Method and system for detecting audio and video synchronization

• US 8,699,351 B2
• Filed: 12/04/2009
• Issued: 04/15/2014
• Est. Priority Date: 12/04/2009
• Status: Expired due to Fees

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Medina, Douglas R., Coppa, Frank Robert, Kennedy, Larry
• Primary Examiner(s): LEVITAN, DMITRY
• Application Number:
  US12/631,512
• Publication Number:
  US 20110134763A1
• Time in Patent Office: 1,593 Days
• Field of Search: 370241-248, 370250-253, 370/464, 370/465, 370/498, 370/503, 370/509, 370516-521, 709/248
• US Class Current: 370/241
• CPC Class Codes: H04L 43/08 Monitoring or testing based on specific metrics, e.g. QoS, energy consumption or environmental parameters
• CPC Class Codes: H04L 43/0852 Delays
• CPC Class Codes: H04N 21/2368 Multiplexing of audio and video streams
• CPC Class Codes: H04N 21/2389 Multiplex stream processing, e.g. multiplex stream encrypting
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams
• CPC Class Codes: H04N 21/4385 Multiplex stream processing, e.g. multiplex stream decrypting

Abstract

A method and system for diagnosing synchronization offsets in IPTV program signals includes generating audio counter values for audio packets and video counter values for video packets, such that synchronized audio packets and video packets have corresponding counter values. The correspondence may be fixed or may be a variable relationship during the IPTV program duration. The difference in arrival times of the audio and video packets may be measured at various IPTV network nodes, and compared to the IPTV program clock. Aberrant values for arrival times may result in a network synchronization alarm at an identified IPTV network node.

Claims

1. A packet transmission method, comprising:

receiving an uncompressed television program signal;

packetizing the television program signal into an IP television program signal comprising a video packet stream including a video packet and an audio packet stream including an audio packet corresponding to the video packet;

including a video counter value in the video packet;

including an audio counter value corresponding to the video counter value in the audio packet;

including a program clock value, distinct from the video counter value, in the video packet, wherein the program clock value is associated with a program clock synchronized with the IP television program signal;

transmitting the packetized IP television program signal over an IP television network;

recording a first arrival time of the audio packet arriving at an IP television network node;

recording a second arrival time of the video packet arriving at the IP television network node;

determining a first synchronization offset based on a difference between the first arrival time and the second arrival time;

obtaining the program clock value from the video packet;

determining a second synchronization offset based on a difference between the first arrival time and the program clock value;

determining a third synchronization offset based on a difference between the second arrival time and the program clock value;

maintaining, for each of a plurality of network nodes, historical values of the first synchronization offset, the second synchronization offset, and the third synchronization offset; and

determining from the historical values, individual network nodes producing offset values exceeding predetermined thresholds.

2. The method of claim 1, wherein the IP program television signal is digitally compressed.

3. The method of claim 1, wherein including the program clock value in the video packet comprises periodically determining a value of the program clock and periodically including the program clock value in a video packet.

4. The method of claim 1, further comprising:

when the absolute value of any one of the first synchronization offset, the second synchronization offset, and the third synchronization offset exceeds a predetermined value, generating a network synchronization alarm for the IP television network node.

5. The method of claim 1, further comprising:

determining the audio counter value based on the video counter value and a ratio of video packets to audio packets in the IP television program signal.

6. A network testing device, comprising:

a processor; and

a non-transitory computer readable storage medium including processor executable instructions that, when executed by the processor, cause the processor to perform operations comprising;

receiving an uncompressed television program signal;

packetizing the television program signal into an IP television program signal comprising a video packet stream including a video packet and an audio packet stream including an audio packet corresponding to the video packet;

including a video counter value in the video packet;

including an audio counter value corresponding to the video counter value in the audio packet;

including a program clock value, distinct from the video counter value, in the video packet, wherein the program clock value is associated with a program clock synchronized with the IP television program signal;

transmitting the packetized IP television program signal over an IP television network;

recording a first arrival time of the audio packet arriving at an IP television network node;

recording a second arrival time of the packet arriving at the IP television network node;

determining a first synchronization offset based on a difference between the first arrival time and the second arrival time;

obtaining the program clock value from the video packet;

determining a second synchronization offset based on a difference between the first arrival time and the program clock value;

determining a third synchronization offset based on a difference between the second arrival time and the program clock value;

maintaining, for each of a plurality of network nodes, historical values of the first synchronization offset, the second synchronization offset, and the third synchronization offset; and

determining from the historical values, individual network nodes producing an offset value exceeding a predetermined threshold.

7. The network testing device of claim 6, wherein the operations include:

when the absolute value of any one of the first arrival time synchronization offset, the second arrival time synchronization offset, and the third arrival time synchronization offset exceeds the predetermined threshold, generating a network synchronization alarm for the IP television network node.

8. The network testing device of claim 7, wherein the operations include:

sending, to an IP television network server, the first arrival time synchronization offset, the second arrival time synchronization offset, and the third arrival time synchronization offset for packets of the IP television program signal, along with an indication of the IP television network node.

9. A non-transitory computer-readable storage medium, including processor executable instructions that, when executed by a processor, cause the processor to perform operations comprising:

receiving an uncompressed television program signal;

packetizing the television program signal into an IP television program signal comprising a video packet stream including a video packet and an audio packet stream including an audio packet corresponding to the video packet;

including a video counter value in the video packet;

including an audio counter value corresponding to the video counter value in the audio packet;

including a program clock value, distinct from the video counter value, in the video packet, wherein the program clock value is associated with a program clock synchronized with the IP television program signal;

transmitting the packetized IP television program signal over an IP television network;

recording a first arrival time of the audio packet arriving at an IP television network node;

recording a second arrival time of the packet arriving at the IP television network node;

determining a first synchronization offset based on a difference between the first arrival time and the second arrival time;

obtaining the program clock value from the video packet;

determining a second synchronization offset based on a difference between the first arrival time and the program clock value;

determining a third synchronization offset based on a difference between the second arrival time and the program clock value;

maintaining, for each of a plurality of network nodes, historical values of the first synchronization offset, the second synchronization offset, and the third synchronization offset; and

determining from the historical values, individual network nodes producing an offset value exceeding a predetermined threshold.

10. The non-transitory computer readable storage media of claim 9, wherein the operations include:

compressing the television program signal in accordance with an H.264 video compression standard.

11. The non-transitory computer readable storage medium of claim 9, wherein the audio counter value increments for each consecutive audio packet, and wherein the video counter value increments for each consecutive video packet.

12. The non-transitory computer readable storage medium of claim 9, wherein the audio counter value is included in an audio packet header, and wherein the video counter value is included in a video packet header.

13. The non-transitory computer readable storage medium of claim 9, wherein the operations include:

determining the audio counter value based on the video counter value and a ratio of video packets to audio packets in the IP television program signal.

14. The non-transitory computer readable storage medium of claim 9, wherein the operations include:

when the absolute value of any of the first synchronization offset, the second synchronization offset, and the third synchronization offset exceeds the predetermined threshold, generating a network synchronization alarm for an identified IP television network node.

15. The non-transitory computer readable storage medium of claim 14, wherein the network synchronization alarm includes an IP television network diagnostic request for the identified IP television network node.