Latency differential mitigation for real time data streams

• US 20080080568A1
• Filed: 09/29/2006
• Published: 04/03/2008
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: Avaya ECS Ltd. (Avaya Incorporated)
• Original Assignee: Avaya ECS Ltd. (Avaya Incorporated)
• Inventors: Douglas, Jim Patrick, Hughes, Simon Derek
• Granted Patent: US 9,374,263 B2
• Time in Patent Office: Days
• US Class Current: 370/519
• CPC Class Codes: H04L 43/0852 Delays
• CPC Class Codes: H04L 65/1083 In-session procedures
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/1104 Session initiation protocol [SIP]
• CPC Class Codes: H04L 65/60 Network streaming of media packets
• CPC Class Codes: H04L 65/80 Responding to QoS

Abstract

Techniques for mitigating effects of differing latencies associated with real time data streams in multimedia communication networks. For example, a technique for mitigating a latency differential between a first media path and a second media path, over which a first device and a second device are able to communicate, includes the following steps. A training phase is performed to determine a latency differential between the first media path and the second media path. Prior to the first device switching a media stream, being communicated to the second device, from the first media path to the second media path, the first device synchronizes the media stream based on the determined latency differential such that a latency associated with the switched media stream is made to be substantially consistent with a latency of the second media path.

Claims

1. A method of mitigating a latency differential between a first media path and a second media path over which a first device and a second device are able to communicate, the method comprising the steps of:

performing of a training phase to determine a latency differential between the first media path and the second media path; and

prior to the first device switching a media stream, being communicated to the second device, from the first media path to the second media path, the first device synchronizing the media stream based on the determined latency differential such that a latency associated with the switched media stream is made to be substantially consistent with a latency of the second media path.

2. The method of claim 1, wherein the training phase performance step further comprises the first device taking one or more data samples from the media stream currently being sent over the first media path.

3. The method of claim 2, wherein the training phase performance step further comprises the first device sending each of the one or more data samples to the second device over the second media path after each of the one or more data samples are sent over the first media path.

4. The method of claim 3, wherein the training phase performance step further comprises the second device determining a match between one or more of the data samples received over the first media path and one or more of the data samples received over the second media path.

5. The method of claim 4, wherein the training phase performance step further comprises the second device computing a latency differential between at least one matching data sample.

6. The method of claim 5, wherein the second device computes a latency differential measure based on an average of latency differentials computed for two or more matched data samples.

7. The method of claim 6, wherein the training phase performance step further comprises the second device sending a message indicating the computed differential latency measure to the first device.

8. The method of claim 7, wherein the steps of the first device sending one or more data samples, the second device determining matching samples, and the second device computing a latency differential measure are repeated such that a statistical measure of variability of the latency differential measure is computed.

9. The method of claim 1, wherein the training phase further comprises:

(i) a first part wherein a training sample is sent in a direction from the first device to the second device so as to determine a latency differential between the first media path and the second media path; and

(ii) a second part wherein a training sample is sent in a direction from the second device to the first device so as to determine a latency differential between the first media path and the second media path.

10. The method of claim 1, wherein the synchronizing step further comprises:

the first device identifying one or more periods of silence in the communicated media stream; and

the first device incrementally removing the determined differential latency during such identified periods.

11. The method of claim 1, wherein the training phase performance step further comprises the first device simultaneously sending the media stream over the first media path and the second media path.

12. The method of claim 11, wherein the training phase performance step further comprises the second device determining a match between one or more data units received over the first data path and one or more of data units received over the second data path.

13. The method of claim 12, wherein the training phase performance step further comprises the second device computing a latency differential between at least one matching data unit.

14. The method of claim 13, wherein the training phase performance step further comprises the second device sending a message indicating the computed differential latency to the first device.

15. The method of claim 1, wherein the first device and the second device are Voice over Internet Protocol clients

16. The method of claim 1, wherein the first device and the second device are Video over Internet Protocol clients.

17. The method of claim 1, wherein the switched media stream represents one or more voice packets or one or more video packets associated with a communication being conducted between the first device and the second device.

18. An article of manufacture for mitigating a latency differential between a first media path and a second media path over which a first device and a second device are able to communicate, comprising a machine recordable medium containing one or more programs stored thereon which when executed implement the steps recited in claim 1.

19. Apparatus for mitigating a latency differential between a first media path and a second media path over which a first device and a second device are able to communicate, comprising:

a memory; and

at least one processor associated with the first device, which is coupled to the memory and operative to;

(i) initiate performance of a training phase to determine a latency differential between the first media path and the second media path; and

(ii) prior to switching a media stream, being communicated to the second device, from the first media path to the second media path, synchronize the media stream based on the determined latency differential such that a latency associated with the switched media stream is made to be substantially consistent with a latency of the second media path.

20. Apparatus for mitigating a latency differential between a first media path and a second media path over which a first device and a second device are able to communicate, comprising:

a memory; and

at least one processor associated with the second device, which is coupled to the memory and operative to participate in a training phase, initiated by the first device, to determine a latency differential between the first media path and the second media path such that, prior to the first device switching a media stream, being communicated to the second device, from the first media path to the second media path, the first device synchronizes the media stream based on the determined latency differential such that a latency associated with the switched media stream is made to be substantially consistent with a latency of the second media path.