Title :
A 128 Kb/s Hi-Fi audio codec based on adaptive transform coding with adaptive block size MDCT
Author :
Iwadare, Masahiro ; Sugiyama, Akihiko ; Hazu, Fumie ; Hirano, Akihiro ; Nishitani, Takao
Author_Institution :
C&C Syst. Res. Lab., NEC Corp., Kanagawa, Japan
fDate :
1/1/1992 12:00:00 AM
Abstract :
A Hi-Fi audio codec with an improved adaptive transform coding (ATC) algorithm is presented using digital signal processors (DSPs). An audio signal with a 20 kHz bandwidth sampled at 48 kHz is coded at a rate of 128 kb/s. The algorithm utilizes adaptive block size selection, which is effective for preecho suppression. A modified discrete cosine transform (MDCT) with a simple window set is employed to reduce block boundary noise without decreasing the performance of transform coding. In addition, a fast MDCT calculation algorithm, based on a fast Fourier transform, is adopted. Weighted bit allocation is employed to quantize the transformed coefficients. The codec was realized by a multiprocessor system composed of newly developed DSP boards. Subjective tests with the codec show that the coding quality is comparable to that of compact disc signals
Keywords :
Hi-Fi equipment; codecs; computerised signal processing; encoding; fast Fourier transforms; multiprocessing systems; 128 kbit/s; 20 kHz; 48 kHz; DSP boards; FFT; Hi-Fi audio codec; adaptive block size MDCT; adaptive block size selection; adaptive transform coding; algorithm; audio signal; bandwidth; block boundary noise; digital signal processors; fast Fourier transform; modified discrete cosine transform; multiprocessor system; preecho suppression; subjective tests; weighted bit allocation; Bandwidth; Bit rate; Codecs; Digital signal processing; Digital signal processors; Discrete cosine transforms; Fast Fourier transforms; Noise reduction; Signal processing algorithms; Transform coding;
Journal_Title :
Selected Areas in Communications, IEEE Journal on
