Force immediate synchronisation with a RTCP-SR using rtpbin

[Thomas Roos]

I need to synchronize audio output on several devices.

The Audio streams are provided by a single sender device.

The idea is to send a RTCP-SR when the first RTP audio data is sent,
so that the receivers can correlate the RTP timestamps to the NTP
tinestamps.

Is there a way to make rtpbin send a RTCP-SR before any RTP audio data
or at least with a minimum delay after sending RTP audio data ?

It is my understanding that rtpbin implements the rules specified in
RFC 3550, which should allow a zero delay.