[Galene] WHEP and Galene [was: Good news...]

[Juliusz Chroboczek <jch@irif.fr>]

CC-ing the IETF WISH working group.

In case not everyone has perfect acronym memory:

  - WHIP is a standardised ingress protocol, that allows pushing a WebRTC
    stream into a server; it is implemented in Galene, and can be used for
    example to get a stream from OBS Studio into Galene;

  - WHEP is the dual of WHIP, it allows pulling a single video stream from
    a server; it is currently a fairly complete draft;

  - WISH is the IETF working group in charge of WHIP and WHEP.

>> Unfortunately, WHEP is not expressive enough to work with Galene.  Galene
>> will occasionally tear down a stream and replace it with a new one (the
>> client hides the transition from the user), for example when changing the
>> simulcast envelope, and I don't see how to express that in WHEP.

> Given that WHEP isn’t signed off yet - we should raise that and see what
> the group says.

WHEP is a simple protocol that has its uses, but, unlike WHIP, I don't
think it can be easily extended to meet the needs of Galene.  WHEP
publishes a single static stream, while Galene needs to publish
a dynamically varying set of streams.

Instead of trying to delay the publication of WHEP until it meets our
needs, we should think about what is the right solution for Galene.  We
could either consider having Galene act as a WHIP client (so it can
publish a full videoconference as a set of WHIP streams), but that would
require the receiver to act as a web server (have a TLS certificate, etc.)
Or we could design a control protocol where a client connects to Galene
over WebSocket or SSE and is instructed by the server to open arbitrary
numbers of WHEP sessions.

Or we could aim for the sky and try to get Galene's native protocol[1]
standardised.  After all, there's already an independent implementation of
the protocol[2], so that should fit the IETF requirements.

[1]: https://galene.org/README.PROTOCOL.html
[2]: https://github.com/erdnaxe/galene-stream

-- Juliusz