Wrong syntax for Opus codec line

[ibc]

The proper way of indicating Opus codec in the SDP is:

a=rtpmap:NNN opus/48000/2

and that is what Chrome generates. But when sdp-transform handles the SDP it converts such a line into:

a=rtpmap:NNN opus/48000

(which is the old syntax for Opus codec)

[clux]

Yes. The grammar for rtpmap is lacking. It's defined in RFC as:

a=rtpmap:<payload type> <encoding name>/<clock rate> [/<encoding parameters>]

and we are just ignoring the encoding parameters. This is one of those annoying ones where you get an extra slash when the parameters are present, otherwise it's not there. Either have to incorporate the slash in the encoding parameters, or just merge clock rate and encoding parameters in one big string.

Alternatively, rewrite the grammar formating to handle such cases better. Undecided atm.

[ibc]

I propose extending the resulting rtpmap Object with a new field "extraParams":

codec: "opus"
payload: 111
rate: 48000
extraParams: [ "2" ]

Of course those params must appear in the given order and make the String so they can hold any kind of value.

[clux]

Yeah, the problem is having to make the writer better with dealing with parameters that are only sometimes there to do that. But I have a sensible solution to deal with conditionals in the format string - will get a version up later.