[whatwg] HTML 5 video tag questions

[Jonas Sicking]

On Sun, Jul 12, 2009 at 11:20 PM, Ian Hickson<ian at hixie.ch> wrote:
> On Fri, 10 Jul 2009, Jonas Sicking wrote:
>> >>
>> >> Hmm.. is that good? What if you want to use an <object> (to use flash
>> >> or java) or a <img> as fallback?
>> >
>> > Then you do it with script.
>> >
>> > The design is based around the assumption that we will eventually find
>> > a common codec so that fallback won't ever be needed in supporting
>> > UAs.
>>
>> I agree that the current design makes sense once there is a common codec
>> supported across all browsers. However currently it seems like we might
>> not reach that point until after all major browsers support <video>.
>>
>> What would be the downside of displaying the fallback contents if none
>> of the videos can be displayed due to unsupported codecs?
>
> When would you fall back? For example, while parsing, would you fall back
> in between the <video> element being parsed and the first <source> element
> being parsed?

You could display the fallback once you've reached the </video> and
not found an acceptable <source>. Technically it'd be when you pop the
video element off the stack of open elements. I don't even think it'd
be hard to pull down all <source>s and check that none of them are
supported before displaying the fallback if types aren't specified on
the <source> element.

> The design you describe is what <object> tried to do, and it proved to be
> extremely problematic in practice -- and that was without another built-in
> fallback mechanism to complicate matters.

While <object> has had a very poor implementation story, I don't think
this was a big reason for that.

Robert O'Callahan, Boris Zbarsky and other gecko layout folks can
answer this better, but at least in gecko I don't think this part of
object was particularly hard to implement correctly once we actually
tried.

Has any browser vendor argued against displaying the fallback due to
high implementation burden?

/ Jonas