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

   1 /* a-comp
   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 #include <math.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <stdbool.h>
  19
  20 #ifdef LV2_EXTENDED
  21 #include <cairo/cairo.h>
  22 #include "ardour/lv2_extensions.h"
  23 #endif
  24
  25 #include "lv2/lv2plug.in/ns/lv2core/lv2.h"
  26
  27 #define ACOMP_URI               "urn:ardour:a-comp"
  28 #define ACOMP_STEREO_URI        "urn:ardour:a-comp#stereo"
  29
  30 typedef enum {
  31         ACOMP_ATTACK = 0,
  32         ACOMP_RELEASE,
  33         ACOMP_KNEE,
  34         ACOMP_RATIO,
  35         ACOMP_THRESHOLD,
  36         ACOMP_MAKEUP,
  37
  38         ACOMP_GAINR,
  39         ACOMP_OUTLEVEL,
  40         ACOMP_SIDECHAIN,
  41
  42         ACOMP_INPUT,
  43         ACOMP_SC,
  44         ACOMP_OUTPUT,
  45 } PortIndexMono;
  46
  47 typedef enum {
  48         ACOMP_STEREO_ATTACK = 0,
  49         ACOMP_STEREO_RELEASE,
  50         ACOMP_STEREO_KNEE,
  51         ACOMP_STEREO_RATIO,
  52         ACOMP_STEREO_THRESHOLD,
  53         ACOMP_STEREO_MAKEUP,
  54
  55         ACOMP_STEREO_GAINR,
  56         ACOMP_STEREO_OUTLEVEL,
  57         ACOMP_STEREO_SIDECHAIN,
  58
  59         ACOMP_STEREO_INPUT0,
  60         ACOMP_STEREO_INPUT1,
  61         ACOMP_STEREO_SC,
  62         ACOMP_STEREO_OUTPUT0,
  63         ACOMP_STEREO_OUTPUT1,
  64 } PortIndexStereo;
  65
  66 typedef struct {
  67         float* attack;
  68         float* release;
  69         float* knee;
  70         float* ratio;
  71         float* thresdb;
  72         float* makeup;
  73
  74         float* gainr;
  75         float* outlevel;
  76         float* sidechain;
  77
  78         float* input0;
  79         float* input1;
  80         float* sc;
  81         float* output0;
  82         float* output1;
  83
  84         float srate;
  85         float old_yl;
  86         float old_y1;
  87         float old_yg;
  88
  89 #ifdef LV2_EXTENDED
  90         bool                     need_expose;
  91         LV2_Inline_Display_Image_Surface surf;
  92         cairo_surface_t*         display;
  93         LV2_Inline_Display*      queue_draw;
  94         uint32_t                 w, h;
  95
  96         /* ports pointers are only valid during run so we'll
  97          * have to cache them for the display, besides
  98          * we do want to check for changes
  99          */
 100         float v_knee;
 101         float v_ratio;
 102         float v_thresdb;
 103         float v_lvl;
 104         float v_lvl_in;
 105         float v_lvl_out;
 106 #endif
 107 } AComp;
 108
 109 static LV2_Handle
 110 instantiate(const LV2_Descriptor* descriptor,
 111             double rate,
 112             const char* bundle_path,
 113             const LV2_Feature* const* features)
 114 {
 115         AComp* acomp = (AComp*)calloc(1, sizeof(AComp));
 116
 117         for (int i=0; features[i]; ++i) {
 118 #ifdef LV2_EXTENDED
 119                 if (!strcmp(features[i]->URI, LV2_INLINEDISPLAY__queue_draw)) {
 120                         acomp->queue_draw = (LV2_Inline_Display*) features[i]->data;
 121                 }
 122 #endif
 123         }
 124
 125         acomp->srate = rate;
 126         acomp->old_yl=acomp->old_y1=acomp->old_yg=0.f;
 127         acomp->need_expose = true;
 128
 129         return (LV2_Handle)acomp;
 130 }
 131
 132
 133 static void
 134 connect_port_mono(LV2_Handle instance,
