[MPlayer-dev-eng] [PATCH] New video filter: deblendlogo

[Oded Shimon]

On Wednesday 23 February 2005 00:58, Oded Shimon wrote:
> On Tuesday 22 February 2005 14:57, Martin Atkins wrote:
> > There seems to be a strange bug with the YV12->BGRA->YV12 path where a
> > green line is introduced with some video sources at the bottom of the
> > image. I can't figure out what's causing it, but some discussion on the
> > #mplayerdev IRC channel led to the conclusion that it was a bug in the
> > scaler. Still, if anyone can see that I'm calling it wrong or something,
> > please let me know.
>
> I dunno about the calling, TBH, I didn't even look at the code, but it
> gives me a green line too. :( So it's not swscaler or uneven res, something
> is wrong.. It's a bit of a stopper, better figure it out...
It's worse than I thought. :/ It's not just the green line, the entire image 
has gone down in quality - it's as if someone used nearest neighboor scale to 
half the size, and then again to twice the size. (i.e., 75% of the pixels 
were completely lost.)
I did find this, using these params, there is no quality defects, no green 
line problem, nothing. Absolute perfection:
-vf 
scale=,format=fmt=rgba,deblendlogo=730:409:chan3-logo.png,scale=,format=fmt=yv12

If I get some time I might look into it and fix the filter. Generally color 
converting at all is (a little) lossy, so if it's possible in some way to 
make this filter work in YUV without converting anything, it would be 
awesome. I think it is possible, as far as I can tell, alpha works just as 
well on YUV as it does on RGB. All you need to do is first convert the input 
png image to YUV instead of RGB (and store the alpha separately or 
something).

- ods15