- From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- Date: Thu, 4 Mar 2010 14:45:43 +1100
- To: Maciej Stachowiak <mjs@apple.com>
- Cc: Eric Carlson <eric.carlson@apple.com>, "Michael(tm) Smith" <mike@w3.org>, HTML Accessibility Task Force <public-html-a11y@w3.org>
On Thu, Mar 4, 2010 at 2:27 PM, Maciej Stachowiak <mjs@apple.com> wrote: > > On Mar 3, 2010, at 12:40 PM, Silvia Pfeiffer wrote: > >> On Thu, Mar 4, 2010 at 3:33 AM, Eric Carlson <eric.carlson@apple.com> >> wrote: >>> >>> On Mar 2, 2010, at 11:14 PM, Silvia Pfeiffer wrote: >>> >>>>> >>>>> You also didn't answer my second question - are track names typically >>>>> unique? Do media container formats generally guarantee the presence of >>>>> unique track names? >>>> >>>> There is no guarantee of their existence - same for the role >>>> attribute. But where they exist, they are unique. >>>> >>> Track IDs (which are numeric) in QuickTime and MPEG-4 files are >>> guaranteed to be unique, track names are not required and are *not* >>> guaranteed to be unique. >> >> >> So maybe for MPEG the track ID is the one that should be mapped to the >> this field here as text? Or alternatively it could be a combination of >> track name and the track ID? > > It seems like you can always provide a numeric indexing API to the tracks > regardless of the media format. How about we make that the primary way to > query for a track, and leave the name as an informative field? > > Using a numeric ID as a string name would be particularly confusing with the > proposed API, since there are both name and index getters. Let's say you > have a track that is first in the MediaTracks list, and it has a numeric > track ID of "2". > > You might expect that myVideoElement.tracks["2"] will get the track with ID > 2. But it will instead get the third track in the tracks list. That's > because index getters take priority over name getters, and > myVideoElement.tracks[2] means the same thing as > myVideoElement.tracks["2"] in JavaScript. For this reason, it is a bad idea > to provide both index getters and name getters when the names may be > numeric. > > I suggest that we drop the name getter, since the index getter is more > fundamental. No matter what kind of query you want to do, you can alway loop > over all the tracks using tracks.length and the tracks index getter. OK, I see the problem. I didn't consider that JavaScript converts sees no difference in [2] and ["2"]. I have no issue with removing the getter on namedItem. I don't think it's important. The other getter already does the index by number. Cheers, Silvia.
Received on Thursday, 4 March 2010 03:46:37 UTC