METHOD AND APPARATUS FOR IMPROVING VIDEO PERFORMANCE IN A WIRELESS SURVEILLANCE SYSTEM

• US 20080239075A1
• Filed: 03/26/2008
• Published: 10/02/2008
• Est. Priority Date: 03/26/2007
• Status: Active Grant

• Current Assignee: Pelco (Schneider Electric SE)
• Original Assignee: Pelco (Schneider Electric SE)
• Inventors: Bakst, Lawrence E., Aghdasi, Farzin, Mehrotra, Praveen
• Granted Patent: US 9,300,923 B2
• Time in Patent Office: Days
• US Class Current: 348/143
• 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 7/181 for receiving images from a plurality of remote sources

Abstract

A method of improving video performance in video surveillance system having a wireless encoder connected to a video surveillance network by a wireless access point device comprises the steps of allocating channel bandwidth to the wireless encoder from the wireless access point device, transmitting packets of video data from the wireless encoder to the wireless access point device, transmitting signals from the wireless access point device to the wireless encoder, monitoring the strength of the signals received by the wireless access point device, the strength of the signals received by the wireless encoder, and the number of lost packets of video data transmitted from the wireless encoder to the wireless access point device, sending a request from the wireless encoder to the wireless access point device to change the bit transmission rate of the wireless encoder if the strength of the signals received by the wireless access point device is less than a first threshold, if the strength of the signals received by the wireless encoder is less than a second threshold, or if the number of lost packets of video data is greater than a third threshold, and changing the bit transfer rate of the wireless encoder if the wireless access point device approves the change.

Claims

1. A method of improving video performance in video surveillance system having a wireless encoder connected to a video surveillance network by a wireless access point device, said method comprising the steps of:

allocating channel bandwidth to the wireless encoder from the wireless access point device;

transmitting packets of video data from the wireless encoder to the wireless access point device;

transmitting signals from the wireless access point device to the wireless encoder;

monitoring the strength of the signals received by the wireless access point device, the strength of the signals received by the wireless encoder, and the number of lost packets of video data transmitted from the wireless encoder to the wireless access point device;

sending a request from the wireless encoder to the wireless access point device to change the bit transmission rate of the wireless encoder if the strength of the signals received by the wireless access point device is less than a first threshold, if the strength of the signals received by the wireless encoder is less than a second threshold;

or if the number of lost packets of video data is greater than a third threshold; and

changing the bit transfer rate of the wireless encoder if the wireless access point device approves the change.

2. A method as recited in claim 1 further comprising the step of transmitting packets of video data containing an I-frame from the wireless encoder with a higher retransmission threshold than packets of video data containing P-frames if the wireless access point device does not approve the change in the bit transfer rate of the wireless encoder.

3. A method as recited in claim 1 further comprising the step of transmitting packets of video data containing an I-frame from the wireless encoder with a higher retransmission threshold than packets of video data containing P-frames if the wireless access point device approves the change in the bit transfer rate of the wireless encoder and after the change the strength of the signals received by the wireless access point device remain less than a first threshold or the strength of the signals received by the wireless encoder remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

4. A method as recited in claim 2 further comprising the step of transmitting packets of video data containing an I-frame from the wireless encoder with a higher retransmission threshold than packets of video data containing P-frames if the wireless access point device approves the change in the bit transfer rate of the wireless encoder and after the change the strength of the signals received by the wireless access point device remain less than a first threshold or the strength of the signals received by the wireless encoder remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

5. A method as recited in claim 1 further comprising the step of notifying the application receiving the packets of video from the wireless encoder to lower the requested video image resolution or to lower the requested bit transfer rate if the wireless access point device does not approve the change in the bit transfer rate of the wireless encoder.

