git.sesse.net Git - mlt/blob - src/modules/decklink/consumer_decklink.cpp

   1 /*
   2  * consumer_decklink.c -- output through Blackmagic Design DeckLink
   3  * Copyright (C) 2010 Dan Dennedy <dan@dennedy.org>
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with consumer library; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 #define __STDC_FORMAT_MACROS  /* see inttypes.h */
  21 #include <framework/mlt.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <pthread.h>
  25 #include <unistd.h>
  26 #include <sys/time.h>
  27 #include <limits.h>
  28 #ifdef WIN32
  29 #include <objbase.h>
  30 #include "DeckLinkAPI_h.h"
  31 #else
  32 #include "DeckLinkAPI.h"
  33 #endif
  34
  35 static const unsigned PREROLL_MINIMUM = 3;
  36
  37 class DeckLinkConsumer
  38         : public IDeckLinkVideoOutputCallback
  39 {
  40 private:
  41         mlt_consumer_s              m_consumer;
  42         IDeckLink*                  m_deckLink;
  43         IDeckLinkOutput*            m_deckLinkOutput;
  44         IDeckLinkDisplayMode*       m_displayMode;
  45         int                         m_width;
  46         int                         m_height;
  47         BMDTimeValue                m_duration;
  48         BMDTimeScale                m_timescale;
  49         double                      m_fps;
  50         uint64_t                    m_count;
  51         int                         m_channels;
  52         unsigned                    m_dropped;
  53         IDeckLinkMutableVideoFrame* m_decklinkFrame;
  54         bool                        m_isAudio;
  55         int                         m_isKeyer;
  56         IDeckLinkKeyer*             m_deckLinkKeyer;
  57         bool                        m_terminate_on_pause;
  58         uint32_t                    m_preroll;
  59         uint32_t                    m_acnt;
  60
  61         IDeckLinkDisplayMode* getDisplayMode()
  62         {
  63                 mlt_profile profile = mlt_service_profile( MLT_CONSUMER_SERVICE( getConsumer() ) );
  64                 IDeckLinkDisplayModeIterator* iter;
  65                 IDeckLinkDisplayMode* mode;
  66                 IDeckLinkDisplayMode* result = 0;
  67
  68                 if ( m_deckLinkOutput->GetDisplayModeIterator( &iter ) == S_OK )
  69                 {
  70                         while ( !result && iter->Next( &mode ) == S_OK )
  71                         {
  72                                 m_width = mode->GetWidth();
  73                                 m_height = mode->GetHeight();
  74                                 mode->GetFrameRate( &m_duration, &m_timescale );
  75                                 m_fps = (double) m_timescale / m_duration;
  76                                 int p = mode->GetFieldDominance() == bmdProgressiveFrame;
  77                                 mlt_log_verbose( getConsumer(), "BMD mode %dx%d %.3f fps prog %d\n", m_width, m_height, m_fps, p );
  78
  79                                 if ( m_width == profile->width && m_height == profile->height && p == profile->progressive
  80                                          && m_fps == mlt_profile_fps( profile ) )
  81                                         result = mode;
  82                         }
  83                 }
  84
  85                 return result;
  86         }
  87
  88 public:
  89         mlt_consumer getConsumer()
  90                 { return &m_consumer; }
  91
  92         ~DeckLinkConsumer()
  93         {
  94                 if ( m_deckLinkKeyer )
  95                         m_deckLinkKeyer->Release();
  96                 if ( m_deckLinkOutput )
  97                         m_deckLinkOutput->Release();
  98                 if ( m_deckLink )
  99                         m_deckLink->Release();
 100         }
 101
 102         bool open( unsigned card = 0 )
 103         {
 104                 unsigned i = 0;
 105 #ifdef WIN32
 106                 IDeckLinkIterator* deckLinkIterator = NULL;
 107                 HRESULT result =  CoInitialize( NULL );
 108                 if ( FAILED( result ) )
 109                 {
 110                         mlt_log_error( getConsumer(), "COM initialization failed\n" );
 111                         return false;
 112                 }
 113                 result = CoCreateInstance( CLSID_CDeckLinkIterator, NULL, CLSCTX_ALL, IID_IDeckLinkIterator, (void**) &deckLinkIterator );
 114                 if ( FAILED( result ) )
 115                 {
 116                         mlt_log_error( getConsumer(), "The DeckLink drivers not installed.\n" );
 117                         return false;
 118                 }
 119 #else
 120                 IDeckLinkIterator* deckLinkIterator = CreateDeckLinkIteratorInstance();
 121
 122                 if ( !deckLinkIterator )
 123                 {
