Using videomixer and alpha channel

[Eric Trousset]

> -----Original Message-----
> From: Sebastian Dröge [mailto:sebastian at centricular.com]
> Sent: mercredi 27 novembre 2013 15:47
> To: Discussion of the development of and with GStreamer
> Subject: Re: Using videomixer and alpha channel
> 
> On Mi, 2013-11-27 at 15:23 +0100, Eric Trousset wrote:
> > Merci !!!
> >
> > Setting the output format of the mixer to ARGB format fixed my issue with
> the alpha blending !
> >
> > Should I file this as a bug? Or maybe a line should be added to the
> documentation?
> 
> Did you have to add a videoconvert element too, or just a capsfilter to force
> ARGB output? videomixer tries to use an alpha format if any of inputs is
> having an alpha channel... so if you just added the capsfilter and changed
> nothing else this would be a bug.

I had the videomixer directly linked to the autovideosink.
I fixed the issue by adding a videoconvert that I linked using gst_element_link_filtered with a caps "video/x-raw, format=(string)ARGB" (videomixer->filteredlink->videoconvert->videosink)
Maybe I could have linked the videomixer to the videosink directly using filtered link?

Eric T.

> 
> --
> Sebastian Dröge <sebastian at centricular.com> Centricular Ltd -
> http://www.centricular.com Expertise, Straight from the Source