[MPlayer-users] A little OT: 720x576 or 768x576?

[Martin Collins]

On Wed, 28 May 2003 15:54:03 +0200
Fabio Papa <f.papa at mcmspa.it> wrote:

> I'm using mencoder lately to capture some of my favourite TV
> programs, and I 
> was wondering, if PAL format is 720x576, do I have to capture in
> that format, or do I have to respect the 4:3 (1.33) ratio of PC
> monitor, capturing at 768x576?
> Sorry again if this is a little OT, but I know there's some really
> good video gurus in here...

I can't claim to be a guru but I can tell how I do it.
PAL pixels aren't square, the 720 you capture need to be stretched to
768 at some stage to look right. You can do this when encoding by scaling
the picture, or you can do it when playing back by specifying an aspect
ratio.

I specify an aspect ratio when encoding. Mencoder writes this into the
file and mplayer reads it and scales the picture accordingly. However,
other players do not recognise the aspect ratio header that mencoder
writes so for those you will have to specify it manually, if possible.

If you scale the movie when encoding all players will play it correctly
but it will take up more space as you have increased the size of the
picture (unless you scale the vertical down to 540 instead).

If you want to maximise portability and minimise cpu use go with the
second method. If you want to minimise file size and will only play
them with mplayer on a fast machine go with the first.

Martin