[MPlayer-users] mencoder bitrate error problem

[Eric Potter]

On Sun, 2002-12-29 at 11:20, Robin Phillips wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Hi,
> 
> Since at least 0.90pre10 I've been unable to get the bitrate part of 
> mencoder to work properly (and possibly I've never had it working right so 
> I could be something I'm doing wrong).
> 
> I've attached the three command lines I used below, plus the last few 
> lines of output from each run. I also tried adding vqdiff=31 as per a 
> response to a similar report in the mailing list archive from July 2002 
> but that made no difference.
> 
> Note the problem is that I give the bitrate as 1411 as suggested by the 
> output from the first pass. However the actual bitrate it uses during the 
> second pass is 1128 which then hardly changes during the 3rd pass.
> 
I see that you are using qmin=2 and the problem could be that you are
"maxed-out" in terms of how many bits you can fit into a quantizer
of 2.  Try using qmin=1 which will allow the maximum amount of bits
to be used.
 
> I can get the right bitrate simply by adjusting the recommended value up 
> by the appropriate ratio but obviously I'd prefer to try and get this 
> right the first time through.
> 
> I note also that the bitrate for two CDs does not seem to be double the 
> bitrate for one CD which I can't make any sense out of.
> 
That is because the audio will be split between the 2 cd's, leaving
more space for video on each.

> Thanks for any suggestions
> 
> Robin
> 
> -----------------------------------------
> >cat vob/001/*vob | nice -19 mencoder -ovc frameno -o frameno.avi -oac 
> mp3lame -lameopts abr:br=128 -
> 
> Pos:3813.8s  91488f ( 0%) 153fps Trem:   0min   0mb  A-V:-0.030 [0:113]
> Writing AVI index...
> Fixup AVI header...
> Recommended video bitrate for 650MB CD: 1301
> Recommended video bitrate for 700MB CD: 1411
> Recommended video bitrate for 800MB CD: 1631
> Recommended video bitrate for 2 x 650MB CD: 2731
> Recommended video bitrate for 2 x 700MB CD: 2951
> Recommended video bitrate for 2 x 800MB CD: 3391
> 
> Video stream:    0.768 kbit/s  (95 bps)  size: 365952 bytes  3813.760 secs  
> 91488 frames
> 
> Audio stream:  113.392 kbit/s  (14173 bps)  size: 54063480 bytes  3814.272 
> secs
> 
> -----------------------------------------
> >cat vob/001/*vob | nice -19 mencoder -oac copy -o startrek0.avi -ovc lavc 
> -lavcopts vcodec=mpeg4:vbitrate=1411:vhq:vpass=1:vqmin=2:vqmax=31 -vop pp 
> -
> 
> 
> Pos:3813.7s  91488f ( 0%)  25fps Trem:   0min   0mb  A-V:0.000 [1128:113]
> Writing AVI index...
> Fixup AVI header...
> 
> Video stream: 1128.770 kbit/s  (141096 bps)  size: 538102681 bytes  
> 3813.726 secs  91488 frames
> 
> Audio stream:  113.394 kbit/s  (14174 bps)  size: 54063192 bytes  3814.200 
> secs
>  
> 
> 
> -----------------------------------------
> >cat vob/001/*vob | nice -19 mencoder -oac copy -o startrek0.avi -ovc lavc 
> -lavcopts vcodec=mpeg4:vbitrate=1411:vhq:vpass=2:vqmin=2:vqmax=31 -vop pp 
> -
> 
>  
>  Pos:3813.7s  91488f ( 0%)  24fps Trem:   0min   0mb  A-V:0.000 [1129:113]
> Writing AVI index...
> Fixup AVI header...
> 
> Video stream: 1129.260 kbit/s  (141157 bps)  size: 538335861 bytes  
> 3813.726 secs  91488 frames
> 
> Audio stream:  113.394 kbit/s  (14174 bps)  size: 54063192 bytes  3814.200 
> secs
> 
> 
> 
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