From f6fb536f87e687a4aacca75dd9ad1c7b71ffa731 Mon Sep 17 00:00:00 2001 From: Uoti Urpala Date: Sat, 29 Jan 2011 03:27:47 +0200 Subject: DOCS/tech/: remove several obsolete files Some of the files contain some usable stuff, but overall they're obsolete enough that it's better to remove the current versions. --- DOCS/tech/snow.txt | 89 ------------------------------------------------------ 1 file changed, 89 deletions(-) delete mode 100644 DOCS/tech/snow.txt (limited to 'DOCS/tech/snow.txt') diff --git a/DOCS/tech/snow.txt b/DOCS/tech/snow.txt deleted file mode 100644 index be531fcb5c..0000000000 --- a/DOCS/tech/snow.txt +++ /dev/null @@ -1,89 +0,0 @@ - HOW TO TEST SNOW - ---------------- - -Snow is an experimental wavelet-based codec made by the FFmpeg developers, -and while it is still in heavy development, it is already giving very good -results. -Be very careful though, as the format of the bitstream produced might -change, do not rely on it to store videos that you value. -For this reason, MEncoder will not encode without 'vstrict=-2' on the -command line. - - -OPTIONS RECOGNIZED BY SNOW - - * vqscale=<0.0-255.0> - Encoding quality, sane range 1-10. 0 is lossless. - May be fractional. - A given quality in snow needs a somewhat lower qscale than the same - quality in MPEG-4. - - * vpass=<1-3> - Activates internal two (or more) pass mode. - - * vbitrate= - Specify bitrate of 1pass CBR or 2pass ABR. default: 800 kbit/s. - This is not very accurate for short videos. - - * lmin, lmax, vqcomp, vratetol, vrc_eq, vrc_override - Generic multipass ratecontrol options, subject to the same suggestions - as in other codecs. - lmin=1 can be useful for medium to high bitrates (see vqscale). - - * cmp, subcmp, mbcmp - Set the comparison function, default: 0 (SAD). - useful values = 0 (SAD), 1 (SSD), 2 (SATD), - 11 (5/3 wavelet), 12 (9/7 wavelet). - SAD is fastest and lowest quality. - SSD is the only function that makes correct decisions about intra vs - inter (mbcmp) when using fast motion estimation, but is not the best for - the actual search (cmp, subcmp). - The wavelet functions (use the one that matches pred) are best quality, - especially with vme=8, but are very slow. - SATD is a good balance. - You can add 256 to any of the options to enable chroma motion - estimation for that comparison (e.g. mbcmp=257 for SSD with chroma), - but it doesn't seem to help much for the moment. - - * pred=<0-2> - Wavelet type. - 0 = 9/7 wavelet, default. - 1 = 5/3 wavelet. - 2 = 13/7 wavelet. - 9/7 is probably better for for lossy coding, and 5/3 for lossless. - NOTE: 9/7 wavelet doesn't work with lossless mode. - - * qpel - Refines motion estimation, default: off. - This setting always helps compressibility, but costs some CPU time - both while encoding and decoding. - - * v4mv - Allows smaller motion partitions, default: off. - v4mv is theoretically good, but in practice isn't really working yet. - The current MB decision algorithm doesn't make very good use of this: - It improves quality, but also increases bitrate. (You could get - more quality per bitrate by reducing quantizer instead.) - - * vme=<4|8> - The default EPZS (4) is the same as in other formats. - Snow also supports iterative motion estimation (8), which jointly - optimizes adjacent blocks to make the most of OBMC. This significantly - improves compression, but is very slow. - Iterative ME currently does not perform scenecut detection, so should - be used only in the second pass of a two pass encode. - - * refs=<1-8> - Allows each block to choose which of several reference frames to - motion compensate from. Default: 1. Larger values always improve - compression, but cost lots of CPU-time when encoding and extra - memory when decoding. - -In short: -The best options in almost all cases are -vcodec=snow:vstrict=-2:vpass=1:vbitrate=$B:pred=0:cmp=2:subcmp=2:mbcmp=1:qpel -vcodec=snow:vstrict=-2:vpass=2:vbitrate=$B:pred=0:cmp=12:subcmp=12:mbcmp=1:qpel:vme=8:refs=8 - -Decent, fast options are -vcodec=snow:vstrict=-2:vpass=1:vbitrate=$B:pred=0:cmp=1:subcmp=1:mbcmp=1 -vcodec=snow:vstrict=-2:vpass=2:vbitrate=$B:pred=0:cmp=2:subcmp=2:mbcmp=1:refs=2 -- cgit v1.2.3