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 #ifndef M_PI
  31 #  define M_PI 3.14159265358979323846
  32 #endif
  33
  34 #ifdef COMPILER_MSVC
  35 #include <float.h>
  36 #define isfinite_local(val) (bool)_finite((double)val)
  37 #else
  38 #define isfinite_local isfinite
  39 #endif
  40
  41 typedef enum {
  42         ACOMP_ATTACK = 0,
  43         ACOMP_RELEASE,
  44         ACOMP_KNEE,
  45         ACOMP_RATIO,
  46         ACOMP_THRESHOLD,
  47         ACOMP_MAKEUP,
  48
  49         ACOMP_GAINR,
  50         ACOMP_OUTLEVEL,
  51         ACOMP_SIDECHAIN,
  52         ACOMP_ENABLE,
  53
  54         ACOMP_A0,
  55         ACOMP_A1,
  56         ACOMP_A2,
  57         ACOMP_A3,
  58         ACOMP_A4,
  59 } PortIndex;
  60
  61 typedef struct {
  62         float* attack;
  63         float* release;
  64         float* knee;
  65         float* ratio;
  66         float* thresdb;
  67         float* makeup;
  68
  69         float* gainr;
  70         float* outlevel;
  71         float* sidechain;
  72         float* enable;
  73
  74         float* input0;
  75         float* input1;
  76         float* sc;
  77         float* output0;
  78         float* output1;
  79
  80         float srate;
  81         float old_yl;
  82         float old_y1;
  83         float old_yg;
  84
  85         float makeup_gain;
  86         float tau;
  87
  88 #ifdef LV2_EXTENDED
  89         LV2_Inline_Display_Image_Surface surf;
  90         bool                     need_expose;
  91         cairo_surface_t*         display;
  92         LV2_Inline_Display*      queue_draw;
  93         uint32_t                 w, h;
  94
  95         /* ports pointers are only valid during run so we'll
  96          * have to cache them for the display, besides
  97          * we do want to check for changes
  98          */
  99         float v_knee;
 100         float v_ratio;
 101         float v_thresdb;
 102         float v_makeup;
 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->tau = (1.0 - exp (-2.f * M_PI * 25.f / acomp->srate));
 128 #ifdef LV2_EXTENDED
 129         acomp->need_expose = true;
 130 #endif
 131
 132         return (LV2_Handle)acomp;
 133 }
 134
 135
 136 static void
 137 connect_port(LV2_Handle instance,
 138              uint32_t port,
 139              void* data)
 140 {
 141         AComp* acomp = (AComp*)instance;
 142
 143         switch ((PortIndex)port) {
 144                 case ACOMP_ATTACK:
 145                         acomp->attack = (float*)data;
 146                         break;
 147                 case ACOMP_RELEASE:
 148                         acomp->release = (float*)data;
 149                         break;
 150                 case ACOMP_KNEE:
 151                         acomp->knee = (float*)data;
 152                         break;
 153                 case ACOMP_RATIO:
 154                         acomp->ratio = (float*)data;
 155                         break;
 156                 case ACOMP_THRESHOLD:
 157                         acomp->thresdb = (float*)data;
 158                         break;
 159                 case ACOMP_MAKEUP:
 160                         acomp->makeup = (float*)data;
 161                         break;
 162                 case ACOMP_GAINR:
 163                         acomp->gainr = (float*)data;
 164                         break;
 165                 case ACOMP_OUTLEVEL:
 166                         acomp->outlevel = (float*)data;
 167                         break;
