a previous VBR.

8. The method of claim 6 , wherein the LVBR is a VBR of a last time interval without packet loss.

9. The method of claim 1 , wherein the BREF=(1.0+C 2 ), where C 2 >0.

10. The method of claim 1 , further comprising reducing the second VBR to a VBR of a last time interval without packet loss, if the PL at the second VBR is greater than the PL threshold.

11. The method of claim 1 , wherein the ntMax is a consecutive maximum integer number of time intervals.

12. A method for increasing a maximum integer number of time intervals (ntMax) between adjustments to a video bit rate (VBR) during transmission of video data over a packet-switched network, comprising the steps of:

increasing a first VBR by a bit rate enhancement factor (BREF) to obtain a second VBR, if the PL over the ntMax is less than or equal to the PL threshold;

increasing the ntMax, if the PL at the second VBR is greater than the PL threshold; and

reducing the second VBR to the first VBR if the PL at the second VBR is greater than the PL threshold.

13. The method of claim 12 , further comprising continuously repeating the steps increasing the first VBR, increasing the ntMax, and reducing the second VBR.

14. The method of claim 12 , wherein the step of increasing the ntMax further comprises increasing the ntMax by adding a predefined integer number of time intervals N to the ntMax.

15. A system for adjusting a video bit rate (VBR) during transmission of video data over a packet-switched network, comprising:

means for reducing the VBR to no less than a minimum video bit rate threshold (VBRmin), if a packet loss (PL) over a time interval is greater than a PL threshold;

means for increasing the reduced VBR by a bit rate enhancement factor (BREF) to obtain a second VBR, if the PI over a maximum integer number of time intervals (ntMax) is less than or equal to the PL threshold;

means for increasing the ntMax if the PL at the second VBR is greater than the PL threshold; and

means for increasing the second VBR by the BREF for each consecutive time interval until a VBRmax is reached, if the PL for each previous time interval is less than or equal to the PL threshold.

Assignments (10)