Systems and methods for encoding & decoding speech for lossy transmission networks

• US 20020159472A1
• Filed: 04/15/2002
• Published: 10/31/2002
• Est. Priority Date: 05/06/1997
• Status: Active Grant

• Current Assignee: Audiocodes Limited
• Original Assignee: Audiocodes Limited
• Inventors: Bialik, Leon
• Granted Patent: US 7,554,969 B2
• Time in Patent Office: Days
• US Class Current: 370/442
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm

Abstract

A voice encoder which utilizes future data, such as the lookahead data typically available for linear predictive coding (LPC), to partially encode a future packet and to send the partial encoding as part of the current packet. A decoder utilizes the partial encoding of the previous packet to decode the current packet if the latter did not arrive properly.

Claims

1. A voice data packet comprising:

a current frame portion including data encoding a current frame of voice data; and

a future frame portion including data at least partially encoding at least a section of a future frame of voice data which was used to encode said current frame.

2. A voice data packet according to claim 1 and wherein said future frame portion is smaller than said current frame portion.

3. A voice data packet according to claim 1 and wherein said future frame follows said current frame in time.

4. A voice data packet according to claim 1 and wherein said future frame includes an unvoiced flag if said future frame is an unvoiced frame.

5. A voice encoder comprising:

an encoder for partially encoding future data used to encode a current frame; and

a packet creator for creating a packet from a current packet and said partial future data.

6. A voice encoder according to claim 5 and wherein said encoder comprises a pitch change processor for determining a pitch in said future data as a change over a current pitch of said current frame.

7. A voice encoder according to claim 6 and wherein said pitch change processor includes a voiced/unvoiced state determiner based on the quality of the pitch change determination.

8. A voice decoder comprising:

a packet receiver for receiving a packet including a current frame portion including data encoding a current frame of voice data and a future frame portion including data at least partially encoding at least a section of a future frame of voice data which was used to encode said current frame; and

a decoder for at least decoding a future frame of voice data from at least the future frame portion of a previously properly received packet when said current packet is improperly received.

9. A method for encoding voice signals, the method comprising:

at least partially encoding at least a section of a future frame of voice data which was used to encode a current frame; and

creating a packet from an encoded current frame and said encoded at least a section of said future frame.

10. A method according to claim 9 and wherein said encoding includes determining a pitch in said section of a future frame as a change over a current pitch of said current frame.

11. A method according to claim 10 and wherein determining includes determining a voiced/unvoiced state based on the quality of the pitch change determination.

14. A voice encoder according to claim 13 and wherein said encoder comprises a pitch change processor for determining a pitch in said lookahead data as a change over a current pitch of said encoded frame.

15. A voice encoder according to claim 14 and wherein said pitch change processor includes a voiced/unvoiced state determiner based on the quality of the pitch change determination.

12. A method for decoding a packet of voice data, the method comprising:

randomly selecting a pitch value for an improperly received packet having an unvoiced flag; and

decoding a frame of voice data at least from said selected pitch value.

13. A voice encoder comprising:

an encoder for partially encoding lookahead data used for LPC encoding to encode a partial future packet; and

a packet creator for creating a packet from said encoded frame and said partial future packet.