[ogg-dev] handling multitrack Ogg

Silvia Pfeiffer silviapfeiffer1 at gmail.com
Tue Feb 2 13:47:03 PST 2010

On Wed, Feb 3, 2010 at 5:07 AM, Frank Barchard <fbarchard at google.com> wrote:
> It sounds like you're on the right track.  There are 2 places I would start
> looking - DVD's, and Quicktime.
> Quicktime is mature and the container is the basis for mp4 and 3gp.

That's what the post referred to - how it was done in QuickTime.

> Can you find a way to transcode to Ogg maintaining the track information?

Part of the result of putting such information into Skeleton will be
that such transcoding will be enabled, yes.

> 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.
> A nice feature in iMovie is that it does 'ducking', so the commentary pushes
> the audio levels of other tracks down as needed.

Yup, that's what editors are supposed to do. Hopefully some of the
open source editors will eventually evolve to contain such

> Re
> if (video.tracks[1].lang == "fr")          video.tracks[1].enabled = true;
> It would help for W3C to standardize language codes.  Quicktime uses 3
> characters, Ogg uses 2 characters?
> There are also variations of the same language.  Can a script find a closest
> match?

There are standards for language codes. They are not all 2 characters long.
http://www.w3.org/TR/REC-html40/struct/dirlang.html explains what is
in use in W3C.

> In addition to scripting, a system level setting could be used to select
> preferred tracks.

Indeed, at least a browser preference setting would be nice. This is a
call that the browser vendors have to make, not us.

> What ever you do, should equally apply to subtitles.

Of course. This was just an example. We are also talking textual audio
descriptions, btw.


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