Patent ID: 7684978
Filing Date: 2010-03-23
Classification: G10L

Abstract:
1. An apparatus for trans-coding between code excited linear prediction (CELP) type codecs having different bandwidths, comprising: a first type converting means for receiving formant parameters from the input bit stream and converting formant parameters from the type specified in the input CELP format to a suitable type for formant bandwidth conversion; a formant parameter translating means for translating formant parameters from input CELP format to output CELP format and generating translated formant parameters in an output CELP format, the formant parameter translating means to include a formant bandwidth converting means to generate bandwidth-corrected formant parameters, the formant parameter translating means further to include a formant frame rate converting means to generate frame rate-corrected formant parameters, a formant parameter quantizing means for receiving the translated formant parameters and quantizing the translated formant parameters; an excitation parameter translating means for translating excitation parameters from input CELP format to output CELP format and generating excitation parameters in an output CELP format, the excitation parameter translating means to receive the frame rate-corrected formant parameters from the formant frame rate converting means before the translated formant parameters are quantized by the formant parameter quantizing means, the excitation parameter translating means further to convert the frame rate-corrected formant parameters to generate converted parameters, to interpolate the converted parameters by weighing sub-frames to generate interpolated parameters, and to construct a perceptual weighing filter by using the interpolated parameters; and an excitation quantizing means for receiving the translated excitation parameters and quantizing the translated excitation parameters, wherein the excitation parameter translating means comprises: