W3C home > Mailing lists > Public > public-web-and-tv@w3.org > October 2017

Re: Overview of Media Technologies for the Web

From: Ingar Mæhlum Arntzen <ingar.arntzen@gmail.com>
Date: Mon, 2 Oct 2017 12:07:50 +0200
Message-ID: <CAOFBLLpPWWQWtz46YQ2w1eMj75ubRbJWb4xphmH8MSeaU4bK+Q@mail.gmail.com>
To: François Daoust <fd@w3.org>
Cc: public-web-and-tv <public-web-and-tv@w3.org>
Francois,

comments inline


>> Some comments - mostly related to the Multi-device Timing CG.
>>
>> - Media Control. One aspect of media that could additionally be
>> addressed here relates to flexibility. For example, can a media
>> experience be controlled from two devices or by multiple users? Can
>> control easily be handed over from one device to another? In a group,
>> can media control be symmetric (everybody can control) or asymmetric
>> (only a select few can control). This would be an area were exploratory
>> work is covered by the Multi-device Timing CG.
>>
>
> The Multi-Device Timing CG is mentioned in the exploratory work section,
> but the description can certainly be improved. Goal is to keep the text
> short for each feature to ease maintenance. Would you have some concrete
> text to propose by any chance? :)
>
>
I'll see if I can come up with a few lines :)



> - Media Rendering vs Content Orchestration. The distinction between
>> these two categories at first seems a bit unclear to me, with
>> distributed playback being a theme of both.
>> The way I read it Media Rendering is focused on standalone playback
>> components, plus mechanisms for piping media output to another device.
>> Content orchestration seems to be about temporal coordination of
>> independent playback components (be it within a single web page or
>> across different devices)
>> Would this be correct?
>>
>
> That is correct, and it is imperfect indeed. I don't think there exists a
> clean hierarchy to divide technologies, and some of them are listed in
> different places. That's not a bug. I think I'm going to add cross-links
> between pages (for instance, the Media Rendering page mentions the Timing
> Object spec, but the Content Orchestration page will provide more details,
> so it would make sense to link to that page from the Media Rendering one)
>
>
Sounds good. As these two themes do have similarities, a note (cross-link)
pointing out subtle differences may be very helpful.


>
> - Content Orchestration. Could it rather be named Media Orchestration?
>> Within MPEG there is already an on-going initiative [1] using this term.
>>
>> [1] https://mpeg.chiariglione.org/standards/mpeg-b/media-orchestration
>>
>
> I'm trying to remember how we ended up with Content Orchestration. I
> suppose the idea was that you'll want to orchestrate media and non-media
> content at the same time. I'm fine renaming the section to Media
> Orchestration though. Also, this would mean we'll have "Media" as common
> prefix to all page titles, which seems good.
>
>
Excellent.


>
> - Media Capture. Please include also the aspect of timestamp accuracy in
>> captured content. This is of great importance to for any multi-angle
>> media productions involving video and audio, and more generally all
>> media production where captured media should be precisely relateable to
>> a real-world clock (epoch).
>>
>> Capturing devices may provide a timestamp, but it is rarely known when
>> exactly this timestamp was taken (i.e. sometime after requesting an
>> image and before the image is available in JS - this could be hundreds
>> of milliseconds). Equally important, upstream delays in sensor
>> processing pipeline must be known, so that timestamps can be
>> compensated. This is analogous to work done in the Web Audio API where
>> downstream delays are exposed for media output. As delays may not always
>> be known, techniques for measurements and calibrations should likely be
>> explored.
>> This is addressed as exploratory work within the Multi-device Timing CG.
>>
>
> Isn't it what the latency media track capability would provide?
> http://www.w3.org/TR/mediacapture-streams/#def-constraint-latency



> I'm fine adding an exploratory work section that mentions discussions on
> timestamp accuracy in captured content. Concrete text welcome as well ;)
>
>
Excellent. Good thing this is already in specs for media streams. I
couldn't see it mentioned in the media capture page though. Also, the
relevance isn't Iimited to media streams, so I thought it be worthy of a
mention as part of the media capture description.


Thanks,

Ingar Arntzen
Received on Monday, 2 October 2017 10:08:15 UTC

This archive was generated by hypermail 2.3.1 : Monday, 2 October 2017 10:08:15 UTC