[MPlayer-users] info on -cbp -mv0 and -qprd

[Wayde Milas]

On Fri, 2004-02-27 at 14:41, D Richard Felker III wrote:

> > Darnit, my cut and copy skills arent good today. that line should read:
> > mencoder dvd://1 -o blah.avi -mc 0 -noskip -skiplimit 0 -oac copy -ovc
> > lavc -vf crop=www:xxx:y:z -lavcopts
> > vcodec=mpeg4:vqscale=2:mbd=2:trell:vmax_b_frames=1:v4mv:autoaspect
> 
> What are www, xxx, y, and x? Width and height must both be multiples
> of 16 unless you're going to scale afterwards, horizontal offset must
> be even, and vertical offset should be even or a multiple of 4. Also,

I realize this. They are just place holders. I'm obtaining these numbers
from cropdetect so everything is good.
> the following options might improve quality:
> 
> mv0
> cbp
> cmp=2
> subcmp=2
> qpel

mv0 and cbp. cbp might because it looks like its an optimized version of
trellis, but I'm not sure.. What exactly does it do?

mv0 I'm clueless on.

qpel adds more bits to a q=2 stream (from observation). I've heard
reports that there is no difference in quality (I cant see any) and the
stream is larger so....

maybe its because i havent messed around with cmp and subcmp.

> 
> Further, if you're not using insanely high bitrates, you should
> probably use the denoise3d filter to remove noise and scale down to an
> appropriate size (still multiples of 16!) so that there's less
> information to encode. Otherwise you'll have blocking and/or ringing
> artefacts.

As noted above, I'm using vqscale=2. I am using a very high bit rate.
I'm copying my dvd collection onto the house server to distribute to
setup media boxes. Basicly I could get away with q=3 or 4. I can tell
the defference between q=5 and 2 so I dont want to go with 5. Since I
have the room, q=2 seems to be acceptable even though it does generate a
large bit stream.

> 
> Finally, I don't see anything about 2pass encoding in your post. 1pass
> will definitely give you very bad quality unless you use a really high
> bitrate.

From everything I've read, 2pass encoding is not needed with a VBR (ie,
a static q with an uncapped bit rate). Am I mistaken about this?

Wayde
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