fastmath.signal — generateme/fastmath 2.1.5

Signal processing (effect) and generation (oscillators).

Singal is any sequence with double values.

Signal processing

To process signal use apply-effects or apply-effects-raw (operates on double-array only) function.

Effect is signal filter, created by effect multimethod. Effects can be composed with compose-effects. Effect can be treated as function and can be called for given sample.

Each effect has it's own parametrization which should be passed during creation.

List of all available effects is under effects-list value.

Effects parametrization

Each effect has its own parameters.

:simple-lowpass, :simple-highpass

• :rate - sample rate (default 44100.0)
• :cutoff - cutoff frequency (default 2000.0)

:biquad-eq

Biquad equalizer

• :fc - center frequency
• :gain - gain
• :bw - bandwidth (default: 1.0)
• :fs - sampling rate (defatult: 44100.0)

:biquad-hs, :biquad-ls

Biquad highpass and lowpass shelf filters

• :fc - center frequency
• :gain - gain
• :slope - shelf slope (default 1.5)
• :fs - sampling rate (default 44100.0)

:biquad-lp, :biquad-hp, :biquad-bp

Biquad lowpass, highpass and bandpass filters

• :fc - cutoff/center frequency
• :bw - bandwidth (default 1.0)
• :fs - sampling rate (default 44100.0)

:dj-eq

• :high - high frequency gain (10000Hz)
• :mid - mid frequency gain (1000Hz)
• :low - low frequency gain (100Hz)
• :shelf-slope - shelf slope for high frequency (default 1.5)
• :peak-bw - peak bandwidth for mid and low frequencies (default 1.0)
• :rate - sampling rate (default 44100.0)

:phaser-allpass

• :delay - delay factor (default: 0.5)

:divider

• :denom (long, default 2.0)

:fm

Modulate and demodulate signal using frequency

• :quant - quantization value (0.0 - if no quantization, default 10)
• :omega - carrier factor (default 0.014)
• :phase - deviation factor (default 0.00822)

:bandwidth-limit

https://searchcode.com/file/18573523/cmt/src/lofi.cpp#

• :rate - sample rate (default 44100.0)
• :freq - cutoff frequency (default 1000.0)

:distort

• :factor - distortion factor (default 1.0)

:foverdrive

Fast overdrive

• :drive - drive (default 2.0)

:decimator

• :bits - bit depth (default 2)
• :fs - decimator sample rate (default 4410.0)
• :rate - input sample rate (default 44100.0)

:basstreble

• :bass - bass gain (default 1.0)
• :treble - treble gain (default 1.0)
• :gain - gain (default 0.0)
• :rate - sample rate (default 44100.0)
• :slope - slope for both (default 0.4)
• :bass-freq - bass freq (default 250.0)
• :treble-freq - treble freq (default 4000.0)

:echo

• :delay - delay time in seconds (default 0.5)
• :decay - decay (amount echo in signal, default 0.5)
• :rate - sample rate (default 44100.0)

Warning! Echo filter uses mutable array as a internal state, don't use the same filter in paraller processing.

:vcf303

• :rate - sample rate (default 44100.0)
• :trigger - boolean, trigger some action (default false), set true when you reset filter every line
• :cutoff - cutoff frequency (values 0-1, default 0.8)
• :resonance - resonance (values 0-1, default 0.8)
• :env-mod - envelope modulation (values 0-1, default 0.5)
• :decay - decay (values 0-1, default 1.0)
• :gain - gain output signal (default: 1.0)

:slew-limit

http://git.drobilla.net/cgit.cgi/omins.lv2.git/tree/src/slew_limiter.c

• :rate - sample rate
• :maxrise - maximum change for rising signal (in terms of 1/rate steps, default 500)
• :maxfall - maximum change for falling singal (default 500)

:mda-thru-zero

• :rate - sample rate
• :speed - effect rate
• :depth
• :mix
• :depth-mod
• :feedback

Warning: internal state is kept in doubles array.

