Connecting two independent pipelines - sync timestamps

[Matthias Dodt]

Hey guys!

I have two pipelines that i want to connect. One for displaying video
and one for streaming on the network. These 2 pipelines should be
independent from each other, meaning: If the network pipeline crashes,
the other pipeline should keep on running no matter what. Therefore i
separated the two pipelines and used an appsink in the first pipeline
and an appsrc in the second to connect them:

Audiotestsrc ! Audioconvert ! Appsink

Appsrc ! Queue ! rtpL16pay ...

Appsink and Appsrc are connected via static callbacks and the data is
being pushed from the appsink to the appsrc:

static GstFlowReturn onNewBuffer (GstAppSink *appsink, gpointer
user_data)
{
	GstFlowReturn rv = GST_FLOW_ERROR;
	GstAppSrc *appsrc = ((GstAppSrc*)(user_data));
	GstBuffer *buf = gst_app_sink_pull_buffer(appsink);
	rv = gst_app_src_push_buffer(appsrc,buf);
	return rv;
}

This works, but if I use the 2nd pipeline in the RTSP Server and connect
with a client I get "timing out collisions" error messages from the
rtpsession.c implementation. If I put all in one pipeline it works. I
experimented with 

gst_element_get_base_time (...);
gst_element_set_start_time (pipeline,GST_CLOCK_TIME_NONE);
gst_element_set_base_time (pipeline,time);

To synchorinze the timestamps and got it to work with some video
pipelines, but can't get it to work with this audio example. What would
be the right way to synchronize these 2 pipelines?

Thanks,

mat