Playing with element transitions

[Thibault Saunier]

Hello,

Did you notice that GES has APIs to handle keyframe/interpolation[0]?

We are using it in pitivi quite intensively (we can keyframe any
propery of effects or the alpha/volume properties of GESAudioUriSource
and GESVideoUriSource), you can find the code (which is probably not
the simple example here[1].

Also there is a blogpost from Mathieu about how to use that API[2]

Regards,

Thibault Saunier

[0] http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-
editing-services/html/GESTrackElement.html#ges-track-element-set-
control-source

[1] https://phabricator.freedesktop.org/diffusion/PTV/browse/master/pit
ivi/timeline/elements.py;c17fd0f095dc1e8d8b8ff6e6934a26e8d4dc502a$73

[2] http://mathieuduponchelle.github.io/coding/2013/06/08/Fun-with-vide
omixer.html

On Wed, 2016-01-06 at 13:59 -0800, waldemar wrote:
> Hi Sebastian, thanks for your answer.
> 
> I've been trying to use the GstController class to test some
> transitions. At
> the moment I'm just trying to see it run with the app project I
> working on,
> here's an example of the implementation:
> 
> 
> I'm using a GES Pipeline, the GESVideoSource components use GL
> elements for
> transformations. The code compiles and runs with no problems, excepts
> that
> no movement is seen bound to that property. I also tested it on other
> elements (lika alpha) with the same lack of results.
> 
> I like the approach of modifying the properties on some sort of
> callback
> function, triggered by a Pipeline event probably, but I'm not sure
> what kind
> of event that would be and how to hook that function up the Pipeline.
> Theoretically I'll need to modify properties per frame in the case of
> video
> elements and on enought-data events for audio maybe?? I'm considering
> to use
> these easing functions (http://easings.net/) with the CppTweening lib
> rary.
> 
> Where could I set such kind of bus or event call functions to modify
> element
> properties??
> 
> 
> 
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