Re: Media WG meeting next week

Happy New Year to you all!

Thanks, I have updated the agenda to add those Media Session and MSE issues.

Chris
________________________________
From: Xiaohan Wang (王消寒) <xhwang@google.com>
Sent: 10 January 2025 08:17
To: Jean-Yves Avenard <jean-yves.avenard@apple.com>
Cc: Chris Needham <chris.needham@bbc.co.uk>; public-media-wg@w3.org <public-media-wg@w3.org>
Subject: Re: Media WG meeting next week


External: Think before clicking

Happy New Year!

I also have a conflict so I cannot attend. Hopefully I'll be able to attend the next one!

Xiaohan

On Thu, Jan 9, 2025 at 4:41 PM Jean-Yves Avenard <jean-yves.avenard@apple.com<mailto:jean-yves.avenard@apple.com>> wrote:
Hi

Happy new year !

I’d like to add an agenda related to the support of Tracks on SourceBuffer with MSE in a worker.

I’ll be lodging an issue today on GitHub.

In short; when the MediaSource was created in a worker, a SourceBuffer still expose tracks via AudioTrackList / VideoTrackList / TextTrackList

Track objects are currently only exposed at the Window level.
An issue was open to expose them at the Worker level
<https://github.com/w3c/media-source/issues/280>
MSE-in-Workers: {Audio,Video,Text}Track{,List} IDL in HTML need additional DedicatedWorker in Exposed · Issue #280 · w3c/media-source<https://github.com/w3c/media-source/issues/280>
github.com<https://github.com/w3c/media-source/issues/280>
        [apple-touch-icon-180x180-a80b8e11abe2.png] <https://github.com/w3c/media-source/issues/280>


Our (webkit) proposal is that tracks shouldn’t be exposed in the worker at all. It doesn’t make much sense to outside the Window and for text track, it’s just not an object that will ever be usable in a Work. TextTrack’s cues can only be rendered via DOM.

Considering no User-Agent currently supports tracks in a worker, I recommend we stop exposing
```
  readonly attribute AudioTrackList<https://html.spec.whatwg.org/multipage/media.html#audiotracklist> audioTracks<https://w3c.github.io/media-source/#dom-sourcebuffer-audiotracks>;

  readonly  attribute VideoTrackList<https://html.spec.whatwg.org/multipage/media.html#videotracklist> videoTracks<https://w3c.github.io/media-source/#dom-sourcebuffer-videotracks>;
  readonly  attribute TextTrackList<https://html.spec.whatwg.org/multipage/media.html#texttracklist> textTracks<https://w3c.github.io/media-source/#dom-sourcebuffer-texttracks>;

```

When in a worker.

Also related: https://github.com/w3c/media-source/issues/281




On 10 Jan 2025, at 4:02 am, Chris Needham <chris.needham@bbc.co.uk<mailto:chris.needham@bbc.co.uk>> wrote:

Hi Media WG,

There's a WG meeting scheduled for Tuesday next week, but I'll be away this time.

The agenda is currently empty, but looking at current activity in GitHub, these might be candidates, although I'm not sure they really need in-person discussion:

Https://github.com/w3c/mediasession/pull/350<https://github.com/w3c/mediasession/pull/350>

https://github.com/w3c/webcodecs/issues/857


Suggestions for other topics welcome!

Many thanks,

Chris