- From: Joe D Williams <joedwil@earthlink.net>
- Date: Sun, 7 Mar 2010 07:16:18 -0800
- To: "Maciej Stachowiak" <mjs@apple.com>, "David Singer" <singer@apple.com>
- Cc: "'HTML WG'" <public-html@w3.org>
Maciej Stachowiak Sent: Friday, March 05, 2010 10:38 PM > > 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. OK, each <source> can use @type and @media along with @src to decide upon playing the resource. But <video> @src> does not get that help from any @type or @media. If it is necessary or helpful for <source @src @type @media> then why not <video @src @media @type>? I guess the real intent may be to just have <video> carry info for the controls, etc. and let <source>(s) carry the media info. So, still, I think that allowing <video @src> without any access to @type and @media seems inconsistent. That makes me want to think about droping @src in <video>. Always use <source> to specify the resource. > >> 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. void/empty not displayed part of the dom element metadata? Not a media element. > >> >> 3. Why does <video> @src empty or missing mean that <source> >> elements >> may be included? > > @src and <source> are mutually exclusive. > if only <video @src> then (not actually specified default) is as if media="all" and no type >> >> 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. Do we mean not conforming like ignored, or with warning. > >> If the attribute is not present or empty, one or more <source> are >> conforming?. > > Also correct. That seems like it would work better because of added info by @type and @media. This time fully specified default is media="all" and no type. So for <video src='mediaresourcevalidurl.joe'> if .joe was a standardized file extension considered for loading then we have a very simple construction that plays the media=all resource at the valid URL., but with an opportunity for confusion if the URL is not @media='all' and type=''. > >> 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. Fine, the single recognized source, or else fallback. > >> 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. I am not seeing that fallback or resouce <source> element fallback sequence described anywhere. As a final step in that sequence, if all else fallis, isn't the final fallback then show the flow or phrasing content? . >> 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. That script example in <source> shows the script doing the checking and deciding fallback. From descriptions, it doesn't appear automated. 4. source element is: The following list shows some examples of how to use the codecs= MIME parameter in the type attribute. should be?: The following list shows some examples of how to include the codec parameter in the type attribute. 5. video element is: <p><video src="tgif.vid" autoplay controls onerror="failed(event)"></video></p> <p><a href="tgif.vid">Download the video file</a>.</p> should be: <video src="tgif.vid" autoplay controls> <p><a href="tgif.vid">Download the video file.</a></p></video> The <p>...</p> in the second example represents the flow or phrasing content shown in the event that no video can play. It should be contained by the <video> element. It is hidden unless the video fails. The current script example show what to do if <video> is not recognized, it seems out of place due to <video> fallback technique. The second example here should work to show the fallback content if <video> not recognized or won't play the @src. It would be appropriate to show at least one example of simulated spec behavior relating to automated fallback.. > > Regrds, > Maciej > Thank You, Joe
Received on Sunday, 7 March 2010 15:16:54 UTC