Application Element interaction

[Thiago Santos]

On 05/08/2014 11:30 PM, Yogesh Tyagi wrote:
>  If I add a probe to src pad of my element and emit a signal from this 
> probe handler which will be received by the application.Upon receiving 
> this signal, application is supposed to do state change of this element.
> Will it be a valid implementation? Does g_signal_emit or signal 
> handler(in application) run in pipeline context?
Can you describe what you are trying to do from high level? It would 
help coming up with a proper solution. Why do you need to change state 
when first buffer is received?

And to answer your question, the signal emission happens from the thread 
that does it, so it would be done from a thread from the pipeline and it 
usually isn't safe to perform state changes from it.

>
> Thanks,
> Yogesh
>
>
> On Fri, May 9, 2014 at 5:42 AM, Luis de Bethencourt 
> <luis at debethencourt.com <mailto:luis at debethencourt.com>> wrote:
>
>     Hi Yogesh,
>
>     You could use a gst_pad_add_probe () to be notified of the change
>     you are looking for in the element's video source pad.
>
>     http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html#GstPadProbeType
>
>
>     Hope this helps,
>     Luis
>
>
>     On 8 May 2014 14:18, Yogesh Tyagi <yogesh.bit2006 at gmail.com
>     <mailto:yogesh.bit2006 at gmail.com>> wrote:
>
>         I want to notify the application when first buffer is received
>         on video source pad of my demux element.
>
>
>         Thanks,
>         Yogesh
>
>
>         On Thu, May 8, 2014 at 6:36 PM, Yogesh Tyagi
>         <yogesh.bit2006 at gmail.com <mailto:yogesh.bit2006 at gmail.com>>
>         wrote:
>
>             Hi,
>
>             What is best mechanism for application and element
>             interaction in gstreamer?
>
>             Thanks,
>             Yogesh
>
>
>
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-- 
Thiago Sousa Santos
Senior Multimedia Engineer, Open Source Group
Samsung Research America - Silicon Valley

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