GnlComposition Signals

[Angel Martin]

Dear Edward,

2011/2/28 Edward Hervey <bilboed at gmail.com>

> On Mon, 2011-02-28 at 09:21 +0100, Angel Martin wrote:
> > Dear all,
> >
> > I have the next problem.
> >
> > When 3 contents are played and afterwards only 1 is performed using
> > gnlcomposition an error appears, but if i remove one by one it works:
> > Content A start 0 dur 10
> > Content B start 0 dur 10
> > Content C start 0 dur 10
> > Content D start 10 dur 10
> > -> Seek Error
> > ERROR         gnlcomposition
> > gnlcomposition.c:1724:no_more_pads_object_cb:<video-composition>
> > Sending seek event failed!
>
>   You're not giving enough information. What priorities are you using ?
>

My application is in someway a pitivi app but with transitions based on
operations and concurrent image and video contents, I mean xpos and ypos
parameters management from videomixer sinkpads to achieve overlapped
multimedia.

In my case A, B and C are imagefreezed images and after a video is played
Videomixer that places xpos, ypos and zorder has Priority 0
The Content A has Priority 2
The Content B has Priority 3
The Content C has Priority 4
The Content D has Priority 5

Do you have any other object apart from those 4 ?
>
Yes, I have another gnlcomposition that has a single mp3 file performed
through all the A, B, C and D image/video contents, but I am quite sure that
I have isolated the problem.

Anyway, as far as I understood I think that, according to the GST_DEBUG
logs, the problem could be in gnloperation, because it does not remove all
the sink pads of the videomixer (only 1) and gstreamer try to perform a seek
event over a sink pad that in fact I doesn't have anything connected.

However, when all the sink pads of the videomixer are removed, by a modified
gnloperation synchronize_sinks function, the content D is never played,
because all the sinkpads have been removed and there is no unlinked sinkpad
to be assigned to the content D. So at least one of the sinkpads of the
video mixer should not be removed (operation->realsinks >=1??).


> >
> > Content A start 0 dur 10
> > Content B start 0 dur 9
> > Content C start 0 dur 8
> > Content D start 10 dur 10
> > -> Ok!
> >
> > In my case I have a gnloperation that places each content through the
> > xpos, ypos and zorder attributes of the sinkpad of the videomixer.
> >
> > gnloperation = gst_element_factory_make ("gnloperation",
> > "general-video-composition");
> > videomixer = gst_element_factory_make ("videomixer",
> > "general-video-adder");
> >
> > gst_bin_add (GST_BIN (gnloperation), videomixer);
> > g_object_set(G_OBJECT (gnloperation),
> >     "expandable", TRUE,
> >     "priority", 0,
> >     NULL);
> > gst_bin_add (GST_BIN (gnlcomposition), gnloperation);
> >
> > g_signal_connect(gnloperation, "input-priority-changed", G_CALLBACK
> > (onPriorityChange), data);
> >
> > In the onPriorityChange function I assign to each video/image content
> > the xpos, ypos and zorder parameters mentioned before.
> >
> > So, as far as i understood it is supposed that the videomixer should
> > manage properly the request_new_pad and release_request_pad calls, and
> > no redefinition would be needed.
> >
> > However, depending on the number of performed contents the Seek Error
> > appears or not.
> >
> > After trying to understand the problem from the code of videomixer,
> > gnlcomposition and gnloperation, I think that the problem could be the
> > "gnloperation" element.
> >
> > In the code of of the function "synchronize_sinks" there is a call
> > to:
> >     /* Remove pad */
> >     /* FIXME, which one do we remove ? :) */
> >     remove_sink_pad (operation, NULL);
> >
> > I think that this is the tricky point, because this function seems not
> > be prepared to remove several sinks at once, so gstreamer try to seek
> > a sinkpad that in fact doesn't have any source "connected".
> >
> > So a loop inside "synchronize_sinks" could fix it.
> >     /* Find unlinked sinkpads */
> >     GstPad * sinkpad;
> >     while ((sinkpad = get_unlinked_sink_ghost_pad (operation)) !=
> > NULL) {
> >        remove_sink_pad (operation, sinkpad);
> >     }
>
>   Fixed that in a pending branch, will try to push the commit later
> today.
>

Ok! great news!


>
> >
> > According to the GST_DEBUG log I think that the function
> > "synchronize_sinks" is not called for each multimedia content removed
> > by the composition, but once, so this code could fix it.
> >
> > But, again the Content D try to find a videomixer sink pad and it
> > can't be found, so the pipeline freezes.
> >
> > Could someone provide any idea to fix this situation?
> >
> > Thank you in advance.
> >
> > Best Regards,
> >
> >
>

Thank you for your quick reply.

Best,

Angel
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