sph-sp

c code and shared library for sound synthesis and sequencing. the sound processor implementations can also serve as examples.

features

• basics
  • processing of non-interleaved sample arrays with one array per channel
  • unlimited number of channels and unlimited sample rate
  • 64 bit float sample format by default, other formats possible for many processors
  • 32 bit float wav file output and input
  • plotting of samples and sound spectra using gnuplot
  • fast fourier transform (fft) and inverse fast fourier transform (ifft)
• processors that work seamlessly on blocks of continuous data streams
  • windowed-sinc low-pass, high-pass, band-pass and band-reject filters
  • convolution
  • moving average filter
• synthesis
  • linear and bezier interpolation between points for envelopes and other control data
  • lookup-table oscillator for sinusoids and other wave shapes with a stable phase and time-dependent frequency and amplitude changes provided by arrays
  • white noise generator
• sequencing
  • event renderer for parallel block processing with custom routines
  • events for sines and filtered noise
  • event groups that compose for instruments, riffs and songs
  • per channel configuration
• array processing
  • arithmetic, permutations, statistics, and more

code example

see other/examples/example.c or alternatively other/examples/example.sc

sound example

these files came about during testing in development: 1, 2, 3, 4 (one stream of non-repeating patterns per channel).

documentation

• c manual
• sc manual
• api listing

dependencies

• linux or compatible (libc)
• gcc and shell for the provided compile script
• optional: gnuplot
• optional: sph-sc, for development on sph-sp itself or for using the sc macros

setup

• install dependencies as needed
• execute the following from the project directory

./exe/compile-c
./exe/install

the first argument to exe/install can be the destination path prefix, for example ./exe/install /tmp.

installed files

• /usr/include/sph-sp.h
• /usr/include/sph-sp/*
• /usr/lib/libsph-sp.so
• /usr/share/sph-sp/sc-macros.sc

compile-time configuration options

the ifndefs at the top of source/c-precompiled/sph-sp/sph-sp.h can be customised before compilation. custom preprocessor variables can be set before including the header when embedding the full code, or a customized header must be used when using a shared library that has been compiled with the same configuration.

some options that can be configured:

name	default	description
sp_channel_count_t	uint8_t	data type for numbers of channels
sp_channel_limit	2	maximum number of channels
sp_sample_t	double	float data type for samples (quasi continuous)
sp_time_t	uint32_t	integer data type for sample counts (discrete)

c usage

#include <sph-sp.h>

call sp_initialize(cpu_count, default_channel_count, default_sample_rate) once before using other features. for example sp_initialize(1, 2, 48000).

compilation of programs using sph-sp with gcc

gcc -lsph-sp main.c

license

• files under source/c/foreign/nayuki-fft: mit license
• rest: lgpl3+

thanks to

• tom roelandts on whose information the windowed sinc filters are based on
• mborg for the first fft implementation that was used
• mhroth for a simple example of reading/writing wav files
• nayuki for the concise fft implementation that is currently used
• steve smith's dspguide for information about dsp theory
• xoshiro.di.unimi.it for the pseudorandom number generator

similar projects

• clm
• puredata
• csound, supercollider, cmix, cmusic, and arctic