Stream Labels in SDP

Asterisk Asterisk APIs
1

When using Confbridge, each stream is labelled with the channel id that ‘owns’ it and this is relayed the the client in the SDP in the form:

a=label:example-1683802292.2456

This is great because it allows the client to know which stream belongs to which confbridge participant and label them in its UI accordingly

However, If I switch out the Confbridge application for an ARI application that functions in a similar manner, placing callers into a mixing bridge (sfu), then this label is not added to the SDP for each stream meaning I lose this functionality in the client.

Is there any way for me to configure the bridge or channel to add these labels?

Failing that, could anyone point me to the place in the code where Confbridge does this?

2

ConfBridge doesn’t directly do this, but the functionality has to be enabled[1] which ARI doesn’t do.

[1] asterisk/app_confbridge.c at master · asterisk/asterisk · GitHub

3

Damn, that’s a little disappointing. I can’t really think of another way of matching up these streams with channel which means this ARI app is pretty much dead in the water.

Is there a reason that this option shouldn’t be enabled on bridges by default? Not sure what the downsides are other than marginally longer SIP message length.

4

Some slight information disclosure and increase in packet size. It would need to be an option as part of bridge creation.

5

I am going to have a go at adding support for this on bridge create in the ARI, I’ll submit a PR if I get anywhere with it.

6

I managed to get this working so I will post a pull request shortly on github to get some feedback.

7

pr here: Add 'sendSDPLabel' parameter to ARI bridge creation. by jjsearle · Pull Request #92 · asterisk/asterisk · GitHub