rtpsession: Forward stream-start events to send_rtcp srcpad

Submitted by Carlos Rafael Giani

Link to original bug (#747829)

Description

Created attachment 301514
Patch to forward stream-start events to send_rtcp srcpad

Currently, if the send_rtp sinkpad receives a stream-start event, it is only forwarded to the send_rtp srcpad, not the send_rtcp one. Any sink linked to the send_rtcp srcpad will not ever receive stream-start events. But sinks need to receive these events so they can post stream-start messages, and in GStreamer, the pipeline will not dispatch stream-start messages until all sinks have posted this message. As a result, the application's bus watch / bus sync handler will never see stream-start events.

This patch corrects that by simply sending stream-start & caps & segment events to the send_rtcp srcpad when the stream-start event is received. With it, application bus watch/sync handler callbacks receive stream-start messages again.

I am not sure if this could be done in an easier way, probably by using sticky events. But the relevant events are sticky on the send_rtp sinkpad, not on the send_rtcp srcpad.

Patch 301514, "Patch to forward stream-start events to send_rtcp srcpad":
0001-rtpsession-send-stream-start-caps-segment-events-to-.patch