- From: Maciej Stachowiak <mjs@apple.com>
- Date: Fri, 05 Mar 2010 22:38:30 -0800
- To: Joe D Williams <joedwil@earthlink.net>
- Cc: 'HTML WG' <public-html@w3.org>
On Mar 5, 2010, at 10:00 PM, Joe D Williams wrote: > questions for <video> > > 1. Why does <video> not include @type and @media? > If <source> uses/needs them, then why not <video> if only @src? > If no <source> then @type and @media would not be present. @type and @media are used to select from among multiple sources. It's not allowed to combine @src and <source>. So <video src> has only one possible source, and therefore there's no need for information that would be used to choose a source in that case. > 2. Why would <source> (or <param>) include Global attributes? > None are rendered and only the container really needs these. Some global attributes, such as id, class, and data-*, definitely do make sense even on non-visible elements. For other global attributes, I expect it is more trouble than it's worth to make them specifically disallowed for non-visible elements. > > 3. Why does <video> @src empty or missing mean that <source> elements > may be included? @src and <source> are mutually exclusive. > > a src attribute, or zero or more source elements, followed by some or > none flow content or phrasing content > > http://dev.w3.org/html5/spec/video.html#attr-media-src > > "There are two ways to specify a media resource, the src attribute, or > source elements. The attribute overrides the elements." > > But if the attribute is present, <source> not conforming? Correct. > If the attribute is not present or empty, one or more <source> are > conforming?. Also correct. > Sorry if I apparently hadn't looked at <video> in this detail before. > I just thought it seemed natural that this was a two level fallback > plan where is the <video> @src didn't play, then try <source> @src > content in sequence and if still no go then show the flow or phrasing > content. That's not how it works. You can only use <video src> in the case where there is a single source. Otherwise you have to use <source> elements. > Why doesn't the standard at least imply that the browser does anything > 'automatic' in the fallback scheme? The spec does say that the browser does something automatic, and in fact describes exactly what the browser is supposed to do: <http://dev.w3.org/html5/spec/Overview.html#concept-media-load-algorithm >. Notice that if there is a src attribute, it always takes precedence. Otherwise, the <source> elements are tried in order. > Are the <source> elements in there just so I can include some script > to do fallback? That's not the intent. Hopefully the above answers clarify how it works. Regrds, Maciej
Received on Saturday, 6 March 2010 06:39:05 UTC