Oscillators

oscillator creates function which generates signal value for given time.

To sample generated wave to signal, call oscillator->signal with following parameters:

• f - oscillator
• samplerate - sample rate (samples per second)
• seconds - duration

To convert signal to oscillator (using interpolation) use signal->oscillator passing signal and duration.

Add oscillators using oscillators-sum.

Smoothing filter

Savitzky-Golay smoothing filter savgol-filter.

File operations

You can save-signal or load-signal. Representation is 16 bit signed, big endian. Use Audacity or SoX to convert to/from audio files.

apply-effects clj

(apply-effects in effects)

(apply-effects in effects reset)

Apply effects to signal as any sequence.

If reset is positive, reinit state each reset number of samples.

Returns new signal.

apply-effects-raw clj

(apply-effects-raw in effects)

(apply-effects-raw in effects reset)

Apply effects to signal as double-array.

If reset is positive, reinit state each reset number of samples.

Returns new signal as double-array.

compose-effects clj

(compose-effects e & es)

Compose effects.

db->linear clj

(db->linear x)

DB to Linear

effect clj multimethod

Create effect for given name (as keyword) and optional parameters.

List of all possible effects is under effects-list.

Effect is a custom type which contains: name, sample (result of last call), effect function and current state.

Effect can be considered as function: call with sample to effect with next state or call without parameter to obtain latest result. Effects are also composable with compose-effects.

effects-list clj

List of effects.

kernel-smoothing-filter clj

(kernel-smoothing-filter kernel)

(kernel-smoothing-filter kernel length)

(kernel-smoothing-filter kernel length step)

Creates Nadaraya-Watson kernel-weighted average

Arguments:

• kernel - [[kernel]] function (default gaussian)
• length - length of the kernel (default: 5)
• step - distance between consecutive samples (default: 1.0)

Returns filtering function. See also savgol-filter.

linear->db clj

(linear->db x)

Linear to DB

load-signal clj

(load-signal filename)

Read signal from file

Expected representation is 16 bit signed, big endian file.

moving-average-filter clj

(moving-average-filter)

(moving-average-filter length)

Creates moving average filter.

Arguments:

• length - length of the kernel (default: 5)

Returns filtering function. See also savgol-filter.

oscillator clj multimethod

Create oscillator.

Parameters are:

• oscilator name (see oscillators variable)
• frequency
• amplitude
• phase (0-1)

Multimethod creates oscillator function accepting double (as time) and returns double from [-1.0 1.0] range.

To convert oscillator to signal, call [[signal-from-oscillator]].

To add oscillators, call [[sum-oscillators]].

oscillator->signal clj

(oscillator->signal f samplerate seconds)

Create signal from oscillator.

Parameters are:

• f - oscillator
• samplerate - in Hz
• seconds - duration

Returns sampled signal as double array.

oscillator-gain clj

(oscillator-gain fs gain)

oscillators clj

List of oscillator names used with oscillator

oscillators-sum clj

(oscillators-sum & fs)

Create oscillator which is sum of all oscillators.

save-signal clj

(save-signal sig filename)

Save signal to file.

Representation is: 16 bit signed, big endian file You can use Audacity/SOX utilities to convert files to audio.

savgol-filter clj

(savgol-filter)

(savgol-filter length)

(savgol-filter length order)

(savgol-filter length order derivative)

Creates Savitzky-Golay smoothing filter.

Arguments:

• length - length of the kernel (default: 5)
• order - polynomial order (default: 2)
• derivative - signal derivative (default: 0)

Returns filtering function which accepts collection of numbers and returns filtered signal.

signal->oscillator clj

(signal->oscillator sig seconds)

(signal->oscillator sig seconds interpolator)

Create oscillator from signal.

Parameters:

• sig - signal as sequence
• seconds - duration
• interpolator - interpolation (see fastmath.interpolation). Default: [[linear-smile]].