[whatwg] on codecs in a 'video' tag.

Christoph Päper christoph.paeper at crissov.de
Tue Mar 27 10:58:00 PDT 2007

Anne van Kesteren:
> Also, I think the HTML specification should mandate (as SHOULD- 
> level requirement, probably) support for the various supported  
> image formats as it gives a clear indication of what authors can  
> rely on and what user agents have to implement in order to support  
> the web.

Which format would this be for animated true-colour images, lossy or  
lossless? MNG/JNG, APNG, JS+PNG/JPEG, SVG+PNG/JPEG ...? Or is there  
no need to require one? If so why not?

I am still not convinced (X)HTML5 should recommend support for  
anything but itself. Although HTTP, CSS, JS, GIF and JPEG/JFIF might  
seem safe, they all have certain (exotic) features that are not  
implemented (the same / correctly / at all) in current browsers. I  
think informative advise is all there needs to be, but RFC 2119 does  
not have something between 'should' and 'may', like 'ought' and  
'suggested' or 'advocated' perhaps.

RFC 2119:
     'must'       = 'shall'      = 'required'
     'must not'   = 'shall not'
                    'should'     = 'recommended'
                    'should not' = 'not recommended'
     'may'        =                'optional'

Terms not defined therein, but sometimes encountered in "Web  
standards" are for example 'forbidden', 'mandatory', 'prescribed',  
'compulsory', 'permissive', 'allowed', deprecated', 'obsolete',  
'will', 'would'.

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