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

Carl Eugen Hoyos ceffmpeg at gmail.com
Mon Feb 1 00:11:44 EET 2021

Am So., 31. Jan. 2021 um 22:43 Uhr schrieb Craig Turner
<turner.craig at gmail.com>:

> I'm trying to decode and convert a VP8 video with an alpha channel to a 32-bit
> RGBA for rendering in my application. The decoding with libvpx works fine, but
> I can't get the alpha channel through into the RGBA. Am I doing something
> wrong with libswscale?

Did you check the value of _codecCtx->pix_fmt ?
If it is not yuva420p, then the alpha channel was not decoded.

Carl Eugen

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