Variance Adaptive Quantization (VAQ) is a video encoding algorithm that was first introduced in the open source video encoder
x264
x264 is a free and open-source software library and a command-line utility developed by VideoLAN for encoding video streams into the H.264/MPEG-4 AVC video coding format. It is released under the terms of the GNU General Public License.
Histor ...
. According to Xvid Builds FAQ: "It's an algorithm that tries to optimally choose a
quantizer for each
macroblock using advanced math algorithms." It was later ported to programs which encode video content in other video standards, like
MPEG-4 ASP or
MPEG-2.
In the case of
Xvid
Xvid (formerly "XviD") is a video codec library following the MPEG-4 video coding standard, specifically MPEG-4 Part 2 Advanced Simple Profile (ASP). It uses ASP features such as b-frames, global and quarter pixel motion compensation, lumi mas ...
, the algorithm is intended to make up for the earlier limitations in its Adaptive Quantization mode. The first Xvid library containing this improvement was released in February 2008.
References
External links
Implementation of variance-based adaptive quantization in x264
{{Tv-tech-stub
Signal processing
Video compression