Internet voice transmission

• US 6,389,032 B1
• Filed: 02/11/1999
• Issued: 05/14/2002
• Est. Priority Date: 02/11/1999
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Cohen, Ran
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): PHAN, MAN U
• Application Number:
  US09/249,586
• Time in Patent Office: 1,188 Days
• Field of Search: 370/235, 370/216, 370/252, 370/266, 370/391, 370/394, 370/395, 370/392, 370/389, 370/412, 370/429, 370/428, 370/471, 370/474, 370/516, 710/56, 704/201, 704/262
• US Class Current: 370/412
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• CPC Class Codes: H04L 12/6418 Hybrid transport
• CPC Class Codes: H04L 2012/6481 Speech, voice
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/28 in relation to timing considerations
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A method of providing audio packets received from a network to a speaker which plays the packets. The method includes accumulating the received audio packets in a buffer having a variable size, calculating a parameter indicative of a feature of data flow in the network, adjusting the size of the buffer responsive to the parameter, and providing the speaker with audio packets from the buffer.

Claims

1. A method of providing audio packets received from a network to a speaker which plays the packets, comprising:

accumulating the received audio packets in a buffer having a variable size;

calculating a parameter indicative of a feature of data flow in the network;

adjusting the size of the buffer responsive to the parameter; and

providing the speaker with audio packets from the buffer,

wherein calculating the parameter comprises calculating the parameter substantially each time the size of the buffer changes due to insertion of a packet thereinto or removal of a packet therefrom.

2. A method according to claim 1, wherein accumulating the packets comprises storing the packets in a buffer defined by two pointers, and wherein adjusting the size of the buffer comprises moving at least one of the pointers.

3. A method according to claim 1, wherein accumulating the packets comprises storing the packets in the buffer responsive to ordering labels in the packets.

4. A method according to claim 1, wherein providing the speaker with the audio packets comprises providing the packets substantially independently of a rate of accumulating the packets in the buffer.

5. A method according to claim 1, wherein providing the speaker with the audio packets comprises providing the packets after a minimal delay which is dependent on the size of the buffer.

6. A method according to claim 1, wherein calculating the parameter comprises calculating the parameter responsive to the accumulation of the received audio packets.

7. A method according to claim 1, wherein calculating the parameter comprises calculating the parameter substantially irrespective of the accumulation of the received audio packets.

8. A method according to claim 1, wherein calculating the parameter comprises calculating a jitter of the network.

9. A method according to claim 8, wherein calculating the jitter comprises calculating a change in the size of the buffer in two consecutive measurements of the buffer size.

10. A method according to claim 1, wherein adjusting the size of the buffer comprises adding or removing one or more leading silent packets in the buffer.

11. A method according to claim 1, wherein adjusting the size of the buffer comprises adding or removing one or more silent packets between audio packets representing words in the buffer.

12. A method according to claim 1, wherein adjusting the size of the buffer comprises changing the time required to play at least some of the audio data in the buffer.

13. A method according to claim 12, wherein changing the time required to play the audio data comprises changing a speed of playing the audio data substantially without effecting the pitch of the resultant audio signals.

14. A method of providing audio packets received from a network to a speaker which plays the packets, comprising:

accumulating the received audio packets in a buffer having a variable size;

calculating a parameter indicative of a feature of data flow in the network;

adjusting the size of the buffer responsive to the parameter; and

providing the speaker with audio packets from the buffer,

wherein adjusting the size of the buffer responsive to the parameter comprises determining a watermark representing a desired size of the buffer.

15. A method according to claim 14, wherein determining the watermark comprises changing the watermark if the parameter is not within a desired range of the watermark.

16. A method according to claim 14, wherein determining the watermark comprises enlarging the watermark when the data flow in the network is relatively irregular and reducing the watermark when the data flow is relatively regular.

17. Apparatus for providing audio packets received from a network to a speaker which plays the packets, comprising:

a processor which accumulates the received audio packets in a buffer having a variable size, calculates a parameter indicative of a feature of data flow in the network, adjusts the size of the buffer responsive to the parameter, and provides the audio data to the speaker,

wherein the processor updates the parameter each time the size of the buffer changes.

18. Apparatus according to claim 17, wherein the processor defines the buffer using two pointers and adjusts the size of the buffer by moving at least one of the pointers.

19. Apparatus according to claim 17, wherein the processor provides the audio packets to the speaker substantially independently of a rate of accumulating the packets in the buffer.

20. Apparatus according to claim 17, wherein the parameter comprises a jitter.

21. Apparatus according to claim 17, wherein the processor adjusts the size of the buffer by adding or removing one or more leading silent packets in the buffer.

22. Apparatus according to claim 17, wherein the processor adjusts the size of the buffer by adding or removing one or more silent packets between audio packets representing words in the buffer.

23. Apparatus for providing audio packets received from a network to a speaker which plays the packets, comprising:

a processor which accumulates the received audio packets in a buffer having a variable size, calculates a parameter indicative of a feature of data flow in the network, adjusts the size of the buffer responsive to the parameter, and provides the audio data to the speaker,

wherein the processor determines a watermark which represents a desired size of the buffer.

24. Apparatus according to claim 23, wherein the processor changes the watermark such that the parameter will substantially always be within a desired range of the watermark.

25. Apparatus according to claim 23, wherein the processor enlarges the watermark when the data flow in the network is relatively irregular and reduces the watermark when the data flow is relatively regular.

26. Apparatus according to claim 23, wherein the processor adjusts the size of the buffer by changing the time required to play at least some of the audio data in the buffer.

27. A computer program product having computer readable program code embodied therein, which code causes a computer receiving audio packets over a network to accumulate the received audio packets in a buffer having a variable size and to calculate a parameter indicative of a feature of data flow in the network and adjust the size of the buffer responsive to the parameter, wherein the computer conveys the audio packets to a speaker which plays the packets, and wherein the code causes the computer to update the parameter substantially each time the size of the buffer changes.

28. A computer program product having computer readable program code embodied therein, which code causes a computer receiving audio packets over a network to accumulate the received audio packets in a buffer having a variable size and to calculate a parameter indicative of a feature of data flow in the network and adjust the size of the buffer responsive to the parameter, wherein the computer conveys the audio packets to a speaker which plays the packets, and wherein the code causes the computer to determine a watermark which represents a desired size of the buffer.