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Re: <video> attributes and children

From: Joe D Williams <joedwil@earthlink.net>
Date: Tue, 9 Mar 2010 14:26:37 -0800
Message-ID: <00E590E5E5C545008486B7263F1DBB09@joe1446a4150a8>
To: "Joe D Williams" <joedwil@earthlink.net>, "Maciej Stachowiak" <mjs@apple.com>, "David Singer" <singer@apple.com>
Cc: "'HTML WG'" <public-html@w3.org>
>>> 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>

>
> I am not seeing that fallback or resouce <source> element fallback 
> sequence described anywhere.

Thank You, I see it now and will look at more details.

Best Regards,
Joe
.

----- Original Message ----- 
From: "Joe D Williams" <joedwil@earthlink.net>
To: "Maciej Stachowiak" <mjs@apple.com>; "David Singer" 
<singer@apple.com>
Cc: "'HTML WG'" <public-html@w3.org>
Sent: Sunday, March 07, 2010 7:16 AM
Subject: Re: <video> attributes and children


>
> 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 Tuesday, 9 March 2010 22:27:14 UTC

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