GnlComposition Signals

[Angel Martin]

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!

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);
    }

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,

Angel

-- 

Ángel Martín Navas
Investigador / Researcher
Televisión Digital y Servicios Multimedia / Digital TV & Multimedia Services

Vicomtech - Visual Interaction Communication Technologies
Mikeletegi Pasealekua, 57 - Parque Tecnológico
20009 Donostia - San Sebastián - Spain
Tel: +[34] 943 30 92 30
Fax: +[34] 943 30 93 93
e-mail: amartin at vicomtech.org
www.vicomtech.org

*** member of IK4 Research Alliance ****
www.ik4.es
*** member of GraphicsMedia.net ****
www.graphicsmedia.net



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