[Audacity-nyquist] Re: selection for analyzer plugs

[Roger B. D. <rb...@cs...>]

I get the digested version of this list, and the images and sounds =
Domonkos
included arrived here as hex rather than attachments I could easily =
view.
Anyway, I gather the problem is that the plug-in does not get =
information
about the location of the selection.

I'm not sure what is the best solution. Nyquist sounds are more than =
just
samples; they contain a scale factor, a start time, a logical stop time =
(the
start time of the next element in a sequence), and a physical stop time
(after this point, all samples are zero). It would make sense for =
Audacity
to pass the selection to Nyquist with a start time that reflects the =
offset
from the beginning of the file. It would also make sense to set up the
Nyquist environment to indicate the start time of the selection (see the
AT-ABS behavior). I think Dominic and I talked about these possibilities
long ago and Dominic wanted to keep things simpler by just having sounds
start at time zero. I'll be the first to admit that while Nyquist does a
pretty good job of doing the "right thing" with all these time offsets =
and
transformations, it can be very confusing and counterintuitive. Since =
people
usually test Nyquist code without time offsets, it's easy to create bugs
that don't show up until you test it under a time transformation. A lot =
of
users might be confused when their code stops working when applied to a
selection because the selection runs their code with a time offset or
stretch factor corresponding to the selection.

An easy solution is simply to pass in selection information by setting =
some
globals and let the plug-in deal with it. This would inelegantly bypass =
some
nifty features in Nyquist already set up to handle such problems, but on =
the
other hand, it might make life easier overall.

This is probably at least a good time to revisit the original design and
make sure it's still a good idea we want to perpetuate.

	-Roger