TwinVQ

TwinVQ (transform-domain weighted interleave vector quantization) is an audio compression technique developed by Nippon Telegraph and Telephone Corporation (NTT) Human Interface Laboratories (now Cyber Space Laboratories) in 1994. The compression technique has been used in both standardized and proprietary designs.

In the context of the MPEG-4 Audio (MPEG-4 Part 3), TwinVQ is an audio codec optimized for audio coding at ultra low bitrates around 8 kbit/s.

TwinVQ is one of the object types defined in MPEG-4 Audio, published as subpart 4 of ISO/IEC 14496-3 (for the first time in 1999 - a.k.a. MPEG-4 Audio version 1). This object type is based on a general audio transform coding scheme which is integrated with the AAC coding frame work, a spectral flattening module, and a weighted interleave vector quantization module. This scheme reportedly has high coding gain for low bit rate and potential robustness against channel errors and packet loss, since it does not use any variable length coding and adaptive bit allocation. It supports bitrate scalability, both by means of layered TwinVQ coding and in combination with the scalable AAC.

Note that some commercialized products such as Metasound (Voxware), SoundVQ (Yamaha), and SolidAudio (Hagiwara) are also based on the TwinVQ technology, but the configurations are different from the MPEG-4 TwinVQ.

A proprietary audio compression format called TwinVQ was developed by Nippon Telegraph and Telephone Corporation (NTT) (in NTT's Human Interface Laboratories) and marketed by Yamaha under the name SoundVQ. The NTT also offered a TwinVQ demonstration software for non-commercial purposes - NTT TwinVQ Encoder and TwinVQ Player, encoder API, decoder API and header file format. The filename extension is .vqf.

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