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