450 lines
14 KiB
C++
450 lines
14 KiB
C++
/*
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* Brickworks
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*
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* Copyright (C) 2023 Orastron Srl unipersonale
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*
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* Brickworks is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 3 of the License.
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*
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* Brickworks is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Brickworks. If not, see <http://www.gnu.org/licenses/>.
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*
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* File author: Stefano D'Angelo
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*/
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/*!
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* module_type {{{ dsp }}}
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* version {{{ 1.0.0 }}}
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* requires {{{ bw_common bw_math bw_one_pole }}}
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* description {{{
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* Antialiased hard clipper with parametric bias and gain
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* (compensation) and output bias removal.
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*
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* In other words this implements (approximately)
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*
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* > y(n) = clip(gain \* x(n) + bias, -1, 1) - clip(bias, -1, 1)
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*
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* with antialiasing and optionally dividing the output by gain.
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*
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* As a side effect, antialiasing causes attenuation at higher frequencies
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* (about 3 dB at 0.5 × Nyquist frequency and rapidly increasing at higher
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* frequencies).
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*
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* The antialiasing technique used here is described in
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*
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* J. D. Parker, V. Zavalishin, and E. Le Bivic, "Reducing the Aliasing of
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* Nonlinear Waveshaping Using Continuous-Time Convolution", Proc. 19th Intl.
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* Conf. Digital Audio Effects (DAFx-16), pp. 137-144, Brno, Czech Republic,
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* September 2016.
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* }}}
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* changelog {{{
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* <ul>
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* <li>Version <strong>1.0.0</strong>:
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* <ul>
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* <li>Changed default value for gain compensation to off.</li>
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* <li>Added overloaded C++ <code>reset()</code> functions taking
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* arrays as arguments.</li>
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* <li><code>bw_clip_process()</code> and
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* <code>bw_clip_process_multi()</code> now use <code>size_t</code>
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* to count samples and channels.</li>
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* <li>Added more <code>const</code> and <code>BW_RESTRICT</code>
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* specifiers to input arguments and implementation.</li>
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* <li>Moved C++ code to C header.</li>
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* <li>Added overloaded C++ <code>process()</code> function taking
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* C-style arrays as arguments.</li>
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* <li>Removed usage of reserved identifiers.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.6.0</strong>:
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* <ul>
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* <li>Removed dependency on bw_config.</li>
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* </ul>
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* </li>
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* <li>Version <strong>0.5.0</strong>:
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* <ul>
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* <li>First release.</li>
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* </ul>
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* </li>
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* </ul>
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* }}}
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*/
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#ifndef BW_CLIP_H
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#define BW_CLIP_H
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#include <bw_common.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*! api {{{
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* #### bw_clip_coeffs
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* ```>>> */
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typedef struct bw_clip_coeffs bw_clip_coeffs;
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/*! <<<```
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* Coefficients and related.
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*
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* #### bw_clip_state
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* ```>>> */
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typedef struct bw_clip_state bw_clip_state;
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/*! <<<```
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* Internal state and related.
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*
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* #### bw_clip_init()
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* ```>>> */
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static inline void bw_clip_init(bw_clip_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Initializes input parameter values in `coeffs`.
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*
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* #### bw_clip_set_sample_rate()
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* ```>>> */
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static inline void bw_clip_set_sample_rate(bw_clip_coeffs *BW_RESTRICT coeffs, float sample_rate);
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/*! <<<```
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* Sets the `sample_rate` (Hz) value in `coeffs`.
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*
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* #### bw_clip_reset_coeffs()
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* ```>>> */
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static inline void bw_clip_reset_coeffs(bw_clip_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Resets coefficients in `coeffs` to assume their target values.
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*
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* #### bw_clip_reset_state()
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* ```>>> */
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static inline void bw_clip_reset_state(const bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT state, float x_0);
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/*! <<<```
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* Resets the given `state` to its initial values using the given `coeffs`
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* and the quiescent/initial input value `x_0`.
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*
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* #### bw_clip_update_coeffs_ctrl()
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* ```>>> */
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static inline void bw_clip_update_coeffs_ctrl(bw_clip_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Triggers control-rate update of coefficients in `coeffs`.
