[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 

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.)

Carl Eugen

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