[whatwg] HTML5 video element - default to fallback in cases where UA can't play format

[Philip Jägenstedt]

On Thu, 03 Dec 2009 14:31:41 +0100, Kornel Lesiński <kornel at geekhood.net>  
wrote:

>>> Can someone explain to me how this works, given Aryeh's response  
>>> above? Surely if the iPhone can determine its capacity to be able to  
>>> play a video file, other UAs could do likewise and fall back on the  
>>> content accordingly as UAs with zero <video> support do?
>>
>> I know nothing about the iPhone, but any UA can know if it can play a  
>> resource or not simply by trying and adjusting the UI as appropriate.  
>> One *could* use the same hooks to display fallback content in those  
>> cases, but it is a very bad idea. Apart from the things Aryeh mention,  
>> because of how the resource selection algorithm works, you can never  
>> know if there will be a playable resource later, so there's no point  
>> where it's appropriate to show the fallback content. The only remaining  
>> option is flip-flopping between replaced content (video) and fallback  
>> content, which don't want (especially considering that the fallback  
>> content is likely to contain <object> for Flash or some other legacy  
>> fallback).
>
> How about making end of selection algorithm explicit?
>
> Something like video.imDoneWithSourcesEitherPlayOrShowFallback() method,  
> which upon failure permanently locks <video> in fallback state (to avoid  
> flip-flopping).
>
> or a special source that, if selected, triggers fallback:
>
> <video>
> 	<source src=file>
> 	<source fallback> (or <source src="#fallback">?)
> </video>
>

This has been proposed before, it is technically possible, but I don't  
particularly support it because it adds complexity for very little gain.  
Is the only problem we are trying to solve falling back to some legacy  
markup when the video format isn't supported? Given that there are only 2  
relevant formats so far, that doesn't seem like a problem worthwhile  
solving.

-- 
Philip Jägenstedt
Core Developer
Opera Software