Minutes interim-2024-moq-15: Mon 16:00
minutes-interim-2024-moq-15-202407081600-00

2024-07-08
MoQ Working Group virtual interim

Agenda:

• Note Well

• Administrivia

  • scribe: Mike English
  • today is draft deadline

  • interop?

    • draft-04 to draft-05 diff is almost entirely priorities
    • need to add priority fields (at least) to try interop even
      if not able to implement priority handling behaviors fully
      in time
      • Cullen: we've done OK with just link conditioning for
        testing, happy to try interop testing of priorities with
        others if you let us know what you'd like to test
      • Will: do we know Apple's link conditioner is robust for
        QUIC?
        • Jana: it works fine if you're just trying to create
          some simple congestion conditions, good starting
          point, probably adequate
        • Luke: doesn't model bufferbloat well, but that's
          probably OK for this stage

  • MoQ-based live stream of IETF sessions?

    • Jordi: need to work with A/V team and get dedicated
      connection because connectivity at these events is often not
      good
    • Alan: was thinking more ad hoc with a laptop or similar, but
      can ask about more
    • Jordi: our implementation can be used, but interop might be
      tricky because we use LoC whereas Luke's implementation uses
      CMAF
    • Suhas: we can test with some relays
    • Luke: we haven't focused on standardizing media yet in the
      WG, relays are generic

  • other topics for Vancouver?

    • Cullen: would be nice to wrap up our discussions of timeout
      before folks forget what we've discussed
    • Ian: subscribe done, announce issues, would be nice to have
      PRs for some of the proposals
    • Ian: subscribe ids... should subscriptions be their own
      streams (do we use QUIC max streams or create our own
      mechanism?)
    • Alan: if people have issues they want to resolve, please
      flag to chairs in the next week
      • someone will need to write things down on slides we can
        discuss (not just presenting the GitHub issues)

• PRs in flight:

  • https://github.com/moq-wg/moq-transport/pull/479
    • merged while on this call

• Jordi: priorities are definitely the big thing to work on since
  we've talked about how MoQ can do this a lot, but haven't done it
  until now

• Jordi: also curious if others have implemented the different modes
  of delivery on the server side (datagrams, etc.)

  • Alan: moxygen can forward all of them at least

    • Jordi: no...
      • Alan: well it should be able do, we can discuss offline

  • Luke: I've implemented them all and it's painful, they require
    several distinct code paths

  • ... (scribe falling behind)

• Victor: question about metrics: what do you want to do if you're
  falling behind and can't send metrics?

  • this highlights problem with stream per track
  • also with stream per track if anything goes wrong it means you
    need to tear down and start over
  • Luke: you could get almost the same behavior by using just one
    group
    • Want to force people to use groups, use GoP per stream, not
      just reimplement RTMP in QUIC with little benefit
    • Alan: for what it's worth, what Meta does today is kind of
      like this and we do see some benefits (which is why we did
      it), so there's not no benefit

• Ian: added stream mapping to list of things to talk about

• Ian: let's try to focus on sorting out timeout before IETF

• Ian: can someone write up slides for announce issues? Or even a PR?

  • Cullen: I can. Already have some material from previous make
    before break discussions

• Luke: can you summarize the announce topic?

  • Alan: clarifying what happens when A announces something and B
    announces the same thing, also things about make before break,
    redundant publishers, and similar issues
  • Luke: we need to talk about whether relays forward announces or
    not
  • Alan: yes, this has come up with moq-chat and other people
    trying to build similar systems

• Will: made a request to get agenda time for catalog and WARP
  streaming format

  • Not wanting to take up too much time, but we should keep in the
    back of our mind building something that can interop at the
    media / streaming format layer
  • Alan: yes, Jordi also brought up LoC earlier, don't remember if
    we've adopted that yet, but if people see value there maybe we
    should?

• ...

• Jordi: player can send subscribe before announce which can lead to
  subscribe error, one solution is to sleep and retry

  • also, LoC plays really nicely with WebCodecs in the browser

• Luke: I have a service that can advertise/aggregate announces as a
  new track with wildcard matching (moq-dir)

  • might be nice to have something like this in the protocol itself

• Will: working on making WARP both LOC and CMAF compatible. Can see
  value in using both.

