Controller Troubles for setting brightness programmatically

[Sebastian Dröge]

On Mi, 2013-12-11 at 18:14 +0100, Urs Hofer wrote:
> Am 11.12.2013 um 18:02 schrieb Sebastian Dröge <sebastian at centricular.com>:
> 
> > On Mi, 2013-12-11 at 00:13 +0100, Urs Hofer wrote:
> >> Dear Tim
> >> 
> >> Indeed, volume works now if I use a bin containing
> >> volume and autoaudiosink and attach it to the playbin setting the audio-sink
> >> property.
> >> 
> >> Thanks for pointing to gst-inspect: indeed, brightness is not controllable in
> >> xvimagesink, so I could try for ages ;). As for sound, it also works if I use 
> >> the videobalance element before xvimagesink.
> > 
> > You could probably make the brightness (and others) properties of
> > xvimagesink controllable. Note that many drivers don't support these
> > settings anymore nowadays, especially in texture overlay mode which is
> > used on most modern desktops (e.g. it does not work on my Intel GPU in
> > GNOME3).
> > 
> 
> Right now, I'm using the videobalance element in the pipeline. That makes
> it a little bit more flexible if i'm using other sinks than xvimagesink (i.e. on
> other hardware like the RaspberryPi). I think I'll stick with that.

Using videobalance will likely be too slow on the RaspberryPi, and the
only way to do fast decoding there is to decode via hardware to a
EGLImage, which then can only be used in OpenGL ES.

> >> (This raises another question, which would be the fastest, most accelerated 
> >> way of fading in and out)
> > 
> > Probably something that renders both videos in an OpenGL scene and fades
> > them there. However you need to check if your hardware has fast ways of
> > providing the video frames as GL textures.
> > 
> 
> I used gStreamer with openFrameworks, where everything is handled by OpenGL
> Textures. There it is quite easy to do fades, but the performance is very bad. So
> I switched to a direct approach using GTK and two Overlays and fading with gStreamer.

Depends a bit on where you run it and what possibilities you have here
to decode and render video. On the Raspberry Pi for example your
approach wouldn't work, already because there's no XV support there.

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