- From: Bob Lund <B.Lund@CableLabs.com>
- Date: Fri, 29 Apr 2011 09:24:48 -0600
- To: Mark Watson <watsonm@netflix.com>, Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- CC: HTML Accessibility Task Force <public-html-a11y@w3.org>
> -----Original Message----- > From: public-html-a11y-request@w3.org [mailto:public-html-a11y- > request@w3.org] On Behalf Of Mark Watson > Sent: Thursday, April 28, 2011 11:44 PM > To: Silvia Pfeiffer > Cc: HTML Accessibility Task Force > Subject: Re: Track kinds > > > On Apr 28, 2011, at 6:07 PM, Silvia Pfeiffer wrote: > > > On Fri, Apr 29, 2011 at 6:52 AM, Mark Watson <watsonm@netflix.com> > wrote: > >> All, > >> I updated the wiki page > >> (http://www.w3.org/WAI/PF/HTML/wiki/Track_Kinds) > >> based on our discussion yesterday. There are now three tables, the > >> kinds in the current spec, the kinds that have been suggested and the > >> subset that we have agreed should be added to the spec (currently > just "captions"). > >> If I understand rightly, the general idea is that we should provide > >> precise, container-independent definitions for all the kinds we agree > >> on in a W3C document other than the HTML specification and propose > >> that the HTML specification just define the text labels to be used > with HTML. > >> In parallel, various people will work on introducing the same kinds > >> to various container specifications. > >> We decided to continue the discussion of which ones to propose should > >> be added to the specification on the list. To that end the three that > >> Sylvia suggested yesterday were: > >> - supplementary > >> - commentary > >> - clear audio > >> Comments ? > > > > Thanks for the great work on the wiki page. It is good to pull this > together. > > > > I think the list that we have in the spec right now is a good start > > and should likely be sufficient for a reply to the 3GPP. > > > > As for further values: > > > > I think adding "supplementary" makes sense, because it states that a > > track can be active at the same time as the "main" tracks. > > The "supplementary" value from 3GPP is rather subtle. Usually the main > audio and video tracks have equal "importance" to the overall > presentation. "supplementary" was supposed to convey the idea that this > track is somehow less important than the "main" one. One use for this > information would be that in an extreme bandwidth crunch you should > maintain the "main" track in preference to the "supplementary" one. > Examples are that for a music video the audio is more important than the > video (though I wonder if that is more true of music videos from the 80s > than today) or for sports the video is more important than the audio > (except perhaps competitive yodeling?!?). > > > > > I am not so fussed about any of the others because I think as we > > implement this the list will likely grow. I don't mind adding > > "captions" and "commentary" because I know there is material that has > > in-line captions and there are commentary tracks. Alternatively, > > "captions" could be marked as "alternative" and "commentary as > > "supplementary" with a description of what it actually is in the > > label. > > If they are for well-understood things then explicit values are useful > because people can create UI elements specifically for those things. > Particularly for captions it would be nice for them to be accessed > through the UI in the same way, whether they are burned in or in text > tracks. > > For UI consistency, also, I would prefer to have a "Directors > Commentary" UI element, rather than relying on every directors > commentary track having the same label. > > Btw, what is the situation with labels in media container formats ? I > don't think DASH has anything yet. > > > > > As for "clear audio", I think we first need to clarify what it is > > exactly. As I understood from our requirements discussions, a "clear > > audio" track is a track that has only the speech part of the video so > > that it is possible to turn this sound up through controls in > > comparison to the main audio track. If this is the case, then it > > compares to the "audio/speech" value of the Ogg roles. If instead it > > is as David describes a track which has the speech part amplified in > > comparison to the main audio, then it is actually a replacement for > > the main audio track and would be covered with "alternative" and a > > description in label as "clear audio". > > This is a more general question about how to signal whether a track is > "additive" or "alternative". I think we discussed this before (or maybe > that was a different list, I forget). > > In the context of audio descriptions I've seen it stated that sometimes > an audio description track is a replacement for the main audio track and > in other cases it's intended to be mixed in (i.e. the descriptions fit > somehow into gaps in the main audio track.) > > Does anyone on this list know whether that is true ? > Yes, this is true for commercial video providers delivering content to devices that do not have the capability to mix two audio tracks. So the "descriptive video" track will be a composite of the main and descriptions. They will want to repurpose this same content to HTML5 based devices. Bob Lund > As with the repetitive stimulus question there are three approaches: > (a) treat it as a new property (additive vs alternative) > (b) allow multiple kinds (so we wold have "alternate clearaudio" and > just "clearaudio") > (c) define separate kinds for the different cases, where it makes sense > ("clearaudio-alt" and "clearaudio-mix") > > Personally, I prefer (c) as I don't think the concept is universal > enough to warrant a separate property. > > ...Mark > > > > > Cheers, > > Silvia. > > >
Received on Friday, 29 April 2011 15:25:14 UTC