[Libav-user] Difficulty decoding libvpx VP8 with Alpha as RGBA

Craig Turner turner.craig at gmail.com
Mon Feb 1 12:52:12 EET 2021

OK thank you very much for the tips. I will have to dig into that a bit
deeper, so far I haven't had to build the libraries myself. One further
question: do you expect similar dependencies/config for vp9 with alpha as

Can you confirm that in general alpha-decoding should work with the ffmpeg
libraries? At least "the Internet" claims ffmpeg can handle these streams
and I was able to create a pre-multiplied version of the video using libvpx
which suggests it does work somehow with that same build.

On Mon, Feb 1, 2021 at 10:43 AM Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

> > Am 01.02.2021 um 00:08 schrieb Craig Turner <turner.craig at gmail.com>:
> >
> > You are absolutely right - the format is AV_PIX_FMT_YUV420P, so it seems
> the alpha channel is not being decoded. Is there something specific I need
> to do to ensure it does indeed get decoded?
> It may be necessary to configure with --disable-decoder=vp8
> Carl Eugen
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