test: add rtcp_mux test

[cspiel1]

• test: add rtcp_mux test
• test: rtcp test wait for RTCP SR instead off RTCP APP

[cspiel1]

The RTCP_APP packet is received in stream.c rtp_handler() because the rs->rtcp_mux in rtp.c was not set fast enough.

[cspiel1]

stream->rtcp_mux is set if SDP media remote attribute rtcp-mux was set. Thus it most likely will be set too late. I have no clue how to fix this.

[cspiel1]

So currently the test stops if an RCTP APP packet is received. Which I guess is only meant to open a NAT pinhole for RTCP. Do we really need the RTCP APP at the receiver at the very beginning of the call?

Shouldn't we prefer to test if an RTCP SR is received?
For that we have to specify an audio source. Otherwise no RTP packets are sent and no RTP tx stat is available.

I will add an audio source and try to activate the RTCP SR. This will fix the RTCP mux test.

[cspiel1]

updated the description

@sreimers : pls could we first merge this?
Then I'll rebase rx_thread_1 and rx_thread_stream_receiver. With the later I'll repeat the sanitizer checks you mentioned.

[cspiel1]

Thanks! This would be another PR for test_call_rtcp_base(): #2687
I have a series of commits that finally adds more tests for RX thread. Do you have time for review?