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RE: Proposed clarification of checkpoint 9.4

From: Denis Anson <danson@miseri.edu>
Date: Fri, 5 May 2000 21:17:28 -0400
To: "Ian Jacobs" <ij@w3.org>, <w3c-wai-ua@w3.org>

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.


-----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


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:

  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]

We do have a definition of "rendered content".

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
Received on Friday, 5 May 2000 21:14:21 UTC

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