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         int i;
 132         Aeq* aeq = (Aeq*)malloc(sizeof(Aeq));
 133         aeq->srate = rate;
 134
 135 #ifdef LV2_EXTENDED
 136         for (int i=0; features[i]; ++i) {
 137                 if (!strcmp(features[i]->URI, LV2_INLINEDISPLAY__queue_draw)) {
 138                         aeq->queue_draw = (LV2_Inline_Display*) features[i]->data;
 139                 }
 140         }
 141 #endif
 142
 143         for (i = 0; i < BANDS; i++)
 144                 linear_svf_reset(&aeq->v_filter[i]);
 145
 146         aeq->need_expose = true;
 147         aeq->display = NULL;
 148
 149         return (LV2_Handle)aeq;
 150 }
 151
 152 static void
 153 connect_port(LV2_Handle instance,
 154              uint32_t port,
 155              void* data)
 156 {
 157         Aeq* aeq = (Aeq*)instance;
 158
 159         switch ((PortIndex)port) {
 160         case AEQ_SHELFTOGL:
 161                 aeq->shelftogl = (float*)data;
 162                 break;
 163         case AEQ_FREQL:
 164                 aeq->f0[0] = (float*)data;
 165                 break;
 166         case AEQ_GAINL:
 167                 aeq->g[0] = (float*)data;
 168                 break;
 169         case AEQ_FREQ1:
 170                 aeq->f0[1] = (float*)data;
 171                 break;
 172         case AEQ_GAIN1:
 173                 aeq->g[1] = (float*)data;
 174                 break;
 175         case AEQ_BW1:
 176                 aeq->bw[1] = (float*)data;
 177                 break;
 178         case AEQ_FREQ2:
 179                 aeq->f0[2] = (float*)data;
 180                 break;
 181         case AEQ_GAIN2:
 182                 aeq->g[2] = (float*)data;
 183                 break;
 184         case AEQ_BW2:
 185                 aeq->bw[2] = (float*)data;
 186                 break;
 187         case AEQ_FREQ3:
 188                 aeq->f0[3] = (float*)data;
 189                 break;
 190         case AEQ_GAIN3:
 191                 aeq->g[3] = (float*)data;
 192                 break;
 193         case AEQ_BW3:
 194                 aeq->bw[3] = (float*)data;
 195                 break;
 196         case AEQ_FREQ4:
 197                 aeq->f0[4] = (float*)data;
 198                 break;
 199         case AEQ_GAIN4:
 200                 aeq->g[4] = (float*)data;
 201                 break;
 202         case AEQ_BW4:
 203                 aeq->bw[4] = (float*)data;
 204                 break;
 205         case AEQ_SHELFTOGH:
 206                 aeq->shelftogh = (float*)data;
 207                 break;
 208         case AEQ_FREQH:
 209                 aeq->f0[5] = (float*)data;
 210                 break;
 211         case AEQ_GAINH:
 212                 aeq->g[5] = (float*)data;
 213                 break;
 214         case AEQ_MASTER:
 215                 aeq->master = (float*)data;
 216                 break;
 217         case AEQ_FILTOGL:
 218                 aeq->filtog[0] = (float*)data;
 219                 break;
 220         case AEQ_FILTOG1:
 221                 aeq->filtog[1] = (float*)data;
 222                 break;
 223         case AEQ_FILTOG2:
 224                 aeq->filtog[2] = (float*)data;
 225                 break;
 226         case AEQ_FILTOG3:
 227                 aeq->filtog[3] = (float*)data;
 228                 break;
 229         case AEQ_FILTOG4:
 230                 aeq->filtog[4] = (float*)data;
 231                 break;
 232         case AEQ_FILTOGH:
 233                 aeq->filtog[5] = (float*)data;
 234                 break;
 235         case AEQ_INPUT:
 236                 aeq->input = (float*)data;
 237                 break;
 238         case AEQ_OUTPUT:
 239                 aeq->output = (float*)data;
 240                 break;
 241         }
 242 }
 243
 244 static void
 245 activate(LV2_Handle instance)
