opus configuration (e.g. in-band fec)

[chcunningham]

in issue #9 @murillo128 requested a way to configure opus in-band fec.

https://www.opus-codec.org/docs/html_api/group__encoderctls.html#ga5b67dc832aa46c1c2f35752c46380545

[padenot]

That's a registry type thing isn't it. Maybe we should tag those.

[aboba]

Yes. Here is a list of other potential Opus configuration settings.

Also: https://datatracker.ietf.org/doc/html/rfc7587#section-6.1

[chcunningham]

Editors Call: from list above, FEC and DTX are the most important used in WebRTC SDP currently. Complexity defaults to 9.

[chcunningham]

Cisco / Webex folks mentioned lack of complexity option (present in @aboba's earlier link) is hurting CPU perf for their use case.

[chcunningham]

Timeline: lets spec this in the current quarter (Q2). Real users + low hanging fruit.

[JSmith01]

folks, is there any update?

[dalecurtis]

@tguilbert-google in case this ends up getting discussed at TPAC this week.

[tguilbert-google]

My proposal would be to expand the OpusEncoderConfig to include these parameters. This is very similar to #371, which is scheduled to be discussed tomorrow; assuming no pushback, I would also edit the spec to include these extra parameters.

I don't know which parameters we'd want to add from the ones linked by @aboba above. There is a lot of demand for adding useinbandfec, but are there any other obvious candidates? Keeping in mind that it is always easier to add parameters than to remove them.

[dalecurtis]

I think FEC, DTX, and complexity are the ones to add given the editors consensus above. Others can come later as you say.

[sdanahy]

Hi, I think some version of OPUS_SET_PACKET_LOSS_PERC needs to be accessible if FEC is going to be enabled:

https://draft.ortc.org/#dfn-packetlossperc

[tguilbert-google]

Thanks @sdanahy2, that is also relevant for FEC. See #594