Meeting minutes
Agenda
Slideset:
https://
cpn: launching web
applications on TV devices (follow-up)
… Issue #107 Channels 2.0
… Issue #4 Frame accurate seeking of HTML5
MediaElement
… Volumetric media
… TPAC 2024 Plans
… anything else?
Launching web applications on TV devices
cpn: What do we do for
the next step?
… It seems we need conversations with
manufacturers, but have not had much response yet.
… We got response from one manufacturer, suggesting
to have some more comprehensive documentation
… A lot of this have been done already in the MEIG
repo.
Developing web applications on consumer products
cpn: Would hear from you about suggestions, and contacts you may have at manufacturers.
cl: We have the video
too.
… I'm happy to join any meetings, also happy to
work through the discussion.
kaz: Just to make sure, the "charter.md" is a charter for a possible TF, right?
cpn: Right
kaz: In that case, the
title of the document should say "some TF" explicitly
… also we should make an official call for
participation to the whole IG to see who will work on this
topic.
cpn: Chris Lorenzo, let's continue to talk with the manufacturers directly about web apps on consumer devices.
Channels 2.0
cpn: This is a proposal
on GitHub, covers a lot of use cases, e.g, content related to TV
channels, interactive experiences, homapages
… having sub-channels in addition to
channels
… and then proposes an XML format to
describe
kaz: It's kind of big and need some more clarifications
cpn: Yes, would need analysing for different components. Channels aren't really in scope at W3C, it's more for TV industry specific groups
<Zakim> fd, you wanted to react to kaz
fd: We previously reviewed schema.org metadata, seems related to this.
fd: Also, as an idea, could look at what data is surfaced through Media Session API in the UI
johnriv: I did skim this, it comes from an end user perspective, but to move forward needs to be a pain point for manufacturers or streaming services
Frame accurate seeking of HTML5 MediaElement
Issue 4 - Frame accurate seeking of HTML5 MediaElement
cpn: This is a long
discussion thread. It covers a number of topics and use
cases:
… frame accurate rendering, seeking,
single-stepping of individual video frames
… essentially needed for non-linear video editing
applications. Can be either editing directly in the browser, or
using as a proxy to cloud-stored media.
… I've had some conversations recently about
browser based video editing applications, with BBC colleagues but
also other companies
… BBC R&D created a frame-accurate seeking
video player using WebCodecs. Some complexity, particularly with
managing buffers of encoded video and decoded
VideoFrames.
… Francois presented frame accurate seeking gaps at
TPAC 2019,
… and quite a lot of things have been changed since
then.
cpn: We now have
HTMLVideoElement.requestVideoFrameCallback(), and there's an
example showing how to use it to seek to specific frames, using
timestamps. But not always accurate.
… DOM Event timeStamp is now DOMHighResTimeStamp,
although this is a "coarse" timestamp, so I don't know if there are
still issues.
… The interest in high resolution event timestamps
came from multi-device synchronization, also enabling
synchronisation within the same client.
… Improvements to TextTrackCue event timing in
Chromium, resulting from our work here on Media Timed
Events.
… WebCodecs is the major new feature, it enables
decoding to VideoFrame objects, lets you build a player that
renders to a canvas.
… WASM enebles cross-compilation of
libavformat/libavcodec. Allows use of professional codecs that
WebCodecs doesn't support.
… Improvements to TexTrackCue event synchronisation
in Chromium. It's not frame-accurate but much more accurate
now.
… With WebCodecs, how to manage the memory of all
the decoded data, it's still challenging to build a player for
non-linear video editing.
… Web Audio AudioWorklet is good for audio
rendering.
… Overall it's all possible but quite
difficult.
… If there is sufficient interest, happy to deal
with any of these issues again.
cpn: What still
remains?
… HTML issue whatwg/html#3754 is about negative
playbackRate not supported across all browsers. The use case is
from NRK of a web page including video and images,
… and responds to the user scrolling the page. The
video should play backwards if the user scrolls up the
page.
… But because that is not well-supported, the page
needs some complex code to update the current time.
… Anybody interested should follow the
link.
… Something Nigel pointed out before is audio
seeking in MP3 is not accurate. I also found this with my open
source waveform visualiser library.
… Needs more investigation for the possible
resolution?
… Then, on 360/VR video rendering, there's this
Chromium bug on synchronising the video element state with
WebGL,
… I don't know the details, but some need for
identifying the frame in the GL frame buffer.
… Finally, there is SEI timed metadata events. Is
it enough for web apps to handle these, or should we expect
WebCodecs to parse them and attach them to VideoFrame
objects?
… There is an Explainer from @leonardoFu that
describes their needs.
kaz: So you're reviewing some interesting topics for this year in MEIG, potentially.
cpn: Yes, if there's interest we can start discussions about those topics.
Francois: You mentioned
rVFC, it's still an incubation, but supported everywhere except
Firefox. It should have moved to a WG, but hasn't yet.
… It shouldn't be in incubation any more, so worth
investigating that
kaz: which WG do you mean?
cpn: Potentially it goes to WHATWG, or maybe Media WG if it's in the charter as a potential deliverable. Media WG will need to discuss.
Volumetric media
cpn: Metaverse
Standards Forum (MSF) has a WG on Volumetric Media
Interoperability
… discussion between multiple SDOs and industry
forums
… There's an initial meeting next week, 14:00 UTC
on Thu. 13 June 2024
… and an invitation to join. MSF membership
required to participate, but there's no cost.
… I will send an invitation with more details to
the mailing list.
kaz: What is the Membership mechanism?
cpn: You need an MSF membership but it's free. Also W3C is one of their Members.
Kaz: If people are interested in that discussion, they're encouraged to join the forum?
cpn: Yes
TPAC 2024 plans
cpn: TPAC is 23-27 Sep
in Anaheim, California, US
… Here is the proposed schedule.
… MEIG: Monday 9-10:30, 11-12:30; Thursday
16:30-18:00
… Media WG: Monday 14-16; THursday 11-12:30, 14-16,
16:30-18; Friday 9-10:30
… Timed Text, Audio and Second Screen will also
meet
… if you want to present anything, please let me
know and we'll be preparing within the next few
months.
… During the morning session, I expect we'll talk
about next generation audio (also in previous TPACs), but there
should be time for other agenda items.
kaz: On Monday, 23 Sep during the MEIG meeting, right?
cpn: Right
… Please let me know if you have any suggestions,
and we'll see how to include them.
… that's it
… any comments, questions?
(none)
[adjourned]