 135              uint32_t port,
 136              void* data)
 137 {
 138         AComp* acomp = (AComp*)instance;
 139
 140         switch ((PortIndexMono)port) {
 141         case ACOMP_ATTACK:
 142                 acomp->attack = (float*)data;
 143                 break;
 144         case ACOMP_RELEASE:
 145                 acomp->release = (float*)data;
 146                 break;
 147         case ACOMP_KNEE:
 148                 acomp->knee = (float*)data;
 149                 break;
 150         case ACOMP_RATIO:
 151                 acomp->ratio = (float*)data;
 152                 break;
 153         case ACOMP_THRESHOLD:
 154                 acomp->thresdb = (float*)data;
 155                 break;
 156         case ACOMP_MAKEUP:
 157                 acomp->makeup = (float*)data;
 158                 break;
 159         case ACOMP_GAINR:
 160                 acomp->gainr = (float*)data;
 161                 break;
 162         case ACOMP_OUTLEVEL:
 163                 acomp->outlevel = (float*)data;
 164                 break;
 165         case ACOMP_SIDECHAIN:
 166                 acomp->sidechain = (float*)data;
 167                 break;
 168         case ACOMP_INPUT:
 169                 acomp->input0 = (float*)data;
 170                 break;
 171         case ACOMP_SC:
 172                 acomp->sc = (float*)data;
 173                 break;
 174         case ACOMP_OUTPUT:
 175                 acomp->output0 = (float*)data;
 176                 break;
 177         }
 178 }
 179
 180 static void
 181 connect_port_stereo(LV2_Handle instance,
 182              uint32_t port,
 183              void* data)
 184 {
 185         AComp* acomp = (AComp*)instance;
 186
 187         switch ((PortIndexStereo)port) {
 188         case ACOMP_STEREO_ATTACK:
 189                 acomp->attack = (float*)data;
 190                 break;
 191         case ACOMP_STEREO_RELEASE:
 192                 acomp->release = (float*)data;
 193                 break;
 194         case ACOMP_STEREO_KNEE:
 195                 acomp->knee = (float*)data;
 196                 break;
 197         case ACOMP_STEREO_RATIO:
 198                 acomp->ratio = (float*)data;
 199                 break;
 200         case ACOMP_STEREO_THRESHOLD:
 201                 acomp->thresdb = (float*)data;
 202                 break;
 203         case ACOMP_STEREO_MAKEUP:
 204                 acomp->makeup = (float*)data;
 205                 break;
 206         case ACOMP_STEREO_GAINR:
 207                 acomp->gainr = (float*)data;
 208                 break;
 209         case ACOMP_STEREO_OUTLEVEL:
 210                 acomp->outlevel = (float*)data;
 211                 break;
 212         case ACOMP_STEREO_SIDECHAIN:
 213                 acomp->sidechain = (float*)data;
 214                 break;
 215         case ACOMP_STEREO_INPUT0:
 216                 acomp->input0 = (float*)data;
 217                 break;
 218         case ACOMP_STEREO_INPUT1:
 219                 acomp->input1 = (float*)data;
 220                 break;
 221         case ACOMP_STEREO_SC:
 222                 acomp->sc = (float*)data;
 223                 break;
 224         case ACOMP_STEREO_OUTPUT0:
 225                 acomp->output0 = (float*)data;
 226                 break;
 227         case ACOMP_STEREO_OUTPUT1:
 228                 acomp->output1 = (float*)data;
 229                 break;
 230         }
 231 }
 232
 233 // Force already-denormal float value to zero
