[FFmpeg-user] vp9_vaapi bad color range when using rgb input

[Stéphane Chauveau]

And just in case someone would not know 'convert', that is one of the 
ImageMagick tools.

On 6/26/19 5:26 PM, Stéphane Chauveau wrote:
> convert -negate -size 512x512 pattern:checkerboard A.png
> convert -size 512x512 gradient: B.png
> convert \
>     -negate -size 512x512 pattern:checkerboard \
>     -size 512x512 gradient: \
>     -compose Mathematics -define compose:args="0,1,0.2,-0.1" -composite \
>     -depth 8 -define png:color-type=2 range-pattern.png