Re: [Audacity-devel] Export multiple discarding track start information

[Richard A. <ri...@au...>]

On Sat, 2009-02-28 at 10:44 +0100, Markus Meyer wrote:
> when I use "export multiple", using tracks as separation criterion, the 
> empty space, i.e. silence at the beginning of the tracks is not 
> exported. That is, when one uses "export multiple", then later imports 
> the tracks again, those are not aligned anymore.
> 
> Is this the expected behaviour?

It is, and certainly it has been the behaviour for as long as I've been
doing things to Export Multiple. What gets exported is all the audio
data in the track. Given that the long blank space before the track is
not composed of silent samples but space with no data in it, it doesn't
get exported.

This is correct for the purposes for which Export Multiple is mostly
used, i.e. breaking up a long recording into multiple short tracks,
because you split the long track into many short tracks, which get
exported (minus their leading silence) as the items in the recording.

I can see however that for other purposes (e.g. translating an Audacity
project into another package) there is a need to keep the tracks
exported aligned with each other. I think what this really needs is a
header in each of the exported files that says where it is supposed to
go (in some defined time units) and can be read by a loading application
to put the files in the right places.

This isn't a new idea, it's pretty much what AES31 support does using
BWF for the exported files and defining a timecode header in the BWF
chunk in order to locate each file on the timeline when the audio is
imported. I'm not sure what the adoption has been like, but it seems a
good route to pursue if that is what you are trying to achieve.

Richard