[MPlayer-dev-eng] -vop scale

[Michael Niedermayer]

Hi

On Tuesday 16 July 2002 15:20, Kim Minh Kaplan wrote:
> Hello,
>
> I recently started using -vop scale=640:-2,crop=... instead of
> calculating the scaled width myself.  But the code in vf_scale.c is
> not restrictive enough: it can result in dimensions (height here) that
> are not usable because it is not even.  So I came up with the
> attached patch which does the job quite well and rounds to the nearest even
> height.
>
> I want to commit this but to be complete I have to do the same thing
> for the width.  But what value does it have to be a multiple of? 8, 16
> or 32?
that depends upon what ur trieing to achieve ...
*2 for w/h should be enough for bugfree playback on any bugfree player but *16 
for width & height has some advantages (better compression as mpeg uses 16x16 
blocks internally) but the aspect ratio will get messed up the more rounding 
we do ...
32 and larger are not usefull

[...]

Michael