First International Conference on Spoken Language Processing (ICSLP 90)

Kobe, Japan
November 18-22, 1990

Adaptive Transform Coding With an Adaptive Block Size Using a Modified DCT

Fumie Hazu, Akihiko Sugiyama, Masahiro Iwadare, Takao Nishitani

C&C Systems Research Laboratories, NEC Corporation, Kanagawa, Japan

A Modified Discrete Cosine Transform (MDCT), which is effective for reducing block boundary noise, is applied to Adaptive Transform Coding with an Adaptive Block Size (ATC-ABS) reported by authors. As original MDCT is defined to have a fixed block size for realizing time domain aliasing cancellation, a new overlap window set is introduced to enable variable block size existence, in ATC-ABS. In addition to MDCT employment, a new adaptive bit assignment algorithm based on the auditory characteristic is also introduced to prevent distortion by deficiency of assigned quantization bit amount. In the results of paired comparison tests, the original signals and the reproduced signals by the proposed algorithm are preferred by more than 40% of the subjects, while the reproduced signal by ATC-ABS is preferred by less than 10% of the subjects. The proposed method is promising for digital recording media and for digital communications.

Full Paper

Bibliographic reference.  Hazu, Fumie / Sugiyama, Akihiko / Iwadare, Masahiro / Nishitani, Takao (1990): "Adaptive transform coding with an adaptive block size using a modified DCT", In ICSLP-1990, 649-652.