[MPlayer-users] quick question about mencoder

[D Richard Felker III]

On Sun, Jan 12, 2003 at 06:25:58PM -0600, Jeremy Brown wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Hey guys,
> 
> I've been trying to use mencoder to convert some of my mpg files to divx 
> format to conserve a bit of space.  I do this with the command:
> 
> mencoder -oac mp3lame -ovc divxf -o output.avi input.mpg

You should be using libavcodec, not divx4. It gives much better visual
quality at same bitrate and has fewer bugs.

> Two things I've noticed but can't put my finger on:
> 
> 1) The resulting AVI file always seems to have a slightly incorrect 
> aspect ratio.  Usually it's not very noticeable, but the height is a 
> little bit smaller than it was in the mpg file (maybe an inch or less 
> smaller on my 19" monitor).

If the source file is 352x240 (VCD), it's meant to be played at 4:3
aspect ratio. You can either rescale to 320x240 or 352x264 (but the
latter is a bad idea because 264 is not divisible by 16, and it'll
look bad if scaled to watch on a TV), or you can encode with lavc and
use the -lavcopts aspect=4/3 option. This will encode the aspect ratio
in the mpeg4 headers so that mplayer prescales it correctly (as it did
when the file was mpeg1). Unfortunately mplayer seems to be the ONLY
player that will read the aspect ratio from mpeg4 video, so your file
will still be slightly disproportionate looking if viewed on another
player, but this is probably still the best approach.

> 2) The sound seems to be a little bit off...the sound is early with 
> respect to the video.  I've compiled the newest version of LAME to make 
> sure that I wasn't dealing with a problematic LAME library, but that 
> didn't fix the problem.

Not sure what's wrong here...

Rich