From 3dbf18b1263090c283536ee26652751fda587b4a Mon Sep 17 00:00:00 2001 From: gpoirier Date: Sun, 10 Apr 2005 23:19:45 +0000 Subject: Initial commit. Encoding tips about experimental codec snow. git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@15118 b3059339-0415-0410-9bf9-f77b7e298cf2 --- DOCS/tech/snow.txt | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 DOCS/tech/snow.txt (limited to 'DOCS') diff --git a/DOCS/tech/snow.txt b/DOCS/tech/snow.txt new file mode 100644 index 0000000000..2f548f99e0 --- /dev/null +++ b/DOCS/tech/snow.txt @@ -0,0 +1,58 @@ + 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=-1' on the +command line. + + +OPTIONS OBEYED BY SNOW + + * vqscale=<0.01-255> + Encoding quality, sane range 1-10, default: 0 (lossless). + A given quality in snow needs a somewhat lower qscale than the same + quality in MPEG-4. + Note that 0 may not be specified; if you want lossless encoding, you + must leave out vqscale. (Yes, quantizer can be fractional.) + + * cmp, subcmp, mbcmp + Set the comparison function, default: 0 (SAD). + useful values = 0 (SAD), 1 (SSD), 11 (5/3 wavelet), 12 (9/7 wavelet). + Experience shows that SSD is the best most of the time, while SAD is + slightly better the remainder of the time. + 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), 1 (5/3 wavelet), 2 (13/7 wavelet). + 9/7 is probably better for for lossy coding, and 5/3 for lossless. + + * last_pred=<0-3> + Tries a few extra predicted motion vectors before doing EPZS search, + default=0. + This option has negligible effect on both speed and quality of snow, + so just leave it off. (it does, however, help mpeg4.) + + * 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. + The current MB decision algorithm doesn't make very good use of this: + It improves quality, but also increases bitrate. (and you could get + more quality per bitrate by reducing quantizer instead.) + + +v4mv and the wavelet cmp functions are theoretically good, but in practice +won't work well until we get OBMC-aware motion estimation. + +In short: +The best options in almost all cases are +vcodec=snow:vstrict=-1:vqscale=$N:pred=0:cmp=1:subcmp=1:mbcmp=1:qpel \ No newline at end of file -- cgit v1.2.3