Card-sized portable audio player using high quality audio coding technology Twin VQ

This paper presents a new implementation of the solid state audio player equipped with Twin VQ decoder. Twin VQ is an advanced high quality coding technology, and its basic algorithm is utilized in MPEG-4/Audio standardized by ISO (International Standardization Organization). Using Twin VQ coding, 44.1 kHz sampled audio data can be compressed at a very low bitrate of 40 kbit/s/ch with better sound quality than conventional coding methods as MPEG-1/Audio layer-3. Another feature of the player is that it is extremely compact, business-card-sized, 10 mm thick, including battery as a result of the efficient design. Decoding algorithms are optimized and implemented into 16 bit fixed-point DSP, and a very thin rechargeable lithium polymer battery is contained integral with the player. As a result, the new player has very practical performance with low power consumption, and 6 hours of 44 kHz stereo audio can be continuously played when the battery is fully charged.