[MPlayer-users] help wanted: using mencoder to make NTSC DVD from transport stream

[Ville Saari]

On Sat, Mar 05, 2005 at 07:33:02PM -0500, D Richard Felker III wrote:

> it later), but be sure to use -lavcopts aspect=16/9 so the final file
> is marked as having 16:9 aspect.

The correct lavcopts aspect for the so called "16:9" DVD is not 16/9,
but 144/79 for NTSC or 640/351 for PAL. Those ratios are about 2.5%
wider than 16/9 because DVD (or D1) image contains a few pixels of
horizontal blanking area that is not counted as part of the 16:9
picture.

This of course applies to 4:3 image too. The numbers are 108/79 for
NTSC and 160/117 for PAL.

Many DVDs and DV cameras utilise those extra pixels for wider picture
instead of leaving them blank. If you watch such source on TV, you
see a cropped picture. Some software DVD players also do this cropping,
but mplayer does not. Mplayer however plays DVDs squeezed horizontally
2.5% too narrow, because it incorrectly thinks that a 16:9 DVD really
is 16:9. This affects mencoder too, so -lavcopts autoaspect does not
work for DVD source.

-- 
 Ville