[MPlayer-users] mbd, vqscale, and vpass mechanisms

[Elmo]

Hello,

I remember a discussion a while back about vqscale, but I don't believe 
a conclusion was ever really reached.  Anyway, I have a few questions 
about these mechanisms in the encoding process.

What I have typically been using as a command line to encode a dvd is:

mencoder dvd://1 -o movie.avi -oac lavc -ovc lavc -alang en -lavcopts 
vcodec=mpeg4:acodec=ac3:vqscale=3:mbd=1 -vf crop=<foo> scale=<foo>

I figure that this will give me a constant quality of 3, which is pretty 
much unnoticable, use the "vhq" method, which is the best quality 
encoding, and the size will be whatever is required to get the necessary 
quality.

I don't see why people use 2-pass encoding with vqscale, basically.  If 
you're encoding at a constant quality, how does getting information 
about the bitrates help the encoding quality?  Should I be doing this 
differently to get a better overall movie, or am I misunderstanding the 
way that vqscale works with vpass?  Also, mbd has three options, and I 
don't really know which is the "best" in terms of quality.

Perhaps we should update the encoding-tips.txt file on the mplayer user 
site at some point, I think it's getting outdated.

Thanks,
-Brian