6. A method as recited in claim 1 further comprising the step of notifying the application receiving the packets of video data from the wireless encoder to lower the requested video image resolution or to lower the requested bit transfer rate if the wireless access point device approves the change in the bit transfer rate of the wireless encoder and after the change the strength of the signals received by the wireless access point device remain less than a first threshold or the strength of the signals received by the wireless encoder remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

7. A method as recited in claim 2 further comprising the step of notifying the application receiving the packets of video data from the wireless encoder to lower the requested video image resolution or to lower the requested bit transfer rate if the wireless access point device approves the change in the bit transfer rate of the wireless encoder and after the change the strength of the signals received by the wireless access point device remain less than a first threshold or the strength of the signals received by the wireless encoder remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

8. A method as recited in claim 5 further comprising the step of notifying the application receiving the packets of video data from the wireless encoder to lower the requested video image resolution or to lower the requested bit transfer rate if the wireless access point device approves the change in the bit transfer rate of the wireless encoder and after the change the strength of the signals received by the wireless access point device remain less than a first threshold or the strength of the signals received by the wireless encoder remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

9. A method of improving video performance in a video surveillance system having an encoder connected to a first wireless bridge transmitting packets of video data to a second wireless bridge connected to a video surveillance network, said method comprising the steps of:

transmitting packets of video data from the first wireless bridge to the second wireless bridge;

transmitting signals from the second wireless bridge to the first wireless bridge;

monitoring the strength of the signals received by the second wireless bridge, the strength of the signals received by the first wireless bridge, and the number of lost packets of video data transmitted from the first wireless bridge to the second wireless bridge;

sending a request from the first wireless bridge to the second wireless bridge to change the bit transmission rate of the first wireless bridge if the strength of the signals received by the second wireless bridge is less than a first threshold, if the strength of the signals received by the second wireless encoder is less than a second threshold, or if the number of lost packets of video data is greater than a third threshold.

10. A method as recited in claim 9 further comprising the step of transmitting packets of video data containing an I-frame from the first wireless bridge with a higher retransmission threshold than packets of video data containing P-frames if after the change in bit transfer rate the strength of the signals received by the second wireless bridge remain less than a first threshold or the strength of the signals received by the first wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

11. A method as recited in claim 9 further comprising the step of notifying the application receiving the packets of video from the second wireless bridge to lower the requested video image resolution or to lower the requested bit transfer rate if after the change in the bit transfer rate the strength of the signals received by the second wireless bridge remain less than a first threshold or the strength of the signals received by the first wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

12. A method as recited in claim 10 further comprising the step of notifying the application receiving the packets of video from the second wireless bridge to lower the requested video image resolution or to lower the requested bit transfer rate if after the change in the bit transfer rate the strength of the signals received by the second wireless bridge remain less than a first threshold or the strength of the signals received by the first wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

13. A method as recited in claim 9 further comprising the step of if after the change in the bit transfer rate the strength of the signals received by the second wireless bridge remain less than a first threshold or the strength of the signals received by the first wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold transmitting I-frames at a lower bit rate than P-frames.

14. A method as recited in claim 12 further comprising the step of if after the change in the bit transfer rate the strength of the signals received by the second wireless bridge remain less than a first threshold or the strength of the signals received by the first wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold transmitting I-frames at a lower bit rate than P-frames.

15. A video surveillance system comprising:

a network;

a wireless access point connected to said network;

a camera;

a wireless encoder connected to said camera for transmitting packets of video data from said camera to said wireless access point, said wireless access point allocating channel bandwidth to said wireless encoder and transmitting signals to said wireless encoder indicating the strength of the signals received from said wireless encoder and the number of lost packets of video data, said wireless encoder determining the strength of the signals received from said wireless access point, said wireless encoder monitoring the strength of the signals received by said wireless access point device, the strength of the signals received by said wireless encoder, and the number of lost packets of video data transmitted from said wireless encoder to said wireless access point device, said wireless encoder sending a request to said wireless access point to change the bit transmission rate of said wireless encoder if the strength of the signals received by said wireless access point is less than a first threshold, if the strength of the signals received by said wireless encoder is less than a second threshold;

or if the number of lost packets of video data is greater than a third threshold; and

changing the bit transfer rate of said wireless encoder if said wireless access point approves the change.

