Routing Rules Update

[aboba]

Routing Rules update to address outstanding issues as well as to be more compatible with Section 6 of https://tools.ietf.org/html/draft-ietf-rtcweb-jsep-17#page-66

Addresses the following issues: #368, #546, #547

[ibc]

LGTM

[aboba]

@ibc Can you review?

[ibc]

Yes, I'll do it on next week (holidays now)

[ibc]

May be I miss something, but I see a problem within the following example:

codecs:
[
  { payloadType: 100, name: "audio/opus" }
  { payloadType: 101, name: "audio/CN" } 
],
encodings:
[
  { codecPayloadType: 100 }
]

AFAIU, with the new algorithm in the PR, "audio/CN" will be ignored. Am I wrong?

[aboba]

@ibc What if we set pt_table[parameters.codecs[j].payloadType] to receiver for all values of j from 0 to codecs.length-1, with the exception of entries for parameter.encodings[i].codecPayloadType where parameter.encodings[i].ssrc is set, for values of i from 0 to encodings.length-1?

[ibc]

That would create conflicts (InvalidParameter rejection) if the same transport is used for two RtpReceiver instances and both RtpParameters include CN or DTMF codecs with same PT values (which will happen when receiving two audio streams from a SFU via the same transport).

[ibc]

IMHO this should be more strict, something such as:

If there is any encodings[i].ssrc or encodings[i].rtx.ssrc or encodings[i].fec.ssrc for all values of i from 0 to encodings.length-1, then pt_table should not be filled at all.

This is, don't allow incomplete parameters. All or none.

[aboba]

@ibc With respect to your Issue #546 : if encodings[i].ssrc is filled but encodings[i].rtx is missing we still want the RTX payload type table entry to be filled, correct? The same would also be true of RED and FEC, right?

[ibc]

Ideally yes but, as noted above, there is no perfect solution. That's why I suggest "all or none", this is:

• If SSRC are given, they all must be given (including ssrc for all the encodings[i] and encodings[i].rtx and encodings[i].fex) and hence, pt_table must not be filled.
• If codecs[i].name is "audio/rtx" for some i, encodings[i].ssrc is given, and encodings[i].rtx.ssrc is not given, then I would consider that an error.

[aboba]

@ibc OK. Let me come up with a revised PR.