[FFmpeg-user] -qcomp 0.8 with no effect
Carl Eugen Hoyos
cehoyos at ag.or.at
Sun Sep 23 18:16:55 CEST 2012
Hugo Wau <hugowau <at> gmx.net> writes:
> > then you should remove -sameq and add -b:v to set the bitrate.
> > from my experience with mencoder, -qcomp is used to balance how bitrate
> > will be used between high motion and still image, and extremely usefull
> > with two pass encoding. -qcomp doesn't have effect on resulting size, but
> > resulting quality.
> Well, nevertheless it works for me now, I just reduced the size of the
> video, which with -sameq (CARL, WHAT DOES THIS REALLY MEAN - IF IT IS
> NOT SAME QUALITY?)
Please do not shout;-)
It means same quantiser (which in your case is
definitely not same quality).
As correctly explained, -qcomp should be used to affect
the rate control in two-pass mode. That it also affects
one-pass encoding is probably not unintended, but i'd
say you abuse the option (to your disadvantage).
The correct way for you to achieve what you want is to
calculate a video bit-rate (you know the length of the
video and the audio size), and use two-pass encoding to
reach the desired file size.
(If you are not completely happy with the result, you
can use -qcomp to change the quality distribution.)
More information about the ffmpeg-user