libs/plugins/a-eq.lv2/a-eq.c

   1 /* a-eq
   2  * Copyright (C) 2016 Damien Zammit <damien@zamaudio.com>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #ifndef _GNU_SOURCE
  16 #define _GNU_SOURCE // needed for M_PI
  17 #endif
  18
  19 #include <math.h>
  20 #include <complex.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <stdbool.h>
  24 #include <stdio.h>
  25
  26 #include "lv2/lv2plug.in/ns/lv2core/lv2.h"
  27
  28 #ifdef LV2_EXTENDED
  29 #include <cairo/cairo.h>
  30 #include "ardour/lv2_extensions.h"
  31 #endif
  32
  33 #define AEQ_URI "urn:ardour:a-eq"
  34 #define BANDS   6
  35
  36 #ifndef MIN
  37 #define MIN(A,B) ((A) < (B)) ? (A) : (B)
  38 #endif
  39
  40 typedef enum {
  41         AEQ_SHELFTOGL = 0,
  42         AEQ_FREQL,
  43         AEQ_GAINL,
  44         AEQ_FREQ1,
  45         AEQ_GAIN1,
  46         AEQ_BW1,
  47         AEQ_FREQ2,
  48         AEQ_GAIN2,
  49         AEQ_BW2,
  50         AEQ_FREQ3,
  51         AEQ_GAIN3,
  52         AEQ_BW3,
  53         AEQ_FREQ4,
  54         AEQ_GAIN4,
  55         AEQ_BW4,
  56         AEQ_SHELFTOGH,
  57         AEQ_FREQH,
  58         AEQ_GAINH,
  59         AEQ_MASTER,
  60         AEQ_FILTOGL,
  61         AEQ_FILTOG1,
  62         AEQ_FILTOG2,
  63         AEQ_FILTOG3,
  64         AEQ_FILTOG4,
  65         AEQ_FILTOGH,
  66         AEQ_INPUT,
  67         AEQ_OUTPUT,
  68 } PortIndex;
  69
  70 static inline float
  71 to_dB(float g) {
  72         return (20.f*log10(g));
  73 }
  74
  75 static inline float
  76 from_dB(float gdb) {
  77         return (exp(gdb/20.f*log(10.f)));
  78 }
  79
  80 struct linear_svf {
  81         double g, k;
  82         double a[3];
  83         double m[3];
  84         double s[2];
  85 };
  86
  87 static void linear_svf_reset(struct linear_svf *self)
  88 {
  89         self->s[0] = self->s[1] = 0.0;
  90 }
  91
  92 typedef struct {
  93         float* shelftogl;
  94         float* shelftogh;
  95         float* f0[BANDS];
  96         float* g[BANDS];
  97         float* bw[BANDS];
  98         float* filtog[BANDS];
  99         float* master;
 100
 101         float srate;
 102
 103         float* input;
 104         float* output;
 105
 106         struct linear_svf v_filter[BANDS];
 107         float v_g[BANDS];
 108         float v_bw[BANDS];
 109         float v_f0[BANDS];
 110         float v_filtog[BANDS];
 111         float v_shelftogl;
 112         float v_shelftogh;
 113         float v_master;
 114
 115         bool need_expose;
 116
 117 #ifdef LV2_EXTENDED
 118         LV2_Inline_Display_Image_Surface surf;
 119         cairo_surface_t*                 display;
 120         LV2_Inline_Display*              queue_draw;
 121         uint32_t                         w, h;
 122 #endif
 123 } Aeq;
 124
 125 static LV2_Handle
 126 instantiate(const LV2_Descriptor* descriptor,
 127             double rate,
 128             const char* bundle_path,
 129             const LV2_Feature* const* features)
 130 {
 131         Aeq* aeq = (Aeq*)malloc(sizeof(Aeq));
 132         aeq->srate = rate;
 133
 134 #ifdef LV2_EXTENDED
 135         for (int i=0; features[i]; ++i) {
 136                 if (!strcmp(features[i]->URI, LV2_INLINEDISPLAY__queue_draw)) {
 137                         aeq->queue_draw = (LV2_Inline_Display*) features[i]->data;
 138                 }
 139         }
 140 #endif
 141
 142         for (int i = 0; i < BANDS; i++)
 143                 linear_svf_reset(&aeq->v_filter[i]);
 144
 145         aeq->need_expose = true;
 146         aeq->display = NULL;
 147
 148         return (LV2_Handle)aeq;
 149 }
 150
 151 static void
 152 connect_port(LV2_Handle instance,
 153              uint32_t port,
 154              void* data)
 155 {
 156         Aeq* aeq = (Aeq*)instance;
 157
 158         switch ((PortIndex)port) {
 159         case AEQ_SHELFTOGL:
