[MPlayer-users] variable bitrate, fixed quality

Nikolaus Rath Nikolaus at rath.org
Mon Jul 7 19:54:07 CEST 2003


Hans Meine <hans_meine at gmx.net> wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> On Monday 07 July 2003 18:49, Nikolaus Rath wrote:
>> I want to encode a video with a completely variable bitrate but with a
>> fixed quality. I don't want to use a fixed quantizer too, because this
> 
> The bitrate is what you are looking for. Using 2-pass encoding will try to 
> achieve constant quality. If you don't want to constrain the quality, specify 
> an enormous bitrate (recall that bitrates above some value are not kbits 
> anymore, but bits, so add some more zeroes) and lavc will do as good as it 
> can.

This doesn't work. I tried it and lavc compressed nearly all frames
with a quantizer of 3, even if most of them would be perfect with 6. I
have the impression that lavc wants to reach the given bitrate at all
costs. If this isn't the case, I need an option to adjust the
quantizer selection (=the quality), because lavc uses to low
quantizers for simple frames.

   --Nikolaus



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