.TH one-bit-instrument 7 "February 2012" "numm" "Numm Tutorials"
.SH NAME
one bit instrument \- how to make a gnarly synth with \fBnumm-run\fR
.SH SYNOPSIS
numm-run \fIFILE\fR
.SH DESCRIPTION
In this tutorial we will learn how to live-code
a one-bit synthesizer
controlled by mouse position.
It is intended as a gentle introduction to
development with \fBnumm-run\fR.
.PP
To get started,
create a text file with the following method stubs:
.IP
.EX
def audio_out(a):
    pass
def video_out(a):
    pass
.EE
.PP
Save the file as \fIonebit.py\fR,
and then launch it with \fBnumm-run\fR:
.IP
numm-run onebit.py
.PP
You should see a blank window appear.
We will now make some sound and light
by changing the value of \fIa\fR in the
\fIaudio_out\fR and \fIvideo_out\fI functions:
.IP
.EX
def audio_out(a):
    a[::100] = 2**15
def video_out(a):
    a.flat[::100] = 255
.EE
.PP
Save the file, and you should see and hear the sketch update.
This is using numpy's array-indexing to turn every hundredth
audio sample and pixel-color on.
The audio sample rate is by default 44100Hz, so it produces
a series of clicks that will be perceived as a 441Hz tone.
We can turn this into an instrument by connecting
mouse motion to frequency:
.IP
.EX
period = 100
def audio_out(a):
    a[::period] = 2**15
def video_out(a):
    a.flat[::period] = 255
def mouse_in(type,px,py,button):
    global period
    period = px*1000
.EE
.PP
Finally, let's use the keyboard to record and jump to notes.
The first time you press a key, it records the period,
and subsequant depressions play the saved period:
.IP
.EX
period = 100
record = {}
def audio_out(a):
    a[::period] = 2**15
def video_out(a):
    a.flat[::period] = 255
def mouse_in(type,px,py,button):
    global period
    period = px*1000
def keyboard_in(type,key):
    global period
    if record.has_key(key):
        period = record[key]
    elif record.has_key(key):
        record[] = period
.EE
.PP
.SH SEE ALSO
.BR numm-run (1),
.BR numm.getting-started (7),
.BR numm.spectral-analysis (7)