Method and Apparatus for Performing Packet Loss or Frame Erasure Concealment
First Claim
1. A method for creating an output signal in response to received packets, said method including the steps of (a) decoding an available packet to form an audio signal segment, and (b) synthesizing an audio signal segment when a packet is unavailable, where an available packet is a packet that is received when expected and is decodable, and a packet is unavailable when it is not received when expected or is not decodable, the improvement comprising:
- performing an overlap-add operation on audio signal segment, that is decoded by said step of decoding and which follows a number of consecutive audio signal segments Rj-1, Rj-2, . . . Rj-k, that were synthesized by said step of synthesizing, where k is 1 or more, to modify a portion of said segment Rj-1 with a portion of said segment Rj to form a modified segment, R′
j where duration of said portion is a function of k; and
outputting segment R′
j.
3 Assignments
0 Petitions
Accused Products
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.
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Citations
3 Claims
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1. A method for creating an output signal in response to received packets, said method including the steps of (a) decoding an available packet to form an audio signal segment, and (b) synthesizing an audio signal segment when a packet is unavailable, where an available packet is a packet that is received when expected and is decodable, and a packet is unavailable when it is not received when expected or is not decodable, the improvement comprising:
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performing an overlap-add operation on audio signal segment, that is decoded by said step of decoding and which follows a number of consecutive audio signal segments Rj-1, Rj-2, . . . Rj-k, that were synthesized by said step of synthesizing, where k is 1 or more, to modify a portion of said segment Rj-1 with a portion of said segment Rj to form a modified segment, R′
j where duration of said portion is a function of k; andoutputting segment R′
j. - View Dependent Claims (3)
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2. The method of claim 2 where said duration is ¼
- pitch period plus
Specification