Re: Gstreamermm plugin initialization error

[Krzesimir Nowak <qdlacz gmail com>]

On Sat, 2011-06-25 at 17:43 +0200, Fernando Herrero Carrón wrote:
> Hello everyone,
> 
> I am beginning to play with gstreamermm (and gstreamer in general, for
> that matter) eventhough I have been using gtk-- for a long time.
> 
> I'm using gstreamermm on FreeBSD 8.2-STABLE with the system compiler:
> 
> g++ (GCC) 4.2.2 20070831 prerelease [FreeBSD]
> 
> Compiling and installing gstreamermm from ports was flawless, and I can
> compile, link and run simple examples against it. However, some plugins
> that work OK for C programs fail to load when using the C++ wrappers.
> 
> For example, running
> 
> $> gstreamer-properties --gst-debug-level=5
> 
> yields
> 
> [...]
> GST_PLUGIN_LOADING gstpluginfeature.c:107:gst_plugin_feature_load: loading plugin for feature 0x8067007e0; 'fakesink'
> GST_PLUGIN_LOADING gstpluginfeature.c:111:gst_plugin_feature_load: loading plugin coreelements
> GST_PLUGIN_LOADING gstplugin.c:1293:gst_plugin_load_by_name: looking up plugin coreelements in default registry
> GST_PLUGIN_LOADING gstplugin.c:1296:gst_plugin_load_by_name: loading plugin coreelements from file /usr/local/lib/gstreamer-0.10/libgstcoreelements.so
> GST_PLUGIN_LOADING gstplugin.c:737:gst_plugin_load_file: attempt to load plugin "/usr/local/lib/gstreamer-0.10/libgstcoreelements.so"
> GST_PLUGIN_LOADING gstplugin.c:834:gst_plugin_load_file: Plugin 0x806767150 for file "/usr/local/lib/gstreamer-0.10/libgstcoreelements.so" prepared, calling entry function...
> GST_PLUGIN_LOADING gstplugin.c:841:gst_plugin_load_file: Plugin 0x806767150 for file "/usr/local/lib/gstreamer-0.10/libgstcoreelements.so" prepared, registering...
> GST_PLUGIN_LOADING gstplugin.c:540:gst_plugin_register_func: plugin "/usr/local/lib/gstreamer-0.10/libgstcoreelements.so" looks good
> GST_ELEMENT_FACTORY gstelementfactory.c:232:gst_element_register:<registry0> update existing feature 0x8067005a0 (capsfilter)
> GST_ELEMENT_FACTORY gstelementfactory.c:232:gst_element_register:<registry0> update existing feature 0x8067006c0 (fakesrc)
> GST_ELEMENT_FACTORY gstelementfactory.c:232:gst_element_register:<registry0> update existing feature 0x8067007e0 (fakesink)
> [...]
> 
> This looks like once a plugin gets loaded, all its features get registered.
> 
> Now I compile the following program:
> 
> #include <gstreamermm.h>
> 
> int main(int argc, char **argv) {
> 	// Initialize Gstreamermm:
> 	Gst::init(argc, argv);
> 
> 	// Create elements:
> 	Glib::RefPtr<Gst::Element> fakesrc = Gst::ElementFactory::create_element("fakesrc");
> 
> 	if(fakesrc == Glib::RefPtr<Gst::Element>(NULL))
> 		throw -1;
> 
> 	return 0;
> }
> 
> And if I run it with --gst-debug-level=5 I get the following errors:
> 
> [...]
> GST_PLUGIN_LOADING gstpluginfeature.c:111:gst_plugin_feature_load: loading plugin coreelements
> GST_PLUGIN_LOADING gstplugin.c:1293:gst_plugin_load_by_name: looking up plugin coreelements in default registry
> GST_PLUGIN_LOADING gstplugin.c:1296:gst_plugin_load_by_name: loading plugin coreelements from file /usr/local/lib/gstreamer-0.10/libgstcoreelements.so
> GST_PLUGIN_LOADING gstpluginfeature.c:116:gst_plugin_feature_load: loaded plugin coreelements
> GST_PLUGIN_LOADING gstpluginfeature.c:146:gst_plugin_feature_load: Tried to load plugin containing feature 'fakesrc', but feature was not found.
> 
> (mygstreamer:31703): GStreamer-CRITICAL **: gst_element_factory_get_element_type: assertion `GST_IS_ELEMENT_FACTORY (factory)' failed
> 
> (mygstreamer:31703): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed
> 
> (mygstreamer:31703): GStreamer-CRITICAL **: gst_element_register: assertion `g_type_is_a (type, GST_TYPE_ELEMENT)' failed
> GST_PLUGIN_LOADING gstplugin.c:559:gst_plugin_register_func: plugin "/usr/local/lib/gstreamer-0.10/libgstcoreelements.so" failed to initialise
> GST_PLUGIN_LOADING gstplugin.c:846:gst_plugin_load_file: gst_plugin_register_func failed for plugin "/usr/local/lib/gstreamer-0.10/libgstcoreelements.so"
> GST_PLUGIN_LOADING gstplugin.c:1301:gst_plugin_load_by_name: load_plugin error: File "/usr/local/lib/gstreamer-0.10/libgstcoreelements.so" appears to be a GStreamer plugin, but it failed to initialize
> GST_PLUGIN_LOADING gstpluginfeature.c:133:gst_plugin_feature_load: Failed to load plugin containing feature 'capsfilter'.
> [...]
> GST_PLUGIN_LOADING gstpluginfeature.c:146:gst_plugin_feature_load: Tried to load plugin containing feature 'fakesrc', but feature was not found.
> GST_ELEMENT_FACTORY gstelementfactory.c:409:gst_element_factory_create:<elementfactory3> loading plugin containing feature (null) returned NULL!
> GST_ELEMENT_FACTORY gstelementfactory.c:470:gst_element_factory_make:<elementfactory3> couldn't create instance!
> terminate called after throwing an instance of 'int'
> 
> 
> Here it looks like it is trying to initialize a plugin that has been
> already loaded, is that possible?
> 
> Any help with this will be appreciated.
> 
> Thank you very much,
> Fernando

Shooting in the dark here, but maybe everything is alright. Probably
this strange Glib::RefPtr<Gst::Element>(NULL) is messing with you. Try
using 'if (fakesrc) { ... }'.

I'm no gstreamer guy, but this use of Glib::RefPtr caught my eye.

> 
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