diff options
Diffstat (limited to 'libs/fluidsynth/src/fluid_iir_filter.h')
| -rw-r--r-- | libs/fluidsynth/src/fluid_iir_filter.h | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/libs/fluidsynth/src/fluid_iir_filter.h b/libs/fluidsynth/src/fluid_iir_filter.h new file mode 100644 index 0000000000..7dc5de14a5 --- /dev/null +++ b/libs/fluidsynth/src/fluid_iir_filter.h @@ -0,0 +1,75 @@ +/* FluidSynth - A Software Synthesizer + * + * Copyright (C) 2003 Peter Hanappe and others. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Library General Public License + * as published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Library General Public License for more details. + * + * You should have received a copy of the GNU Library General Public + * License along with this library; if not, write to the Free + * Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA + */ + +#ifndef _FLUID_IIR_FILTER_H +#define _FLUID_IIR_FILTER_H + +#include "fluidsynth_priv.h" + +typedef struct _fluid_iir_filter_t fluid_iir_filter_t; + + +void fluid_iir_filter_apply(fluid_iir_filter_t* iir_filter, + fluid_real_t *dsp_buf, int dsp_buf_count); + +void fluid_iir_filter_reset(fluid_iir_filter_t* iir_filter); + +void fluid_iir_filter_set_q_dB(fluid_iir_filter_t* iir_filter, + fluid_real_t q_dB); + +void fluid_iir_filter_set_fres(fluid_iir_filter_t* iir_filter, + fluid_real_t fres); + +void fluid_iir_filter_calc(fluid_iir_filter_t* iir_filter, + fluid_real_t output_rate, + fluid_real_t fres_mod); + +/* We can't do information hiding here, as fluid_voice_t includes the struct + without a pointer. */ +struct _fluid_iir_filter_t +{ + /* filter coefficients */ + /* The coefficients are normalized to a0. */ + /* b0 and b2 are identical => b02 */ + fluid_real_t b02; /* b0 / a0 */ + fluid_real_t b1; /* b1 / a0 */ + fluid_real_t a1; /* a0 / a0 */ + fluid_real_t a2; /* a1 / a0 */ + + fluid_real_t b02_incr; + fluid_real_t b1_incr; + fluid_real_t a1_incr; + fluid_real_t a2_incr; + int filter_coeff_incr_count; + int compensate_incr; /* Flag: If set, must compensate history */ + fluid_real_t hist1, hist2; /* Sample history for the IIR filter */ + int filter_startup; /* Flag: If set, the filter will be set directly. + Else it changes smoothly. */ + + fluid_real_t fres; /* the resonance frequency, in cents (not absolute cents) */ + fluid_real_t last_fres; /* Current resonance frequency of the IIR filter */ + /* Serves as a flag: A deviation between fres and last_fres */ + /* indicates, that the filter has to be recalculated. */ + fluid_real_t q_lin; /* the q-factor on a linear scale */ + fluid_real_t filter_gain; /* Gain correction factor, depends on q */ +}; + +#endif + |