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.
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.
[5][6][7][8][9] 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.
This could be attributed to the proprietary nature of the format — third party software was scarce and there was no hardware support.
The format was reverse-engineered in 2009 by the FFmpeg project and decoding of vqf files is supported by the open-source libavcodec library,[26] which makes it supported in players that utilize the library, such as VLC media player.