 160                 aeq->shelftogl = (float*)data;
 161                 break;
 162         case AEQ_FREQL:
 163                 aeq->f0[0] = (float*)data;
 164                 break;
 165         case AEQ_GAINL:
 166                 aeq->g[0] = (float*)data;
 167                 break;
 168         case AEQ_FREQ1:
 169                 aeq->f0[1] = (float*)data;
 170                 break;
 171         case AEQ_GAIN1:
 172                 aeq->g[1] = (float*)data;
 173                 break;
 174         case AEQ_BW1:
 175                 aeq->bw[1] = (float*)data;
 176                 break;
 177         case AEQ_FREQ2:
 178                 aeq->f0[2] = (float*)data;
 179                 break;
 180         case AEQ_GAIN2:
 181                 aeq->g[2] = (float*)data;
 182                 break;
 183         case AEQ_BW2:
 184                 aeq->bw[2] = (float*)data;
 185                 break;
 186         case AEQ_FREQ3:
 187                 aeq->f0[3] = (float*)data;
 188                 break;
 189         case AEQ_GAIN3:
 190                 aeq->g[3] = (float*)data;
 191                 break;
 192         case AEQ_BW3:
 193                 aeq->bw[3] = (float*)data;
 194                 break;
 195         case AEQ_FREQ4:
 196                 aeq->f0[4] = (float*)data;
 197                 break;
 198         case AEQ_GAIN4:
 199                 aeq->g[4] = (float*)data;
 200                 break;
 201         case AEQ_BW4:
 202                 aeq->bw[4] = (float*)data;
 203                 break;
 204         case AEQ_SHELFTOGH:
 205                 aeq->shelftogh = (float*)data;
 206                 break;
 207         case AEQ_FREQH:
 208                 aeq->f0[5] = (float*)data;
 209                 break;
 210         case AEQ_GAINH:
 211                 aeq->g[5] = (float*)data;
 212                 break;
 213         case AEQ_MASTER:
 214                 aeq->master = (float*)data;
 215                 break;
 216         case AEQ_FILTOGL:
 217                 aeq->filtog[0] = (float*)data;
 218                 break;
 219         case AEQ_FILTOG1:
 220                 aeq->filtog[1] = (float*)data;
 221                 break;
 222         case AEQ_FILTOG2:
 223                 aeq->filtog[2] = (float*)data;
 224                 break;
 225         case AEQ_FILTOG3:
 226                 aeq->filtog[3] = (float*)data;
 227                 break;
 228         case AEQ_FILTOG4:
 229                 aeq->filtog[4] = (float*)data;
 230                 break;
 231         case AEQ_FILTOGH:
 232                 aeq->filtog[5] = (float*)data;
 233                 break;
 234         case AEQ_INPUT:
 235                 aeq->input = (float*)data;
 236                 break;
 237         case AEQ_OUTPUT:
 238                 aeq->output = (float*)data;
 239                 break;
 240         }
 241 }
 242
 243 static void
 244 activate(LV2_Handle instance)
 245 {
 246         int i;
 247         Aeq* aeq = (Aeq*)instance;
 248
 249         for (i = 0; i < BANDS; i++)
 250                 linear_svf_reset(&aeq->v_filter[i]);
 251 }
 252
 253 // SVF filters
 254 // http://www.cytomic.com/files/dsp/SvfLinearTrapOptimised2.pdf
 255
 256 static void linear_svf_set_hp(struct linear_svf *self, float sample_rate, float cutoff, float resonance)
 257 {
 258         double f0 = (double)cutoff;
 259         double q = (double)resonance;
 260         double sr = (double)sample_rate;
 261
 262         self->g = tan(M_PI * (f0 / sr));
 263         self->k = 1.0 / q;
 264
 265         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 266         self->a[1] = self->g * self->a[0];
 267         self->a[2] = self->g * self->a[1];
 268
 269         self->m[0] = 1.0;
 270         self->m[1] = -self->k;
 271         self->m[2] = -1.0;
 272 }
 273
