Re: [MSE] Resolving Bug 24370

Comments inline.

On Wed, Apr 2, 2014 at 1:31 AM, David Singer <singer@apple.com> wrote:

>
> On Apr 2, 2014, at 2:17 , Aaron Colwell <acolwell@google.com> wrote:
>
> > So right now Bug 24370 is the only bug left against MSE. That bug
> triggered the creation of Bug 24563 which has resulted in a spirited
> discussion. Then about 2 weeks ago I had an IM conversation with Hixie to
> sort things out and he was still leaning towards not allowing these
> attributes to become mutable.
> >
> > Here is a summary of what I believe his concerns are:
> > 1. kind & language changing during playback was never intended to work
> in HTML5. This being possible in out-of-band tracks was just an artifact of
> using HTML to specify tracks.
> > 2. Allowing kind & language to change during playback could result in
> all sorts of added complexity to the HTML5 spec.
> > 3. There don't appear to be compelling use cases to justify the
> complexity.
> > 4. If the web application is getting the kind & language data from the
> manifest instead of the media file, then why shouldn't the web application
> be responsible for selecting appropriate tracks instead of the UA?
> >
> > After the IM discussion with Hixie, I am starting to wonder myself what
> people are actually trying to accomplish with the mutable language and
> track attributes. If you look closely at the HTML5 spec there isn't any
> existing spec text that talks about what happens if this information
> changes after readyState transitions to HAVE_METADATA.
> >
> > I'd like the people who care about this particular feature to answer the
> following questions so that we can make some progress.
> >
> > 1. What do you expect the UA to do when kind and/or language is changed
> on a xxxTrack object?
> > 2. Why isn't the language & kind data simply placed in the
> initialization segments instead of only being in a DASH manifest?
>
> You assume they are not.  Language is in MP4 files, and we’re interested
> in putting kind in there.
>

This came from a comment from someone, I don't remember who, when we
originally introduced the feature. I'm pretty sure someone said that the
information may only be available in the manifest. Perhaps they were only
referring to kind at the time. I am all for mandating that this information
be in the initialization segment if it is to be reflected in the xxxTrack
objects.

Aaron