• Jana: what are the big rocks/boulders we still need to move in this
  group?

  • Alan: besides what we mentioned earlier?

  • Cullen: security. Don't want to deal with that until after
    Vancouver, but that's something we've largely punted on so far

    • Alan: what aspects, specifically?

      • Cullen: authn/authz tokens, things that integrate with
        billing models, need a systematic pass through the whole
        draft for security, also privacy, need to write down
        more guardrails

    • Alan: Ian, would it be useful to capture these in issues?
      e.g. with a DoS tag, etc.?

      • Ian: yes. DoS, Auth, etc.
      • Ian: we haven't really decided if namespaces mean
        something yet...?
      • Ian: let's label these DoS and/or security/privacy
        • Ian: I'll create a DoS tag and a security tag today
        • happy to punt until after Vancouver

• Will: we're building a fundamentally open system by default and
  retrofitting content protection after the fact (something I promised
  I'd never do again), also advertising / dynamic ad insertion,
  personalized ad injection will require the edge to do something
  different, also congestion response for non-realtime - something
  more like bitrate adaptation like what Zafer has raised

  • (three main points)

    • content protection
    • ad insertion
    • bitrate adaptation

  • Jana:

    • re: content protection: ...
    • ad insertion: don't understand well what's used today
      • Alan: probably a good number of folks here who do
        understand this, should we use one of these virtual
        interim sessions to do some education on this?
      • Will: yes, especially since we should support existing
        infrastructure for this as a baseline

• Lucas: we did talk about qlog at one point, would be happy to talk
  more about that face to face, will also be around at the hackathon,
  can treat that as open office hours time to ask question or whatever

• Luke: need feedback for RTC use case

  • need some mechanism for adjusting the encoder's bitrate
  • this is one of the hardest layering things to get right for
    scaling
  • don't do the full WebRTC thing, but we need something

• Ian: re: congestion control - maybe we can define some properties
  for what works well for CC in this context, but we're not the CC WG
  so we're not designing those algorithms here

  • Jana: it is slightly different in that there's a different
    entity responding to signals

• Jana: are there people wanting to use MoQ for live streaming?

  • [terminology clarifications]
  • ...
    • (several people chimed in that they have this use case)

Google Meet chat:

Ian Swett
12:04 PM
https://github.com/moq-wg/moq-transport/pull/479
Luke Curley
12:06 PM
WebRTC does prioritize audio above video :p
libwebrtc I mean
Ian Swett
12:07 PM
I'm on a Disney Cruise, so we're on opposite sides of this
Lucas Pardue
12:16 PM
its 100% inadequate if you're not on a mac LOL
Jana Iyengar
12:17 PM
netem on linux, dummynet on BSD, NLC on macOS (which is based on
dummynet AFAIK)... and if you're on windows, why?
Luke Curley
12:38 PM
quic.video is basically JSON catalog + CMAF groups
Will Law
12:39 PM
I may put a short little survey together to compare how quic.video,
moxygen, LOC and QUICR work on the media mapping side.
Ian Swett
12:44 PM
Everything
Luke Curley
12:45 PM
ANNOUNCE auth to, so you can't just ANNOUNCE to hijack an existing
broadcast since latest wins
too*
somebody is going to ANNOUNCE "bbb" to steal my demo stream
Luke Curley
12:55 PM
warp-01 had a section like that
if you want to yoink it
Mirja Kühlewind
12:56 PM
we used to have a whole wg on real-time media congestion control: rmcat

Luke Curley
12:57 PM
https://www.ietf.org/archive/id/draft-lcurley-warp-01.html#name-congestion-control

Ian Swett
12:58 PM
Yes
Luke Curley
12:58 PM
yes when I was representing Twitch :)
MoQ is great for 1s - 3s latency, but it's probably too expensive for
anything higher @Jana
Mirja Kühlewind
1:01 PM
bye