 274 static void linear_svf_set_lp(struct linear_svf *self, float sample_rate, float cutoff, float resonance)
 275 {
 276         double f0 = (double)cutoff;
 277         double q = (double)resonance;
 278         double sr = (double)sample_rate;
 279
 280         self->g = tan(M_PI * (f0 / sr));
 281         self->k = 1.0 / q;
 282
 283         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 284         self->a[1] = self->g * self->a[0];
 285         self->a[2] = self->g * self->a[1];
 286
 287         self->m[0] = 0.0;
 288         self->m[1] = 0.0;
 289         self->m[2] = 1.0;
 290 }
 291
 292 static void linear_svf_set_peq(struct linear_svf *self, float gdb, float sample_rate, float cutoff, float bandwidth)
 293 {
 294         double f0 = (double)cutoff;
 295         double q = (double)pow(2.0, 1.0 / bandwidth) / (pow(2.0, bandwidth) - 1.0);
 296         double sr = (double)sample_rate;
 297         double A = pow(10.0, gdb/40.0);
 298
 299         self->g = tan(M_PI * (f0 / sr));
 300         self->k = 1.0 / (q * A);
 301
 302         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 303         self->a[1] = self->g * self->a[0];
 304         self->a[2] = self->g * self->a[1];
 305
 306         self->m[0] = 1.0;
 307         self->m[1] = self->k * (A * A - 1.0);
 308         self->m[2] = 0.0;
 309 }
 310
 311 static void linear_svf_set_highshelf(struct linear_svf *self, float gdb, float sample_rate, float cutoff, float resonance)
 312 {
 313         double f0 = (double)cutoff;
 314         double q = (double)resonance;
 315         double sr = (double)sample_rate;
 316         double A = pow(10.0, gdb/40.0);
 317
 318         self->g = tan(M_PI * (f0 / sr));
 319         self->k = 1.0 / q;
 320
 321         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 322         self->a[1] = self->g * self->a[0];
 323         self->a[2] = self->g * self->a[1];
 324
 325         self->m[0] = A * A;
 326         self->m[1] = self->k * (1.0 - A) * A;
 327         self->m[2] = 1.0 - A * A;
 328 }
 329
 330 static void linear_svf_set_lowshelf(struct linear_svf *self, float gdb, float sample_rate, float cutoff, float resonance)
 331 {
 332         double f0 = (double)cutoff;
 333         double q = (double)resonance;
 334         double sr = (double)sample_rate;
 335         double A = pow(10.0, gdb/40.0);
 336
 337         self->g = tan(M_PI * (f0 / sr));
 338         self->k = 1.0 / q;
 339
 340         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 341         self->a[1] = self->g * self->a[0];
 342         self->a[2] = self->g * self->a[1];
 343
 344         self->m[0] = 1.0;
 345         self->m[1] = self->k * (A - 1.0);
 346         self->m[2] = A * A - 1.0;
 347 }
 348
 349 static float run_linear_svf(struct linear_svf *self, float in)
 350 {
 351         double v[3];
 352         double din = (double)in;
 353         double out;
 354
 355         v[2] = din - self->s[1];
 356         v[0] = (self->a[0] * self->s[0]) + (self->a[1] * v[2]);
 357         v[1] = self->s[1] + (self->a[1] * self->s[0]) + (self->a[2] * v[2]);
 358
 359         self->s[0] = (2.0 * v[0]) - self->s[0];
 360         self->s[1] = (2.0 * v[1]) - self->s[1];
 361
 362         out = (self->m[0] * din)
 363                 + (self->m[1] * v[0])
 364                 + (self->m[2] * v[1]);
 365
 366         return (float)out;
 367 }
 368
 369 static void
 370 run(LV2_Handle instance, uint32_t n_samples)
 371 {
 372         Aeq* aeq = (Aeq*)instance;
 373
 374         const float* const input = aeq->input;
 375         float* const output = aeq->output;
 376
 377         float srate = aeq->srate;
 378         float in0, out;
 379         uint32_t i, j;
 380
 381         if (*(aeq->shelftogl) > 0.5) {
 382                 linear_svf_set_lowshelf(&aeq->v_filter[0], *(aeq->g[0]), srate, *(aeq->f0[0]), 0.7071068);
 383         } else {
