Hi there,
After weeks of unrelated-to-rosegarden delays, I'm finally updating the pitch
tracker in
branches/glasgow-pitchtracker-2009
The branch code currently just prints frequencies on the command-line; the goal
is to show the frequency graphically, as in:
http://www.n-ism.org/Projects/Microtonalism/rg-perf-review-screenshot.png
NB: if you check out this branch, please bear in mind that I'm not responsible
for the original code. I will make sure that it's in good quality before
submitting patches for trunk, but my priority to date was just getting far
enough that I could meaningfully discuss the below questions. Having spent
about 10 hours working on the previous guy's code, I'm entertaining various
fantasies of a violent nature. Fortunately, he's off in South America, so I'm
safe (he could totally whip me in a fight!).
1) Getting audio samples. In order to display a realtime visual display of
the pitch, we obvious need to compute the pitch, which requires raw audio
samples. At the moment, I've used the old src/sound/JackCaptureClient from
earlier work. However, I'm not certain if this is the best way to do things;
if I were maintaining rosegarden, I'd be tempted to insist that the
contributors rewrite src/sound/JackDriver to add realtime capture to the
framework.
If the JackCaptureClient approach is acceptable, I'll rewrite it to fix the
horribly ugly code. If not, I'll make a first pass at working on JackDriver.
2) Is slot pointerPositionChanged the best way of getting continual updates
about time? Currently, in src/gui/editors/pitchtracker.cpp, I've attached that
signal to my PitchTrackerView::slotUpdateValues(timeT time), which polls the
JackCaptureClient for data, and feeds that to the pitch detector. Is there a
better way of doing this?
3) In order to use the old pitch detector code, I needed to add fftw3 to
Makefile.in. Is that ok? I normally wouldn't like to add a dependency, but
fftw3f was in there anyway.
4) Could somebody fix the page about code style? I always get a blank page:
http://rosegardenmusic.com/wiki/dev:coding_style
I know my additions don't match the existing code style (particular the older
code that I haven't touched), and I can see some problems by comparing it to
the existing rosegarden code, but it would be nice if that wiki page showed
something.
5) I dumped the pitch detector code into src/misc/PitchDetector. What the
right place for it?
This class takes a buffer of samples and produces a pitch value. I didn't
think it was really sound/ material, since it wasn't an audio driver; it
definitely isn't gui/, sequencer/, commands/, or document/. That leaves base/
and misc/... unless you'd prefer it to be in sound/ or
gui/editors/pitchtracker/. I don't mind where it goes; just let me know where
to put it.
Cheers,
- Graham
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