 168                 case ACOMP_SIDECHAIN:
 169                         acomp->sidechain = (float*)data;
 170                         break;
 171                 case ACOMP_ENABLE:
 172                         acomp->enable = (float*)data;
 173                         break;
 174                 default:
 175                         break;
 176         }
 177 }
 178
 179 static void
 180 connect_mono(LV2_Handle instance,
 181              uint32_t port,
 182              void* data)
 183 {
 184         AComp* acomp = (AComp*)instance;
 185         connect_port (instance, port, data);
 186
 187         switch ((PortIndex)port) {
 188                 case ACOMP_A0:
 189                         acomp->input0 = (float*)data;
 190                         break;
 191                 case ACOMP_A1:
 192                         acomp->sc = (float*)data;
 193                         break;
 194                 case ACOMP_A2:
 195                         acomp->output0 = (float*)data;
 196                         break;
 197         default:
 198                 break;
 199         }
 200 }
 201
 202 static void
 203 connect_stereo(LV2_Handle instance,
 204                uint32_t port,
 205                void* data)
 206 {
 207         AComp* acomp = (AComp*)instance;
 208         connect_port (instance, port, data);
 209
 210         switch ((PortIndex)port) {
 211                 case ACOMP_A0:
 212                         acomp->input0 = (float*)data;
 213                         break;
 214                 case ACOMP_A1:
 215                         acomp->input1 = (float*)data;
 216                         break;
 217                 case ACOMP_A2:
 218                         acomp->sc = (float*)data;
 219                         break;
 220                 case ACOMP_A3:
 221                         acomp->output0 = (float*)data;
 222                         break;
 223                 case ACOMP_A4:
 224                         acomp->output1 = (float*)data;
 225                         break;
 226         default:
 227                 break;
 228         }
 229 }
 230
 231 // Force already-denormal float value to zero
 232 static inline float
 233 sanitize_denormal(float value) {
 234         if (!isnormal(value)) {
 235                 value = 0.f;
 236         }
 237         return value;
 238 }
 239
 240 static inline float
 241 from_dB(float gdb) {
 242         return (exp(gdb/20.f*log(10.f)));
 243 }
 244
 245 static inline float
 246 to_dB(float g) {
 247         return (20.f*log10(g));
 248 }
 249
 250 static void
 251 activate(LV2_Handle instance)
 252 {
 253         AComp* acomp = (AComp*)instance;
 254
 255         *(acomp->gainr) = 0.0f;
 256         *(acomp->outlevel) = -45.0f;
 257         acomp->old_yl=acomp->old_y1=acomp->old_yg=0.f;
 258 }
 259
 260 static void
 261 run_mono(LV2_Handle instance, uint32_t n_samples)
 262 {
 263         AComp* acomp = (AComp*)instance;
 264
 265         const float* const input = acomp->input0;
 266         const float* const sc = acomp->sc;
 267         float* const output = acomp->output0;
 268
 269         float srate = acomp->srate;
 270         float width = (6.f * *(acomp->knee)) + 0.01;
 271         float cdb=0.f;
 272         float attack_coeff = exp(-1000.f/(*(acomp->attack) * srate));
 273         float release_coeff = exp(-1000.f/(*(acomp->release) * srate));
 274
 275         float max = 0.f;
 276         float lgaininp = 0.f;
 277         float Lgain = 1.f;
 278         float Lxg, Lxl, Lyg, Lyl, Ly1;