 234 static inline float
 235 sanitize_denormal(float value) {
 236         if (!isnormal(value)) {
 237                 value = 0.f;
 238         }
 239         return value;
 240 }
 241
 242 static inline float
 243 from_dB(float gdb) {
 244         return (exp(gdb/20.f*log(10.f)));
 245 }
 246
 247 static inline float
 248 to_dB(float g) {
 249         return (20.f*log10(g));
 250 }
 251
 252 static void
 253 activate(LV2_Handle instance)
 254 {
 255         AComp* acomp = (AComp*)instance;
 256
 257         *(acomp->gainr) = 0.0f;
 258         *(acomp->outlevel) = -45.0f;
 259         acomp->old_yl=acomp->old_y1=acomp->old_yg=0.f;
 260 }
 261
 262 static void
 263 run_mono(LV2_Handle instance, uint32_t n_samples)
 264 {
 265         AComp* acomp = (AComp*)instance;
 266
 267         const float* const input = acomp->input0;
 268         const float* const sc = acomp->sc;
 269         float* const output = acomp->output0;
 270
 271         float srate = acomp->srate;
 272         float width = (6.f * *(acomp->knee)) + 0.01;
 273         float cdb=0.f;
 274         float attack_coeff = exp(-1000.f/(*(acomp->attack) * srate));
 275         float release_coeff = exp(-1000.f/(*(acomp->release) * srate));
 276
 277         float max = 0.f;
 278         float lgaininp = 0.f;
 279         float Lgain = 1.f;
 280         float Lxg, Lxl, Lyg, Lyl, Ly1;
 281         int usesidechain = (*(acomp->sidechain) < 0.5) ? 0 : 1;
 282         uint32_t i;
 283         float ingain;
 284         float in0;
 285         float sc0;
 286         float ratio = *(acomp->ratio);
 287         float thresdb = *(acomp->thresdb);
 288
 289 #ifdef LV2_EXTENDED
 290         if (acomp->v_knee != *acomp->knee) {
 291                 acomp->v_knee = *acomp->knee;
 292                 acomp->need_expose = true;
 293         }
 294
 295         if (acomp->v_ratio != *acomp->ratio) {
 296                 acomp->v_ratio = *acomp->ratio;
 297                 acomp->need_expose = true;
 298         }
 299
 300         if (acomp->v_thresdb != *acomp->thresdb) {
 301                 acomp->v_thresdb = *acomp->thresdb;
 302                 acomp->need_expose = true;
 303         }
 304 #endif
 305
 306         float in_peak = 0;
 307
 308         for (i = 0; i < n_samples; i++) {
 309                 in0 = input[i];
 310                 sc0 = sc[i];
 311                 ingain = usesidechain ? fabs(sc0) : fabs(in0);
 312                 Lyg = 0.f;
 313                 Lxg = (ingain==0.f) ? -160.f : to_dB(ingain);
 314                 Lxg = sanitize_denormal(Lxg);
 315
 316                 Lyg = Lxg + (1.f/ratio-1.f)*(Lxg-thresdb+width/2.f)*(Lxg-thresdb+width/2.f)/(2.f*width);
 317
 318                 if (2.f*(Lxg-thresdb) < -width) {
 319                         Lyg = Lxg;
 320                 } else {
 321                         Lyg = thresdb + (Lxg-thresdb)/ratio;
 322                         Lyg = sanitize_denormal(Lyg);
 323                 }
 324
 325                 Lxl = Lxg - Lyg;
 326
 327                 acomp->old_y1 = sanitize_denormal(acomp->old_y1);
 328                 acomp->old_yl = sanitize_denormal(acomp->old_yl);
 329                 Ly1 = fmaxf(Lxl, release_coeff * acomp->old_y1+(1.f-release_coeff)*Lxl);
 330                 Lyl = attack_coeff * acomp->old_yl+(1.f-attack_coeff)*Ly1;
 331                 Ly1 = sanitize_denormal(Ly1);
 332                 Lyl = sanitize_denormal(Lyl);
 333
 334                 cdb = -Lyl;