 384                 linear_svf_set_hp(&aeq->v_filter[0], srate, *(aeq->f0[0]), 0.7071068);
 385         }
 386         linear_svf_set_peq(&aeq->v_filter[1], *(aeq->g[1]), srate, *(aeq->f0[1]), *(aeq->bw[1]));
 387         linear_svf_set_peq(&aeq->v_filter[2], *(aeq->g[2]), srate, *(aeq->f0[2]), *(aeq->bw[2]));
 388         linear_svf_set_peq(&aeq->v_filter[3], *(aeq->g[3]), srate, *(aeq->f0[3]), *(aeq->bw[3]));
 389         linear_svf_set_peq(&aeq->v_filter[4], *(aeq->g[4]), srate, *(aeq->f0[4]), *(aeq->bw[4]));
 390
 391         if (*(aeq->shelftogh) > 0.5) {
 392                 linear_svf_set_highshelf(&aeq->v_filter[5], *(aeq->g[5]), srate, *(aeq->f0[5]), 0.7071068);
 393         } else {
 394                 linear_svf_set_lp(&aeq->v_filter[5], srate, *(aeq->f0[5]), 0.7071068);
 395         }
 396
 397         for (i = 0; i < n_samples; i++) {
 398                 in0 = input[i];
 399                 out = in0;
 400                 for (j = 0; j < BANDS; j++) {
 401                         if (*(aeq->filtog[j]) > 0.5)
 402                                 out = run_linear_svf(&aeq->v_filter[j], out);
 403                 }
 404                 output[i] = out * from_dB(*(aeq->master));
 405         }
 406
 407         for (i = 0; i < BANDS; i++) {
 408                 if (aeq->v_f0[i] != *(aeq->f0[i])) {
 409                         aeq->v_f0[i] = *(aeq->f0[i]);
 410                         aeq->need_expose = true;
 411                 }
 412                 if (aeq->v_g[i] != *(aeq->g[i])) {
 413                         aeq->v_g[i] = *(aeq->g[i]);
 414                         aeq->need_expose = true;
 415                 }
 416                 if (i != 0 && i != 5 && aeq->v_bw[i] != *(aeq->bw[i])) {
 417                         aeq->v_bw[i] = *(aeq->bw[i]);
 418                         aeq->need_expose = true;
 419                 }
 420                 if (aeq->v_filtog[i] != *(aeq->filtog[i])) {
 421                         aeq->v_filtog[i] = *(aeq->filtog[i]);
 422                         aeq->need_expose = true;
 423                 }
 424                 if (aeq->v_shelftogl != *(aeq->shelftogl)) {
 425                         aeq->v_shelftogl = *(aeq->shelftogl);
 426                         aeq->need_expose = true;
 427                 }
 428                 if (aeq->v_shelftogh != *(aeq->shelftogh)) {
 429                         aeq->v_shelftogh = *(aeq->shelftogh);
 430                         aeq->need_expose = true;
 431                 }
 432                 if (aeq->v_master != *(aeq->master)) {
 433                         aeq->v_master = *(aeq->master);
 434                         aeq->need_expose = true;
 435                 }
 436         }
 437
 438 #ifdef LV2_EXTENDED
 439         if (aeq->need_expose && aeq->queue_draw) {
 440                 aeq->need_expose = false;
 441                 aeq->queue_draw->queue_draw (aeq->queue_draw->handle);
 442         }
 443 #endif
 444 }
 445
 446
 447 #ifdef LV2_EXTENDED
 448 static float
 449 eq_curve (Aeq* self, float f) {
 450         float SR = self->srate;
 451         double complex H = 1.0;
 452         double theta = f * 2. * M_PI / SR;
 453         double complex z = cexp(I * theta);
 454         double A;
 455         double m0, m1, m2, g, k;
 456         int j = 0;
 457
 458         // low
 459         if (self->v_filtog[0]) {
 460                 A = pow(10.0, self->v_g[0]/40.0);
 461                 m0 = self->v_filter[0].m[0];
 462                 m1 = self->v_filter[0].m[1];
 463                 m2 = self->v_filter[0].m[2];
 464                 g = self->v_filter[0].g;
 465                 k = self->v_filter[0].k;
 466                 if (self->v_shelftogl) {
 467                         // lowshelf
 468                         H *= (A*m0*(z-1.0)*(z-1.0) + g*g*(m0+m2)*(1.0+z)*(1.0+z) + sqrt(A)*g*(k*m0+m1) * (z*z-1.0)) / (A*(z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z) + sqrt(A)*g*k*(z*z-1.0));