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*
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* #### bw_clip_update_coeffs_audio()
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* ```>>> */
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static inline void bw_clip_update_coeffs_audio(bw_clip_coeffs *BW_RESTRICT coeffs);
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/*! <<<```
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* Triggers audio-rate update of coefficients in `coeffs`.
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*
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* #### bw_clip_process1()
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* ```>>> */
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static inline float bw_clip_process1(const bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT state, float x);
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static inline float bw_clip_process1_comp(const bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT state, float x);
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/*! <<<```
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* These function process one input sample `x` using `coeffs`, while using
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* and updating `state`. They return the corresponding output sample.
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*
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* In particular:
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* * `bw_clip_process1()` assumes that gain compensation is disabled;
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* * `bw_clip_process1_comp()` assumes that gain compensation is enabled.
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*
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* #### bw_clip_process()
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* ```>>> */
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static inline void bw_clip_process(bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT state, const float *x, float *y, size_t n_samples);
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/*! <<<```
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* Processes the first `n_samples` of the input buffer `x` and fills the
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* first `n_samples` of the output buffer `y`, while using and updating both
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* `coeffs` and `state` (control and audio rate).
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*
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* #### bw_clip_process_multi()
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* ```>>> */
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static inline void bw_clip_process_multi(bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT const *BW_RESTRICT state, const float * const *x, float * const *y, size_t n_channels, size_t n_samples);
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/*! <<<```
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* Processes the first `n_samples` of the `n_channels` input buffers `x` and
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* fills the first `n_samples` of the `n_channels` output buffers `y`, while
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* using and updating both the common `coeffs` and each of the `n_channels`
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* `state`s (control and audio rate).
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*
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* #### bw_clip_set_bias()
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* ```>>> */
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static inline void bw_clip_set_bias(bw_clip_coeffs *BW_RESTRICT coeffs, float value);
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/*! <<<```
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* Sets the input bias `value` in `coeffs`.
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*
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* Default value: `0.f`.
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*
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* #### bw_clip_set_gain()
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* ```>>> */
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static inline void bw_clip_set_gain(bw_clip_coeffs *BW_RESTRICT coeffs, float value);
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/*! <<<```
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* Sets the gain `value` in `coeffs`.
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*
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* Do not set it to `0.f`, obviously.
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*
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* Default value: `1.f`.
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*
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* #### bw_clip_set_gain_compensation()
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* ```>>> */
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static inline void bw_clip_set_gain_compensation(bw_clip_coeffs *BW_RESTRICT coeffs, char value);
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/*! <<<```
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* Sets whether the output should be divided by gain (`value` non-`0`) or not
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* (`0`).
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*
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* Default value: `0` (off).
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* }}} */
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#ifdef __cplusplus
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}
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#endif
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/*** Implementation ***/
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/* WARNING: This part of the file is not part of the public API. Its content may
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* change at any time in future versions. Please, do not use it directly. */
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#include <bw_math.h>
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#include <bw_one_pole.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct bw_clip_coeffs {
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// Sub-components
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bw_one_pole_coeffs smooth_coeffs;
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bw_one_pole_state smooth_bias_state;
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bw_one_pole_state smooth_gain_state;
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// Coefficients
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float bias_dc;
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float inv_gain;
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// Parameters
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float bias;
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float gain;
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char gain_compensation;
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};
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struct bw_clip_state {
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float x_z1;
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float F_z1;
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};
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static inline void bw_clip_init(bw_clip_coeffs *BW_RESTRICT coeffs) {
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bw_one_pole_init(&coeffs->smooth_coeffs);
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bw_one_pole_set_tau(&coeffs->smooth_coeffs, 0.005f);
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bw_one_pole_set_sticky_thresh(&coeffs->smooth_coeffs, 1e-3f);
