[MPlayer-users] cropdetect accuracy with mplayer-1.0pre6a

D Richard Felker III dalias at aerifal.cx
Fri Feb 18 23:42:45 CET 2005

On Fri, Feb 18, 2005 at 11:49:47PM +0159, Ville Saari wrote:
> On Fri, Feb 18, 2005 at 03:33:57PM -0500, D Richard Felker III wrote:
> > not the codec matter, rather image formats. basically all the image
> > formats used in movies are 4:2:0, meaning that non-even crop offsets
> > or sizes are _complete nonsense_, i.e. not possible without first
> > resampling.
> Not complete nonsense, because it _is_ possible with resampling.
> You said:
> > quite often you'll scale after cropping though,
> And if you scale, you resample anyway. That resampling could be
> ulilised for fractional pixel cropping if the scale filter does
> the cropping.

the scale filter does not do cropping, and i don't see any reason it
should. there's no point in cropping at finer granularity than the
largest sample granularity in the _source_ video.

in any case this is all about the crop filter, which does not, and
will never do, any resampling because it does not belong there. thus i
maintain that it's complete nonsense to use non-even offsets with
4:2:0 video.


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