 246 {
 247         int i;
 248         Aeq* aeq = (Aeq*)instance;
 249
 250         for (i = 0; i < BANDS; i++)
 251                 linear_svf_reset(&aeq->v_filter[i]);
 252 }
 253
 254 // SVF filters
 255 // http://www.cytomic.com/files/dsp/SvfLinearTrapOptimised2.pdf
 256
 257 static void linear_svf_set_hp(struct linear_svf *self, float sample_rate, float cutoff, float resonance)
 258 {
 259         double f0 = (double)cutoff;
 260         double q = (double)resonance;
 261         double sr = (double)sample_rate;
 262
 263         self->g = tan(M_PI * (f0 / sr));
 264         self->k = 1.0 / q;
 265
 266         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 267         self->a[1] = self->g * self->a[0];
 268         self->a[2] = self->g * self->a[1];
 269
 270         self->m[0] = 1.0;
 271         self->m[1] = -self->k;
 272         self->m[2] = -1.0;
 273 }
 274
 275 static void linear_svf_set_lp(struct linear_svf *self, float sample_rate, float cutoff, float resonance)
 276 {
 277         double f0 = (double)cutoff;
 278         double q = (double)resonance;
 279         double sr = (double)sample_rate;
 280
 281         self->g = tan(M_PI * (f0 / sr));
 282         self->k = 1.0 / q;
 283
 284         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 285         self->a[1] = self->g * self->a[0];
 286         self->a[2] = self->g * self->a[1];
 287
 288         self->m[0] = 0.0;
 289         self->m[1] = 0.0;
 290         self->m[2] = 1.0;
 291 }
 292
 293 static void linear_svf_set_peq(struct linear_svf *self, float gdb, float sample_rate, float cutoff, float bandwidth)
 294 {
 295         double f0 = (double)cutoff;
 296         double q = (double)pow(2.0, 1.0 / bandwidth) / (pow(2.0, bandwidth) - 1.0);
 297         double sr = (double)sample_rate;
 298         double A = pow(10.0, gdb/40.0);
 299
 300         self->g = tan(M_PI * (f0 / sr));
 301         self->k = 1.0 / (q * A);
 302
 303         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 304         self->a[1] = self->g * self->a[0];
 305         self->a[2] = self->g * self->a[1];
 306
 307         self->m[0] = 1.0;
 308         self->m[1] = self->k * (A * A - 1.0);
 309         self->m[2] = 0.0;
 310 }
 311
 312 static void linear_svf_set_highshelf(struct linear_svf *self, float gdb, float sample_rate, float cutoff, float resonance)
 313 {
 314         double f0 = (double)cutoff;
 315         double q = (double)resonance;
 316         double sr = (double)sample_rate;
 317         double A = pow(10.0, gdb/40.0);
 318
 319         self->g = tan(M_PI * (f0 / sr));
 320         self->k = 1.0 / q;
 321
 322         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 323         self->a[1] = self->g * self->a[0];
 324         self->a[2] = self->g * self->a[1];
 325
 326         self->m[0] = A * A;
 327         self->m[1] = self->k * (1.0 - A) * A;
 328         self->m[2] = 1.0 - A * A;
 329 }
 330
 331 static void linear_svf_set_lowshelf(struct linear_svf *self, float gdb, float sample_rate, float cutoff, float resonance)
 332 {
 333         double f0 = (double)cutoff;
 334         double q = (double)resonance;
 335         double sr = (double)sample_rate;
 336         double A = pow(10.0, gdb/40.0);
 337
 338         self->g = tan(M_PI * (f0 / sr));
 339         self->k = 1.0 / q;
 340
 341         self->a[0] = 1.0 / (1.0 + self->g * (self->g + self->k));
 342         self->a[1] = self->g * self->a[0];
 343         self->a[2] = self->g * self->a[1];
 344
 345         self->m[0] = 1.0;
 346         self->m[1] = self->k * (A - 1.0);
 347         self->m[2] = A * A - 1.0;
 348 }
 349
 350 static float run_linear_svf(struct linear_svf *self, float in)
 351 {
 352         double v[3];
 353         double din = (double)in;
 354         double out;
 355
 356         v[2] = din - self->s[1];
