[Audacity-devel] Sticky Tracks - Change Speed and more, now in CVS

[Mark D <ma...@gm...>]

First, the list of changes from the wiki:

   - Added support for Change Speed.
      - Slowing down a section in a wave track adds silence to linked wave
      tracks.
      - Speeding up a section adds silence to that wave track.
      - Labels shift accordingly.
   - Added support for Generate functions. Chirp, DTMF, Noise, Tone and
   Silence all behave as Pastes.
   - Fixed linking button not toggling states (Push down/pop-up).
   - Turned linking on by default.
   - Renamed menu item from "Link Wave and Label Tracks" to "Link Audio and
   Label Tracks".
   - Fixed bug related to cuts/deletes from label tracks. Selecting only a
   region in a label track and deleting it will delete that region in linked
   wave tracks. Selecting a label track in addition to a wave track is now the
   same as selecting only the wave track. If linking is off, the previous
   behaviour is used.
   - Fixed Cut behaviour when selecting multiple tracks. It previously
   copied one track, then ran the group clear, shifting the track. The rest of
   the copy calls would be copying the wrong selection. OnCut() no longer calls
   the wave track's cut functions (which call copy->clear), but instead calls
   the copy and clear functions directly.

The way I handle Change Speed may not be done. I was talking to Martyn, and
he said that the length of the new track has an extra 10 samples at the end
that may or may not be used. I'm by no means an expert on audio/signals so I
don't really understand the nuts and bolts of the algorithm. So is the usage
pattern of those samples the same for all tracks? Like, if I drag a
selection over 10 tracks, and run Change Speed on them, will they all either
use the extra 10 samples, or all use no extra samples, but no mixing and
matching (five use it and five don't)? Also, isn't 10 samples a matter of
microseconds with regular sampling rates?

The problem with getting the length of the track after it's been adjusted
and using that is that I do the shifting/inserting inside Process(), and not
ProcessOne(), to avoid it being run multiple times. So, I'm anticipating the
final size.

Any opinions on changing OnCut()? It was a lot easier to do that than try to
figure out some way to intercept the problematic cases after they've been
called.

Again, haven't built this on Windows/OS X.

James: Thanks for the suggestion on simplifying the shift cases. I like it.
=)

Mark