 124                         mlt_log_error( getConsumer(), "The DeckLink drivers not installed.\n" );
 125                         return false;
 126                 }
 127 #endif
 128
 129                 // Connect to the Nth DeckLink instance
 130                 do {
 131                         if ( deckLinkIterator->Next( &m_deckLink ) != S_OK )
 132                         {
 133                                 mlt_log_error( getConsumer(), "DeckLink card not found\n" );
 134                                 deckLinkIterator->Release();
 135                                 return false;
 136                         }
 137                 } while ( ++i <= card );
 138                 deckLinkIterator->Release();
 139
 140                 // Obtain the audio/video output interface (IDeckLinkOutput)
 141                 if ( m_deckLink->QueryInterface( IID_IDeckLinkOutput, (void**)&m_deckLinkOutput ) != S_OK )
 142                 {
 143                         mlt_log_error( getConsumer(), "No DeckLink cards support output\n" );
 144                         m_deckLink->Release();
 145                         m_deckLink = 0;
 146                         return false;
 147                 }
 148
 149                 // Get the keyer interface
 150                 IDeckLinkAttributes *deckLinkAttributes = 0;
 151                 m_deckLinkKeyer = 0;
 152                 if ( m_deckLink->QueryInterface( IID_IDeckLinkAttributes, (void**) &deckLinkAttributes ) == S_OK )
 153                 {
 154 #ifdef WIN32
 155                         BOOL flag = FALSE;
 156 #else
 157                         bool flag = false;
 158 #endif
 159                         if ( deckLinkAttributes->GetFlag( BMDDeckLinkSupportsInternalKeying, &flag ) == S_OK && flag )
 160                         {
 161                                 if ( m_deckLink->QueryInterface( IID_IDeckLinkKeyer, (void**) &m_deckLinkKeyer ) != S_OK )
 162                                 {
 163                                         mlt_log_error( getConsumer(), "Failed to get keyer\n" );
 164                                         m_deckLinkOutput->Release();
 165                                         m_deckLinkOutput = 0;
 166                                         m_deckLink->Release();
 167                                         m_deckLink = 0;
 168                                         return false;
 169                                 }
 170                         }
 171                         deckLinkAttributes->Release();
 172                 }
 173
 174                 // Provide this class as a delegate to the audio and video output interfaces
 175                 m_deckLinkOutput->SetScheduledFrameCompletionCallback( this );
 176
 177                 return true;
 178         }
 179
 180         bool start( unsigned preroll )
 181         {
 182                 unsigned i;
 183                 mlt_properties properties = MLT_CONSUMER_PROPERTIES( getConsumer() );
 184
 185                 // Initialize members
 186                 m_count = 0;
 187                 m_dropped = 0;
 188                 m_decklinkFrame = NULL;
 189                 preroll = preroll < PREROLL_MINIMUM ? PREROLL_MINIMUM : preroll;
 190                 m_channels = mlt_properties_get_int( properties, "channels" );
 191                 m_isAudio = !mlt_properties_get_int( properties, "audio_off" );
 192                 m_terminate_on_pause = mlt_properties_get_int( properties, "terminate_on_pause" );
 193
 194
 195                 m_displayMode = getDisplayMode();
 196                 if ( !m_displayMode )
 197                 {
 198                         mlt_log_error( getConsumer(), "Profile is not compatible with decklink.\n" );
 199                         return false;
 200                 }
 201
 202                 // Set the keyer
 203                 if ( m_deckLinkKeyer && ( m_isKeyer = mlt_properties_get_int( properties, "keyer" ) ) )
 204                 {
 205                         bool external = (m_isKeyer == 2);
 206                         double level = mlt_properties_get_double( properties, "keyer_level" );
 207
 208                         if ( m_deckLinkKeyer->Enable( external ) != S_OK )
 209                                 mlt_log_error( getConsumer(), "Failed to enable %s keyer\n",
 210                                         external ? "external" : "internal" );
 211                         m_deckLinkKeyer->SetLevel( level <= 1 ? ( level > 0 ? 255 * level : 255 ) : 255 );
 212                 }
 213                 else if ( m_deckLinkKeyer )
 214                 {
 215                         m_deckLinkKeyer->Disable();
 216                 }
 217
 218                 // Set the video output mode
 219                 if ( S_OK != m_deckLinkOutput->EnableVideoOutput( m_displayMode->GetDisplayMode(), bmdVideoOutputFlagDefault) )
