[MPlayer-dev-eng] [PATCH] vf_crop to pass on field-order
Zoltan Hidvegi
mplayer at hzoli.2y.net
Sat Oct 11 18:38:29 CEST 2003
> Hi,
>
> > > > + vf->dmpi->fields ^= MP_IMGFIELD_TOP_FIRST;
> > > [..]
> > > > + dmpi->fields ^= MP_IMGFIELD_TOP_FIRST;
> > >
> > > Should those here really be XOR ?
> >
> > Yes, if you crop odd number of lines from the top, then previously top
> > field becomes the bottom field (i.e. previously even lines become the
> > odd lines), so the MP_IMGFIELD_TOP_FIRST flag should be inverted. If
> > not XOR, what else culd you use?
> >
> > Zoli
>
> actually we shouldnt allow cropping odd numbe rof lines from top and left.
> it will also trash chroma upsampling at 4:2:0 formats.
Yes, actually for interlaced 4:2:0 content, we should only allow
cropping a multiple of 4. Unfortunately vf_crop cannot know if it is
interlaced or not. But with 4:2:2 and 4:4:4 you can crop as many
lines as you wish, so inverting the flag is still useful. This patch
just sets the field flags if you crop odd lines. It is a different
issue to prevent odd cropping.
More information about the MPlayer-dev-eng
mailing list