tree b1e0338658f0ae38d084f31a331769a31a59229e
parent d6769ea2073a455ca32dd39909611a7cd34715dd
author Pau Espin Pedrol <pespin@sysmocom.de> 1625658079 +0200
committer pespin <pespin@sysmocom.de> 1625739495 +0000

Take into account Marker bit when patching RTP stream

On a deployed osmo-mgw with RTP traffic coming from a thirdparty
RTP source, it was usual to see log messages like following one from
time to time:
"The input timestamp has an alignment error of 159 on SSRC"

Doing a quick traffic analysis showed that the above mentioned RTP
source was generating traffic from time to time containing RTP packets
with the Marker (M) bit.

Those messages were logged because the verification & patching funcions
in osmo-mgw were not Marker-bit aware. Hence, this patch implements
support for Marker bit when handling RTP packets.

The Marker bit is usually used as a start of a talkspurt, and has to be
considered a syncrhonization point, where timestamp and relation to real
time don't need to match with last received RTP packet in the stream.

Related: SYS#5498
Change-Id: I1fb449eda49e82607649122b9b9d983a9e5983fa