 469                 } else {
 470                         // hp:
 471                         H *= ((z-1.0)*(z-1.0)) / ((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z) + g*k*(z*z-1.0));
 472                 }
 473                 j++;
 474         }
 475
 476         // peq1:
 477         if (self->v_filtog[1]) {
 478                 A = pow(10.0, self->v_g[1]/40.0);
 479                 m0 = self->v_filter[1].m[0];
 480                 m1 = self->v_filter[1].m[1];
 481                 m2 = self->v_filter[1].m[2];
 482                 g = self->v_filter[1].g;
 483                 k = self->v_filter[1].k;
 484                 H *= (g*k*m0*(z*z-1.0) + A*(g*(1.0+z)*(m1*(z-1.0) + g*m2*(1.0+z)) + m0*((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z)))) / (g*k*(z*z-1.0) + A*((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z)));
 485                 j++;
 486         }
 487
 488         // peq2:
 489         if (self->v_filtog[2]) {
 490                 A = pow(10.0, self->v_g[2]/40.0);
 491                 m0 = self->v_filter[2].m[0];
 492                 m1 = self->v_filter[2].m[1];
 493                 m2 = self->v_filter[2].m[2];
 494                 g = self->v_filter[2].g;
 495                 k = self->v_filter[2].k;
 496                 H *= (g*k*m0*(z*z-1.0) + A*(g*(1.0+z)*(m1*(z-1.0) + g*m2*(1.0+z)) + m0*((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z)))) / (g*k*(z*z-1.0) + A*((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z)));
 497                 j++;
 498         }
 499
 500         // peq3:
 501         if (self->v_filtog[3]) {
 502                 A = pow(10.0, self->v_g[3]/40.0);
 503                 m0 = self->v_filter[3].m[0];
 504                 m1 = self->v_filter[3].m[1];
 505                 m2 = self->v_filter[3].m[2];
 506                 g = self->v_filter[3].g;
 507                 k = self->v_filter[3].k;
 508                 H *= (g*k*m0*(z*z-1.0) + A*(g*(1.0+z)*(m1*(z-1.0) + g*m2*(1.0+z)) + m0*((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z)))) / (g*k*(z*z-1.0) + A*((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z)));
 509                 j++;
 510         }
 511
 512         // peq4:
 513         if (self->v_filtog[4]) {
 514                 A = pow(10.0, self->v_g[4]/40.0);
 515                 m0 = self->v_filter[4].m[0];
 516                 m1 = self->v_filter[4].m[1];
 517                 m2 = self->v_filter[4].m[2];
 518                 g = self->v_filter[4].g;
 519                 k = self->v_filter[4].k;
 520                 H *= (g*k*m0*(z*z-1.0) + A*(g*(1.0+z)*(m1*(z-1.0) + g*m2*(1.0+z)) + m0*((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z)))) / (g*k*(z*z-1.0) + A*((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z)));
 521                 j++;
 522         }
 523
 524         // high
 525         if (self->v_filtog[5]) {
 526                 A = pow(10.0, self->v_g[5]/40.0);
 527                 m0 = self->v_filter[5].m[0];
 528                 m1 = self->v_filter[5].m[1];
 529                 m2 = self->v_filter[5].m[2];
 530                 g = self->v_filter[5].g;
 531                 k = self->v_filter[5].k;
 532                 if (self->v_shelftogh) {
 533                         // highshelf:
 534                         H *= ( sqrt(A) * g * (1.0 + z) * (m1 * (z - 1.0) + sqrt(A)*g*m2*(1.0+z)) + m0 * ( (z-1.0)*(z-1.0) + A*g*g*(1.0+z)*(1.0+z) + sqrt(A)*g*k*(z*z-1.0))) / ((z-1.0)*(z-1.0) + A*g*g*(1.0+z)*(1.0+z) + sqrt(A)*g*k*(z*z-1.0));
 535                 } else {
 536                         // lp:
 537                         H *= (g*g*(1.0+z)*(1.0+z)) / ((z-1.0)*(z-1.0) + g*g*(1.0+z)*(1.0+z) + g*k*(z*z-1.0));
 538                 }
 539                 j++;
 540         }
 541
