TwinVQ (transform-domain weighted interleave
vector quantization
Vector quantization (VQ) is a classical quantization technique from signal processing that allows the modeling of probability density functions by the distribution of prototype vectors. It was originally used for data compression. It works by di ...
) is an
audio compression technique developed by
Nippon Telegraph and Telephone Corporation
, commonly known as NTT, is a Japanese telecommunications company headquartered in Tokyo, Japan. Ranked 55th in ''Fortune'' Global 500, NTT is the fourth largest telecommunications company in the world in terms of revenue, as well as the third la ...
(NTT) Human Interface Laboratories (now Cyber Space Laboratories) in 1994. The compression technique has been used in both standardized and proprietary designs.
TwinVQ in MPEG-4
In the context of the
MPEG-4
MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related t ...
Audio (
MPEG-4 Part 3
MPEG-4 Part 3 or MPEG-4 Audio (formally ISO/IEC 14496-3) is the third part of the ISO/IEC MPEG-4 international standard developed by Moving Picture Experts Group. It specifies audio coding methods. The first version of ISO/IEC 14496-3 was publish ...
), TwinVQ is an audio
codec
A codec is a device or computer program that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder.
In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or ...
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
The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and r ...
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
Vector quantization (VQ) is a classical quantization technique from signal processing that allows the modeling of probability density functions by the distribution of prototype vectors. It was originally used for data compression. It works by di ...
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.
TwinVQ as a proprietary audio format
A