 279         int usesidechain = (*(acomp->sidechain) <= 0.f) ? 0 : 1;
 280         uint32_t i;
 281         float ingain;
 282         float in0;
 283         float sc0;
 284
 285         float ratio = *acomp->ratio;
 286         float thresdb = *acomp->thresdb;
 287         float makeup = *acomp->makeup;
 288         float makeup_target = from_dB(makeup);
 289         float makeup_gain = acomp->makeup_gain;
 290
 291         const float tau = acomp->tau;
 292
 293         if (*acomp->enable <= 0) {
 294                 ratio = 1.f;
 295                 thresdb = 0.f;
 296                 makeup = 0.f;
 297                 makeup_target = 1.f;
 298         }
 299
 300 #ifdef LV2_EXTENDED
 301         if (acomp->v_knee != *acomp->knee) {
 302                 acomp->v_knee = *acomp->knee;
 303                 acomp->need_expose = true;
 304         }
 305
 306         if (acomp->v_ratio != ratio) {
 307                 acomp->v_ratio = ratio;
 308                 acomp->need_expose = true;
 309         }
 310
 311         if (acomp->v_thresdb != thresdb) {
 312                 acomp->v_thresdb = thresdb;
 313                 acomp->need_expose = true;
 314         }
 315
 316         if (acomp->v_makeup != makeup) {
 317                 acomp->v_makeup = makeup;
 318                 acomp->need_expose = true;
 319         }
 320 #endif
 321
 322         float in_peak = 0;
 323
 324         for (i = 0; i < n_samples; i++) {
 325                 in0 = input[i];
 326                 sc0 = sc[i];
 327                 ingain = usesidechain ? fabs(sc0) : fabs(in0);
 328                 in_peak = fmaxf (in_peak, ingain);
 329                 Lyg = 0.f;
 330                 Lxg = (ingain==0.f) ? -160.f : to_dB(ingain);
 331                 Lxg = sanitize_denormal(Lxg);
 332
 333
 334                 if (2.f*(Lxg-thresdb) < -width) {
 335                         Lyg = Lxg;
 336                 } else if (2.f*(Lxg-thresdb) > width) {
 337                         Lyg = thresdb + (Lxg-thresdb)/ratio;
 338                         Lyg = sanitize_denormal(Lyg);
 339                 } else {
 340                         Lyg = Lxg + (1.f/ratio-1.f)*(Lxg-thresdb+width/2.f)*(Lxg-thresdb+width/2.f)/(2.f*width);
 341                 }
 342
 343                 Lxl = Lxg - Lyg;
 344
 345                 acomp->old_y1 = sanitize_denormal(acomp->old_y1);
 346                 acomp->old_yl = sanitize_denormal(acomp->old_yl);
 347                 Ly1 = fmaxf(Lxl, release_coeff * acomp->old_y1+(1.f-release_coeff)*Lxl);
 348                 Lyl = attack_coeff * acomp->old_yl+(1.f-attack_coeff)*Ly1;
 349                 Ly1 = sanitize_denormal(Ly1);
 350                 Lyl = sanitize_denormal(Lyl);
 351
 352                 cdb = -Lyl;
 353                 Lgain = from_dB(cdb);
 354
 355                 *(acomp->gainr) = Lyl;
 356
 357                 lgaininp = in0 * Lgain;
 358
 359                 makeup_gain += tau * (makeup_target - makeup_gain) + 1e-12;
 360                 output[i] = lgaininp * makeup_gain;
 361
 362                 max = (fabsf(output[i]) > max) ? fabsf(output[i]) : sanitize_denormal(max);
 363
 364                 // TODO re-use local variables on stack
 365                 // store values back to acomp at the end of the inner-loop
 366                 acomp->old_yl = Lyl;
 367                 acomp->old_y1 = Ly1;
 368                 acomp->old_yg = Lyg;
 369         }
 370
 371         *(acomp->outlevel) = (max < 0.0056f) ? -45.f : to_dB(max);
