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mpv/DOCS/tech/libavc-options.txt
michael cee7e46e2a docu for the new options of the patched version
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@6257 b3059339-0415-0410-9bf9-f77b7e298cf2
2002-06-01 02:37:24 +00:00

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Description of what all thouse libavcodec options do ...
WARNING: iam no encoding expert so the recomanditions might be bad ...
if u find any errors, missing stuff, ... send a patch or cvs commit if u have an cvs account :)
vqmin 1-31 (minimum quantizer) for pass1/2
1 is not recomanded (much larger file, little quality difference and possible other weird things)
2 is recommanded for normal mpeg4/mpeg1video encoding
3 is recommanded for h263(p)/msmpeg4 (default)
the reason for 3 instead of 2 is that 2 could lead to overflows (this will be fixed for h263(p)
by chageing the quanizer per MB in the future, but msmpeg4 doesnt support that so it cant be fixed
for that)
vqscale 1-31 quantizer for constant quantizer /constant quality encoding
1 is not recomanded (much larger file, little quality difference and possible other weird things)
lower means better quality but larger files
see vqmin
vqmax 1-31 (maximum quantizer) for pass1/2
15 default
10-31 should be a sane range
vqdiff 1-31 (maximum quantizer difference between I or P frames) for pass1/2
3 default
vmax_b_frames 0-4 (maximum number of b frames between non b frames)
0 no b frames (default)
vme 0-5 (motion estimation)
0 none (not recommanded, very lq)
1 full (not recommanded, too slow)
2 log (not recommanded, lq)
3 phods (not recommanded, lq)
4 EPZS (default)
5 X1
vhq (high quality mode)
encode each MB as in all modes and choose the best (this is slow but better filesize/quality)
disabled by default
v4mv
allow 4 MV per MB (little difference in filesize/quality)
disabled by default
cannot be used with b frames or in lq mode currently
disabled by default
keyint 0-300 (maximum interval between keyframes)
keyframes are needed for seeking as seeking is only possible to a keyframe but keyframes need more space
than non keyframes so larger numbers here mean slightly smaller files
0 no keyframes
>300 is not recomanded as the quality might be bad (depends upon decoder & encoder & luck)
vb_strategy 0-1 for pass 2
0 allways use the max number of b frames (default)
1 avoid b frames in high motion scenes (this will cause bitrate missprediction)
vpass
1 first pass
2 second pass
vbitrate (kbits per sec) for pass1/2
800 is default
vratetol (filesize tolerance in kbit) for pass1/2
this is just approximate, the real difference can be much smaller or larger
1000- 100000 is a sane range
8000 is default
vb_qfactor (1.0-31.0) (BFrame quantizer= PFrame quantizer * vb_qfactor) for pass1/2
2.0 is default
tip: to do constant quantizer encoding with different quantizers for I/P and B frames
u can use vqmin=<ip-quant>:vqmax=<ip-quant>:vb_qfactor=<b_quant/ip_quant>
vqblur (0.0-1.0) quantizer blur (for pass1)
0.0 qblur disabled
0.5 is the default
1.0 average the quantizer over all previous frames
larger values will average the quantizer over time more so that the quantizer will be changed slower
vqcomp (0.0-1.0) quantizer compression (for pass1/2)
0.0 constant bitrate encoding, so fast moton frames will get as many bits as low motion
(high motion scenes look bad)
0.5 (default)
1.0 constant quantizer encoding (low motion scenes look bad)
vrc_strategy (0,1,2)
FIXME
----------- the following options are only available in the patched version of libavcodec
patch at http://www.mplayerhq.hu/~michael/
patch will be merged into ffmpeg cvs in a few days (the reason that its not in cvs yet is that
the other ffmpeg developers didnt want big untested changes before release)
vlelim (0-1000) single coefficient elimination threshold for luminance
0 disabled (default)
4 (JVT recomandition)
vcelim (0-1000) single coefficient elimination threshold for chrominance
0 disabled (default)
7 (JVT recomandition)
vstrict strict standart compliance
only recomanded if u want to feed the output into the mpeg4 reference decoder
vdpart data partitioning
+2 byte per video packet, and much better looking if the file becomes damaged
lavdopts: (decoder options)
ver error resilience
-1 needed for some very broken, encoders which completly ignore the standarts
0 (default)
1 more aggressive error detection, lavc might think that some correct streams contain errors
vbug manual workaround encoder bugs
0 (default)
1 (workaround for some old lavc generated msmpeg4v3 files)
Notes: 1. lavc will strictly follows the quantizer limits vqmin, vqmax, vqdiff even if
it violates the bitrate / bitrate tolerance
2. changing some options between pass1 & 2 can reduce the quality
FAQ: Q: the file is much too small
A: vqmin=2 or 1 (be carefull with 1, it could cause strange things to happen)
Q: i want to use -pass 1 & -pass 2 with vmax_b_frames>0
A: read DOCS/tech/patches.txt and send a patch ;)
glossary:
MB Macroblock (16x16 luminance & 8x8 chrominance samples)
MV Motion vector
ME Motion estimation
MC Motion compensation
example:
mencoder foobar.avi -lavcopts vcodec=mpeg4:vhq:keyint=300:vqscale=2 -o new-foobar.avi