Patent ID: 7805292

Claim:
An apparatus for transcoding an audio signal between a CELP-based coder and a hybrid coder, the apparatus comprising: a source bitstream unwrapper configured to: receive a source bitstream; extract one or more CELP compression parameters from the source bitstream; and construct an audio signal vector from the source bitstream while maintaining the one or more extracted CELP compression parameters; a frame interpolator coupled to the source bitstream unwrapper, the frame interpolator being configured to interpolate the one or more extracted CELP compression parameters and the constructed audio signal vector between a source frame rate and a destination frame rate and a source subframe rate and a destination subframe rate; a compression parameter converter coupled to frame interpolator, the compression parameter converter being configured to calculate output compression parameters from at least one of the interpolated compression parameters or the one or more extracted CELP compression parameters; a destination bitstream wrapper coupled to the compression parameter converter, the destination bitstream wrapper being configured to construct a destination bitstream; and a mapping parameter tuner coupled to the frame interpolator, the mapping parameter tuner being configured to select one or more parameters for use by the compression parameter converter.