High-Quality Speech Coder (HQSC)

HQSC, a medium-data-rate coder, is useful for high-quality digital recording and playback of speech and for bandwidth-efficient wireless voice communication.

HQSC achieves efficient speech compression by employing advanced speech production modeling (including formant, pitch and glottal excitation), optimal trellis vector quantization, and psychoacoutic perceptual weighting for speech analysis.

HQSC is available in three signal bandwidths: 4, 5,and 7-kHz, with corresponding sample rate at 8, 11.025, and 16 kHz, respectively. HQSC offers multiple user-selectable data rates. By "embedded coding", the lower-rate coding is easily realized by dropping bits from the higher-rate coding.

FEATURES

• User-selectable multiple data rates:

  - HQSC-4: 3.6/4.8/6.0/7.2/8.4/9.6/10.8/12/13.2/14.4 kbit/s.

  - HQSC-5: 6.5/9.1/11.8/14.5/17.1/19.8 kbit/s.

  - HQSC-7: 7.2/9.6/12.0/14.4/16.8/19.2 kbit/s.

• Robust speech/audio quality even with acoustic background noise.
• I/O format: 16 bit/sample linear PCM.