gst-launch - animate videobox alpha

[Nicolas Dufresne]

Le mardi 05 mai 2015 à 10:39 -0700, aetitcomb a écrit :
> Is there a way for me to animate the alpha value for a videobox over 
> time in
> a gst-launch pipeline?
> 
> I have something similar to this:
> 
> gst-launch -e videotestsrc pattern="snow" ! video/x-raw-yuv, 
> framerate=10/1,
> width=200, height=150 ! \
>    videobox border-alpha=0 alpha=0.6 top=-20 left=-25 ! videomixer 
> name=mix
> ! ffmpegcolorspace ! xvimagesink \
>    videotestsrc ! video/x-raw-yuv, framerate=10/1, width=640, 
> height=360 !
> mix.

gst-launch-1.0 is just a test tool, it will not let you change the
pipelien dynamically. To animate a property, you will have to write
your own application.

> 
> Can I animate the videobox's alpha over a specified time?

By looking into the output of gst-inspect-1.0 videobox, you will
notice that this property is controllable. What this mean is that you
can animate this property base on the time. For this you have to write
your own GStreamer program and learn how to use the associated API.
You can find example here:

http://cgit.freedesktop.org/gstreamer/gstreamer/tree/tests/examples/con
troller

I notice the use of gst-launch (without -1.0) which lead me to think
you are doing development on top of an very old version of GStreamer.
Make sure to use recent version of GStreamer, this way you will have
better and more accurate support on this ML.

cheers,
Nicolas

p.s. current stable GStreamer can be found through:
http://gstreamer.freedesktop.org/download/
p.s. Most major Linux distribution ships 1.4 stable version of
GStreamer