 372         acomp->makeup_gain = makeup_gain;
 373
 374 #ifdef LV2_EXTENDED
 375         acomp->v_lvl += .1 * (in_peak - acomp->v_lvl) + 1e-12;  // crude LPF TODO use n_samples/rate TC
 376         if (!isfinite_local (acomp->v_lvl)) {
 377                 acomp->v_lvl = 0.f;
 378         }
 379         const float v_lvl_in = (acomp->v_lvl < 0.001f) ? -60.f : to_dB(acomp->v_lvl);
 380         const float v_lvl_out = (max < 0.001f) ? -60.f : to_dB(max);
 381         if (fabsf (acomp->v_lvl_out - v_lvl_out) >= 1 || fabsf (acomp->v_lvl_in - v_lvl_in) >= 1) {
 382                 // >= 1dB difference
 383                 acomp->need_expose = true;
 384                 acomp->v_lvl_in = v_lvl_in;
 385                 acomp->v_lvl_out = v_lvl_out - to_dB(makeup_gain);
 386         }
 387         if (acomp->need_expose && acomp->queue_draw) {
 388                 acomp->need_expose = false;
 389                 acomp->queue_draw->queue_draw (acomp->queue_draw->handle);
 390         }
 391 #endif
 392 }
 393
 394 static void
 395 run_stereo(LV2_Handle instance, uint32_t n_samples)
 396 {
 397         AComp* acomp = (AComp*)instance;
 398
 399         const float* const input0 = acomp->input0;
 400         const float* const input1 = acomp->input1;
 401         const float* const sc = acomp->sc;
 402         float* const output0 = acomp->output0;
 403         float* const output1 = acomp->output1;
 404
 405         float srate = acomp->srate;
 406         float width = (6.f * *(acomp->knee)) + 0.01;
 407         float cdb=0.f;
 408         float attack_coeff = exp(-1000.f/(*(acomp->attack) * srate));
 409         float release_coeff = exp(-1000.f/(*(acomp->release) * srate));
 410
 411         float max = 0.f;
 412         float lgaininp = 0.f;
 413         float rgaininp = 0.f;
 414         float Lgain = 1.f;
 415         float Lxg, Lxl, Lyg, Lyl, Ly1;
 416         int usesidechain = (*(acomp->sidechain) <= 0.f) ? 0 : 1;
 417         uint32_t i;
 418         float ingain;
 419         float in0;
 420         float in1;
 421         float sc0;
 422         float maxabslr;
 423
 424         float ratio = *acomp->ratio;
 425         float thresdb = *acomp->thresdb;
 426         float makeup = *acomp->makeup;
 427         float makeup_target = from_dB(makeup);
 428         float makeup_gain = acomp->makeup_gain;
 429
 430         const float tau = acomp->tau;
 431
 432         if (*acomp->enable <= 0) {
 433                 ratio = 1.f;
 434                 thresdb = 0.f;
 435                 makeup_target = 1.f;
 436         }
 437
 438 #ifdef LV2_EXTENDED
 439         if (acomp->v_knee != *acomp->knee) {
 440                 acomp->v_knee = *acomp->knee;
 441                 acomp->need_expose = true;
 442         }
 443
 444         if (acomp->v_ratio != ratio) {
 445                 acomp->v_ratio = ratio;
 446                 acomp->need_expose = true;
 447         }
 448
 449         if (acomp->v_thresdb != thresdb) {
 450                 acomp->v_thresdb = thresdb;
 451                 acomp->need_expose = true;
 452         }
 453
 454         if (acomp->v_makeup != makeup) {
 455                 acomp->v_makeup = makeup;
 456                 acomp->need_expose = true;
 457         }
 458 #endif
 459
 460         float in_peak = 0;
 461
 462         for (i = 0; i < n_samples; i++) {
 463                 in0 = input0[i];
 464                 in1 = input1[i];
 465                 sc0 = sc[i];
 466                 maxabslr = fmaxf(fabs(in0), fabs(in1));