 542         return cabs(H);
 543 }
 544
 545 static LV2_Inline_Display_Image_Surface *
 546 render_inline (LV2_Handle instance, uint32_t w, uint32_t max_h)
 547 {
 548         Aeq* self = (Aeq*)instance;
 549         uint32_t h = MIN (w * 9 / 16, max_h);
 550
 551         if (!self->display || self->w != w || self->h != h) {
 552                 if (self->display) cairo_surface_destroy(self->display);
 553                 self->display = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, w, h);
 554                 self->w = w;
 555                 self->h = h;
 556         }
 557
 558         cairo_t* cr = cairo_create (self->display);
 559
 560         // clear background
 561         cairo_rectangle (cr, 0, 0, w, h);
 562         cairo_set_source_rgba (cr, .2, .2, .2, 1.0);
 563         cairo_fill (cr);
 564
 565         cairo_set_line_width(cr, 1.0);
 566
 567         // draw grid 5dB steps
 568         const double dash2[] = {1, 3};
 569         cairo_save (cr);
 570         cairo_set_line_cap(cr, CAIRO_LINE_CAP_ROUND);
 571         cairo_set_dash(cr, dash2, 2, 2);
 572         cairo_set_source_rgba (cr, 0.5, 0.5, 0.5, 0.5);
 573
 574         for (uint32_t d = 1; d < 8; ++d) {
 575                 const float y = -.5 + floorf (h * (d * 5.f / 40.f));
 576                 cairo_move_to (cr, 0, y);
 577                 cairo_line_to (cr, w, y);
 578                 cairo_stroke (cr);
 579         }
 580         cairo_restore (cr);
 581
 582
 583         // draw curve
 584         cairo_set_source_rgba (cr, .8, .8, .8, 1.0);
 585         cairo_move_to (cr, 0, h);
 586
 587         for (uint32_t x = 0; x < w; ++x) {
 588                 // plot 20..20kHz +-20dB
 589                 const float x_hz = 20.f * powf (1000.f, (float)x / (float)w);
 590                 const float y_db = to_dB(eq_curve(self, x_hz)) + self->v_master;
 591                 const float y = h * -y_db / 40.0 + h / 2;
 592                 cairo_line_to (cr, x, y);
 593                 //printf("(hz,H,db)=(%f, %f, %f)\n", x_hz, from_dB(y_db), y_db);
 594         }
 595         cairo_stroke_preserve (cr);
 596
 597         cairo_line_to (cr, w, h);
 598         cairo_close_path (cr);
 599         cairo_clip (cr);
 600
 601         // create RGBA surface
 602         cairo_destroy (cr);
 603         cairo_surface_flush (self->display);
 604         self->surf.width = cairo_image_surface_get_width (self->display);
 605         self->surf.height = cairo_image_surface_get_height (self->display);
 606         self->surf.stride = cairo_image_surface_get_stride (self->display);
 607         self->surf.data = cairo_image_surface_get_data  (self->display);
 608
 609         return &self->surf;
 610 }
 611 #endif
 612
 613 static const void*
 614 extension_data(const char* uri)
 615 {
 616 #ifdef LV2_EXTENDED
 617         static const LV2_Inline_Display_Interface display  = { render_inline };
 618         if (!strcmp(uri, LV2_INLINEDISPLAY__interface)) {
 619                 return &display;
 620         }
 621 #endif
 622         return NULL;
 623 }
 624
 625 static void
 626 cleanup(LV2_Handle instance)
 627 {
 628 #ifdef LV2_EXTENDED
 629         Aeq* aeq = (Aeq*)instance;
 630         if (aeq->display) {
 631                 cairo_surface_destroy (aeq->display);
 632         }
 633 #endif
 634         free(instance);
 635 }
 636
 637 static const LV2_Descriptor descriptor = {
 638         AEQ_URI,
 639         instantiate,
 640         connect_port,
 641         activate,
 642         run,
 643         NULL,
 644         cleanup,
 645         extension_data
 646 };
 647
 648 LV2_SYMBOL_EXPORT
 649 const LV2_Descriptor*
 650 lv2_descriptor(uint32_t index)
 651 {
 652         switch (index) {
 653         case 0:
 654                 return &descriptor;
 655         default:
 656                 return NULL;
 657         }
 658 }