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coeffs->bias = 0.f;
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coeffs->gain = 1.f;
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coeffs->gain_compensation = 0;
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}
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static inline void bw_clip_set_sample_rate(bw_clip_coeffs *BW_RESTRICT coeffs, float sample_rate) {
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bw_one_pole_set_sample_rate(&coeffs->smooth_coeffs, sample_rate);
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bw_one_pole_reset_coeffs(&coeffs->smooth_coeffs);
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}
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static inline void bw_clip_do_update_coeffs(bw_clip_coeffs *BW_RESTRICT coeffs, char force) {
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float bias_cur = bw_one_pole_get_y_z1(&coeffs->smooth_bias_state);
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if (force || coeffs->bias != bias_cur) {
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bias_cur = bw_one_pole_process1_sticky_abs(&coeffs->smooth_coeffs, &coeffs->smooth_bias_state, coeffs->bias);
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coeffs->bias_dc = bw_clipf(bias_cur, -1.f, 1.f);
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}
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float gain_cur = bw_one_pole_get_y_z1(&coeffs->smooth_gain_state);
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if (force || coeffs->gain != gain_cur) {
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gain_cur = bw_one_pole_process1_sticky_rel(&coeffs->smooth_coeffs, &coeffs->smooth_gain_state, coeffs->gain);
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coeffs->inv_gain = bw_rcpf(gain_cur);
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}
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}
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static inline void bw_clip_reset_coeffs(bw_clip_coeffs *BW_RESTRICT coeffs) {
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bw_one_pole_reset_state(&coeffs->smooth_coeffs, &coeffs->smooth_bias_state, coeffs->bias);
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bw_one_pole_reset_state(&coeffs->smooth_coeffs, &coeffs->smooth_gain_state, coeffs->gain);
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bw_clip_do_update_coeffs(coeffs, 1);
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}
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static inline void bw_clip_reset_state(const bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT state, float x_0) {
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const float x = bw_one_pole_get_y_z1(&coeffs->smooth_gain_state) * x_0 + bw_one_pole_get_y_z1(&coeffs->smooth_bias_state);
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const float a = bw_absf(x_0);
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state->x_z1 = x;
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state->F_z1 = a > 1.f ? a - 0.5f : 0.5f * a * a;
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}
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static inline void bw_clip_update_coeffs_ctrl(bw_clip_coeffs *BW_RESTRICT coeffs) {
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(void)coeffs;
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}
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static inline void bw_clip_update_coeffs_audio(bw_clip_coeffs *BW_RESTRICT coeffs) {
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bw_clip_do_update_coeffs(coeffs, 0);
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}
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static inline float bw_clip_process1(const bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT state, float x) {
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x = bw_one_pole_get_y_z1(&coeffs->smooth_gain_state) * x + bw_one_pole_get_y_z1(&coeffs->smooth_bias_state);
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const float a = bw_absf(x);
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const float F = a > 1.f ? a - 0.5f : 0.5f * a * a;
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const float d = x - state->x_z1;
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const float y = d * d < 1e-6f ? bw_clipf(0.5f * (x + state->x_z1), -1.f, 1.f) : (F - state->F_z1) * bw_rcpf(d);
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state->x_z1 = x;
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state->F_z1 = F;
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return y - coeffs->bias_dc;
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}
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static inline float bw_clip_process1_comp(const bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT state, float x) {
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float y = bw_clip_process1(coeffs, state, x);
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return coeffs->inv_gain * y;
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}
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static inline void bw_clip_process(bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT state, const float *x, float *y, size_t n_samples) {
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if (coeffs->gain_compensation)
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for (size_t i = 0; i < n_samples; i++) {
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bw_clip_update_coeffs_audio(coeffs);
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y[i] = bw_clip_process1_comp(coeffs, state, x[i]);
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}
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else
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for (size_t i = 0; i < n_samples; i++) {
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bw_clip_update_coeffs_audio(coeffs);
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y[i] = bw_clip_process1(coeffs, state, x[i]);
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}
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}
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static inline void bw_clip_process_multi(bw_clip_coeffs *BW_RESTRICT coeffs, bw_clip_state *BW_RESTRICT const *BW_RESTRICT state, const float * const *x, float * const *y, size_t n_channels, size_t n_samples) {
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if (coeffs->gain_compensation)
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for (size_t i = 0; i < n_samples; i++) {
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bw_clip_update_coeffs_audio(coeffs);
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for (size_t j = 0; j < n_channels; j++)
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y[j][i] = bw_clip_process1_comp(coeffs, state[j], x[j][i]);
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}
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else
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for (size_t i = 0; i < n_samples; i++) {
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bw_clip_update_coeffs_audio(coeffs);
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for (size_t j = 0; j < n_channels; j++)
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y[j][i] = bw_clip_process1(coeffs, state[j], x[j][i]);
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}
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}
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static inline void bw_clip_set_bias(bw_clip_coeffs *BW_RESTRICT coeffs, float value) {
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coeffs->bias = value;
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}
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static inline void bw_clip_set_gain(bw_clip_coeffs *BW_RESTRICT coeffs, float value) {
