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Diffstat (limited to 'src/formant_filter.c')
| -rw-r--r-- | src/formant_filter.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/src/formant_filter.c b/src/formant_filter.c new file mode 100644 index 0000000..afbf4f7 --- /dev/null +++ b/src/formant_filter.c @@ -0,0 +1,213 @@ +/* Formant filter plugin. Copyright 2005-2011 David Robillard. + * + * Based on SSM formant filter, + * Copyright 2001 David Griffiths <dave@pawfal.org> + * + * Based on public domain code from alex@smartelectronix.com + * + * This plugin is free software; you can redistribute it and/or modify it under + * the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at your option) + * any later version. + * + * This plugin 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 General Public License for + * details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA + */ + +#define _XOPEN_SOURCE 600 /* strdup */ +#include <stdlib.h> +#include <string.h> +#include <math.h> + +#include <lv2/lv2plug.in/ns/lv2core/lv2.h> + +#define FORMANT_BASE_ID 4300 + +#define FORMANT_NUM_PORTS 3 + +/* Port Numbers */ +#define FORMANT_VOWEL 0 +#define FORMANT_INPUT 1 +#define FORMANT_OUTPUT 2 + +/* Vowel Coefficients */ +const double coeff[5][11] = { + { /* A */ 8.11044e-06, + 8.943665402, -36.83889529, 92.01697887, -154.337906, 181.6233289, + -151.8651235, 89.09614114, -35.10298511, 8.388101016, -0.923313471 + }, + { /* E */ 4.36215e-06, + 8.90438318, -36.55179099, 91.05750846, -152.422234, 179.1170248, + -149.6496211, 87.78352223, -34.60687431, 8.282228154, -0.914150747 + }, + { /* I */ 3.33819e-06, + 8.893102966, -36.49532826, 90.96543286, -152.4545478, 179.4835618, + -150.315433, 88.43409371, -34.98612086, 8.407803364, -0.932568035 + }, + { /* O */ 1.13572e-06, + 8.994734087, -37.2084849, 93.22900521, -156.6929844, 184.596544, + -154.3755513, 90.49663749, -35.58964535, 8.478996281, -0.929252233 + }, + { /* U */ 4.09431e-07, + 8.997322763, -37.20218544, 93.11385476, -156.2530937, 183.7080141, + -153.2631681, 89.59539726, -35.12454591, 8.338655623, -0.910251753 + } +}; + +/* All state information for plugin */ +typedef struct +{ + /* Ports */ + float* vowel; + float* input; + float* output; + + double memory[5][10]; +} Formant; + +/* Linear interpolation */ +inline static float +linear(float bot, float top, float pos, float val1, float val2) +{ + float t = (pos - bot) / (top - bot); + return val1 * t + val2 * (1.0f - t); +} + +/* Construct a new plugin instance */ +static LV2_Handle +instantiate(const LV2_Descriptor* descriptor, + double sample_rate, + const char* bundle_path, + const LV2_Feature* const* features) +{ + return (LV2_Handle)malloc(sizeof(Formant)); +} + +/** Activate an instance */ +static void +activate(LV2_Handle instance) +{ + Formant* plugin = (Formant*)instance; + int i, j; + + for (i = 0; i < 5; ++i) + for (j = 0; j < 10; ++j) + plugin->memory[i][j] = 0.0; +} + +/* Connect a port to a data location */ +static void +connect_port(LV2_Handle instance, + uint32_t port, + void* data) +{ + Formant* plugin = (Formant*)instance; + switch (port) { + case FORMANT_VOWEL: + plugin->vowel = (float*)data; + break; + case FORMANT_INPUT: + plugin->input = (float*)data; + break; + case FORMANT_OUTPUT: + plugin->output = (float*)data; + break; + } +} + +static void +run(LV2_Handle instance, uint32_t nframes) +{ + Formant* plugin = (Formant*)instance; + float vowel; + float in; + float* out; + float res; + float o[5]; + size_t n, v; + + for (n=0; n < nframes; ++n) { + vowel = plugin->vowel[0]; + in = plugin->input[n]; + out = plugin->output; + + for (v=0; v < 5; ++v) { + res = (float) (coeff[v][0] * (in * 0.1f) + + coeff[v][1] * plugin->memory[v][0] + + coeff[v][2] * plugin->memory[v][1] + + coeff[v][3] * plugin->memory[v][2] + + coeff[v][4] * plugin->memory[v][3] + + coeff[v][5] * plugin->memory[v][4] + + coeff[v][6] * plugin->memory[v][5] + + coeff[v][7] * plugin->memory[v][6] + + coeff[v][8] * plugin->memory[v][7] + + coeff[v][9] * plugin->memory[v][8] + + coeff[v][10] * plugin->memory[v][9] ); + + plugin->memory[v][9] = plugin->memory[v][8]; + plugin->memory[v][8] = plugin->memory[v][7]; + plugin->memory[v][7] = plugin->memory[v][6]; + plugin->memory[v][6] = plugin->memory[v][5]; + plugin->memory[v][5] = plugin->memory[v][4]; + plugin->memory[v][4] = plugin->memory[v][3]; + plugin->memory[v][3] = plugin->memory[v][2]; + plugin->memory[v][2] = plugin->memory[v][1]; + plugin->memory[v][1] = plugin->memory[v][0]; + plugin->memory[v][0] = (double)res; + + o[v] = res; + } + + // Mix between formants + if (vowel <= 0) + out[n] = o[0]; + else if (vowel > 0 && vowel < 1) + out[n] = linear(0.0f, 1.0f, vowel, o[1], o[0]); + else if (vowel == 1) + out[n] = o[1]; + else if (vowel > 1 && vowel < 2) + out[n] = linear(0.0f, 1.0f, vowel - 1.0f, o[2], o[1]); + else if (vowel == 2) + out[n] = o[2]; + else if (vowel > 2 && vowel < 3) + out[n] = linear(0.0f, 1.0f, vowel - 2.0f, o[3], o[2]); + else if (vowel == 3) + out[n] = o[3]; + else if (vowel > 3 && vowel < 4) + out[n] = linear(0.0f, 1.0f, vowel - 3.0f, o[4], o[3]); + else //if (vowel >= 4) + out[n] = o[4]; + } +} + +static void +cleanup(LV2_Handle instance) +{ + free(instance); +} + +static const LV2_Descriptor descriptor = { + "http://drobilla.net/plugins/omins/formant_filter", + instantiate, + connect_port, + activate, + run, + NULL, + cleanup, + NULL, +}; + +LV2_SYMBOL_EXPORT const LV2_Descriptor* +lv2_descriptor(uint32_t index) +{ + switch (index) { + case 0: return &descriptor; + default: return NULL; + } +} |