Method and apparatus for performing packet loss or frame erasure concealment

• US 20080140409A1
• Filed: 09/12/2006
• Published: 06/12/2008
• Est. Priority Date: 04/19/1999
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property II LP (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Kapilow, David A.
• Granted Patent: US 7,797,161 B2
• Time in Patent Office: Days
• US Class Current: 704/265
• CPC Class Codes: G10L 19/0017 Lossless audio signal coding; Perfect reconstruction of coded audio signal by transmission of coding error G10L19/24 takes precedence
• CPC Class Codes: G10L 19/005 Correction of errors induced by the transmission channel, if related to the coding algorithm
• CPC Class Codes: G10L 19/028 Noise substitution, i.e. substituting non-tonal spectral components by noisy source comfort noise for discontinuous speech transmission G10L19/012
• CPC Class Codes: G10L 21/003 Changing voice quality, e.g. pitch or formants

Abstract

A method for performing packet loss or Frame Erasure Concealment (FEC) for a speech coder receives encoded frames of compressed speech information transmitted from an encoder. The method determines whether an encoded frame has been lost, corrupted in transmission, or erased, synthesizes properly received frames, and decides on an overlap-add window to use in combining a portion of the synthesized speech signal with a subsequent speech signal resulting from a received and decoded packet, where the size of the overlap-add window is based on the unavailability of packets. If it is determined that an encoded frame has been lost, corrupted in transmission, or erased, the method performed an overlap-add operation on the portion of the synthesized speech signal and the subsequent speech signal, using the decided-on overlap-add window.

Claims

1. In a process for concealing the effect of missing speech information, said speech information having been compressed and transmitted in packets to a receiver to which less than all of the transmitted packets are available or suitable for decoding, a method for concealing unavailable packets in decoded speech, comprising:

synthesizing a speech signal corresponding to at least one unavailable packet;

determining an overlap-add window to use in combining a portion of the synthesized speech signal with a subsequent speech signal resulting from a received packet being decoded by the receiver, wherein the size of the overlap-add window is based on the unavailability of packets; and

performing an overlap-add operation on the portion of the synthesized speech signal and the subsequent speech signal using the overlap-add window.