A design of Twin VQ audio-codec for personal communication systems

An improved design for a transform-domain weighted interleave vector quantization (Twin VQ) audio-codec is proposed that is applicable to personal communication systems. Twin VQ is a low-bit-rate audio-coding method that achieves high-quality under error-free conditions, at less than 64 kbit/s. To make this method applicable to wireless systems, which have a higher bit-error rate due to inferior transfer conditions, the Twin VQ coding algorithm has been improved. About 90% of Twin VQ encoded bits were found to be insensitive to channel errors, so using the BS-FEC method, error protection is weighted to the sensitive bits. Subjective evaluation tests showed that Twin VQ with BS-FEC maintains good quality over, high bit-error-rate channels.