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

AW: Public feedback on HTML5 video

From: Scheppe, Kai-Dietrich <k.scheppe@telekom.de>
Date: Mon, 28 Dec 2009 22:11:49 +0100
Message-Id: <FF6AD6C11AA23F4F9866E9A3C57602ED9C2097@QEO00217.de.t-online.corp>
To: Philip Jägenstedt <philipj@opera.com>, "Aryeh Gregor" <Simetrical+w3c@gmail.com>
Cc: "HTMLwg" <public-html@w3.org>


> - whether a poster frame is to be loaded or not (the poster attribute 
> does this)
>   However, there is also mention of doing so only when no video is 
> available...that is not enough.  A poster frame should simply be a 
> choice of the author.

I honestly don't understand what you are saying here. What is not enough? 
Does something need to be changed in the spec?
 

Also Philip asked:

> - whether a poster frame is to be loaded or not (the poster attribute 
> does this)
>   However, there is also mention of doing so only when no video is 
> available...that is not enough.  A poster frame should simply be a 
> choice of the author.

I honestly don't understand what you are saying here. What is not enough? 
Does something need to be changed in the spec?


Kai:  With this I mean the spec currently mentions "The poster attribute gives the address of an image file that the user agent can show while no video data is available."

What if the author wants to specfiy a poster image even though the video data is available?
That is what is not enough.

> - perhaps even where on the timeline the poster frame is to be found, if 
> it is not an explicit file

The poster image can only be an image file, where from the video it is 
taken (if at all) hardly needs to be represented in HTML.

Kai: Why ask the author to create a separate image if a frame of the existing video is sufficient?

> - the explicit dimensions of the video and let the video be covered 
> partially if it is larger than that.

Let the video be covered by what? The poster image and video are never 
displayed at the same time.

Kai: If the dimensions of the video are larger than the space alloted to it, what is to happen?  
In CSS one option is to hide the content "behind" the surrounding content.



>> Assuming a page with 100s of <video>s with poster images,
>> downloading even just enough to get the duration might add up
>> to a significant amount of data (and time), while not
>> downloading anything and pretending that the duration is +Inf
>> and dimensions unknown is likely to cause headaches for
>> authors that actually use that data in their scripts before playing.
>
> If an author were to decide to offer 100s of videos on one page, then he 
> better have a very good reason to do so.
> One that his audience agrees with :-)
> Arguing in extremes is not useful as I can break any system that way.

This "extreme" is the only case which is interesting to discuss. For a 
single <video> the buffering behavior hardly matters at all since the 
options are (1) downloading nothing and (2) downloading a few 100 KB from 
the beginning and end of the video.

Kai: Again, speaking only of hundreds of videos or a single one is merely covering extremes.
the most likely scenario are "a few videos".

> Poster images are marketing tools...it's what makes the user want to 
> click on it.
> It also fills the spot...otherwise you might have a hole in your page 
> with, at best, a PLAY icon being displayed.
> As such it is highly useful.
> Using it to download some meta data about the video seems very 
> resonable, as it would allow display of such info and decision making by 
> the user.

Downloading and decoding an image is not necessarily faster than 
downloading and decoding the first frame of a video. I agree that it is 
useful because it can represent something other than the first frame of 
the video (which is often black). However, this really isn't related to 
the buffering behavior.

Correct, but you had asked why this is important.

-- Kai
Received on Monday, 28 December 2009 21:17:00 UTC

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