 335                 Lgain = from_dB(cdb);
 336
 337                 *(acomp->gainr) = Lyl;
 338
 339                 if (ingain > in_peak) {
 340                         in_peak = ingain;
 341                 }
 342                 lgaininp = in0 * Lgain;
 343                 output[i] = lgaininp * from_dB(*(acomp->makeup));
 344
 345                 max = (fabsf(output[i]) > max) ? fabsf(output[i]) : sanitize_denormal(max);
 346
 347                 // TODO re-use local variables on stack
 348                 // store values back to acomp at the end of the inner-loop
 349                 acomp->old_yl = Lyl;
 350                 acomp->old_y1 = Ly1;
 351                 acomp->old_yg = Lyg;
 352         }
 353
 354         *(acomp->outlevel) = (max < 0.0056f) ? -45.f : to_dB(max);
 355
 356 #ifdef LV2_EXTENDED
 357         acomp->v_lvl += .1 * (in_peak - acomp->v_lvl);  // crude LPF TODO use n_samples/rate TC
 358         const float v_lvl_in = (acomp->v_lvl < 0.001f) ? -60.f : to_dB(acomp->v_lvl);
 359         const float v_lvl_out = (max < 0.001f) ? -60.f : to_dB(max);
 360         if (fabsf (acomp->v_lvl_out - v_lvl_out) >= 1 || fabsf (acomp->v_lvl_in - v_lvl_in) >= 1) {
 361                 // >= 1dB difference
 362                 acomp->need_expose = true;
 363                 acomp->v_lvl_in = v_lvl_in;
 364                 acomp->v_lvl_out = v_lvl_out - *acomp->makeup;
 365         }
 366         if (acomp->need_expose && acomp->queue_draw) {
 367                 acomp->need_expose = false;
 368                 acomp->queue_draw->queue_draw (acomp->queue_draw->handle);
 369         }
 370 #endif
 371 }
 372
 373 static void
 374 run_stereo(LV2_Handle instance, uint32_t n_samples)
 375 {
 376         AComp* acomp = (AComp*)instance;
 377
 378         const float* const input0 = acomp->input0;
 379         const float* const input1 = acomp->input1;
 380         const float* const sc = acomp->sc;
 381         float* const output0 = acomp->output0;
 382         float* const output1 = acomp->output1;
 383
 384         float srate = acomp->srate;
 385         float width = (6.f * *(acomp->knee)) + 0.01;
 386         float cdb=0.f;
 387         float attack_coeff = exp(-1000.f/(*(acomp->attack) * srate));
 388         float release_coeff = exp(-1000.f/(*(acomp->release) * srate));
 389
 390         float max = 0.f;
 391         float lgaininp = 0.f;
 392         float rgaininp = 0.f;
 393         float Lgain = 1.f;
 394         float Lxg, Lxl, Lyg, Lyl, Ly1;
 395         int usesidechain = (*(acomp->sidechain) < 0.5) ? 0 : 1;
 396         uint32_t i;
 397         float ingain;
 398         float in0;
 399         float in1;
 400         float sc0;
 401         float maxabslr;
 402         float ratio = *(acomp->ratio);
 403         float thresdb = *(acomp->thresdb);
 404
 405 #ifdef LV2_EXTENDED
 406         if (acomp->v_knee != *acomp->knee) {
 407                 acomp->v_knee = *acomp->knee;
 408                 acomp->need_expose = true;
 409         }
 410
 411         if (acomp->v_ratio != *acomp->ratio) {
 412                 acomp->v_ratio = *acomp->ratio;
 413                 acomp->need_expose = true;
 414         }
 415
 416         if (acomp->v_thresdb != *acomp->thresdb) {
 417                 acomp->v_thresdb = *acomp->thresdb;
 418                 acomp->need_expose = true;
 419         }
 420 #endif
 421
 422         float in_peak = 0;
 423
 424         for (i = 0; i < n_samples; i++) {
 425                 in0 = input0[i];