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coeffs->gain = value;
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}
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static inline void bw_clip_set_gain_compensation(bw_clip_coeffs *BW_RESTRICT coeffs, char value) {
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coeffs->gain_compensation = value;
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}
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#ifdef __cplusplus
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}
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#include <array>
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namespace Brickworks {
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/*** Public C++ API ***/
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/*! api_cpp {{{
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* ##### Brickworks::Clip
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* ```>>> */
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template<size_t N_CHANNELS>
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class Clip {
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public:
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Clip();
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void setSampleRate(float sampleRate);
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void reset(float x_0 = 0.f);
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void reset(const float *BW_RESTRICT x_0);
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void reset(const std::array<float, N_CHANNELS> x_0);
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void process(
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const float * const *x,
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float * const *y,
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size_t nSamples);
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void process(
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const std::array<const float *, N_CHANNELS> x,
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const std::array<float *, N_CHANNELS> y,
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size_t nSamples);
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void setBias(float value);
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void setGain(float value);
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void setGainCompensation(bool value);
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/*! <<<...
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* }
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* ```
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* }}} */
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/*** Implementation ***/
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/* WARNING: This part of the file is not part of the public API. Its content may
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* change at any time in future versions. Please, do not use it directly. */
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private:
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bw_clip_coeffs coeffs;
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bw_clip_state states[N_CHANNELS];
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bw_clip_state *BW_RESTRICT statesP[N_CHANNELS];
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};
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template<size_t N_CHANNELS>
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inline Clip<N_CHANNELS>::Clip() {
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bw_clip_init(&coeffs);
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for (size_t i = 0; i < N_CHANNELS; i++)
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statesP[i] = states + i;
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}
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template<size_t N_CHANNELS>
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inline void Clip<N_CHANNELS>::setSampleRate(float sampleRate) {
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bw_clip_set_sample_rate(&coeffs, sampleRate);
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}
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template<size_t N_CHANNELS>
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inline void Clip<N_CHANNELS>::reset(float x_0) {
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bw_clip_reset_coeffs(&coeffs);
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for (size_t i = 0; i < N_CHANNELS; i++)
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bw_clip_reset_state(&coeffs, states + i, x_0);
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}
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template<size_t N_CHANNELS>
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inline void Clip<N_CHANNELS>::reset(const float *BW_RESTRICT x_0) {
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bw_clip_reset_coeffs(&coeffs);
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for (size_t i = 0; i < N_CHANNELS; i++)
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bw_clip_reset_state(&coeffs, states + i, x_0[i]);
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}
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template<size_t N_CHANNELS>
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inline void Clip<N_CHANNELS>::reset(const std::array<float, N_CHANNELS> x_0) {
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reset(x_0.data());
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}
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template<size_t N_CHANNELS>
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inline void Clip<N_CHANNELS>::process(
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const float * const *x,
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float * const *y,
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size_t nSamples) {
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bw_clip_process_multi(&coeffs, statesP, x, y, N_CHANNELS, nSamples);
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}
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template<size_t N_CHANNELS>
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inline void Clip<N_CHANNELS>::process(
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const std::array<const float *, N_CHANNELS> x,
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const std::array<float *, N_CHANNELS> y,
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size_t nSamples) {
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process(x.data(), y.data(), nSamples);
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}
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template<size_t N_CHANNELS>
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inline void Clip<N_CHANNELS>::setBias(float value) {
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bw_clip_set_bias(&coeffs, value);
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}
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template<size_t N_CHANNELS>
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inline void Clip<N_CHANNELS>::setGain(float value) {
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bw_clip_set_gain(&coeffs, value);
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}
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||
|
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template<size_t N_CHANNELS>
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inline void Clip<N_CHANNELS>::setGainCompensation(bool value) {
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bw_clip_set_gain_compensation(&coeffs, value);
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||
}
|
||
|
||
}
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||
#endif
|
||
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||
#endif
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