Using videomixer and alpha channel

[Lautaro Woites]

Hi Eric,
             I had the same problem on gst 0.10. My pipeline had a
videomixer with 2 inputs (an mkv file and a png with alpha).
My solution was to fix all the mixer's input caps to  "video/x-raw-rgb,
alpha=255".





2013/11/25 Eric Trousset <etrousset at awox.com>

>
>
> > -----Original Message-----
> > From: Sebastian Dröge [mailto:sebastian at centricular.com]
> > Sent: vendredi 22 novembre 2013 20:52
> > To: Discussion of the development of and with GStreamer
> > Subject: Re: Using videomixer and alpha channel
> >
> > On Mi, 2013-11-20 at 12:10 +0100, Eric Trousset wrote:
> > > Hi,
> > >
> > > I am using, videomixer to mixer to streams, but it seems the alpha
> channel
> > is not used for the mixing, eg, part of the image with a 0 alpha aren't
> > transparent...
> > >
> > > Is there a way to enable alpha transparency in the video mixer?
>
> >
> > Are you making sure that the video input to videomixer is still having
> the
> > alpha channel, i.e. there's no videoconvert element in front of it that
> > converts it to something without alpha channel?
> >
> > The blending code in videomixer should use the alpha channel already.
>
> Yes I had a videoconvert element. So I removed it but still, it seems the
> pixel alpha is not taken into account. I can see the checker background
> only if I set the pad's "alpha" property to some value.
>
> >
> > > Also, I am using imagefreeze to display a still image. Is there a way
> to make
> > this element to ask the source for a new image at some point?
> >
> > There isn't, but it could be implemented with some custom event. Or maybe
> > all this should just handle the request-keyunit event. Nothing is
> > implemented yet for that.
>
>
> That would be a great feature :)
>
>
> >
> > --
> > Sebastian Dröge <sebastian at centricular.com> Centricular Ltd -
> > http://www.centricular.com Expertise, Straight from the Source
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