 426                 in1 = input1[i];
 427                 sc0 = sc[i];
 428                 maxabslr = fmaxf(fabs(in0), fabs(in1));
 429                 ingain = usesidechain ? fabs(sc0) : maxabslr;
 430                 Lyg = 0.f;
 431                 Lxg = (ingain==0.f) ? -160.f : to_dB(ingain);
 432                 Lxg = sanitize_denormal(Lxg);
 433
 434                 Lyg = Lxg + (1.f/ratio-1.f)*(Lxg-thresdb+width/2.f)*(Lxg-thresdb+width/2.f)/(2.f*width);
 435
 436                 if (2.f*(Lxg-thresdb) < -width) {
 437                         Lyg = Lxg;
 438                 } else {
 439                         Lyg = thresdb + (Lxg-thresdb)/ratio;
 440                         Lyg = sanitize_denormal(Lyg);
 441                 }
 442
 443                 Lxl = Lxg - Lyg;
 444
 445                 acomp->old_y1 = sanitize_denormal(acomp->old_y1);
 446                 acomp->old_yl = sanitize_denormal(acomp->old_yl);
 447                 Ly1 = fmaxf(Lxl, release_coeff * acomp->old_y1+(1.f-release_coeff)*Lxl);
 448                 Lyl = attack_coeff * acomp->old_yl+(1.f-attack_coeff)*Ly1;
 449                 Ly1 = sanitize_denormal(Ly1);
 450                 Lyl = sanitize_denormal(Lyl);
 451
 452                 cdb = -Lyl;
 453                 Lgain = from_dB(cdb);
 454
 455                 *(acomp->gainr) = Lyl;
 456
 457                 if (ingain > in_peak) {
 458                         in_peak = ingain;
 459                 }
 460                 lgaininp = in0 * Lgain;
 461                 rgaininp = in1 * Lgain;
 462                 output0[i] = lgaininp * from_dB(*(acomp->makeup));
 463                 output1[i] = rgaininp * from_dB(*(acomp->makeup));
 464
 465                 max = (fmaxf(fabs(output0[i]), fabs(output1[i])) > max) ? fmaxf(fabs(output0[i]), fabs(output1[i])) : sanitize_denormal(max);
 466
 467                 // TODO re-use local variables on stack
 468                 // store values back to acomp at the end of the inner-loop
 469                 acomp->old_yl = Lyl;
 470                 acomp->old_y1 = Ly1;
 471                 acomp->old_yg = Lyg;
 472         }
 473
 474         *(acomp->outlevel) = (max < 0.0056f) ? -45.f : to_dB(max);
 475
 476 #ifdef LV2_EXTENDED
 477         acomp->v_lvl += .1 * (in_peak - acomp->v_lvl);  // crude LPF TODO use n_samples/rate TC
 478         const float v_lvl_in = (acomp->v_lvl < 0.001f) ? -60.f : to_dB(acomp->v_lvl);
 479         const float v_lvl_out = (max < 0.001f) ? -60.f : to_dB(max);
 480         if (fabsf (acomp->v_lvl_out - v_lvl_out) >= 1 || fabsf (acomp->v_lvl_in - v_lvl_in) >= 1) {
 481                 // >= 1dB difference
 482                 acomp->need_expose = true;
 483                 acomp->v_lvl_in = v_lvl_in;
 484                 acomp->v_lvl_out = v_lvl_out - *acomp->makeup;
 485         }
 486         if (acomp->need_expose && acomp->queue_draw) {
 487                 acomp->need_expose = false;
 488                 acomp->queue_draw->queue_draw (acomp->queue_draw->handle);
 489         }
 490 #endif
 491 }
 492
 493 static void
 494 deactivate(LV2_Handle instance)
 495 {
 496         activate(instance);
 497 }
 498
 499 static void
 500 cleanup(LV2_Handle instance)
 501 {
 502 #ifdef LV2_EXTENDED
 503         AComp* acomp = (AComp*)instance;
 504         if (acomp->display) {
 505                 cairo_surface_destroy (acomp->display);
 506         }
 507 #endif
 508
 509         free(instance);
 510 }
 511
 512
