Thanks for the analysis, but two pieces of feedback:
1) Though sub-titles and captions are the most common accessibility
issue for audio/video content, they are not the only one. There are
people:
-- who cannot see, and need audio description of video
-- who cannot hear, and prefer sign language
-- who have vision issues and prefer high or low contrast video
-- who have audio issues and prefer audio that lacks background
music, noise, etc.
This is only a partial list. Note that some content is only
available with open captions (aka burned-in). Clearly sub-optimal,
but better than nothing.
2) I think the environment can and should help select and configure
type-1 resources, where it can. It shouldn't need to be always a
manual step by the user interacting with the media player. That is,
I don't see why we cannot have the markup express "this source is
better for people who have accessibility need X" (probably as a media
query). However, media queries are CSS, not HTML...
--
David Singer
Multimedia Standards, Apple Inc.
