[FFmpeg-devel] [PATCH 2/2] swscale: Add swscale and fate support for AYUV

[Fu, Linjie]

> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of Carl Eugen Hoyos
> Sent: Wednesday, August 28, 2019 14:58
> To: FFmpeg development discussions and patches <ffmpeg-
> devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH 2/2] swscale: Add swscale and fate
> support for AYUV
> 
> 
> 
> > Am 28.08.2019 um 08:22 schrieb Linjie Fu <linjie.fu at intel.com>:
> >
> > Add swscale support for AYUV and make it more robust.
> 
> The path that converts from AYUV to planar YUV(A) seems to be missing the
> handling of alpha values.

Alpha channel information in AYUV are treated in the same way for RGBA/BGRA and
is reusing rgbaToA_c to handle the alpha values.

When converting AYUV to YUA/YUVA, two methods are acceptable:
- For YUV, just cut the alpha and discard the transparency 
- For format which also contains an alpha channel(YUV444P), copy the alpha information seems good.