Appsink RTP timestamps return to 0 after stream discontinuity

[Mike Stirling]

Hi all,

I am attempting to derive wall-clock timestamps from the buffers 
obtained from an off-brand IP camera's RTP stream.  The camera itself 
does not appear to support RTCP sender reports (as observed with 
Wireshark), so I have assembled a pipeline that uses an explicit 
GST_CLOCK_TYPE_REALTIME clock.  The pipeline has the following elements:

rtspsrc->rtph264depay->h264parse->queue->appsink

I can obtain wall-clock time in my appsink by taking the buffer pts + 
gst_element_get_base_time(element) - this works as expected.

The problem arises if I temporarily break the stream (pull the network 
cable) for a few seconds (not long enough to cause the connection to 
drop).  When the stream comes back up the buffer PTS values seem to 
restart from 0, which causes the calculated wall-clock time to jump 
backwards.  I was expecting to see a new-segment event on the appsink's 
sink pad, containing the new start offset, but this doesn't arrive.

What am I missing?

Gstreamer version is 1.6.1 (from source).

Regards
Mike