 467                 ingain = usesidechain ? fabs(sc0) : maxabslr;
 468                 in_peak = fmaxf (in_peak, ingain);
 469                 Lyg = 0.f;
 470                 Lxg = (ingain==0.f) ? -160.f : to_dB(ingain);
 471                 Lxg = sanitize_denormal(Lxg);
 472
 473
 474                 if (2.f*(Lxg-thresdb) < -width) {
 475                         Lyg = Lxg;
 476                 } else if (2.f*(Lxg-thresdb) > width) {
 477                         Lyg = thresdb + (Lxg-thresdb)/ratio;
 478                         Lyg = sanitize_denormal(Lyg);
 479                 } else {
 480                         Lyg = Lxg + (1.f/ratio-1.f)*(Lxg-thresdb+width/2.f)*(Lxg-thresdb+width/2.f)/(2.f*width);
 481                 }
 482
 483                 Lxl = Lxg - Lyg;
 484
 485                 acomp->old_y1 = sanitize_denormal(acomp->old_y1);
 486                 acomp->old_yl = sanitize_denormal(acomp->old_yl);
 487                 Ly1 = fmaxf(Lxl, release_coeff * acomp->old_y1+(1.f-release_coeff)*Lxl);
 488                 Lyl = attack_coeff * acomp->old_yl+(1.f-attack_coeff)*Ly1;
 489                 Ly1 = sanitize_denormal(Ly1);
 490                 Lyl = sanitize_denormal(Lyl);
 491
 492                 cdb = -Lyl;
 493                 Lgain = from_dB(cdb);
 494
 495                 *(acomp->gainr) = Lyl;
 496
 497                 lgaininp = in0 * Lgain;
 498                 rgaininp = in1 * Lgain;
 499
 500                 makeup_gain += tau * (makeup_target - makeup_gain) + 1e-12;
 501
 502                 output0[i] = lgaininp * makeup_gain;
 503                 output1[i] = rgaininp * makeup_gain;
 504
 505                 max = (fmaxf(fabs(output0[i]), fabs(output1[i])) > max) ? fmaxf(fabs(output0[i]), fabs(output1[i])) : sanitize_denormal(max);
 506
 507                 // TODO re-use local variables on stack
 508                 // store values back to acomp at the end of the inner-loop
 509                 acomp->old_yl = Lyl;
 510                 acomp->old_y1 = Ly1;
 511                 acomp->old_yg = Lyg;
 512         }
 513
 514         *(acomp->outlevel) = (max < 0.0056f) ? -45.f : to_dB(max);
 515         acomp->makeup_gain = makeup_gain;
 516
 517 #ifdef LV2_EXTENDED
 518         acomp->v_lvl += .1 * (in_peak - acomp->v_lvl) + 1e-12;  // crude LPF TODO use n_samples/rate TC
 519         if (!isfinite_local (acomp->v_lvl)) {
 520                 acomp->v_lvl = 0.f;
 521         }
 522         const float v_lvl_in = (acomp->v_lvl < 0.001f) ? -60.f : to_dB(acomp->v_lvl);
 523         const float v_lvl_out = (max < 0.001f) ? -60.f : to_dB(max);
 524         if (fabsf (acomp->v_lvl_out - v_lvl_out) >= 1 || fabsf (acomp->v_lvl_in - v_lvl_in) >= 1) {
 525                 // >= 1dB difference
 526                 acomp->need_expose = true;
 527                 acomp->v_lvl_in = v_lvl_in;
 528                 acomp->v_lvl_out = v_lvl_out - to_dB(makeup_gain);
 529         }
 530         if (acomp->need_expose && acomp->queue_draw) {
 531                 acomp->need_expose = false;
 532                 acomp->queue_draw->queue_draw (acomp->queue_draw->handle);
 533         }
 534 #endif
 535 }
 536
 537 static void
 538 deactivate(LV2_Handle instance)
 539 {
 540         activate(instance);
 541 }
 542
 543 static void
 544 cleanup(LV2_Handle instance)
 545 {
 546 #ifdef LV2_EXTENDED
 547         AComp* acomp = (AComp*)instance;
 548         if (acomp->display) {
 549                 cairo_surface_destroy (acomp->display);
 550         }
 551 #endif
 552
 553         free(instance);
