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Re: AW: Public feedback on HTML5 video

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Tue, 29 Dec 2009 14:17:56 +1100
Message-ID: <2c0e02830912281917n3c72448cy8ec2fb80102dddc7@mail.gmail.com>
To: Philip Jägenstedt <philipj@opera.com>
Cc: Aryeh Gregor <Simetrical+w3c@gmail.com>, "Scheppe, Kai-Dietrich" <k.scheppe@telekom.de>, HTMLwg <public-html@w3.org>
On Tue, Dec 29, 2009 at 10:23 AM, Philip Jägenstedt <philipj@opera.com> wrote:
> On Mon, 28 Dec 2009 23:56:39 +0100, Aryeh Gregor <Simetrical+w3c@gmail.com>
> wrote:
>
>> On Mon, Dec 28, 2009 at 5:44 PM, Philip Jägenstedt <philipj@opera.com>
>> wrote:
>>>
>>> The only wiggle-room this leaves for implementation is whether to show
>>> the
>>> poster frame or the first video frame when the first video frame has been
>>> decoded. I think it should be the poster image, if other browser vendors
>>> agree perhaps the spec should simply say that.
>>
>> That seems sensible to me as well.  Why would implementations show the
>> first video frame if a poster is explicitly provided?
>>
>>> If the author doesn't want to use a poster image they simply shouldn't
>>> use
>>> that attribute. To show a certain frame of video, set .currentTime in a
>>> script.
>>
>> That's not equivalent.  In particular, it will change what happens
>> when the user hits play, and will probably change what gets buffered.
>> Not to mention it requires script.
>>
>> Perhaps someone should suggest to the Media Fragments WG that they
>> should create a syntax where you can address a frame of a video like a
>> picture?  The current WD doesn't seem to allow it:
>>
>> http://www.w3.org/2008/WebVideo/Fragments/WD-media-fragments-spec/
>
> Shouldn't using e.g. #t=10,10 do just that?

No, not if you are expecting it to return an actual image. A media
fragment can only return the same mime type as the original resource.
Thus, this will just return the video data for that particular time -
it's still video data and not converted to jpg or png or anything
else. It does essentially the same as setting the currentTime to 10.

The media fragment WG recommends using queries where a image is to be
extracted from a video,
e.g. ?t=10,10&format=image/png .

URI queries have been identified to be important for addressing media,
in particular to extract shorter version of videos or retrieve another
representation of a video (or audio). URI queries create new
resources, so it is possible to do this with URI queries. URI
fragments do not create new resources, so they cannot return a
different mime type.

The possibilities with URI queries are much larger and it is expected
that media servers will develop a large repertoire of URI query
parameters, but for now, the focus is on URI fragments and their
equivalents in URI queries only where the mime type is not changed.

Cheers,
Silvia.
Received on Tuesday, 29 December 2009 03:18:49 UTC

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