[MPlayer-users] File size inverse prop. to bitrate?

[marcogi at libero.it]

Last day happened something strange to me.

I used 3-pass to encode mpeg2 files to divx4:

rm frameno.avi

cat mpeg2file[01]*|~/work/mplayer/mencoder -ovc frameno -lameopts
vbr=3:q=5 -o frameno.avi -

cat mpeg2file[01]*|~/work/mplayer/mencoder -v -oac copy -vop pp,scale=352:264
-npp tn:100:200:1000 -ovc lavc -lavcopts
vcodec=mpeg4:vhq:vbitrate=565:vme=5:vb_strategy=1:vqcomp=0.6:vpass=1 -o
/dev/null -

cat /mnt/media/sttng[01]*|~/work/mplayer/mencoder -v -oac copy -vop 
pp,scale=352:264 -npp tn:100:200:1000 -ovc lavc -lavcopts
vcodec=mpeg4:vhq:vbitrate=565:vme=5:vb_strategy=1:vqcomp=0.6:vpass=2 -o
divx4file.avi -

Well, divx4file.avi I got was about 160MB.
Then I tryed to encode at 550 bitrate using the same audio from frameno.avi:
 
cat mpeg2file[01]*|~/work/mplayer/mencoder -v -oac copy -vop pp,scale=352:264
-npp tn:100:200:1000 -ovc lavc -lavcopts 
vcodec=mpeg4:vhq:vbitrate=550:vme=5:vb_strategy=1:vqcomp=0.6:vpass=1 -o
/dev/null -

cat mpeg2file[01]*|~/work/mplayer/mencoder -v -oac copy -vop pp,scale=352:264
-npp tn:100:200:1000 -ovc lavc -lavcopts
vcodec=mpeg4:vhq:vbitrate=550:vme=5:vb_strategy=1:vqcomp=0.6:vpass=2 -o
divx4file.avi -

This time I got a 200MB file. Is this normal?
btw, where all lavc options are explained? I did not find nothing in ffmpeg
docs.
And, again, how tn and vb/hb vop filters thresholds work?

Thanks.

--
Regards,  Marco Gigante
Student at Pisa University - Computer Engineering