 357         v[0] = (self->a[0] * self->s[0]) + (self->a[1] * v[2]);
 358         v[1] = self->s[1] + (self->a[1] * self->s[0]) + (self->a[2] * v[2]);
 359
 360         self->s[0] = (2.0 * v[0]) - self->s[0];
 361         self->s[1] = (2.0 * v[1]) - self->s[1];
 362
 363         out = (self->m[0] * din)
 364                 + (self->m[1] * v[0])
 365                 + (self->m[2] * v[1]);
 366
 367         return (float)out;
 368 }
 369
 370 static void
 371 run(LV2_Handle instance, uint32_t n_samples)
 372 {
 373         Aeq* aeq = (Aeq*)instance;
 374
 375         const float* const input = aeq->input;
 376         float* const output = aeq->output;
 377
 378         float srate = aeq->srate;
 379         float in0, out;
 380         uint32_t i, j;
 381
 382         if (*(aeq->shelftogl) > 0.5) {
 383                 linear_svf_set_lowshelf(&aeq->v_filter[0], *(aeq->g[0]), srate, *(aeq->f0[0]), 0.7071068);
 384         } else {
 385                 linear_svf_set_hp(&aeq->v_filter[0], srate, *(aeq->f0[0]), 0.7071068);
 386         }
 387         linear_svf_set_peq(&aeq->v_filter[1], *(aeq->g[1]), srate, *(aeq->f0[1]), *(aeq->bw[1]));
 388         linear_svf_set_peq(&aeq->v_filter[2], *(aeq->g[2]), srate, *(aeq->f0[2]), *(aeq->bw[2]));
 389         linear_svf_set_peq(&aeq->v_filter[3], *(aeq->g[3]), srate, *(aeq->f0[3]), *(aeq->bw[3]));
 390         linear_svf_set_peq(&aeq->v_filter[4], *(aeq->g[4]), srate, *(aeq->f0[4]), *(aeq->bw[4]));
 391
 392         if (*(aeq->shelftogh) > 0.5) {
 393                 linear_svf_set_highshelf(&aeq->v_filter[5], *(aeq->g[5]), srate, *(aeq->f0[5]), 0.7071068);
 394         } else {
 395                 linear_svf_set_lp(&aeq->v_filter[5], srate, *(aeq->f0[5]), 0.7071068);
 396         }
 397
 398         for (i = 0; i < n_samples; i++) {
 399                 in0 = input[i];
 400                 out = in0;
 401                 for (j = 0; j < BANDS; j++) {
 402                         if (*(aeq->filtog[j]) > 0.5)
 403                                 out = run_linear_svf(&aeq->v_filter[j], out);
 404                 }
 405                 output[i] = out * from_dB(*(aeq->master));
 406         }
 407
 408         for (i = 0; i < BANDS; i++) {
 409                 if (aeq->v_f0[i] != *(aeq->f0[i])) {
 410                         aeq->v_f0[i] = *(aeq->f0[i]);
 411                         aeq->need_expose = true;
 412                 }
 413                 if (aeq->v_g[i] != *(aeq->g[i])) {
 414                         aeq->v_g[i] = *(aeq->g[i]);
 415                         aeq->need_expose = true;
 416                 }
 417                 if (i != 0 && i != 5 && aeq->v_bw[i] != *(aeq->bw[i])) {
 418                         aeq->v_bw[i] = *(aeq->bw[i]);
 419                         aeq->need_expose = true;
 420                 }
 421                 if (aeq->v_filtog[i] != *(aeq->filtog[i])) {
 422                         aeq->v_filtog[i] = *(aeq->filtog[i]);
 423                         aeq->need_expose = true;
 424                 }
 425                 if (aeq->v_shelftogl != *(aeq->shelftogl)) {
 426                         aeq->v_shelftogl = *(aeq->shelftogl);
 427                         aeq->need_expose = true;
 428                 }
 429                 if (aeq->v_shelftogh != *(aeq->shelftogh)) {
 430                         aeq->v_shelftogh = *(aeq->shelftogh);
 431                         aeq->need_expose = true;
 432                 }
 433                 if (aeq->v_master != *(aeq->master)) {
 434                         aeq->v_master = *(aeq->master);
 435                         aeq->need_expose = true;
 436                 }
 437         }
 438
 439 #ifdef LV2_EXTENDED
 440         if (aeq->need_expose && aeq->queue_draw) {
 441                 aeq->need_expose = false;
 442                 aeq->queue_draw->queue_draw (aeq->queue_draw->handle);