 220                 {
 221                         mlt_log_error( getConsumer(), "Failed to enable video output\n" );
 222                         return false;
 223                 }
 224
 225                 // Set the audio output mode
 226                 if ( !m_isAudio )
 227                 {
 228                         m_deckLinkOutput->DisableAudioOutput();
 229                         return true;
 230                 }
 231                 if ( S_OK != m_deckLinkOutput->EnableAudioOutput( bmdAudioSampleRate48kHz, bmdAudioSampleType16bitInteger,
 232                         m_channels, bmdAudioOutputStreamTimestamped ) )
 233                 {
 234                         mlt_log_error( getConsumer(), "Failed to enable audio output\n" );
 235                         stop();
 236                         return false;
 237                 }
 238
 239                 m_preroll = preroll;
 240
 241                 // preroll frames
 242                 for( i = 0; i < preroll; i++ )
 243                         ScheduleNextFrame( true );
 244
 245                 // start scheduled playback
 246                 m_deckLinkOutput->StartScheduledPlayback( 0, m_timescale, 1.0 );
 247
 248                 // Set the running state
 249                 mlt_properties_set_int( properties, "running", 1 );
 250
 251                 return true;
 252         }
 253
 254         bool stop()
 255         {
 256                 mlt_properties properties = MLT_CONSUMER_PROPERTIES( getConsumer() );
 257
 258                 // set running state is 0
 259                 mlt_properties_set_int( properties, "running", 0 );
 260                 mlt_consumer_stopped( getConsumer() );
 261
 262                 // release decklink frame
 263                 if ( m_decklinkFrame )
 264                         m_decklinkFrame->Release();
 265                 m_decklinkFrame = NULL;
 266
 267                 // Stop the audio and video output streams immediately
 268                 if ( m_deckLinkOutput )
 269                 {
 270                         m_deckLinkOutput->StopScheduledPlayback( 0, 0, 0 );
 271                         m_deckLinkOutput->DisableAudioOutput();
 272                         m_deckLinkOutput->DisableVideoOutput();
 273                 }
 274
 275                 return true;
 276         }
 277
 278         void renderAudio( mlt_frame frame )
 279         {
 280                 mlt_audio_format format = mlt_audio_s16;
 281                 int frequency = bmdAudioSampleRate48kHz;
 282                 int samples = mlt_sample_calculator( m_fps, frequency, m_count );
 283                 int16_t *pcm = 0;
 284
 285                 if ( !mlt_frame_get_audio( frame, (void**) &pcm, &format, &frequency, &m_channels, &samples ) )
 286                 {
 287                         uint32_t written = 0;
 288                         BMDTimeValue streamTime = m_count * frequency * m_duration / m_timescale;
 289                         m_deckLinkOutput->GetBufferedAudioSampleFrameCount(&written);
 290                         if ( written > (m_preroll + 1) * samples )
 291                         {
 292                                 mlt_log_verbose( getConsumer(), "renderAudio: will flush %d audiosamples\n", written);
 293                                 m_deckLinkOutput->FlushBufferedAudioSamples();
 294                         };
 295 #ifdef WIN32
 296                         m_deckLinkOutput->ScheduleAudioSamples( pcm, samples, streamTime, frequency, (unsigned long*) &written );
 297 #else
 298                         m_deckLinkOutput->ScheduleAudioSamples( pcm, samples, streamTime, frequency, &written );
 299 #endif
 300
 301                         if ( written != (uint32_t) samples )
 302                                 mlt_log_verbose( getConsumer(), "renderAudio: samples=%d, written=%u\n", samples, written );
 303                 }
 304         }
 305
 306         bool createFrame( IDeckLinkMutableVideoFrame** decklinkFrame )
 307         {
 308                 BMDPixelFormat format = m_isKeyer? bmdFormat8BitARGB : bmdFormat8BitYUV;
 309                 IDeckLinkMutableVideoFrame* frame = 0;
 310                 uint8_t *buffer = 0;
 311                 int stride = m_width * ( m_isKeyer? 4 : 2 );
 312
 313                 *decklinkFrame = NULL;
 314
 315                 // Generate a DeckLink video frame
 316                 if ( S_OK != m_deckLinkOutput->CreateVideoFrame( m_width, m_height,
 317                         stride, format, bmdFrameFlagDefault, &frame ) )
 318                 {
 319                         mlt_log_verbose( getConsumer(), "Failed to create video frame\n" );
 320                         stop();
 321                         return false;
 322                 }
 323
 324                 // Make the first line black for field order correction.
