public void set_sync_handler
Sets the synchronous handler on the bus.
The function will be called every time a new message is posted on the bus. Note that the function will be called in the same thread context as
the posting object. This function is usually only called by the creator of the bus. Applications should handle messages asynchronously using the
gst_bus watch and poll functions.
You cannot replace an existing sync_handler. You can pass NULL to this function, which will clear the existing handler.
||The handler function to install
||User data that will be sent to the handler function.