Brickworks > API documentation > bw_chorus
Chorus / vibrato / flanger with variable rate and amount.
It outputs a mix of the dry input signal with itself going through a modulated delay and an optional feedback, as explained in
J. Dattorro, "Effect Design, Part 2: Delay-Line Modulation and Chorus", J. Audio Eng. Soc., vol. 45, no. 10, pp. 764-788, October 1997.
Module type: dsp
Version: 1.1.0
Requires:
typedef struct bw_chorus_coeffs bw_chorus_coeffs;
Coefficients and related.
typedef struct bw_chorus_state bw_chorus_state;
Internal state and related.
static inline void bw_chorus_init(
bw_chorus_coeffs * BW_RESTRICT coeffs,
float max_delay);
Initializes input parameter values in coeffs using max_delay (s) as the maximum delay time.
max_delay must be finite and non-negative.
static inline void bw_chorus_set_sample_rate(
bw_chorus_coeffs * BW_RESTRICT coeffs,
float sample_rate);
Sets the sample_rate (Hz) value in coeffs.
static inline size_t bw_chorus_mem_req(
const bw_chorus_coeffs * BW_RESTRICT coeffs);
Returns the size, in bytes, of contiguous memory to be supplied to bw_chorus_mem_set() using coeffs.
static inline void bw_chorus_mem_set(
const bw_chorus_coeffs * BW_RESTRICT coeffs,
bw_chorus_state * BW_RESTRICT state,
void * BW_RESTRICT mem);
Associates the contiguous memory block mem to the given state using coeffs.
static inline void bw_chorus_reset_coeffs(
bw_chorus_coeffs * BW_RESTRICT coeffs);
Resets coefficients in coeffs to assume their target values.
static inline float bw_chorus_reset_state(
const bw_chorus_coeffs * BW_RESTRICT coeffs,
bw_chorus_state * BW_RESTRICT state,
float x_0);
Resets the given state to its initial values using the given coeffs and the initial input value x_0.
Returns the corresponding initial output value.
If parameter coeff_fb has value -1.f or 1.f, then x_0 must be 0.f.
static inline void bw_chorus_reset_state_multi(
const bw_chorus_coeffs * BW_RESTRICT coeffs,
bw_chorus_state * BW_RESTRICT const * BW_RESTRICT state,
const float * x_0,
float * y_0,
size_t n_channels);
Resets each of the n_channels states to its initial values using the given coeffs and the corresponding initial input value in the x_0 array.
The corresponding initial output values are written into the y_0 array, if not BW_NULL.
If parameter coeff_fb has value -1.f or 1.f, then x_0 must only contain 0.f.
static inline void bw_chorus_update_coeffs_ctrl(
bw_chorus_coeffs * BW_RESTRICT coeffs);
Triggers control-rate update of coefficients in coeffs.
static inline void bw_chorus_update_coeffs_audio(
bw_chorus_coeffs * BW_RESTRICT coeffs);
Triggers audio-rate update of coefficients in coeffs.
static inline float bw_chorus_process1(
const bw_chorus_coeffs * BW_RESTRICT coeffs,
bw_chorus_state * BW_RESTRICT state,
float x);
Processes one input sample x using coeffs, while using and updating state. Returns the corresponding output sample.
static inline void bw_chorus_process(
bw_chorus_coeffs * BW_RESTRICT coeffs,
bw_chorus_state * BW_RESTRICT state,
const float * x,
float * y,
size_t n_samples);
Processes the first n_samples of the input buffer x and fills the first n_samples of the output buffer y, while using and updating both coeffs and state (control and audio rate).
static inline void bw_chorus_process_multi(
bw_chorus_coeffs * BW_RESTRICT coeffs,
bw_chorus_state * BW_RESTRICT const * BW_RESTRICT state,
const float * const * x,
float * const * y,
size_t n_channels,
size_t n_samples);
Processes the first n_samples of the n_channels input buffers x and fills the first n_samples of the n_channels output buffers y, while using and updating both the common coeffs and each of the n_channels states (control and audio rate).
static inline void bw_chorus_set_rate(
bw_chorus_coeffs * BW_RESTRICT coeffs,
float value);
Sets the modulation rate value (Hz) in coeffs.
value must be finite.
