[MPlayer-users] mencoder bitrate error problem

[Robin Phillips]

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 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.

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