Method and apparatus for performing packet loss or frame erasure concealment

• US 6,961,697 B1
• Filed: 04/19/2000
• Issued: 11/01/2005
• Est. Priority Date: 04/19/1999
• Status: Expired due to Term

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Kapilow, David A.
• Primary Examiner(s): Dorvil, Richemond
• Assistant Examiner(s): HARPER, V PAUL
• Application Number:
  US09/700,522
• Time in Patent Office: 2,022 Days
• Field of Search: 375/240.16, 375/340, 704/201, 704/202, 704/206, 704/210, 704/219, 704/228, 704/229, 704/270, 704/267, 704/207
• US Class Current: 704/228
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm

Abstract

The invention concerns a method and apparatus for performing packet loss or Frame Erasure Concealment (FEC) for a speech coder that does not have a built-in or standard FEC process. A receiver with a decoder receives encoded frames of compressed speech information transmitted from an encoder. A lost frame detector at the receiver determines if an encoded frame has been lost or corrupted in transmission, or erased. If the encoded frame is not erased, the encoded frame is decoded by a decoder and a temporary memory is updated with the decoder'"'"'s output. A predetermined delay period is applied and the audio frame is then output. If the lost frame detector determines that the encoded frame is erased, a FEC module applies a frame concealment process to the signal. The FEC processing produces natural sounding synthetic speech for the erased frames.

Claims

1. A method for concealing the effect of missing speech information on a speech signal generated at a decoder, said missing speech information having been compressed and transmitted in packets to the decoder which does not receive one or more of such packets, the method comprising the steps of:

generating a speech signal based on received packets representing speech information;

in response to a determination that one or more packets are not available at the receiver to form the speech signal, synthesizing a portion of the speech signal corresponding to the one or more unavailable packets using a portion of the previously formed speech signal, wherein the duration of the previously formed portion used in such synthesis is determined based on a duration of packet unavailability.

2. A method for concealing the effect of missing speech information on generated speech, said speech information having been compressed and transmitted in packets to a receiver which does not receive one or more of such packets, the method comprising the steps of:

forming a speech signal based on received packets representing speech information;

when one or more packets are not available at the receiver to form the speech signal,

determining a duration of packet unavailability;

determining a portion of the previously formed speech signal based on the duration of packet unavailability; and

synthesizing a portion of the speech signal corresponding to the one or more unavailable packets using the determined portion of the previously formed speech signal.