Audio transceiver

• US 5,825,771 A
• Filed: 11/10/1994
• Issued: 10/20/1998
• Est. Priority Date: 11/10/1994
• Status: Expired due to Term

• Current Assignee: YMAX Communications Corporation (B. Riley Financial, Inc.)
• Original Assignee: Vocaltec Limited
• Inventors: Haramaty, Lior, Cohen, Alon
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US08/337,616
• Time in Patent Office: 1,440 Days
• Field of Search: 370/94.1, 370/60, 370/110.1, 370/79, 370/62, 370/58.2, 370/85.1, 370/394, 370/389, 370/265, 370/270, 370/422, 370/522, 370/465, 370/437, 370/494, 370/495, 370/496 , 370/468, 370/411, 370/493, 370/452, 379/80, 379/88, 379/280, 375/27
• US Class Current: 370/394
• 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 2012/6429 Terminal adapters
• CPC Class Codes: H04L 2012/6481 Speech, voice
• CPC Class Codes: H04L 2012/6489 Buffer Management, Threshold setting, Scheduling, Shaping
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 21/4392 involving audio buffer management

Abstract

The present invention is an audio transceiver (having an audio receiver and a transmitter) which, on the receiving side, adaptively controls the amount of audio data in the buffer of a PC audio device, such that the audio device always has something to play. On the transmission side, the audio transmitter provides at least sequence numbers to the audio packets to be sent. The audio receiver is concerned only with the state of the buffer of the audio device. Therefore, the audio transmitter does not have to be synchronized with the audio receiver.

Claims

1. An audio transceiver between an audio device of a personal computer and a packet data network, the audio transceiver comprising:

means for receiving a stream of sequence stamped audio packets from said packet data network;

fullness setting means for transferring at least a silence frame to a playback buffer of said audio device whenever said playback buffer is empty in order to fill said playback buffer to an adjustable fullness level; and

fullness adjusting means for controlling the fullness level of the playback buffer, said fullness adjusting means operating to duplicate or remove at least one frame until a difference between a current fullness level and the desired fullness level is substantially zero.

2. A transceiver according to claim 1 and also comprising

means for sequence- and destination-stamping all of said audio packets;

and

means for transmitting said audio packets via said network.

3. A transceiver according to claim 1 and also comprising voice detection means which stores at least a portion of said received audio packets and sends after said sound threshold level is reached said stored audio packets with audio packets received after said sound threshold level is reached.

4. A transceiver according to claim 1 and wherein said packet data network is a private network.

5. A transceiver according to claim 1 and wherein said packet data network is a public network.

6. A transceiver according to claim 1 and wherein said fullness setting means comprises means for increasing said adjustable fullness level and wherein said fullness adjusting means includes means for decreasing said adjustable fullness level and means for processing audio data within said audio packets in order to fill said playback buffer to the current value of said adjustable fullness level.

7. A transceiver according to claim 6 and wherein said means for processing comprises means for determining the amount of data in said playback buffer during a predetermined window of time.

8. A transceiver according to claim 7 and wherein said means for processing includes means for adding and removing portions of said audio data as a function of whether or not the current amount of data is less or more than said current value of said adjustable fullness level.

9. A transceiver according to claim 8 and wherein said means for adding and removing comprise means for maintaining the size of said portions of audio data until said current amount of data reaches said current value of said adjustable fullness level.

19. A transceiver according to claim 1 wherein said means for receiving further comprising means for duplicating at least one frame of two packets bordering a gap, said gap detected whenever the sequence number of said two adjacent packets is not consecutive.

20. A transceiver according to claim 19 wherein said means for receiving further comprises inserting at least one silence frame between said duplicated frames.

21. A transceiver according to claim 19 wherein said fullness adjusting means remove at least one frame of the frames duplicated by said means for receiving due to said gap.

22. A transceiver according to claim 19 wherein said fullness adjusting means duplicate at least one frame of the frames not duplicated by said means for receiving due to said gap.

23. A transceiver according to claim 1 wherein said adjustable fullness level is determined in accordance with the variations in size of said playback buffer.

10. A method for transmitting and receiving audio data between an audio device of a personal computer and a packet data network, the method comprising the steps of:

receiving a stream of sequence-stamped audio packets from said packet data network;

transferring at least a silence frame to a playback buffer of said audio device whenever said playback buffer is empty in order to fill said playback buffer to an adjustable fullness level; and

controlling the fullness level of the playback buffer, said controlling comprising duplicating or removing at least one frame until a difference between a current fullness level and the desired fullness level is substantially zero.

11. A method according to claim 10 and also comprising the steps of:

sequence- and destination-stamping all of said audio packets; and

transmitting said audio packets via said network.

12. A method according to claim 10 and also comprising the steps of storing at least a portion of audio packets received before a sound threshold level is reached and sending after said sound threshold level is reached said stored audio packets with audio packets received after said sound threshold level is reached.

13. A method according to claim 10 and wherein said packet data network is a private network.

14. A method according to claim 10 and wherein said packet data network is a public network.

15. A method according to claim 10 and wherein said step of transferring includes the step of increasing said adjustable fullness level and wherein the step of adaptively controlling includes the steps of decreasing said adjustable fullness level and processing audio data within said audio packets in order to fill said playback buffer to the current value of said adjustable fullness level.

16. A method according to claim 15 and wherein said step of processing includes the step of determining the amount of data in said playback buffer during a predetermined window of time.

17. A method according to claim 16 and wherein said step of processing includes the step of adding and removing portions of said audio data as a function of whether or not the current amount of data is less or more than said current value of said adjustable fullness level.

18. A method according to claim 17 and wherein said step of adding and removing includes the step of maintaining the size of said portions of audio data until said current amount of data reaches said current value of said adjustable fullness level.

24. A method according to claim 10 wherein said step of receiving further comprising duplicating at least one frame of two packets bordering a gap, said gap detected whenever the sequence number of said two adjacent packets is not consecutive.

25. A method according to claim 24 wherein said step of receiving further comprises inserting at least one silence frame between said duplicated frames.

26. A method according to claim 24 wherein said controlling comprises removing at least one frame of the frames duplicated in said step of receiving due to said gap.

27. A method according to claim 24 wherein said controlling comprises duplicating at least one frame of the frames not duplicated by said means for receiving due to said gap.

28. A method according to claim 10 wherein said controlled fullness level is determined in accordance with the variations in size of said playback buffer.

29. An audio transceiver between an audio device of a personal computer and a packet data network, the audio transceiver comprising:

means for receiving a stream of sequence stamped audio packets from said packet data network;

means for duplicating at least one frame of two received packets bordering a gap, said gap detected whenever the sequence number of said two adjacent received packets is not consecutive; and

means for inserting at least one silence frame between said duplicated frames.

30. A method for transmitting data between an audio device of a personal computer and a packet data network, comprising:

receiving a stream of sequence stamped audio packets from said packet data network;

duplicating frames of two received packets bordering a gap, said gap detected whenever the sequence number of said two adjacent received packets is not consecutive; and

inserting at least one silence frame between said duplicated frames.