W3C home > Mailing lists > Public > public-media-fragment@w3.org > November 2008

Re: subview syntax (Re: Combining media fragments with other time-clipping methods)

From: Conrad Parker <conrad@metadecks.org>
Date: Sat, 29 Nov 2008 15:32:12 +0900
Message-ID: <dba6c0830811282232n3648a706t9dc25e253aebe8e5@mail.gmail.com>
To: "Silvia Pfeiffer" <silviapfeiffer1@gmail.com>
Cc: "Media Fragment" <public-media-fragment@w3.org>

2008/11/29 Silvia Pfeiffer <silviapfeiffer1@gmail.com>:
> On Sat, Nov 29, 2008 at 11:04 AM, Conrad Parker <conrad@metadecks.org> wrote:
>> Hi,
>> 2008/11/27 Dave Singer <singer@apple.com>:
>>>> On 26 nov 2008, at 01:27, Silvia Pfeiffer wrote:
>>>>> Hi Jack, all,
>>>>> This is indeed a very fundamental problem and has to do with exposing
>>>>> the context of the resource or not. I am very torn on this issues.
>>>>> For example, when a browser plays back
>>>>> http://www.example.com/myvideo.ogg#t=20s in a Web browser for a HTML5
>>>>> video element, would we want to see the timeline with an offset or
>>>>> without?
>>> t=20s could be:
>>> * a clip from 20s to 20s
>>> * the whole myvideo, but start playing at 20s (as if the user had dragged
>>> teh slider to 20s before playback)
>>> * 20s to the normal end of the media, with material before 20s removed
>>> The first is not very useful, but both the others are.  However, the second
>>> is not a fragment, but a start-playing-at.
>> I think it is useful to distinguish between these two with syntax. The second
>> (start playing at) is an instruction from the user to the UI. This is where
>> the #fragment syntax makes sense.
>> The third (request media from 20s onwards) is a request from the user
>> agent to the server. I think this is where a query parameter makes sense.
>> To see how these are useful, think of a site like youtube. A user can
>> add "#t=20s" to the URI of the web page to make the embedded video start
>> playing from there, without re-loading the page. Internally, the UI might
>> use the server request "myvideo.ogg?t=20s" in order to retrieve the video
>> data to render.
>> In such a use-case, there's no need to expose the query syntax to the
>> user, and there's also no need to send #fragment to the server.
> If I understand correctly, this is going back to the way in which
> temporal URIs were defined to work. For those not across the details,
> we had:
> * #t=20 meaning: get the whole file, do the offset locally, and use
> the data from there (e.g. for playback - depending on what the user
> agent is asked to do).
> * ?t=20 meaning: get just the fragment from the server and use that
> data for whatever the user agent is requested to do (e.g. playback)
> This is different to the discussion we had in Cannes where # and ?
> were both used as syntax options to get just the fragment from the
> server. In the case of using #, it would need to be signalled to the
> server "out-of-band", i.e. stripped from the URI and put into protocol
> paramters. There is a little information about this at
> http://www.w3.org/2008/WebVideo/Fragments/wiki/Syntax .

Right; I think both use cases should be possible, so I don't think there
is a need to force the use of one syntax.

> To clarify: this is orthogonal to the question that Jack and I were
> actually discussing.

yes, hence the change of subject :-)


Received on Saturday, 29 November 2008 06:32:53 UTC

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