always creating a datachannel and bundling on it #1039
Description
For the next revision of JSEP it would be great to configure the peerconnection in a way that
1/ always creates a datachannel m-line (even before createDataChannels is called)
2/ creates it before the audio and video m-lines and uses it for BUNDLE.
which (mostly) avoids the bundled m-line getting rejected. The current behavior specifies audio/video-then-data, probably for backward compat reasons.
From what I can see this requires two minor modifications:
In https://rtcweb-wg.github.io/jsep/#rfc.section.4.1.1 add a paragraph
The application can specify whether it prefers to always negotiate datachannels
and in https://rtcweb-wg.github.io/jsep/#sec.initial-offers insert
If the application prefers to always negotiate datachannels, a m=section MUST be generated for data [... text from below and update below to reference this]
between the two sentences below
The next step is to generate m= sections, as specified in [RFC4566], Section 5.14. INSERT HERE An m= section is generated
and guard the existing
Lastly, if a data channel has been created, a m= section MUST be generated for data
by a "and no m=section exists for data"