Default value: 1.f.
static inline void bw_chorus_set_delay(
bw_chorus_coeffs * BW_RESTRICT coeffs,
float value);
Sets the center delay value (s) in coeffs.
The actual instantaneous delay is internally limited to avoid buffer overflows.
value must be finite.
Default value: 0.f.
static inline void bw_chorus_set_amount(
bw_chorus_coeffs * BW_RESTRICT coeffs,
float value);
Sets the delay modulation amount (semi-amplitude) value (s) in coeffs.
The actual instantaneous delay is internally limited to avoid buffer overflows.
value must be finite.
Default value: 0.f.
static inline void bw_chorus_set_coeff_x(
bw_chorus_coeffs * BW_RESTRICT coeffs,
float value);
Sets the input coefficient value in coeffs.
value must be finite.
Default value: 1.f.
static inline void bw_chorus_set_coeff_mod(
bw_chorus_coeffs * BW_RESTRICT coeffs,
float value);
Sets the modulated branch coefficient value in coeffs.
value must be finite.
Default value: 0.f.
static inline void bw_chorus_set_coeff_fb(
bw_chorus_coeffs * BW_RESTRICT coeffs,
float value);
Sets the feedback branch coefficient value in coeffs.
Valid range: [-1.f, 1.f].
Default value: 0.f.
static inline char bw_chorus_coeffs_is_valid(
const bw_chorus_coeffs * BW_RESTRICT coeffs);
Tries to determine whether coeffs is valid and returns non-0 if it seems to be the case and 0 if it is certainly not. False positives are possible, false negatives are not.
coeffs must at least point to a readable memory block of size greater than or equal to that of bw_chorus_coeffs.
static inline char bw_chorus_state_is_valid(
const bw_chorus_coeffs * BW_RESTRICT coeffs,
const bw_chorus_state * BW_RESTRICT state);
Tries to determine whether state is valid and returns non-0 if it seems to be the case and 0 if it is certainly not. False positives are possible, false negatives are not.
If coeffs is not BW_NULL extra cross-checks might be performed (state is supposed to be associated to coeffs).
state must at least point to a readable memory block of size greater than or equal to that of bw_chorus_state.
template<size_t N_CHANNELS>
class Chorus {
public:
Chorus(
float maxDelay = 0.01f);
~Chorus();
void setSampleRate(
float sampleRate);
void reset(
float x0 = 0.f,
float * BW_RESTRICT y0 = nullptr);
#ifndef BW_CXX_NO_ARRAY
void reset(
float x0,
std::array<float, N_CHANNELS> * BW_RESTRICT y0);
#endif
void reset(
const float * x0,
float * y0 = nullptr);
#ifndef BW_CXX_NO_ARRAY
void reset(
std::array<float, N_CHANNELS> x0,
std::array<float, N_CHANNELS> * BW_RESTRICT y0 = nullptr);
#endif
void process(
const float * const * x,
float * const * y,
size_t nSamples);
#ifndef BW_CXX_NO_ARRAY
void process(
std::array<const float *, N_CHANNELS> x,
std::array<float *, N_CHANNELS> y,
size_t nSamples);
#endif
void setRate(
float value);
void setDelay(
float value);
void setAmount(
float value);
void setCoeffX(
float value);
void setCoeffMod(
float value);
void setCoeffFB(
float value);
...
}
BW_NULL and BW_CXX_NO_ARRAY.bw_chorus_reset_state().bw_chorus_reset_state_multi() and updated C++ API in this regard.bw_chorus_reset_state() returns the initial output value.reset() functions taking arrays as arguments.size_t instead of BW_SIZE_T.bw_chorus_process() and bw_chorus_process_multi() now use size_t to count samples and channels.const and BW_RESTRICT specifiers to input arguments and implmenetation.process() function taking C-style arrays as arguments.bw_chorus_process_multi().