 443         }
 444 #endif
 445 }
 446
 447
 448 #ifdef LV2_EXTENDED
 449 static float
 450 eq_curve (Aeq* self, float f) {
 451         float SR = self->srate;
 452         double complex H = 1.0;
 453         double theta = f * 2. * M_PI / SR;
 454         double complex z = cexp(I * theta);
 455         double A;
 456         double m0, m1, m2, g, k;
 457         int j = 0;
 458
 459         // low
 460         if (self->v_filtog[0]) {
 461                 A = pow(10.0, self->v_g[0]/40.0);
 462                 m0 = self->v_filter[0].m[0];
 463                 m1 = self->v_filter[0].m[1];
 464                 m2 = self->v_filter[0].m[2];
 465                 g = self->v_filter[0].g;
 466                 k = self->v_filter[0].k;
 467                 if (self->v_shelftogl) {
 468                         // lowshelf
 469                         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));
 470                 } else {
 471                         // hp:
 472                         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));
 473                 }
 474                 j++;
 475         }
 476
 477         // peq1:
 478         if (self->v_filtog[1]) {
 479                 A = pow(10.0, self->v_g[1]/40.0);
 480                 m0 = self->v_filter[1].m[0];
 481                 m1 = self->v_filter[1].m[1];
 482                 m2 = self->v_filter[1].m[2];
 483                 g = self->v_filter[1].g;
 484                 k = self->v_filter[1].k;
 485                 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)));
 486                 j++;
 487         }
 488
 489         // peq2:
 490         if (self->v_filtog[2]) {
 491                 A = pow(10.0, self->v_g[2]/40.0);
 492                 m0 = self->v_filter[2].m[0];
 493                 m1 = self->v_filter[2].m[1];
 494                 m2 = self->v_filter[2].m[2];
 495                 g = self->v_filter[2].g;
 496                 k = self->v_filter[2].k;
 497                 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)));
 498                 j++;
 499         }
 500
 501         // peq3:
 502         if (self->v_filtog[3]) {
 503                 A = pow(10.0, self->v_g[3]/40.0);
 504                 m0 = self->v_filter[3].m[0];
 505                 m1 = self->v_filter[3].m[1];
 506                 m2 = self->v_filter[3].m[2];
 507                 g = self->v_filter[3].g;
 508                 k = self->v_filter[3].k;
 509                 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)));
 510                 j++;
 511         }
 512
 513         // peq4:
 514         if (self->v_filtog[4]) {
 515                 A = pow(10.0, self->v_g[4]/40.0);
 516                 m0 = self->v_filter[4].m[0];
 517                 m1 = self->v_filter[4].m[1];
 518                 m2 = self->v_filter[4].m[2];
 519                 g = self->v_filter[4].g;
 520                 k = self->v_filter[4].k;
 521                 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)));
 522                 j++;
 523         }
 524
 525         // high
 526         if (self->v_filtog[5]) {
 527                 A = pow(10.0, self->v_g[5]/40.0);
 528                 m0 = self->v_filter[5].m[0];
 529                 m1 = self->v_filter[5].m[1];
 530                 m2 = self->v_filter[5].m[2];
 531                 g = self->v_filter[5].g;
 532                 k = self->v_filter[5].k;
 533                 if (self->v_shelftogh) {
 534                         // highshelf:
 535                         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));
 536                 } else {
 537                         // lp:
 538                         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));
 539                 }
 540                 j++;
 541         }
 542
