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

Re: Load event and <video>

From: Robert O'Callahan <robert@ocallahan.org>
Date: Fri, 20 Mar 2009 15:55:51 +1300
Message-ID: <11e306600903191955l6bb5f66cu80ffa55e8e7c35ea@mail.gmail.com>
To: Simon Pieters <simonp@opera.com>
Cc: public-html <public-html@w3.org>
On Fri, Mar 20, 2009 at 5:17 AM, Simon Pieters <simonp@opera.com> wrote:

> We've been discussing a bit regarding the load event and <video>...
>
> As currently specced it seems like the load event could be delayed
> indefinitely if the UA decided to stall the download of the video:
>
>
> Step 2 of the resource selection algorithm sets delaying-the-load-event
> flag to true.
>
> Step 5.2 invokes the resource fetch algorithm.
>
> Step 3 of the resource fetch algorithm allows the UA to stall the download.
>
>
> Is the above analysis correct? Surely we don't want to delay the load event
> indefinitely? Is the intent that UAs have to download enough video data to
> know the dimensions of all videos before sending the load event?
>

Yes. Generally the load event fires when the layout of the document is
"stable".

Perhaps the spec should be changed to suggest that UAs not stall the
download while the element is delaying the load event ... although it's kind
of obvious if you ask me.

We were thinking that if there's a poster image then when the poster image
> has loaded we can stop delayig the load event without downloading any video
> data at all (even though the video dimensions might be different -- if they
> are different then that's the author's fault).


That sounds reasonable to me. We'd want the spec to say that while the
poster image is being displayed, the intrinsic dimensions of the video
element are the dimensions of the image. We'd also want the spec to say that
if there is a poster image, then we stop delaying the load event when the
poster image has finished loading.

On a related note, I think Opera doesn't download images that are
> display:none or visibility:hidden or maybe have 0 height and width. Such
> images don't delay the load event. Maybe the spec should allow this?
>

Gecko doesn't download images at all for display:none but does (and delays
the load event) for visibility:hidden and zero-size images.

Rob
-- 
"He was pierced for our transgressions, he was crushed for our iniquities;
the punishment that brought us peace was upon him, and by his wounds we are
healed. We all, like sheep, have gone astray, each of us has turned to his
own way; and the LORD has laid on him the iniquity of us all." [Isaiah
53:5-6]
Received on Friday, 20 March 2009 02:56:29 UTC

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