- From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- Date: Thu, 17 Feb 2011 13:17:16 +1100
- To: David Singer <singer@apple.com>
- Cc: HTML Accessibility Task Force <public-html-a11y@w3.org>
On Thu, Feb 17, 2011 at 12:22 PM, David Singer <singer@apple.com> wrote: > > On Feb 17, 2011, at 8:07 , Silvia Pfeiffer wrote: > >> Dear all, >> >> as discussed in today's media subgroup call, here is the current >> specification of the MPEG DASH manifest format, which is useful for >> the Media Multitrack API solution (1) at >> http://www.w3.org/WAI/PF/HTML/wiki/Media_Multitrack_Media_API : >> >> http://mpeg.chiariglione.org/working_documents/mpeg-b/dash/dash-dis.zip >> >> I personally think we would need to define a profile of it before it >> will work with our media elements - such as enforcing that only one >> mime type is used per manifest and that it works with the @media query >> of our <source> elements. But I haven't actually read the spec yet. It >> will take some time to work this out. > > It is, alas, a big spec. There are...lots of options. But we can surely help understand it. I can pull in experts on various areas as needed. Ask away. There are also public lists you can join if you want more email. > > In general, it'll be better if the profile talks about what must *be* present and work, and be silent about other stuff. Not sure what you mean by only one mime type per manifest, for example... I'm concretely thinking about the following scenario: <video controls> <source src="webm_manifest.mpd" type="?? - maybe video/mpd+webm" /> <source src="mp4_manifest.mpd" type="?? - maybe video/mpd+mp4" /> </video> mpd is what MPEG specified. The manifest file has a mime type of video/vnd.mpeg.dash.mpd , which is not really useful for us in the realm of the <source> elements. So, for a profile, maybe we can define a more specific mime type, which makes more sense to our circumstances. Also, the use of @media would influence what can be in the manifest file, e.g. only videos below a certain screen size. Hope this clarifies the concern I raised. Cheers, Silvia.
Received on Thursday, 17 February 2011 02:18:09 UTC