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

Ville Saari 113762 at vs.iki.fi
Fri Feb 18 22:50:47 CET 2005


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.

I'm not familiar with the implementation of the mplayer's software
scaler, but the scaling algorithms in general are usually pretty
easy to extend to do cropping with very little overhead.

-- 
 Ville




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