Comparison of two speech and audio coders at 8 kb/s from the viewpoints of coding scheme and quality

Nobuhiko Kitawaki*, Takehiro Moriya, Takao Kaneko, Naoki Iwakami

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Low bit-rate speech and audio codings are key technologies for multimedia communications. A number of coding scheme have been developed for various applications. In Internet application, good speech and audio quality at very low bit-rate (8-16 kb/s) is valuable. Two recently proposed speech and audio-coding schemes, CS-ACELP (Conjugate Structure Algebraic Code Excited Linear Prediction, standardized by the ITU-T in Recommendation G.729) and TwinVQ (Transformdomain Weighted INterleave Vector Quantization, one of the candidates for MPEG-4 audio) were compared from the view-points of coding schemes and quality. Although there are significant differences in their basic structures and frame lengths, this paper describes that both use the same compression techniques, such as LPC (Linear Predictive Coding)-analysis pitch-period estimation and vector quantization. While CS-ACELP provides toll quality for speech at 8 kb/s, the quality it provides for music signals is insufficient. The TwinVQ transform coder is based on LPC and vector quantization and is also capable of operating at 8 kb/s. Evaluation of these two schemes in terms of their fundamental technologies, quality, delay, and complexity showed that the quality of TwinVQ for music signals is better than that of CS-ACELP, and that the quality of CS-ACELP is better for speech signals. Therefore, TwinVQ may be better suited for one-directional Internet applications, and CS-ACELP may be better for two-directional communication.

Original languageEnglish
Pages (from-to)2007-2011
Number of pages5
JournalIEICE Transactions on Communications
Issue number11
Publication statusPublished - 1998
Externally publishedYes


  • Coding quality
  • G.729
  • Internet
  • TwinVQ

ASJC Scopus subject areas

  • Software
  • Computer Networks and Communications
  • Electrical and Electronic Engineering


Dive into the research topics of 'Comparison of two speech and audio coders at 8 kb/s from the viewpoints of coding scheme and quality'. Together they form a unique fingerprint.

Cite this