16. A video surveillance system as recited in claim 15 wherein the packets of video data transmitted by said wireless encoder comprise I-frames and P-frames and said wireless encoder transmits packets of video data containing an I-frame with a higher retransmission threshold than packets of video data containing P-frames if said wireless access point does not approve the change in the bit transfer rate of said wireless encoder.

17. A video surveillance system as recited in claim 15 wherein the packets of video data transmitted by said wireless encoder comprise I-frames and P-frames and said wireless encoder transmits packets of video data containing an I-frame with a higher retransmission threshold than packets of video data containing P-frames if said wireless access point approves the change in the bit transfer rate of said wireless encoder and after the change the strength of the signals received by said wireless access point remain less than a first threshold or the strength of the signals received by said wireless encoder remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

18. A video surveillance system as recited in claim 15 wherein said network comprises an application receiving the packets of video data transmitted by said wireless encoder and said wireless encoder notifies said application to lower the requested video image resolution or to lower the requested bit transfer rate if said wireless access point does not approve the change in the bit transfer rate of said wireless encoder.

19. A video surveillance system as recited in claim 15 wherein said network comprises an application receiving the packets of video data transmitted by said wireless encoder and said wireless encoder notifies said application to lower the requested video image resolution or to lower the requested bit transfer rate if said wireless access point approves the change in the bit transfer rate of said wireless encoder and after the change the strength of the signals received by said wireless access point remain less than a first threshold or the strength of the signals received by said wireless encoder remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

20. An video surveillance system comprising:

a network;

a camera;

an encoder connected to said camera;

a first wireless bridge connected to said encoder;

a second wireless bridge connected to said network;

said first wireless bridge transmitting packets of video data from said camera to said second wireless bridge, said second wireless bridge transmitting signals to said first wireless bridge indicating the strength of the signals received from said first wireless bridge and the number of lost packets of video data, said first wireless bridge determining the strength of the signals received from said second wireless bridge, said first wireless bridge monitoring the strength of the signals received by said first wireless bridge, the strength of the signals received by said second wireless bridge, and the number of lost packets of video data transmitted from said first wireless bridge to said second wireless bridge device, said first wireless bridge changing the bit transmission rate of said wireless encoder if the strength of the signals received by said first wireless bridge is less than a first threshold, if the strength of the signals received by said second wireless bridge is less than a second threshold, or if the number of lost packets of video data is greater than a third threshold.

21. A video surveillance system as recited in claim 20 wherein the packets of video data transmitted by said first wireless bridge comprise I-frames and P-frames and wherein said first wireless bridge transmits packets of video data containing an I-frame with a higher retransmission threshold than packets of video data containing P-frames if after the change in bit transfer rate the strength of the signals received by said first wireless bridge remain less than a first threshold or the strength of the signals received by the second wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

22. A video surveillance system as recited in claim 20 wherein said network comprises an application receiving the packets of video data transmitted by said first wireless bridge and wherein said first wireless bridge notifies said application to lower the requested video image resolution or to lower the requested bit transfer rate if after the change in the bit transfer rate the strength of the signals received by said first wireless bridge remain less than a first threshold or the strength of the signals received by said second wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

23. A video surveillance system as recited in claim 21 wherein said network comprises an application receiving the packets of video data transmitted by said first wireless bridge and wherein said first wireless bridge notifies said application to lower the requested video image resolution or to lower the requested bit transfer rate if after the change in the bit transfer rate the strength of the signals received by said first wireless bridge remain less than a first threshold or the strength of the signals received by said second wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

24. A video surveillance system as recited in claim 20 wherein the packets of video data transmitted by said first wireless bridge comprise I-frames and P-frames and said first wireless bridge transmits the I-frames at a lower bit rate than the P-frames if after the change in the bit transfer rate the strength of the signals received by said first wireless bridge remain less than a first threshold or the strength of the signals received by said second wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.

25. A video surveillance system as recited in claim 23 wherein said first wireless bridge transmits I-frames at a lower bit rate than P-frames if after the change in the bit transfer rate the strength of the signals received by said first wireless bridge remain less than a first threshold or the strength of the signals received by said second wireless bridge remain less than a second threshold or the number of lost packets of video data is greater than a third threshold.