bw_noise_gen

Generator of white noise with uniform distribution.

This module has no internal state, rather its state is stored into a uint64_t value to which the API user supplies a pointer (as in bw_rand).

Examples

Here you can download one or more example VST3 plugins for Windows, macOS and Linux. Source code of the audio engine(s) is included in the archive(s).

VST® is a trademark of Steinberg Media Technologies GmbH, registered in Europe and other countries.

API

Module type: DSP

bw_noise_gen_coeffs

typedef struct bw_noise_gen_coeffs bw_noise_gen_coeffs;

Coefficients and related.

bw_noise_gen_init()

static inline void bw_noise_gen_init(
	bw_noise_gen_coeffs * BW_RESTRICT coeffs,
	uint64_t * BW_RESTRICT            state);

Initializes input parameter values and sets the state pointer to obtain pseudo-random numbers in coeffs.

bw_noise_gen_set_sample_rate()

static inline void bw_noise_gen_set_sample_rate(
	bw_noise_gen_coeffs * BW_RESTRICT coeffs,
	float                             sample_rate);

Sets the sample_rate (Hz) value in coeffs.

bw_noise_gen_reset_coeffs()

static inline void bw_noise_gen_reset_coeffs(
	bw_noise_gen_coeffs * BW_RESTRICT coeffs);

Resets coefficients in coeffs to assume their target values.

bw_noise_gen_update_coeffs_ctrl()

static inline void bw_noise_gen_update_coeffs_ctrl(
	bw_noise_gen_coeffs * BW_RESTRICT coeffs);

Triggers control-rate update of coefficients in coeffs.

bw_noise_gen_update_coeffs_audio()

static inline void bw_noise_gen_update_coeffs_audio(
	bw_noise_gen_coeffs * BW_RESTRICT coeffs);

Triggers audio-rate update of coefficients in coeffs.

bw_noise_gen_process1*()

static inline float bw_noise_gen_process1(
	const bw_noise_gen_coeffs * BW_RESTRICT coeffs);

static inline float bw_noise_gen_process1_scaling(
	const bw_noise_gen_coeffs * BW_RESTRICT coeffs);

These functions generate and return one sample using coeffs, where:

• bw_noise_gen_process1() assumes that sample rate scaling is disabled;
• bw_noise_gen_process1_scaling() assumes that sample rate scaling is enabled.

Whether sample rate scaling is enabled or not is unchecked even for debugging purposes.

bw_noise_gen_process()

static inline void bw_noise_gen_process(
	bw_noise_gen_coeffs * BW_RESTRICT coeffs,
	float * BW_RESTRICT               y,
	size_t                            n_samples);

Generates and fills the first n_samples of the output buffer y using coeffs.

bw_noise_gen_process_multi()

static inline void bw_noise_gen_process_multi(
	bw_noise_gen_coeffs * BW_RESTRICT       coeffs,
	float * BW_RESTRICT const * BW_RESTRICT y,
	size_t                                  n_channels,
	size_t                                  n_samples);

Generates and fills the first n_samples of the n_channels output buffers y using coeffs.

bw_noise_gen_set_sample_rate_scaling()

static inline void bw_noise_gen_set_sample_rate_scaling(
	bw_noise_gen_coeffs * BW_RESTRICT coeffs,
	char                              value);

Sets whether the output should be scaled (value non-0) or not (0) according to the sample rate in coeffs.

In order to maintain the same perceived loudness at different sample rates, a white noise signal with uniform distribution should be accordingly scaled. The 44100 Hz sample rate is used as a reference (that is, the scaling factor at that sample rate is 1.f).

Default value: 0 (off).

bw_noise_gen_get_scaling_k()

static inline float bw_noise_gen_get_scaling_k(
	const bw_noise_gen_coeffs * BW_RESTRICT coeffs);

Returns the sample rate scaling factor that is applied or would be applied if sample rate scaling were enabled, as stored in coeffs.

coeffs must be at least inthe "sample-rate-set" state.

bw_noise_gen_coeffs_is_valid()

static inline char bw_noise_gen_coeffs_is_valid(
	const bw_noise_gen_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_noise_gen_coeffs.

C++ wrapper

Brickworks::NoiseGen

template<size_t N_CHANNELS = 1>
class NoiseGen {
public:
	NoiseGen(
		uint64_t * BW_RESTRICT state);

	void setSampleRate(
		float sampleRate);

	void reset();

	void process(
		float * BW_RESTRICT const * BW_RESTRICT y,
		size_t                                  nSamples);

# ifndef BW_CXX_NO_ARRAY
	void process(
		std::array<float * BW_RESTRICT, N_CHANNELS> y,
		size_t                                      nSamples);
# endif

	void setSampleRateScaling(
		bool value);
	
	float getScalingK();
...
}

Changelog

• Version 1.2.1:
  • Added default value for N_CHANNELS in C++ API.
  • Updated dependencies.
• Version 1.2.0:
  • Added support for BW_INCLUDE_WITH_QUOTES, BW_NO_CXX, and BW_CXX_NO_EXTERN_C.
• Version 1.1.0:
  • Now using BW_NULL and BW_CXX_NO_ARRAY.
• Version 1.0.0:
  • Added bw_noise_gen_reset_coeffs(), bw_noise_gen_update_coeffs_ctrl(), and bw_noise_gen_update_coeffs_audio().
  • bw_noise_gen_process() and bw_noise_gen_process_multi() now use size_t to count samples and channels.
  • Added more const and BW_RESTRICT specifiers to input arguments and implementation.
  • Moved C++ code to C header.
  • Added overloaded C++ process() function taking C-style arrays as arguments.
  • Removed usage of reserved identifiers.
  • Added debugging code.
• Version 0.6.0:
  • Removed dependency on bw_config.
• Version 0.5.0:
  • Added bw_noise_gen_process_multi().
  • Added C++ wrapper.
• Version 0.2.0:
  • Refactored API.
• Version 0.1.0:
  • First release.