[whatwg] video tag: pixel aspect ratio

Pierre-Olivier Latour pol at apple.com
Mon Dec 1 12:14:54 PST 2008

>> <img src="circle.jpg" width="400" height="400"> <!-- circle -->
>> <img src="circle.jpg" width="400" height="300"> <!-- oval -->
>> I think it would be much more consistent if these elements behaved in
>> the same way.
> What is the use case for wanting a video to be stretched?

I can only think of the case when you need to post-fix a video which  
wasn't encoded with the proper pixel aspect ratio. And we already  
covered the likelihood of encountering this case extensively. So I  
guess what's left is purely a convention decision:
- should <video> behaves like <img> by default and have a special  
attribute to scale proportionally,
- or should <video> scale proportionally by default, and maybe have  
some way of defining a stretching behavior?

Eric & I would recommend the later because based on past experience,  
users often specify the wrong width & height for the element, and if  
we stretch by default, then we would often fall off the fast path of  
the media engine (scaling anamorphically can be very expensive). At  
the end of the day, being consistent with <img> wouldn't be worth the  
potential other issues.

Regarding the stretch attribute, we should have this functionally  
available to users but preferably at the CSS level.

Pierre-Olivier Latour - pol at apple.com
Rich Media Team - Apple, Inc.

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