Patent ID: 7519532
Filing Date: 2009-04-14
Classification: G10L

Abstract:
1. A method of transcoding, comprising: (a) decoding input first frames, said first frames encoded with a first ACELP method; (b) finding linear prediction coefficients and pitch delays for second frames of a second ACELP method using said first frames; (c) finding fixed codebook vectors for said second frames by searching over allowed pulse positions, wherein (i) said allowed pulse positions are less than all pulse positions in said second frames, (ii) on each track of one of said second frames said allowed pulse positions include pulse positions of first ACELP fixed codebook vectors for said first frames, and (iii) on each track of one of said second frames said allowed pulse positions include the position of the maximum magnitude of a correlation vector on said each track; and (d) encoding said linear prediction coefficients, pitch delays, and fixed codebook vectors with said second ACELP method; wherein said first ACELP method is EVRC and said second ACELP method is G.729ab.