W3C home > Mailing lists > Public > public-html@w3.org > December 2009

Re: Public feedback on HTML5 video

From: Philip Jägenstedt <philipj@opera.com>
Date: Tue, 29 Dec 2009 15:13:50 +0100
To: "Silvia Pfeiffer" <silviapfeiffer1@gmail.com>
Cc: "Edward O'Connor" <hober0@gmail.com>, "Jeremy Keith" <jeremy@adactio.com>, HTMLwg <public-html@w3.org>
Message-ID: <op.u5pdtcxxatwj1d@sisko.linkoping.osa>
On Tue, 29 Dec 2009 14:26:44 +0100, Silvia Pfeiffer  
<silviapfeiffer1@gmail.com> wrote:

> On Tue, Dec 29, 2009 at 6:52 PM, Philip Jägenstedt <philipj@opera.com>  
> wrote:
>> On Tue, 29 Dec 2009 00:44:50 +0100, Edward O'Connor <hober0@gmail.com>
>> wrote:
>>>> Is the absence of the autobuffer attribute an explicit request not to
>>>> pre-buffer?
>>> I'd rather it not be.
>>> I think it's important for the author to be able to say "hi browser,
>>> please do whatever is most appropriate given your platform / network
>>> connection / memory / etc., insofar as buffering is concerned." In  
>>> fact,
>>> I suspect this to be the most common authoring case. Most authors would
>>> prefer it if, say, cell phone browsers defaulted to no-autobuffering,
>>> whereas they might prefer desktop browsers to behave differently. Given
>>> that, I'd prefer the default/lazy authoring behavior (not specifying  
>>> the
>>> attribute at all) to have this meaning.
>>> Essentially, we have three things we'd like authors to be able to  
>>> convey
>>> to the browser:
>>>  1. Do whatever the browser thinks best.
>>>  2. Please autobuffer.
>>>  3. Please *don't* autobuffer.
>>> And there are a few things we'd like to be able to say about whatever
>>> design we settle on:
>>>  A. (1) above should be the default condition, so its syntax should be
>>>     what most authors will do anyway (not provide attributes at all).
>>>  B. Any new boolean attributes should behave like the other boolean
>>>     attributes already present in HTML (presence means t and absense
>>>     means nil).
>>>  C. If at all possible, we should be able to use different values for
>>>     the same attribute for (2) and (3). (Minting separate attributes
>>>     for (2) and (3) means allowing authors to write nonsensical markup,
>>>     and having to spec what HTML5 processors should do when they're
>>>     both present. What does <video buffer nobuffer> mean?)
>>> There's a lot of tension between (B) and (C), so much so that I think
>>> autobuffer="" should probably become an enumerated attribute[1] instead
>>> of a boolean attribute. Something like the following:
>>>  1. Do whatever the browser thinks best. [no autobuffer attribute]
>>>  2. Please autobuffer. [autobuffer="on"]
>>>  3. Please *don't* autobuffer. [autobuffer="off"]
>>> Ted
>>> 1.
>>> http://www.whatwg.org/specs/web-apps/current-work/multipage/common-microsyntaxes.html#keywords-and-enumerated-attributes
>> I do not support making this distinction, because as an implementor I  
>> cannot
>> act any differently in case 1 and 3. Any browser that has gone to the  
>> effort
>> of being conservative with network resources will want that behavior  
>> even if
>> autobuffer="off" is given. Unless there is some browser vendor who can  
>> see
>> themselves acting differently in case 1 and 3, this just adds a bit of
>> complexity and the illusion of control on part of the author where  
>> there is
>> in fact none.
> I believe as a desktop browser on a web page with only one video in a
> prominent location ("above the fold"), I would decide to autobuffer.
> The same web page on a mobile phone browser, I would not decide to
> autobuffer.
> With more than one video on a page, I would probably autobuffer nothing.
> This is a minor distinction though. Maybe you are right and there is
> never a need to autobuffer unless the autobuffer attribute is given.
> In this case, though, we should change the specification and make it
> clear that when autobuffer is given, it will autobuffer and when
> autobuffer is *not* given it will *not* autobuffer (unless autoplay is
> given).
> There are in fact two problems with the current specification:
> 1. it doesn't allow specification by the page author to *not*
> autobuffer - all the page author (and user) can *hope* for is that by
> not specifying the attribute, the user agent will not buffer.

It just seems to me that any sane browser would conserve bandwidth if it  
knows how to, allowing the author to ask for that is a little bit like  
<script slowdown="no">.

> 2. it does not allow a user override of a page author's decision,
> where the page author actually may not have all the information (e.g.
> that it's running on a mobile phone or on a low-bandwidth connection -
> as Laura's example states; or the opposite - that I want to autobuffer
> everything cause my bandwidth is unlimited)

Since the spec allows the UA to ignore the autobuffer attribute, the UA is  
allowed to have a user-settable pref for this, so I believe this is  
already covered. Perhaps a note or something in the spec would help  
clarify this though.

Philip Jägenstedt
Core Developer
Opera Software
Received on Tuesday, 29 December 2009 14:14:32 UTC

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