 513 #ifndef MIN
 514 #define MIN(A,B) ((A) < (B)) ? (A) : (B)
 515 #endif
 516
 517 #ifdef LV2_EXTENDED
 518 static float
 519 comp_curve (AComp* self, float xg) {
 520         const float knee = self->v_knee;
 521         const float ratio = self->v_ratio;
 522         const float thresdb = self->v_thresdb;
 523
 524         const float width = 6.f * knee + 0.01f;
 525         float yg = 0.f;
 526
 527         if (2.f * (xg - thresdb) < -width) {
 528                 yg = xg;
 529         } else if (2.f * fabs (xg - thresdb) <= width) {
 530                 yg = xg + (1.f / ratio - 1.f ) * (xg - thresdb + width / 2.f) * (xg - thresdb + width / 2.f) / (2.f * width);
 531         } else if (2.f * (xg - thresdb) > width) {
 532                 yg = thresdb + (xg - thresdb) / ratio;
 533         }
 534         return yg;
 535 }
 536
 537 static LV2_Inline_Display_Image_Surface *
 538 render_inline (LV2_Handle instance, uint32_t w, uint32_t max_h)
 539 {
 540         AComp* self = (AComp*)instance;
 541         uint32_t h = MIN (w, max_h);
 542
 543         if (!self->display || self->w != w || self->h != h) {
 544                 if (self->display) cairo_surface_destroy(self->display);
 545                 self->display = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, w, h);
 546                 self->w = w;
 547                 self->h = h;
 548         }
 549
 550         cairo_t* cr = cairo_create (self->display);
 551
 552         // clear background
 553         cairo_rectangle (cr, 0, 0, w, h);
 554         cairo_set_source_rgba (cr, .2, .2, .2, 1.0);
 555         cairo_fill (cr);
 556
 557         cairo_set_line_width(cr, 1.0);
 558
 559         // draw grid 10dB steps
 560         const double dash1[] = {1, 2};
 561         const double dash2[] = {1, 3};
 562         cairo_save (cr);
 563         cairo_set_line_cap(cr, CAIRO_LINE_CAP_ROUND);
 564         cairo_set_dash(cr, dash2, 2, 2);
 565         cairo_set_source_rgba (cr, 0.5, 0.5, 0.5, 0.5);
 566
 567         for (uint32_t d = 1; d < 6; ++d) {
 568                 const float x = -.5 + floorf (w * (d * 10.f / 60.f));
 569                 const float y = -.5 + floorf (h * (d * 10.f / 60.f));
 570
 571                 cairo_move_to (cr, x, 0);
 572                 cairo_line_to (cr, x, h);
 573                 cairo_stroke (cr);
 574
 575                 cairo_move_to (cr, 0, y);
 576                 cairo_line_to (cr, w, y);
 577                 cairo_stroke (cr);
 578         }
 579         if (self->v_thresdb < 0) {
 580                 cairo_set_source_rgba (cr, 0.5, 0.5, 0.5, 1.0);
 581                 const float y = -.5 + floorf (h * (self->v_thresdb / -60.f));
 582                 cairo_set_dash(cr, dash1, 2, 2);
 583                 cairo_move_to (cr, 0, y);
 584                 cairo_line_to (cr, w, y);
 585                 cairo_stroke (cr);
 586                 cairo_move_to (cr, 0, h);
 587                 cairo_line_to (cr, w, 0);
 588                 cairo_stroke (cr);
 589         }
 590         cairo_restore (cr);
 591
 592
 593         // draw curve
 594         cairo_set_source_rgba (cr, .8, .8, .8, 1.0);
 595         cairo_move_to (cr, 0, h);
 596
 597         for (uint32_t x = 0; x < w; ++x) {
 598                 // plot -60..0  dB
 599                 const float x_db = 60.f * (-1.f + x / (float)w);
 600                 const float y_db = comp_curve (self, x_db);
 601                 const float y = h * (y_db / -60.f);
