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Re: Systematic access to media/plugin metadata

From: Laura Carlson <laura.lee.carlson@gmail.com>
Date: Wed, 13 Apr 2011 12:03:40 -0500
Message-ID: <BANLkTim-sFf0gfG2zNJ7tsi-213-iEwFzQ@mail.gmail.com>
To: Eric Carlson <eric.carlson@apple.com>
Cc: Henri Sivonen <hsivonen@iki.fi>, Silvia Pfeiffer <silviapfeiffer1@gmail.com>, Danny Ayers <danny.ayers@gmail.com>, "public-html@w3.org" <public-html@w3.org>
Hi Eric,

Thank you very much for the explanation.

>  I would imagine that whatever mechanism we agree on for linking to
> external long descriptions would work for transcripts as well - as long as
> the descriptions are not in the video file.

That is a possibility all right.

Best Regards,
Laura

On 4/12/11, Eric Carlson <eric.carlson@apple.com> wrote:
>
> On Apr 12, 2011, at 12:20 PM, Laura Carlson wrote:
>
>>
>>>> How does the end user obtain the transcripts if there is no script?
>>>>
>>> They can't, but as far as I know there is no standard way to mark a text
>>> track in an audio or video file as a "transcript"
>>
>> Maybe there should be?
>>
>   First, meta-data is stored and interpreted differently in different media
> file formats so this would have to be done for every format. Therefore I it
> is out of scope for the HTML WG.
>
>   Secondly, I am not sure this would be especially useful because
>
>>> so a script with
>>> hard-coded knowledge about the contents of such a movie will be required
>>> for
>>> this anyway.
>>>
>>> In any case all of the samples in a media file are typically intermixed,
>>> eg. a text track will be broken up into small chunks and spread
>>> throughout
>>> the file. This means that it isn't usually possible to load only a text
>>> track,
>>
>> So are you saying that most captions are not  just a text file with
>> time stamps? Is that correct?
>>
>   Captions are text samples with timing information, but they do not
> necessarily come out of text files. Some media container formats can contain
> text samples (we have been calling these "in band" captions in our WG
> discussions) as well as audio and video data. For example if you have ever
> looked at a movie or video podcast with closed captions on an iPhone or
> iPad, those captions come from the video file, not a separate text file, and
> are being rendered QuickTime.
>
>   I assumed that you were talking about "in-band" captions because your
> original email talked about accessing EXIF, IPTC, and XMP metadata from
> inside of image files.
>
>
>>> and in your example of a user with a slow network connection it will
>>> be necessary to download the entire video file even if they only want the
>>> transcript.
>>
>> Downloading an entire video file would not be an option for a user on
>> a slow connection. Just starting a video grinds everything to a halt.
>>
>   Right, that is why I mentioned that I didn't think in-band transcripts
> would be useful for your use case.
>
>> When I asked Silvia for a transcript of her WebVTT explained Video
>> [1]. She kindly linked to
>> a full transcript of the described video in the form of a WebVTT file
>> [2]. That worked. Is there anyway that transcripts like this could be
>> extracted and offered to users on slow connections automatically?
>>
>   I would imagine that whatever mechanism we agree on for linking to
> external long descriptions would work for transcripts as well - as long as
> the descriptions are not in the video file.
>
> eric



-- 
Laura L. Carlson
Received on Wednesday, 13 April 2011 17:04:08 UTC

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