Re: TTML and aspect ratio

On Feb 3, 2013, at 23:57 , David Ronca <dronca@netflix.com> wrote:

> >Now in so much as the root container defines the coordinate system, then I believe the most
> >general system is one that aligns top left 0,0 with 0,0 of the underlying media, and X,Y
> >with the bottom right of the media. Since X and Y can be any real value, it doesn't really
> > matter what value we use so 100%,100% seems adequate. If we then allow negative values and
> >values beyond 100, we can address any relative position.
>  
> Following this model, if the media is 16:9 but the captions were done using CEA-608 (or another format that uses/assumed a 4:3 presentation),

Hang on, we were talking about pixel aspect ratio before.  16:9 and 4:3 are picture aspect ratios.

But even so, why are we hypothesizing that someone has the energy etc. to re-author the video, but can't adjust the TTML region in which they want the captions displayed?

David Singer
Multimedia and Software Standards, Apple Inc.