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

Re: Public feedback on HTML5 video

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Wed, 30 Dec 2009 13:57:33 +1100
Message-ID: <2c0e02830912291857y6796e70cu7ece82fe40eec815@mail.gmail.com>
To: Philip Jägenstedt <philipj@opera.com>
Cc: "Edward O'Connor" <hober0@gmail.com>, Jeremy Keith <jeremy@adactio.com>, HTMLwg <public-html@w3.org>
On Wed, Dec 30, 2009 at 1:35 AM, Philip Jägenstedt <philipj@opera.com> wrote:
> On Tue, 29 Dec 2009 15:21:43 +0100, Silvia Pfeiffer
> <silviapfeiffer1@gmail.com> wrote:
>
>> On Wed, Dec 30, 2009 at 1:13 AM, Philip Jägenstedt <philipj@opera.com>
>> wrote:
>>>
>>> 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">.
>>
>> I would say that John Gruber's discovery has contradicted this statement.
>
> Isn't it just that most browsers (all except Firefox?) are ignoring the
> autobuffer attribute? It seems that the solution is to implement
> conservative network usage and to let the autobuffer attribute disable this
> behavior. In my opinion, the difficult part is actually being conservative
> to begin with and I don't know if there's any point in introducing shades of
> conservative.

So are you saying that most browsers have not implemented support of
the autobuffer attribute yet and that is the real problem? If so, then
it makes sense to have three states: when autobuffer is implemented
and supported, "on" and "off" needs to be provided, which means "my
browser has control over its buffering behaviour and I can give that
control into the hands of the web developer". And if I do not
implement autobuffer support, then what the video element does is
random - depending on what is more convenient for my browser to do,
i.e. the current state of when autobuffer is not in use.

Or are you saying that really every browser should implement
autobuffer support and then the lack of an autobuffer attribute
signifies that it doesn't do autobuffering? In this case, we need to
rewrite what the lack of @autobuffer means: no autobuffering.

Shades of conservative is what we currently have: every browser can do
what they like when no autobuffer is present. Firefox is more
conservative than Safari. Instead, we need to clarify what is to be
expected by a user.

>> Also, if we really are asking for no autobuffering when the attribute
>> is not present, then this has to be stated in the HTML5 standard. So,
>> either we introduce a autobuffer=yes/no option or we prescribe that
>> when autobuffer is not present it means no autobuffering. Either
>> requires a change to the spec.
>
> We could add a non-normative note to implementors that it's nice if they
> don't waste bandwidth, even though I'm sure all implementors are already
> very aware of this.

Obviously not. Neither Safari nor Chrome implement conservative
bandwidth behaviour - that's two out of three browsers that have
decided (at least for now) to waste bandwidth. After this discussion,
I'm sure they will all change it. But what about others who implement
the text of the standard? They are not required or even requested to
behave well. It does indeed need at minimum a recommendation, if not a
requirement in the spec to make the browsers aware that they should
behave conservative with bandwidth on video.

I actually think that if it's not a required feature, ppl will avoid
it since there are so many other features to implement. Our question
here is: is this a feature that is absolutely necessary to make the
video element usable or not. I believe that the discussions that have
been stirred up through John Gruber's blog post show that it is a
required feature - he clearly states it is "unusable" otherwise, and
others have agreed.


Cheers,
Silvia.
Received on Wednesday, 30 December 2009 02:58:26 UTC

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