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Re: Proposed clarification of checkpoint 9.4

From: David Poehlman <poehlman@clark.net>
Date: Sat, 06 May 2000 11:44:22 -0400
Message-ID: <39143DD6.7A90C762@clark.net>
CC: Ian Jacobs <ij@w3.org>, Denis Anson <danson@miseri.edu>, w3c-wai-ua@w3.org
Ian, the heart of this one seems to ve media delivery progress.  as Dennis
points out, the content must be transferred and than rendered.  it is the
rendering progress that I think we are trying to capture here and we must
also be certain to capture other progresses as well such as progress of page
transfer and progress through a page as it is being scrolled.
Thanks!

Ian Jacobs wrote:
> 
> Denis,
> 
> Basically, I don't know what "to load" means. The HTML spec
> says: "The onload event occurs when the user agent finishes
> loading a window or all frames within a FRAMESET." That doesn't
> help me.
> 
> I am much more comfortable with the terms
> "transfer" (one "T" in HTTP) or"render" (HTML + CSS), both of
> which require time. I think you are correct in that the
> intention of the checkpoint was more about transfer status
> than rendering status. Furthermore, checkpoint 9.5 covers
> the case of position within rendered content.
> 
> I therefore propose changing "loading" to "transferring"
> 
> <NEW>
>    9.4 When transferring content (e.g., document, image, audio, video,
> etc.)                indicate what proportion of the content has been
> transferred
>          and whether the transfer has stalled. [Priority 3]
> </NEW>
> 
> Denis wrote:
> > I'm not sure this works for multimedia content.  When a video, for example,
> > is downloaded, isn't loaded into a buffer somewhere, then rendered a frame
> > at a time?
> 
> > As I understand it, the goal is to find out how much longer I'll have to
> > wait before I can access the information.
> >  In streaming media, this isn't an
> > issue, because the data-stream might be essentially endless.  But for sound
> > files, videos, or even animations, the rendering might not begin until the
> > entire file is available, and the new wording really doesn't seem to capture
> > that.  Or, I might not be using "render" the same way you are.
> >
> > Denis
> >
> > -----Original Message-----
> > From: w3c-wai-ua-request@w3.org [mailto:w3c-wai-ua-request@w3.org]On Behalf
> > Of Ian Jacobs
> > Sent: Friday, May 05, 2000 7:40 PM
> > To: w3c-wai-ua@w3.org
> > Subject: Proposed clarification of checkpoint 9.4
> >
> > Hello,
> >
> > Checkpoint 9.4 of the Proposed Recommendation [1] reads:
> >
> >   9.4 When loading content (e.g., document, image, audio,
> >       video, etc.) indicate what proportion of the content has
> >       loaded and whether loading has stalled. [Priority 3]
> >
> > We do not have a definition of "load". I believe that
> > this means "to put in the viewport", i.e., to render, rather
> > than retrieve (although delays in loading may be due
> > to delays in retrieval initially). I therefore propose
> > the following restatement of the requirement:
> >
> > <NEW>
> >   9.4 When rendering content (e.g., document, image, audio,
> >       video, etc.), indicate what proportion of the content has
> >       been rendered and whether rendering has stalled. [Priority 3]
> > </NEW>
> >
> > We do have a definition of "rendered content".
> >
> > Note:
> > There is still a slight ambiguity, but I propose to not worry
> > about it. The proportion (e.g., percentage) should probably
> > represent the proportion of currently rendered content to the
> > total rendered content. However, user agents that render
> > incrementally may not know how much total rendered content
> > there will be. An approximation based on the byte-size of
> > the document source would be adequate. Document entity
> > length may be known in advance (e.g., through the
> > "Content-Length entity-header field in HTTP/1.1 [2],
> > section 14.13). If I've misquoted the HTTP spec, please let
> > me know.
> >
> >   - Ian
> >
> > P.S. I am proposing this change in an effort to harmonize our
> > use of "content" in the document.
> >
> > [1] http://www.w3.org/TR/2000/PR-UAAG10-20000310
> > [2] http://www.ietf.org/rfc/rfc2616.txt
> > --
> > Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
> > Tel:                         +1 831 457-2842
> > Cell:                        +1 917 450-8783
> 
> --
> Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
> Tel:                         +1 831 457-2842
> Cell:                        +1 917 450-8783

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Received on Saturday, 6 May 2000 11:44:16 GMT

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