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Re: Proposed clarification of checkpoint 9.4

From: Ian Jacobs <ij@w3.org>
Date: Fri, 05 May 2000 21:34:00 -0400
Message-ID: <39137688.A526DE3@w3.org>
To: Denis Anson <danson@miseri.edu>
CC: w3c-wai-ua@w3.org
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
Received on Friday, 5 May 2000 21:34:14 GMT

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