[FFmpeg-user] "Extracting" Alpha Channel

Gavin Kinsey gkinsey at ad-holdings.co.uk
Fri Jul 29 16:56:04 CEST 2011

On Thursday 28 July 2011 12:47:59 Dan Flett wrote:
> How about being able to do something like this?
> format=yuva, lutyuv=y=a:u=minval:v=minval
> Basically, being able to specify that the y (luma) channel output is
> equal to the a (alpha) channel of the input?
> Being able to swap color channels around would be good:
> format=rgb, lutrgb=r=b:g=r:b=g

I've actually written a filter to do this.  I use it to convert a colour 
plane into the alpha channel.  The main limitation is it only works for RGB.  
I'm planning on submitting it to the -devel list when I have time.

Though I expect it will take quite a few revisions before it is acceptable, 
because I copied and pasted another filter then mauled it until it did what I 
needed, so there is a lot of rubbish in it.

Gavin Kinsey
AD Holdings Plc

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