location where to store a pointer to the object whose property got changed, or %NULL
return location for the name of the property that got changed, or %NULL
return location for the new value of the property that got changed, or %NULL. This will only be set if the property notify watch was told to include the value when it was set up
1.10
Parses a property-notify message. These will be posted on the bus only when set up with gst_element_add_property_notify_watch() or gst_element_add_property_deep_notify_watch().