[whatwg] media resources: addressing media fragments through URIs spec

Marques Johansson marques at displague.com
Fri Jul 2 03:18:17 PDT 2010

A point in time, if it relates to an I-frame, is very small set and it
represents an image.

It would be interesting to have
<img src="file.ogg#t=1:00.5,1:00.5">

or animated images in the sense of:
<img src="file.ogg#t=1:00,1:15">

I think the earlier post was looking to display video thumbnails using
this sort of fragment notation.

If the video wasn't being played I would hope that a browser would
fetch the meta data first and then just seek the byte ranges for that

On Fri, Jul 2, 2010 at 4:55 AM, Silvia Pfeiffer
<silviapfeiffer1 at gmail.com> wrote:
> Actually, a point in time is nothing - it's an empty set. You never
> want to actually point to a point in time, but rather to either the
> point in time and an interval after that point in time, or everything
> from that point onwards. That's what these URIs represent.
> Cheers,
> Silvia.
> On Fri, Jul 2, 2010 at 7:56 AM, Jonas Sicking <jonas at sicking.cc> wrote:
>> That would be great. I guess it's unclear to me how the UIs would differ for
>> video.ogv#t=40,50
>> and
>> video.ogv#t=40
>> In particular it seems strange to me that video.ogv#t=40 represents
>> the whole range from the selected point to the end of the video, given
>> that most commonly when wanting to point out a particular point in a
>> video you actually just want to represent a point.
>> / Jonas
>> On Thu, Jul 1, 2010 at 2:46 AM, Silvia Pfeiffer
>> <silviapfeiffer1 at gmail.com> wrote:
>>> BTW: I will try and make a screencast of that firefox plugin, which
>>> should clarify things further. Stay tuned...
>>> Cheers,
>>> Silvia.
>>> On Thu, Jul 1, 2010 at 7:44 PM, Silvia Pfeiffer
>>> <silviapfeiffer1 at gmail.com> wrote:
>>>> Hi Jonas,
>>>> On Thu, Jul 1, 2010 at 4:41 AM, Jonas Sicking <jonas at sicking.cc> wrote:
>>>>> Hi Silvia,
>>>>> Back in may last year I brought [1] up the fact that there are two use
>>>>> cases for temporal media fragments:
>>>>> 1. Skipping to a particular point in a longer resource, such as
>>>>> wanting to start a video at a particular point while still allowing
>>>>> seeking in the entire resource. This is currently supported by for
>>>>> example YouTube [2]. It is also the model used for web pages where
>>>>> including a fragment identifier only scrolls to a particular point,
>>>>> while allowing the user to scroll to any point both before and after
>>>>> the identified fragment.
>>>>> 2. Only displaying part of a video. For example out of a longer video
>>>>> from a discussion panel, only displaying the part where a specific
>>>>> topic is discussed.
>>>>> While there seemed to be agreement [3][4] that these are in fact two
>>>>> separate use cases, it seems like the media fragments draft is only
>>>>> attempting to address one. Additionally, it only addresses the one
>>>>> that has the least precedence as far as current technologies on the
>>>>> web goes.
>>>>> Was this an intentional omission? Is it planned to solve use case 1
>>>>> above in a future revision?
>>>>> [1] http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-May/019596.html
>>>>> [2] http://www.youtube.com/watch?v=fyQrKvc7_NU#t=201
>>>>> [3] http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-May/019718.html
>>>>> [4] http://lists.whatwg.org/htdig.cgi/whatwg-whatwg.org/2009-May/019721.html
>>>> I think you may have misunderstood the specification. Use case 1 is
>>>> indeed the main use case being addressed in the specification. There
>>>> is a Firefox plugin implementation[1] of the specification that shows
>>>> exactly use case 1 in a video element - a URI with a fragment such as
>>>> video.ogv#t=40,50 is being included in a <video> element and the
>>>> effect is that the video is displayed from 40s to 50s, but the
>>>> transport bar (or controls) are still those of the complete resource,
>>>> so you can still seek to any position.
>>>> To be sure, this is just a recommendation of how it is supposed to be
>>>> implemented (see
>>>> http://www.w3.org/TR/media-frags/#media-fragment-display). The group
>>>> only defined what URIs look like that point to such a segment - it
>>>> cannot prescribe what an application (such as a HTML document) does
>>>> with the URI. I would propose that this discussion should be had about
>>>> HTML5 and a sentence be added to the HTML5 spec on how UAs are
>>>> expected to deal with such segments.
>>>> Further, if you are indeed only interested in a subpart of the
>>>> original media resource and want to completely blend out all context
>>>> (i.e. all other bits of the media resource), you should be using the
>>>> URI query addressing method instead of the URI fragment, e.g.
>>>> video.ogv?t=40,50. This URI is supposed to create a new resource that
>>>> consist only of the segment - it will only do so, of course, if your
>>>> server supports this functionality.
>>>> All of this is described in more detail in the spec [2]. If that is
>>>> unclear or anything is confusing, please do point it out so it can be
>>>> fixed.
>>>> Best Regards,
>>>> Silvia.
>>>> [1] http://www.w3.org/2008/WebVideo/Fragments/code/plugin/ (expect some bugs)
>>>> [2] http://www.w3.org/TR/media-frags/

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