clojure2d.extra.signal — clojure2d 1.0.2

Signal processing and generation.

Signal

Signal is array of doubles from range [-1.0.1.0] packed into Signal type.

Signal can be:

• obtained from Pixels with pixels->signal function.
• generated by calling [[signal-from-wave]].
• loaded from file with load-signal function. Signal should be encoded as 16-bit signed integer big endian.

Pixels as Signal

Pixels (Image) can be treated as Signal. Conversion to Signal is based on strategies of converting image to RAW and then converting to audio. It includes channel data layout and packing into integer, encoding, endianess, etc.

To convert Pixels to Signal use pixels->signal function. To convert back use signal->pixels. signal->pixels requires target Pixels object to store result of conversion. Target is mutated then.

To filter Pixels directly (without explicit conversion to and from Signals) you can use [[filter-channels]] with effects-filter.

Wave as Signal

You can create wave function from oscillator. You can also sum waves with sum-waves.

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

• f - wave function
• samplerate - sample rate (samples per second)
• seconds - how many seconds generate

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.

Signal processing

To process Signal use apply-effects function on it.

Effect is signal filter, created with 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 parametrization

: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: like :echo internal state is kept in doubles array.

apply-effects clj

(apply-effects sig effects)

(apply-effects s effects reset)

Apply effects to signal.

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

Returns new signal.

apply-effects-to-pixels clj

(apply-effects-to-pixels effects pixels)

(apply-effects-to-pixels effects reset pixels)

(apply-effects-to-pixels effects config config-back pixels)

(apply-effects-to-pixels effects config config-back reset pixels)

Apply effects directly to Pixels.

Provide configurations to properly convert Pixels to Signal and back. Optionally set reset value (reinit effects' state after reset samples).

If you prefer operating through [[filter-channels]] use [[effect-filter]].

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 parametrization.

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-filter clj

(effects-filter effects)

(effects-filter effects reset)

(effects-filter effects config config-back)

(effects-filter effects config config-back reset)

Creates filter to process Pixels as Signal using [[filter-channels]].

Provide configurations to properly convert Pixels to Signal and back. Optionally set reset value (reinit effects' state after reset samples).

Filter operates on one channel at time and is defined to be used with [[filter-channels]]. If you want to operate on Pixels directly, use apply-effects-to-pixels.

effects-list clj

List of effects.

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.

oscillators clj

List of oscillator names used with wave

pixels->signal clj

(pixels->signal p)

(pixels->signal p
                {:keys [planar? signed? little-endian? bits channels coding]
                 :or {planar? true
                      little-endian? true
                      bits 8
                      signed? false
                      channels [0 1 2]
                      coding :none}})

Convert Pixels to Signal for given specifications.

Specification for conversion is based on Audacity importing options and image to RAW conversions practices. Spec contains:

• planar? - layout of channels data, planar (true, default) or interleaved (false)
• signed? - channel data are encoded as signed (true, default) or unsigned (false) integer.
• little-endian? - for 16 and 24 bits pack channel data with little-endian order (true, default) or big-endian (false)
• bits - pack channel data in 8 (default), 16 or 24 bits.
• channels - list of channels to convert to signal, default [0 1 2] (for all you can use :all keyword).
• coding - encode signal with one of the encoders: :alaw, :alaw-rev, :ulaw, :ulaw-rev or :none (default).

Pixels can be restored from Signal with signal->pixels function.

save-signal clj

(save-signal s filename)

Save signal to file.

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

signal clj

(signal xs)

Signal creator

signal->pixels clj

(signal->pixels sig target)

(signal->pixels sig
                target
                {:keys [planar? signed? little-endian? bits channels coding]
                 :or {planar? true
                      little-endian? true
                      bits 8
                      signed? false
                      channels [0 1 2]
                      coding :none}})

Convert Signal to Pixels storing result into target (mutating it!).

Specification is the same as in [[pixels-signal]] functions.

sum-waves clj

(sum-waves & fs)

Create wave which is sum of all waves.

wave clj multimethod

Create waves from various oscilators

Parameters are:

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

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

To convert wave to Signal, call [[signal-from-wave]].

To add waves, call sum-waves.

wave->signal clj

(wave->signal f samplerate seconds)

Create Signal from wave. Parameters are: f - oscillator, samplerate and number of seconds.