Questions regarding translation

[jensengar]

@legastero Can you provide some insight on the following?

1. Here: https://github.com/otalk/sdp-jingle-json/blob/master/lib/tojson.js#L20 it looks like the port is getting changed? I'm seeing something like m=audio 9 ... (from the offer) be changed to m=audio 1 .... Is there a reason for that? I would think the goal would be to convert sdp to json, and be able to get the original sdp back when converting the json back to sdp.

2. Here: https://github.com/otalk/sdp-jingle-json/blob/master/lib/tosdp.js#L55 It looks like it's basically hard coding the sdp for data channels but this is blowing up for me in chrome with the following error:

"Failed to execute 'setRemoteDescription' on 'RTCPeerConnection': Failed to parse SessionDescription. m=application 1 DTLS/SCTP Expects at least 4 fields."

The sdp being generated for the offer looks like

m=application 9 UDP/DTLS/SCTP webrtc-datachannel

but what's being received looks like this:

m=application 1 DTLS/SCTP

I assume this is a chrome change of some sort because this used to not be a problem. I'm also seeing issues in firefox:

Failed to parse SDP: SDP Parse Error on line 74: No sctp port specified in m= media line, parse failed.

Can you weigh in on these issues?

[xdumaine]

cc @fippo

[fippo]

(1): port 1 should be translated to port 9 these days
(2): this is the result of the format change since Chrome just started sending the new UDP/DTLS/SCTP format. Since the new format should be parsed by all recent (~3 years) browsers it probably makes sense to update.

[jensengar]

Thanks for the info @fippo, I'll work on updating this lib and open a pr. I've also come across this:

a=extmap:1/sendrecv urn:ietf:params:rtp-hdrext:ssrc-audio-level

where the original looked like this:

a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level

Should this be changed also to match the original?

[fippo]

no, those lines can have a direction. Which defaults to sendrecv so sendrecv may be omitted but it should be parsed properly in the current state