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Re: Should <video> buffer control be tri-state?

From: Aryeh Gregor <Simetrical+w3c@gmail.com>
Date: Mon, 4 Jan 2010 13:25:33 -0500
Message-ID: <7c2a12e21001041025u78d7a6e4obec424441ea6976d@mail.gmail.com>
To: robert@ocallahan.org
Cc: Philip J├Ągenstedt <philipj@opera.com>, Maciej Stachowiak <mjs@apple.com>, "Tab Atkins Jr." <jackalmage@gmail.com>, Silvia Pfeiffer <silviapfeiffer1@gmail.com>, "Edward O'Connor" <hober0@gmail.com>, Jeremy Keith <jeremy@adactio.com>, HTMLwg <public-html@w3.org>
On Sun, Jan 3, 2010 at 4:12 PM, Robert O'Callahan <robert@ocallahan.org> wrote:
> Firefox currently doesn't retain buffered media data across page reloads.
>
> I encourage people to actually try some pages with <video> with and without
> "autobuffer" in a browser that supports autobuffer.

Okay.  I tested using this in Firefox 3.5:

data:text/html,<!doctype html><video controls
src="http://videos.mozilla.org/firefox/3.5/meet/meet.ogv"></video>

When I hit play, I see the bar at the bottom immediately begin to
progress.  Less than a second later, the video begins to play.  Even
if I noticed that sub-second lag, I wouldn't care.  But I bet I
wouldn't notice it at all.  I'd just assume that the first half-second
of the video is just a bluish background with no sound.  It even looks
like the bar is moving -- if you don't look closely, you won't notice
that the movement is actually just buffering.  When I try the same URL
with autobuffer, I can notice the difference easily, but only because
I'm actually running both and comparing.

I remain very firmly convinced that many sites will inadvertently omit
the autobuffer attribute.  It's not easily noticeable at all during
testing.  Or even during usage, if you have a fast connection.
Inadvertently *using* autobuffer would be practically impossible to
spot.


What are the actual use-cases for author control over buffering here?
The only reasons I can think of are

1) Improve user experience.
2) Conserve server bandwidth.

For (1), is it likely that typical authors will ever be able to make a
better guess on whether autobuffering is needed than implementers?
Why would this be?  What information would authors have that the
browser couldn't figure out just as well?  This is all keeping in mind
that while browser heuristics will fail sometimes, so will author use
of the autobuffer attribute.

For (2), is a "conserve server bandwidth" feature needed, if browsers
only ever buffer enough to play through the video at worst (i.e.,
don't buffer the whole thing like Firefox 3.5 seems to do if
autobuffer is set), and usually only do that if the user is actually
going to play the video, and authors who really care can use script
hacks?

I'm concerned that autobuffering is too subtle for average authors to
get right even with only two options, let alone if a third is added.
Received on Monday, 4 January 2010 18:26:02 GMT

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