[gst-devel] Re: [gst-cvs] wtay gst-plugins: gst-plugins/ gst-plugins/gst-libs/gst/video/

[Benjamin Otte]

Quoting Ronald Bultje <rbultje at ronald.bitfreak.net>:

> Hi Wim,
> 
> On Fri, 16 Jul 2004, Wim Taymans wrote:
> > Log message:
> >         * gst-libs/gst/video/video.h:
> >         Added 32 bits RGBA. Not sure if we should use another mime-type
> >         for alpha rgb. Currently the presence of the alpha_mask property
> >         signals an alpha channel. Ronald?
> 
> Yes, that's the current way. The good thing is that RGB readers can still
> read RGBA and just discard the alpha-channel, so having the same mimetype
> would make sense in a way. But it's suboptimal in another way, too. I
> personally didn't really bother thinking too much about this because I
> don't see too many RGBA videos nowadays.
> 
The main reason for using a different mimetype is that it might result in 
issues when you link a sink element that requires an alpha channel with a 
source element that doesn't know about alpha channels. That way an alpha 
channel will be negotiated and the sink element will pretend to use it, while 
the source element fills the alpha bytes with random garbage.

If we want to be sure such things can't happen, we have to use a different mime 
type during 0.9. If we don't care abut that case, we keep the old mimetype.

Benjamin