webrtcbin: Always adding rtpulpfecdec makes it impossible to detect packet loss in RTP depayloaders
The following discussion from !1762 (merged) should be addressed:
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@slomo started a discussion: (+1 comment) We need to always add the RTX/RED/ULPFEC elements as rtpbin will only call us once to request aux/fec senders/receivers.
This is actually a very bad idea because
rtpulpfecdec
will mess up the seqnums of all packets then in its chain function :) Even if no ULPFEC is used, downstream (RTP depayloaders) will not be able to detect packet loss anymore unless I'm missing something.