What is Adaptive Quantization/Lumi masking?
Adaptive quantization, called ‘Lumi masking’ in older builds, is a first ‘psychovisual’ innovation in XviD; it is supposed to make use of the fact that the human eye tends to notice encoding errors less if they happen in very dark or very bright parts of the picture. XviD is capable of using different quantizers for each macroblock. Lumi-masking compresses very dark or bright areas stronger than medium ones. So it will use less bits on some frames in the second pass than in the first pass. The saved bits are of course spent again and that way we gain a bit of quality in the medium-brightness part of the picture. As it is experimental, you may sometimes notice more blocks than when it is disabled. Note that Lumi masking is broken in Koepi’s 26062003-1 build, and that it is a bit buggy in many older builds. AQ works in the newer beta and RC builds but is still not very extensively tested. 3d. Interlaced Encoding This allows you to encode the entire clip in interlaced mode. Note however t
