[MPlayer-users] using mencoder with -mf, pixelation

[Martin Collins]

On Fri, 25 Mar 2005 12:32:39 -0800
Brian Craft <bcboy at thecraftstudio.com> wrote:

> So, the question is, what's happening between here:
> 
>     mplayer mf://'*jpg' -mf type=jpeg -vf scale=768:576 
> 
> ... where the video looks great, and here
> 
>     mencoder mf://'*jpg' -mf type=jpeg -vf scale=768:576 -ovc lavc
>     mplayer test.avi
> 
> ... where the video looks blocky. And how do I fix it? I'm looking
> over the encoding options, but they don't mean much to me at this
> point.

Your jpegs are being encoded to mpeg4 with the default bitrate of 800
and no quality-boosting options. You need to specify -lavcopts. Which
ones depends on exactly what you want to achieve.

> The jpegs are much larger than 768:576. I'm trying to scale it down
> to a resonable size, e.g. suitable for the web, or a video cd.

For maximum compatibiity on the web you should use mpeg1 which also
happens to be what standard VCDs require.
Try:
mencoder mf://'*jpg' -mf type=jpeg -vf scale=352:288 -ovc lavc \
 -lavcopts vcodec=mpeg1video:mbd2:v4mv:trell:cbp:vbitrate=500 \
 -nosound -ofps 25 -of mpeg -o filename.mpg

I haven't tesed this. You can adjust the bitrate and framerate though
mpeg1 and VCD may have special requirements which you'll have to look
up.

Martin