[FFmpeg-user] drawtext to a (transparent) bounding box

Jannes Faber jannes.faber at gmail.com
Fri Feb 27 18:54:11 CET 2015

polite bump.

Anyone please?

Using drawtext on a transparent background does not seem to work.


On 23 February 2015 at 17:55, Jannes Faber <jannes.faber at gmail.com> wrote:

> Hi,
> Video editting newbie here.
> I'm trying to use addtext onto a box and then overlay that box on a video.
> That works fine, except when I try to make the bounding box  transparent.
> The problem is that the text itself becomes transparent too, not just the
> bounding box.
> I asked this question here and included some screenshots and example code:
> http://video.stackexchange.com/questions/14924/ffmpeg-drawtext-in-a-transparent-box
> The very helpful comment I got so far:
> "I think what's happening is that drawtext isn't writing the alpha
> channel, so overlay just sees a rectangle with uniform alpha. The opacity
> controls for drawtext just affect how it blends its text into the frames it
> draws on." - Peter Cordes
> It feels a bit like a bug in ffmpeg to me, but I'm sure there's a good
> explanation. And I'm wondering if there's another/better way to do it?
> Thank you.
> --
> Jannes

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