[Ffmpeg-devel] encoding quality

[Corey Hickey]

Zoltan NAGY wrote:
> hello ppl!
> 
> I'd like to ask your advices in an encoding matter.
> I have several files, which I'd like to encode into flv. They're in 
> different formats,
> but most likely wmv2 and wmv3.
> 
> Currently I'm using mplayer:
> mencoder original.wmv -vf harddup -ofps 24 -oac mp3lame -ovc lavc 
> -lavcopts vcodec=ffv1:vstrict=-2 -o out.avi
> 
> then ffmpeg to encode this out.avi into flv:
> ffmpeg -y -i out.avi -f flv -b 512 out_end.flv
> 
> but the flv's quality really sucks. If I change the bitrate to 1024 or 
> 2048 or above,
> then it's ~fine, but the filesize gets bigger and bigger..
> 
> what options could I tweak? I'd like to keep my file's sizes little, but 
> I wouldnt like to
> loss a lot quality..

I'm low on time so forgive me for being terse. ...and for not formatting 
the line below nicely.

for i in 1:turbo 2 ; do mencoder serenity_m420p.mov -oac mp3lame -vf 
harddup -ofps 24 -ovc lavc -lavcopts 
vcodec="flv:vstrict=-2:vbitrate=512:mbd=2:mv0:trell:cbp:sc_factor=6:vrc_eq=(tex+10^8*mcVar)^0.6:precmp=2:cmp=2:subcmp=2:predia=2:dia=2:preme=2:qns=2:vpass=$i" 
-of lavf -lavfopts 
format=flv:i_certify_that_my_video_stream_does_not_use_b_frames -o 
out.flv -nosound ; done


If you think it's too slow, remove qns=2.

vrc_eq=(tex+10^8*mcVar)^0.6 is my experimental ratecontrol equation. Try 
with and without it, and see which you prefer.


See if that works for you. Or:
- throwing bitrate at the problem _will_ make it go away
- downscaling the video size may make it look better, to a point (fewer 
details and fewer blocks)

-Corey