 543         return cabs(H);
 544 }
 545
 546 static LV2_Inline_Display_Image_Surface *
 547 render_inline (LV2_Handle instance, uint32_t w, uint32_t max_h)
 548 {
 549         Aeq* self = (Aeq*)instance;
 550         uint32_t h = MIN (w, max_h);
 551
 552         if (!self->display || self->w != w || self->h != h) {
 553                 if (self->display) cairo_surface_destroy(self->display);
 554                 self->display = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, w, h);
 555                 self->w = w;
 556                 self->h = h;
 557         }
 558
 559         cairo_t* cr = cairo_create (self->display);
 560
 561         // clear background
 562         cairo_rectangle (cr, 0, 0, w, h);
 563         cairo_set_source_rgba (cr, .2, .2, .2, 1.0);
 564         cairo_fill (cr);
 565
 566         cairo_set_line_width(cr, 1.0);
 567
 568         // draw grid 5dB steps
 569         const double dash2[] = {1, 3};
 570         cairo_save (cr);
 571         cairo_set_line_cap(cr, CAIRO_LINE_CAP_ROUND);
 572         cairo_set_dash(cr, dash2, 2, 2);
 573         cairo_set_source_rgba (cr, 0.5, 0.5, 0.5, 0.5);
 574
 575         for (uint32_t d = 1; d < 8; ++d) {
 576                 const float y = -.5 + floorf (h * (d * 5.f / 40.f));
 577                 cairo_move_to (cr, 0, y);
 578                 cairo_line_to (cr, w, y);
 579                 cairo_stroke (cr);
 580         }
 581         cairo_restore (cr);
 582
 583
 584         // draw curve
 585         cairo_set_source_rgba (cr, .8, .8, .8, 1.0);
 586         cairo_move_to (cr, 0, h);
 587
 588         for (uint32_t x = 0; x < w; ++x) {
 589                 // plot 20..20kHz +-20dB
 590                 const float x_hz = 20.f * powf (1000.f, (float)x / (float)w);
 591                 const float y_db = to_dB(eq_curve(self, x_hz)) + self->v_master;
 592                 const float y = h * -y_db / 40.0 + h / 2;
 593                 cairo_line_to (cr, x, y);
 594                 //printf("(hz,H,db)=(%f, %f, %f)\n", x_hz, from_dB(y_db), y_db);
 595         }
 596         cairo_stroke_preserve (cr);
 597
 598         cairo_line_to (cr, w, h);
 599         cairo_close_path (cr);
 600         cairo_clip (cr);
 601
 602         // create RGBA surface
 603         cairo_destroy (cr);
 604         cairo_surface_flush (self->display);
 605         self->surf.width = cairo_image_surface_get_width (self->display);
 606         self->surf.height = cairo_image_surface_get_height (self->display);
 607         self->surf.stride = cairo_image_surface_get_stride (self->display);
 608         self->surf.data = cairo_image_surface_get_data  (self->display);
 609
 610         return &self->surf;
 611 }
 612 #endif
 613
 614 static const void*
 615 extension_data(const char* uri)
 616 {
 617 #ifdef LV2_EXTENDED
 618         static const LV2_Inline_Display_Interface display  = { render_inline };
 619         if (!strcmp(uri, LV2_INLINEDISPLAY__interface)) {
 620                 return &display;
 621         }
 622 #endif
 623         return NULL;
 624 }
 625
 626 static void
 627 cleanup(LV2_Handle instance)
 628 {
 629 #ifdef LV2_EXTENDED
 630         Aeq* aeq = (Aeq*)instance;
 631         if (aeq->display) {
 632                 cairo_surface_destroy (aeq->display);
 633         }
 634 #endif
 635         free(instance);
 636 }
 637
 638 static const LV2_Descriptor descriptor = {
 639         AEQ_URI,
 640         instantiate,
 641         connect_port,
 642         activate,
 643         run,
 644         NULL,
 645         cleanup,
 646         extension_data
 647 };
 648
 649 LV2_SYMBOL_EXPORT
 650 const LV2_Descriptor*
 651 lv2_descriptor(uint32_t index)
 652 {
 653         switch (index) {
 654         case 0:
 655                 return &descriptor;
 656         default:
 657                 return NULL;
 658         }
 659 }