toolbox/src/exampleCode/audio/somePlayback
Good stereo listening.
someWaves.c implements functionality to generate several
oscillators and waveforms. It can also change playback rate,
mix, change pitch, loop audio samples and send them to the
output speaker(s).
This code generates 16 oscillator sound with pulse-width
modulation on an Indigo--8 in the left ear and 8 in the right
ear. It can change the playback rate of the audio sample with
an algorithm that least impacts the CPU just adding and/or
dropping samples. Also included is concise code for
demonstrating looping (specify loop points and it will loop
between those either forward or backward.)
PLEASE NOTE THERE IS A GREAT DEAL OF DOCUMENTATION IN someWaves.c
It appears the Indigo can do at least 21 oscillators (waveform
of any size) with variable pitch and 26 with fixed pitch. All
at 44100 samples/sec. The lower the output sampling rate, the
more oscillators you get.
One can vary the time duration the given program runs for (default
is 10 seconds) as well as indicate a specific output filename:
Usage: -help
-time (seconds > 0) default: 10
<output file name>
The Makefile included builds five different executables:
someSawtoothWaves stereo sawtooth waves: every harmonic
present with an amplitude 1/harmonic#.
Compile with -DSAWTOOTH_WAVE only.
someSquareWaves stereo sawtooth waves: odd harmonics
present with amplitude 1/harmonic#.
Square wave is a pulse wave with a
50% duty cycle.
Compile with -DSQUARE_WAVE only.
somePulseWaves stereo sawtooth waves: pulse wave
with a short duty cycle.
Compile with -DPULSE_WAVE only.
somePulseWidthModulatedWaves stereo sawtooth waves: pulse waves
with a modulated duty cycle.
Compile with -DPULSE_WAVE
and -DPULSE_WIDTH_MODULATION.
someCoolWaves stereo waves: every fifth harmonic
present with an amplitude 1/harmonic#.
Compile with -DCOOL_WAVE only.
Compiling with no flags yields no sound.
Source
Documentation
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