[FFmpeg-devel] [PATCH] Make decoding alpha optional for some codecs.

[Kirill Gavrilov]

On Thu, Sep 19, 2013 at 2:50 PM, Paul B Mahol <onemda at gmail.com> wrote:

> I have just checked what happens when RGBA image converted to RGB using
>> swscale and unfortunately result is incorrect (alpha just discarded).
>>
> What it should do instead?

Well technically it should blend image with background color...
But since there NO such color specified explicitly - it is some kind of
problem.

Although in this case ANY default color (black or white) will be better
than just discarding alpha channel.
Also pixels with full transparency might contain noise depending on how
image has been created.
<kirill at sview.ru>