Great thank, Tanu! > Sink input implementers can override the default message handler with > their own implementation. If they do that, then they usually call > pa_sink_input_process_msg() explicitly for those messages that they > don't want to handle specially (or in addition to handling the messages > specially, they also want the default handler to do what it always > does). You can find many examples this in the code if you grep for > "pa_sink_input_process_msg". So "protocol-native.c" is a implementor for a sink input, right? It has a "sink_input_process_msg" which overrides the default message handler as you said. I have another question: is it possible for a sink input connected to multiple sinks? If yes, in which thread is the message handler is called? Thanks Amanda