 602                 cairo_line_to (cr, x, y);
 603         }
 604         cairo_stroke_preserve (cr);
 605
 606         cairo_line_to (cr, w, h);
 607         cairo_close_path (cr);
 608         cairo_clip (cr);
 609
 610         // draw signal level & reduction/gradient
 611         const float top = comp_curve (self, 0);
 612         cairo_pattern_t* pat = cairo_pattern_create_linear (0.0, 0.0, 0.0, h);
 613         if (top > self->v_thresdb) {
 614                 cairo_pattern_add_color_stop_rgba (pat, 0.0, 0.8, 0.1, 0.1, 0.5);
 615                 cairo_pattern_add_color_stop_rgba (pat, top / -60.f, 0.8, 0.1, 0.1, 0.5);
 616         }
 617         if (self->v_knee > 0) {
 618                 cairo_pattern_add_color_stop_rgba (pat, (self->v_thresdb / -60.f), 0.7, 0.7, 0.2, 0.5);
 619                 cairo_pattern_add_color_stop_rgba (pat, ((self->v_thresdb - self->v_knee) / -60.f), 0.5, 0.5, 0.5, 0.5);
 620         } else {
 621                 cairo_pattern_add_color_stop_rgba (pat, (self->v_thresdb / -60.f), 0.7, 0.7, 0.2, 0.5);
 622                 cairo_pattern_add_color_stop_rgba (pat, ((self->v_thresdb - .01) / -60.f), 0.5, 0.5, 0.5, 0.5);
 623         }
 624         cairo_pattern_add_color_stop_rgba (pat, 1.0, 0.5, 0.5, 0.5, 0.5);
 625
 626         // maybe cut off at x-position?
 627         const float x = w * (self->v_lvl_in + 60) / 60.f;
 628         const float y = h * (self->v_lvl_out + 60) / 60.f;
 629         cairo_rectangle (cr, 0, h - y, x, y);
 630         if (self->v_ratio > 1.0) {
 631                 cairo_set_source (cr, pat);
 632         } else {
 633                 cairo_set_source_rgba (cr, 0.5, 0.5, 0.5, 0.5);
 634         }
 635         cairo_fill (cr);
 636
 637         cairo_pattern_destroy (pat); // TODO cache pattern
 638
 639
 640         // create RGBA surface
 641         cairo_destroy (cr);
 642         cairo_surface_flush (self->display);
 643         self->surf.width = cairo_image_surface_get_width (self->display);
 644         self->surf.height = cairo_image_surface_get_height (self->display);
 645         self->surf.stride = cairo_image_surface_get_stride (self->display);
 646         self->surf.data = cairo_image_surface_get_data  (self->display);
 647
 648         return &self->surf;
 649 }
 650 #endif
 651
 652 static const void*
 653 extension_data(const char* uri)
 654 {
 655         static const LV2_Inline_Display_Interface display  = { render_inline };
 656         if (!strcmp(uri, LV2_INLINEDISPLAY__interface)) {
 657                 return &display;
 658         }
 659         return NULL;
 660 }
 661
 662 static const LV2_Descriptor descriptor_mono = {
 663         ACOMP_URI,
 664         instantiate,
 665         connect_port_mono,
 666         activate,
 667         run_mono,
 668         deactivate,
 669         cleanup,
 670         extension_data
 671 };
 672
 673 static const LV2_Descriptor descriptor_stereo = {
 674         ACOMP_STEREO_URI,
 675         instantiate,
 676         connect_port_stereo,
 677         activate,
 678         run_stereo,
 679         deactivate,
 680         cleanup,
 681         extension_data
 682 };
 683
 684 LV2_SYMBOL_EXPORT
 685 const LV2_Descriptor*
 686 lv2_descriptor(uint32_t index)
 687 {
 688         switch (index) {
 689         case 0:
 690                 return &descriptor_mono;
 691         case 1:
 692                 return &descriptor_stereo;
 693         default:
 694                 return NULL;
 695         }
 696 }