[MPlayer-users] Vbitrate not responding on lavc encoding

[cothrige]

I recently reinstalled mplayer when I changed my system (Slackware
10.0 > Gentoo) and I have not been able to get mencoder to work
properly.  This is with an emerged mplayer and one I compiled myself
directly.  The results are identical with both. 

On a normal dvd I usually encode it with the following (excepting strange
things like interlacing and so on):

"mencoder dvd://1 -noodml -ofps 23.976 -oac mp3lame -ovc lavc -lavcopts
vcodec=mpeg4:mbd=2:vbitrate=1800:keyint=150 -o movie.avi"

This has generally given me a consistent result and a file 99% of the
time perfect for splitting between two cds and yet quite watchable.
Something around 1400Mb is typical, give or take fifty.  However, now
I get nothing of the sort.  Everything is about 900Mb.  

I also noticed that the indicator on the right hand side of the output
is different.  It used to start low and then build up to the target
vbitrate for about twenty seconds and then it would stabilize at that
and remain quite steady.  Now it builds up to about the right point
but then plunges down again back to the 800 or 900 area.  Nothing I do
can change this.  If I do a straight "-oac copy -ovc copy" it gives
the expected 5400 or so number and I get the appropriately large
file.  However this never has lip sync and cannot be divided up.  And
on a lark I ran a test on a movie at 1800, 3000, and 16000.  There was
not a bit of difference in any, other than the initial build up which
was higher for the second and third, though not nearly up to the
target.  They peaked at something like 2500 and then plunged right
back down to the 900ish point.

One other thing which may bear mentioning is that I did recently
replace my DVD drive.  My old one did not burn at all and so I put in
an NEC.  It has played perfectly and burned just as well so far, but I
cannot recall if I have used it to encode from any DVDs and if they
would have been successful.  I don't think I have.

Any ideas on what may cause this?  I really want mencoder and mplayer
to work properly.

Many thanks

Patrick