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Re: Default value of "preload" attribute

From: Ian Hickson <ian@hixie.ch>
Date: Tue, 30 Mar 2010 02:35:34 +0000 (UTC)
To: Philip Jägenstedt <philipj@opera.com>, Robert O'Callahan <robert@ocallahan.org>
Cc: public-html <public-html@w3.org>
Message-ID: <Pine.LNX.4.64.1003300213402.21497@ps20323.dreamhostps.com>
On Mon, 29 Mar 2010, Philip Jägenstedt wrote:
> We haven't implemented preload yet, but I think we'll default to 
> metadata (including decoding the first frame). However, this just means 
> that we start out conservative, as soon as the the video starts playing 
> (or we have some other reason to think it will be used soon) we'll 
> download more aggressively. In other words, preload="metadata" just 
> means "conservative" and preload="auto" means "aggressive"...

On Thu, 25 Mar 2010, Robert O'Callahan wrote:
> Firefox defaults to "metadata". I believe that's the safe option for 
> authors who aren't sure what they're doing.

I've changed the spec to default to metadata.

> > > One more thing ... the resource fetch algorithm says that when 
> > > preload="metadata" UAs should stop loading after the first frame 
> > > (HAVE_CURRENT_DATA). Shouldn't that value be named "firstframe" (or 
> > > something else) then? It's pretty confusing to have 
> > > preload="metadata" not stop after the metadata has loaded.
> >
> > Yeah, the name is mildly misleading. I considered "firstframe" but it 
> > didn't really seem in the style of the Web platform, insofar as the 
> > Web has a style. It's not really that confusing; it's not like authors 
> > are going to say "goodness, why is it that it downloads up to the 
> > first frame instead of stopping 512 bytes earlier at the end of the 
> > metadata?". In fact you could even argue that for many purposes (e.g. 
> > filling in the poster frame if poster="" isn't provided) the first 
> > frame is a kind of metadata anyway.
> I don't really understand why "firstframe" isn't "in the style of the 
> Web platform".

Multiword values are generally rare, and inconsistent in their naming. 
This is highly subjective though, I agree. (Another problem with 
"firstframe" is that the media resource might not be framed based, e.g. an 
audio resource.) If there's a better term than "metadata" I'm certainly 
happy to consider it though.

> Loading the first frame can consume an order of magnitude more data than 
> loading the metadata. Mainly though, I'm concerned that authors will 
> want to preload up to the first frame and will think "hmm, I can preload 
> up to the metadata, but how do I preload up to the first frame?"

If authors start thinking about this that carefully, then it's time to 
invest in porcine-safe umbrellas...

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Tuesday, 30 March 2010 02:36:03 UTC

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