 554 }
 555
 556
 557 #ifndef MIN
 558 #define MIN(A,B) ((A) < (B)) ? (A) : (B)
 559 #endif
 560
 561 #ifdef LV2_EXTENDED
 562 static float
 563 comp_curve (AComp* self, float xg) {
 564         const float knee = self->v_knee;
 565         const float ratio = self->v_ratio;
 566         const float thresdb = self->v_thresdb;
 567         const float makeup = self->v_makeup;
 568
 569         const float width = 6.f * knee + 0.01f;
 570         float yg = 0.f;
 571
 572         if (2.f * (xg - thresdb) < -width) {
 573                 yg = xg;
 574         } else if (2.f * (xg - thresdb) > width) {
 575                 yg = thresdb + (xg - thresdb) / ratio;
 576         } else {
 577                 yg = xg + (1.f / ratio - 1.f ) * (xg - thresdb + width / 2.f) * (xg - thresdb + width / 2.f) / (2.f * width);
 578         }
 579
 580         yg += makeup;
 581
 582         return yg;
 583 }
 584
 585 static LV2_Inline_Display_Image_Surface *
 586 render_inline (LV2_Handle instance, uint32_t w, uint32_t max_h)
 587 {
 588         AComp* self = (AComp*)instance;
 589         uint32_t h = MIN (w, max_h);
 590
 591         if (!self->display || self->w != w || self->h != h) {
 592                 if (self->display) cairo_surface_destroy(self->display);
 593                 self->display = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, w, h);
 594                 self->w = w;
 595                 self->h = h;
 596         }
 597
 598         cairo_t* cr = cairo_create (self->display);
 599
 600         // clear background
 601         cairo_rectangle (cr, 0, 0, w, h);
 602         cairo_set_source_rgba (cr, .2, .2, .2, 1.0);
 603         cairo_fill (cr);
 604
 605         cairo_set_line_width(cr, 1.0);
 606
 607         // draw grid 10dB steps
 608         const double dash1[] = {1, 2};
 609         const double dash2[] = {1, 3};
 610         cairo_save (cr);
 611         cairo_set_line_cap(cr, CAIRO_LINE_CAP_ROUND);
 612         cairo_set_dash(cr, dash2, 2, 2);
 613         cairo_set_source_rgba (cr, 0.5, 0.5, 0.5, 0.5);
 614
 615         for (uint32_t d = 1; d < 6; ++d) {
 616                 const float x = -.5 + floorf (w * (d * 10.f / 60.f));
 617                 const float y = -.5 + floorf (h * (d * 10.f / 60.f));
 618
 619                 cairo_move_to (cr, x, 0);
 620                 cairo_line_to (cr, x, h);
 621                 cairo_stroke (cr);
 622
 623                 cairo_move_to (cr, 0, y);
 624                 cairo_line_to (cr, w, y);
 625                 cairo_stroke (cr);
 626         }
 627         if (self->v_thresdb < 0) {
 628                 cairo_set_source_rgba (cr, 0.5, 0.5, 0.5, 1.0);
 629                 const float y = -.5 + floorf (h * (self->v_thresdb / -60.f));
 630                 cairo_set_dash(cr, dash1, 2, 2);
 631                 cairo_move_to (cr, 0, y);
 632                 cairo_line_to (cr, w, y);
 633                 cairo_stroke (cr);
 634                 cairo_move_to (cr, 0, h);
 635                 cairo_line_to (cr, w, 0);
 636                 cairo_stroke (cr);
 637         }
 638         cairo_restore (cr);
 639
 640
 641         // draw curve
 642         cairo_set_source_rgba (cr, .8, .8, .8, 1.0);
 643         cairo_move_to (cr, 0, h);
 644
 645         for (uint32_t x = 0; x < w; ++x) {
 646                 // plot -60..0  dB
 647                 const float x_db = 60.f * (-1.f + x / (float)w);
 648                 const float y_db = comp_curve (self, x_db);
 649                 const float y = h * (y_db / -60.f);
