W3C home > Mailing lists > Public > public-web-and-tv@w3.org > May 2015

Re: HTML WG media discussion: Alternate content insertion use cases

From: Daniel Davis <ddavis@w3.org>
Date: Wed, 13 May 2015 18:00:19 +0900
Message-ID: <555312A3.1090703@w3.org>
To: Njaal Borch <njaal.borch@norut.no>, Ingar Mæhlum Arntzen <ingar.arntzen@gmail.com>
CC: "public-web-and-tv@w3.org" <public-web-and-tv@w3.org>
Thanks Njål and Ingar for the feedback on these use cases.
I've added a Comments section to the wiki page with links to your mails:

I encourage others in this group to leave comments there as well.

With regards,

On 08/05/15 05:32, Njaal Borch wrote:
> Hi Daniel & all,
> The discussion is very interesting, thanks for letting us know!  In the
> Multi Device Timing Group, we have many similar challenges, and we’d
> like to point out some of our experiences that could be inspirational or
> potential pieces of the puzzle.
> We have had a look at some of the MSE Ad Insertion Use Cases [1]. As we
> synchronize multiple browsers between different operating systems, we
> typically experience the worst case scenario, where media resources have
> different codecs, bit rates and even reside on different servers. They
> are also transported and processed separately.  Still, depending a bit
> on the browser, we are able to synchronize this to within frame accuracy
> [2], down to just 1 millisecond for multiple devices playing audio in
> Chrome or about 7ms between Chrome and Firefox playing video [3].
> Our approach is to conceptually map media and data onto a timeline, then
> use an explicit timing object to control the progress of the
> presentation.  That means that we do not let a media element be the
> master of an experience (e.g. drive the track element). Instead, media
> elements and track elements are both slaves to the timing object. This
> decoupling limits the complexity while also making it very easy to
> switch seamlessly between different media elements, as they for instance
> can overlap (with one hidden), be cross faded using simple CSS or be
> replaced by audio-only (bandwidth savings) etc. In addition, we have
> created something like a generic track element (a sequencer, aka
> “MovingCursor”) which provides us with millisecond precision upcalls. 
> For media synchronization, we have implemented a simple MediaSync
> wrapper which modifies the currentTime and playbackRate properties to
> approximate the ideal position given by the timing object.  
> We have demonstrated that this approach provides excellent results while
> minimising complexity of media elements.  It further extends the high
> levels of flexibility we are used to from HTML, opening for tight timing
> for any data type in a device independent and interoperable way.  Having
> this core functionality standardized would give even more consistent
> experiences, and would likely add very little complexity to the media
> elements.  It would provide a generic and common timing model for the Web.
> The Multi Device Timing CG has a concrete suggestion for an
> HTMLTimingObject [4], which (only) provides high precision timing. 
> While a somewhat similar idea to the MediaController, it provides a
> clearer separation of concerns. The HTMLTimingObject can be used locally
> (synchronize multiple elements) as well as remotely, using the concept
> of Shared Motions for multi-device timing. For further details, a recent
> paper [5] gives a high-level overview.
> We have a simple demonstration putting it all together, showing how we
> “render” our YouTube videos in HTML [6].  A live version of this demo is
> available as well, but beware that it is a shared experience (no
> logins), so anyone in the world can start controlling it.  Controls:
> [7], rendered result [8].  These can of course be run on different or
> multiple devices. If anyone wants to experiment first hand, a commercial
> online timing service is provided by the Motion Corporation [9].  Click
> “developer” and follow the howtos - it will likely take you less than 20
> minutes to have a collaborative video playing!
> [1]:
> https://www.w3.org/wiki/HTML/Media_Task_Force/MSE_Ad_Insertion_Use_Cases
> [2]: https://www.youtube.com/watch?v=lfoUstnusIE
> [3]: http://mcorp.no/publications/dist_html5_sync_2014.pdf
> [4]: http://webtiming.github.io/timingobject/
> [5]: http://mcorp.no/publications/composition_2015.pdf
> [6]: https://www.youtube.com/watch?v=oK6gbU4w7_Q
> [7]: http://mcorp.no/examples/film/
> [8]: http://mcorp.no/examples/film/vid.html
> [9]: http://motioncorporation.com
> Hope you find some of these ideas interesting, and if you like we would
> be very happy to demonstrate the concepts live in an online meeting.
> Best regards,
> Njål Borch and Ingar Arntzen
> ---
> Dr. Njål Borch
> Senior researcher
> Norut Tromsø, Norway
> On 7 May 2015 at 11:24, Daniel Davis <ddavis@w3.org
> <mailto:ddavis@w3.org>> wrote:
>     Hello all,
>     This is to let you know about a discussion within the HTML Working Group
>     Media Task Force that would benefit from wider input, especially from
>     people here in the Web and TV Interest Group.
>     Initially intended as part of the MSE spec, it's currently a collection
>     of use cases for alternate content insertion in media [1]. However at
>     the recent Media Task Force face-to-face meeting [2] it was deemed that
>     the scope could be more than just MSE. There may even be some cross-over
>     with the current GGIE work [3] and so before a solution or target spec
>     is decided on there needs to be more feedback.
>     If this topic is of interest to you please could you take a look at the
>     use cases listed so far and feel free to edit, add or comment based on
>     your experience and requirements? The face-to-face meeting minutes are a
>     good place to see the discussion so far:
>     http://www.w3.org/2015/04/15-html-media-minutes.html#item05
>     Thank you in advance,
>     Daniel Davis
>     W3C
>     [1]
>     https://www.w3.org/wiki/HTML/Media_Task_Force/MSE_Ad_Insertion_Use_Cases
>     [2] https://www.w3.org/wiki/HTML/wg/2015-04-Agenda
>     [3] https://www.w3.org/2011/webtv/wiki/GGIE_TF
Received on Wednesday, 13 May 2015 09:00:52 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 17:57:26 UTC