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

• US 6,389,006 B1
• Filed: 05/06/1998
• Issued: 05/14/2002
• Est. Priority Date: 05/06/1997
• Status: Active Grant

• Current Assignee: Audiocodes Limited
• Original Assignee: Audiocodes Limited
• Inventors: Bialik, Leon
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): NGUYEN, BRIAN D
• Application Number:
  US09/073,687
• Time in Patent Office: 1,469 Days
• Field of Search: 370/352, 370/249, 370/229, 370/435, 370/395, 370/252, 370/389, 370/470, 370/471, 370/474, 704/207, 704/219, 704/208, 704/223, 704/220
• US Class Current: 370/352
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm

Abstract

A voice encoder and decoder which attempt to minimize the effects of voice data packet loss, typically over wide area networks is provided. The voice encoder 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. The 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 decoder comprising:

a packet receiver for receiving a current packet including a current frame portion including a pitch value and short term spectral parameters describing a current frame of voice data and a future frame portion including a pitch change value at least partially describing at least a section of a future frame of voice data;

current decoding means for decoding said current frame of voice data from said current frame portion when said current packet is properly received; and

future decoding means for 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, said future decoding means including;

means for creating a new pitch value for said improperly received packet from said pitch value and said pitch change value of said properly received packet;

an extrapolator for extrapolating new short term spectral parameters for said improperly received packet from said short term spectral parameters of said properly received packet; and

means for decoding said improperly received packet using said new pitch value and said new short term spectral parameters.

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

receiving a current packet including a current frame portion including a pitch value and short term spectral parameters describing a current frame of voice data and a future frame portion including a pitch change value at least partially describing at least a section of a future frame of voice data;

decoding said current frame of voice data from said current frame portion when said current packet is properly received; and

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, including;

creating a new pitch value for said improperly received packet from said pitch value and said pitch change value of said properly received packet;

extrapolating new short term spectral parameters for said improperly received packet from said short term spectral parameters of said properly received packet; and

decoding said improperly received packet using said new pitch value and said new short term spectral parameters.