[FFmpeg-devel] [PATCH] Fix for paletteuse to support transparency

[Carl Eugen Hoyos]

2017-10-20 0:00 GMT+02:00 Bjorn Roche <bjorn at giphy.com>:
> The palettes generated by palettegen include one transparent color.
> This patch enables paletteuse to identify the transparency in incoming
> video and tag transparent pixels on outgoing video.
>
> This requires tracking the transparency index in the palette,
> establishing an alpha threshold below which a pixel is considered
> transparent and above which the pixel is considered opaque, and
> additional changes to track the alpha value throught the conversion
> process. If the format of a color variable has changed in this patch,
> an effort was also made to change the variable name for clarity.
>
> This change is a partial fix for https://trac.ffmpeg.org/ticket/4443
> However, animated GIFs are still output incorrectly due to a bug
> in gif optimization which does not correctly handle transparency.

If Clément doesn't comment, I will probably push this in a few days.

Carl Eugen