[MPlayer-users] undersize avi file ...

[Martin Pavon]

Hi folks !!!!

I'm trying to mencode Shrek dvd (ntsc zone 4) in two 700mb cds but the 
avifiles I got are noticeablely shorters ... and afaik is not a problem of fps.
So I take a sample and do some test with mencoder (a fresh 0.90pre10).

The tests was the following: 

I calculated the videobitrate for a target size of 2, 3, 4 and 5 mb with the
formula 

target_size*1024^2*8/(duration_in_sec *1000)

The sample is 23.2 sec. long so I got VBRATE=723, 1084, 1446 and 1807 approx.

The options for the command line was:

-ofps 23.976 -nosound -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=$VBRATE 
-vop scale=640:352,crop=704:480:8:0

mencoder reached the target size 2mb and 3mb, but it fails in reach 4 and 5
mb, the size of resulting files was in both case exactly the same: 2.9 approx. 
I tried with a videobitrate of 6000, but I got again 2.9mb approx

Later, I repeat the test adding vqmin=1 to lavopts looking for relax the
compress and ... mencoder reached the target size in all the cases as you can
see:

-rw-r--r--    1 m        users       66180 Nov 10 23:21 divx2pass.log
-rw-r--r--    1 m        users    20971520 Nov 10 20:07 shrek-sample.vob
-rw-r--r--    1 m        users         675 Nov 10 23:20 test.sh
-rw-r--r--    1 m        users     2112972 Nov 10 23:03 test2.avi
-rw-r--r--    1 m        users     3006992 Nov 10 23:08 test3.avi
-rw-r--r--    1 m        users     3251710 Nov 10 23:18 test3b.avi
-rw-r--r--    1 m        users     3006992 Nov 10 23:10 test4.avi
-rw-r--r--    1 m        users     4167558 Nov 10 23:19 test4b.avi
-rw-r--r--    1 m        users     3006992 Nov 10 23:15 test5.avi
-rw-r--r--    1 m        users     5281016 Nov 10 23:20 test5b.avi
-rw-r--r--    1 m        users     3006992 Nov 10 23:21 test5c.avi
-rw-r--r--    1 m        users     3006992 Nov 10 23:17 test6000.avi


(3b, 4b, 5b correspond to vqmin=1 .. test5c.avi was made with vqmin=2 and it
must be 5mb)

After this, I guess that I must set vqmin=1 ... But I don't understand why, 
and tech/libavc-options.txt still said vqmin=1 may be buggie (the test looks
fine). 

Can someone explain what happen here? Is this a bug? (and in this case is 
necesary a full bug report or is enough with the info which I give here...)

If you want the sample, you can download it from 
http://mate.dm.uba.ar/~mpavon/tmp/

it sizes 20mb.

Regards,
-- 
Martín Pavón
martin_199ar at yahoo.com.ar
http://mate.dm.uba.ar/~mpavon/