[FFmpeg-user] Encode VP9 (or VP8) WITH alpha channel

Wagner Patriota wagner.patriota at gmail.com
Tue Jan 7 23:31:00 CET 2014

2014/1/7 Wagner Patriota <wagner.patriota at gmail.com>

> Is FFmpeg supporting encoding of WebM with VP9 (or VP8) with alpha channel
> through libvpx?
> I tried the very basic:
> ffmpeg -i input.mov -vcodec libvpx-vp9 output.webm
> but nothing happens... my video doesn´t get the transparency from
> input.mov... any hints?
> Thank you,
> Wagner

Sorry, actualy the encode with VP8 IS WORKING (I can see the transparency
working with Google Chrome).

But I need also to decode it. I can encode VP8 with alpha, but when I
decode it, the alpha information disappears!

STEP1: ffmpeg -i input.mov -vcodec vp8 1.webm (ok, I can see the 1.webm
transparency using Google Chrome)
STEP2: ffmpeg -i 1.webm -vcodec vp8 out.webm (fail, out.webm has no
transparency anymore when encoding again FROM VP8)

In my code (programmatically), I could not get the transparency from the
VP8 video, as well as the command above... what happens here?

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