 650                 cairo_line_to (cr, x, y);
 651         }
 652         cairo_stroke_preserve (cr);
 653
 654         cairo_line_to (cr, w, h);
 655         cairo_close_path (cr);
 656         cairo_clip (cr);
 657
 658         // draw signal level & reduction/gradient
 659         const float top = comp_curve (self, 0);
 660         cairo_pattern_t* pat = cairo_pattern_create_linear (0.0, 0.0, 0.0, h);
 661         if (top > self->v_thresdb) {
 662                 cairo_pattern_add_color_stop_rgba (pat, 0.0, 0.8, 0.1, 0.1, 0.5);
 663                 cairo_pattern_add_color_stop_rgba (pat, top / -60.f, 0.8, 0.1, 0.1, 0.5);
 664         }
 665         if (self->v_knee > 0) {
 666                 cairo_pattern_add_color_stop_rgba (pat, (self->v_thresdb / -60.f), 0.7, 0.7, 0.2, 0.5);
 667                 cairo_pattern_add_color_stop_rgba (pat, ((self->v_thresdb - self->v_knee) / -60.f), 0.5, 0.5, 0.5, 0.5);
 668         } else {
 669                 cairo_pattern_add_color_stop_rgba (pat, (self->v_thresdb / -60.f), 0.7, 0.7, 0.2, 0.5);
 670                 cairo_pattern_add_color_stop_rgba (pat, ((self->v_thresdb - .01) / -60.f), 0.5, 0.5, 0.5, 0.5);
 671         }
 672         cairo_pattern_add_color_stop_rgba (pat, 1.0, 0.5, 0.5, 0.5, 0.5);
 673
 674         // maybe cut off at x-position?
 675         const float x = w * (self->v_lvl_in + 60) / 60.f;
 676         const float y = x + h*self->v_makeup;
 677         cairo_rectangle (cr, 0, h - y, x, y);
 678         if (self->v_ratio > 1.0) {
 679                 cairo_set_source (cr, pat);
 680         } else {
 681                 cairo_set_source_rgba (cr, 0.5, 0.5, 0.5, 0.5);
 682         }
 683         cairo_fill (cr);
 684
 685         cairo_pattern_destroy (pat); // TODO cache pattern
 686
 687
 688         // create RGBA surface
 689         cairo_destroy (cr);
 690         cairo_surface_flush (self->display);
 691         self->surf.width = cairo_image_surface_get_width (self->display);
 692         self->surf.height = cairo_image_surface_get_height (self->display);
 693         self->surf.stride = cairo_image_surface_get_stride (self->display);
 694         self->surf.data = cairo_image_surface_get_data  (self->display);
 695
 696         return &self->surf;
 697 }
 698 #endif
 699
 700 static const void*
 701 extension_data(const char* uri)
 702 {
 703 #ifdef LV2_EXTENDED
 704         static const LV2_Inline_Display_Interface display  = { render_inline };
 705         if (!strcmp(uri, LV2_INLINEDISPLAY__interface)) {
 706                 return &display;
 707         }
 708 #endif
 709         return NULL;
 710 }
 711
 712 static const LV2_Descriptor descriptor_mono = {
 713         ACOMP_URI,
 714         instantiate,
 715         connect_mono,
 716         activate,
 717         run_mono,
 718         deactivate,
 719         cleanup,
 720         extension_data
 721 };
 722
 723 static const LV2_Descriptor descriptor_stereo = {
 724         ACOMP_STEREO_URI,
 725         instantiate,
 726         connect_stereo,
 727         activate,
 728         run_stereo,
 729         deactivate,
 730         cleanup,
 731         extension_data
 732 };
 733
 734 LV2_SYMBOL_EXPORT
 735 const LV2_Descriptor*
 736 lv2_descriptor(uint32_t index)
 737 {
 738         switch (index) {
 739         case 0:
 740                 return &descriptor_mono;
 741         case 1:
 742                 return &descriptor_stereo;
 743         default:
 744                 return NULL;
 745         }
 746 }