It sounds like you're on the right track. There are 2 places I would start looking - DVD's, and Quicktime.<div>Quicktime is mature and the container is the basis for mp4 and 3gp.</div><div>Can you find a way to transcode to Ogg maintaining the track information?</div>
<div><br></div><div>As someone who makes videos, its beyond me to translate audio to other languages, but I would be interested in doing commentary tracks. Right now I do a second version of the video for that.</div><div>
A nice feature in iMovie is that it does 'ducking', so the commentary pushes the audio levels of other tracks down as needed.<br><div><br></div><div>Re</div><div>if (video.tracks[1].lang == "fr") video.tracks[1].en<span class="Apple-style-span" style="background-color: rgb(255, 255, 102);">a</span>bled = true;</div>
<div><br></div><div>It would help for <span class="Apple-style-span" style="font-family: arial, sans-serif; font-size: 13px; border-collapse: collapse; color: rgb(80, 0, 80); ">W3C<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: arial; font-size: small; "> to standardize language codes. Quicktime uses 3 characters, Ogg uses 2 characters?</span></span></div>
<div><span class="Apple-style-span" style="font-family: arial, sans-serif; font-size: 13px; border-collapse: collapse; color: rgb(80, 0, 80); "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: arial; font-size: small; ">There are also variations of the same language. Can a script find a closest match?</span></span></div>
<div><span class="Apple-style-span" style="font-family: arial, sans-serif; font-size: 13px; border-collapse: collapse; color: rgb(80, 0, 80); "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: arial; font-size: small; "><br>
</span></span></div><div><span class="Apple-style-span" style="font-family: arial, sans-serif; font-size: 13px; border-collapse: collapse; color: rgb(80, 0, 80); "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: arial; font-size: small; ">In addition to scripting, a system level setting could be used to select preferred tracks.</span></span></div>
<div><div>What ever you do, should equally apply to subtitles.</div><div><br></div></div><div><div class="gmail_quote">On Tue, Feb 2, 2010 at 3:01 AM, Silvia Pfeiffer <span dir="ltr"><<a href="mailto:silviapfeiffer1@gmail.com">silviapfeiffer1@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">(cc-ed to theora-dev because that will reach a larger audience -<br>
please reply to only one mailing list.)<br>
<br>
Hi all,<br>
<br>
In discussions with the video accessibility subgroup of the W3C HTML<br>
working group, we are currently looking at how to deal with multitrack<br>
video, e.g. such video that has a main video and audio track, plus<br>
e.g. a sign language video track, an audio description audio track, a<br>
caption track and several subtitle tracks in different languages.<br>
(i.e. several theora, several vorbis and several kate tracks)<br>
<br>
We are in the process of developing a JavaScript API for extracting<br>
information from such files and thus be able to control them from<br>
JavaScript, e.g. turn them on/off, find out what is there and what is<br>
relevant etc. In this JavaScript API, it is necessary to address the<br>
tracks.<br>
<br>
Now, I don't think there is an explicit track order in an Ogg file -<br>
tracks are just regarded as parallel entities and differentiated by<br>
serial number, right?<br>
<br>
I found out that the MPEG/QuickTime container format has an explicit<br>
"track ID" that numbers its tracks.<br>
<br>
The track order also determines the display order. "Lower numbered<br>
layers are shown on top of higher-numbered layers. This layering order<br>
is important mainly when multiple video tracks are combined though<br>
graphics modes." (see<br>
<a href="http://developer.apple.com/quicktime/qttutorial/movies.html" target="_blank">http://developer.apple.com/quicktime/qttutorial/movies.html</a>) There is<br>
also an explicit rendering mode, e.g. to alphablend, dither, blend or<br>
copy a layer on top of another one.<br>
<br>
Further, MPEG/QuickTime has an explicit "alternate group ID". This ID<br>
defines tracks that belong to the same group and can thus only be<br>
displayed alternately of each other, e.g. subtitle tracks, audio dubs,<br>
or video tracks with differing video quality.<br>
<br>
I now wonder whether we need to introduce an explicit "track ID" into<br>
Ogg, which will define a fixed order independent of the parsing system<br>
and will allow us in JavaScript to directly address tracks.<br>
<br>
For example, the current draft looks something like this:<br>
<br>
interface MediaTrack {<br>
readonly attribute DOMString title;<br>
readonly attribute DOMString type;<br>
readonly attribute DOMString role;<br>
readonly attribute DOMString lang;<br>
attribute boolean enabled;<br>
...<br>
};<br>
interface MediaTracks {<br>
readonly attribute unsigned long length;<br>
getter MediaTrack item(in unsigned long index);<br>
...<br>
};<br>
interface HTMLMediaElement : HTMLElement {<br>
...<br>
readonly attribute MediaTracks tracks;<br>
...<br>
};<br>
<br>
Which could be used for something like this:<br>
<br>
if (video.tracks[1].role == "caption") video.tracks[1].enbled = true;<br>
if (video.tracks[1].lang == "fr") video.tracks[1].enbled = true;<br>
<br>
<br>
As you can see, there is track index that runs through all the tracks.<br>
If we want to keep them in the same order in every system, we have to<br>
come up with an ordering scheme.<br>
<br>
Right now, I can see two different systems: the order in which their<br>
BOS pages are given in the Ogg header part - or the order in which the<br>
serial numbers go, when ordered. Alternatively, we can introduce an<br>
explicit track ID and order by that number.<br>
<br>
I'm curious what others think.<br>
<br>
Cheers,<br>
Silvia.<br>
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</blockquote></div><br></div></div>