 325                 if ( S_OK == frame->GetBytes( (void**) &buffer ) && buffer )
 326                 {
 327                         if ( m_isKeyer )
 328                         {
 329                                 memset( buffer, 0, stride );
 330                         }
 331                         else for ( int i = 0; i < m_width; i++ )
 332                         {
 333                                 *buffer++ = 128;
 334                                 *buffer++ = 16;
 335                         }
 336                 }
 337
 338                 *decklinkFrame = frame;
 339
 340                 return true;
 341         }
 342
 343         void renderVideo( mlt_frame frame )
 344         {
 345                 mlt_image_format format = m_isKeyer? mlt_image_rgb24a : mlt_image_yuv422;
 346                 uint8_t* image = 0;
 347                 int rendered = mlt_properties_get_int( MLT_FRAME_PROPERTIES(frame), "rendered");
 348
 349                 if ( rendered && !mlt_frame_get_image( frame, &image, &format, &m_width, &m_height, 0 ) )
 350                 {
 351                         uint8_t* buffer = 0;
 352                         int stride = m_width * ( m_isKeyer? 4 : 2 );
 353
 354                         if ( m_decklinkFrame )
 355                                 m_decklinkFrame->Release();
 356                         if ( createFrame( &m_decklinkFrame ) )
 357                                 m_decklinkFrame->GetBytes( (void**) &buffer );
 358
 359                         if ( buffer )
 360                         {
 361                                 int progressive = mlt_properties_get_int( MLT_FRAME_PROPERTIES( frame ), "progressive" );
 362
 363                                 if ( !m_isKeyer )
 364                                 {
 365                                         // Normal non-keyer playout - needs byte swapping
 366                                         if ( !progressive && m_displayMode->GetFieldDominance() == bmdUpperFieldFirst )
 367                                                 // convert lower field first to top field first
 368                                                 swab( (char*) image, (char*) buffer + stride, stride * ( m_height - 1 ) );
 369                                         else
 370                                                 swab( (char*) image, (char*) buffer, stride * m_height );
 371                                 }
 372                                 else if ( !mlt_properties_get_int( MLT_FRAME_PROPERTIES( frame ), "test_image" ) )
 373                                 {
 374                                         // Normal keyer output
 375                                         int y = m_height + 1;
 376                                         uint32_t* s = (uint32_t*) image;
 377                                         uint32_t* d = (uint32_t*) buffer;
 378
 379                                         if ( !progressive && m_displayMode->GetFieldDominance() == bmdUpperFieldFirst )
 380                                         {
 381                                                 // Correct field order
 382                                                 m_height--;
 383                                                 y--;
 384                                                 d += m_width;
 385                                         }
 386
 387                                         // Need to relocate alpha channel RGBA => ARGB
 388                                         while ( --y )
 389                                         {
 390                                                 int x = m_width + 1;
 391                                                 while ( --x )
 392                                                 {
 393                                                         *d++ = ( *s << 8 ) | ( *s >> 24 );
 394                                                         s++;
 395                                                 }
 396                                         }
 397                                 }
 398                                 else
 399                                 {
 400                                         // Keying blank frames - nullify alpha
 401                                         memset( buffer, 0, stride * m_height );
 402                                 }
 403                         }
 404                 }
 405                 if ( m_decklinkFrame )
 406                         m_deckLinkOutput->ScheduleVideoFrame( m_decklinkFrame, m_count * m_duration, m_duration, m_timescale );
 407
 408                 if ( !rendered )
 409                         mlt_log_verbose( getConsumer(), "dropped video frame %u\n", ++m_dropped );
 410         }
 411
 412         HRESULT render( mlt_frame frame )
 413         {
 414                 HRESULT result = S_OK;
 415
 416                 // Get the audio
 417                 double speed = mlt_properties_get_double( MLT_FRAME_PROPERTIES(frame), "_speed" );
 418                 if ( m_isAudio && speed == 1.0 )
 419                         renderAudio( frame );
 420
 421                 // Get the video
 422                 renderVideo( frame );
 423                 ++m_count;
 424
 425                 return result;
 426         }
 427
 428         // *** DeckLink API implementation of IDeckLinkVideoOutputCallback IDeckLinkAudioOutputCallback *** //
 429
 430         // IUnknown needs only a dummy implementation
 431         virtual HRESULT STDMETHODCALLTYPE QueryInterface( REFIID iid, LPVOID *ppv )
 432                 { return E_NOINTERFACE; }
 433         virtual ULONG STDMETHODCALLTYPE AddRef()
 434                 { return 1; }
 435         virtual ULONG STDMETHODCALLTYPE Release()
 436                 { return 1; }
 437
 438         /************************* DeckLink API Delegate Methods *****************************/
 439
 440         virtual HRESULT STDMETHODCALLTYPE ScheduledFrameCompleted( IDeckLinkVideoFrame* completedFrame, BMDOutputFrameCompletionResult completed )
 441         {
 442                 uint32_t cnt;
 443                 m_deckLinkOutput->GetBufferedAudioSampleFrameCount(&cnt);
 444                 if(cnt != m_acnt)
 445                 {
 446                         mlt_log_verbose( getConsumer(),
 447                                 "ScheduledFrameCompleted: GetBufferedAudioSampleFrameCount %u -> %u, m_count=%"PRIu64"\n",
 448                                 m_acnt, cnt, m_count );
 449                         m_acnt = cnt;
 450                 };
 451
 452                 // When a video frame has been released by the API, schedule another video frame to be output
 453
 454                 // ignore handler if frame was flushed
 455                 if(bmdOutputFrameFlushed == completed)
 456                         return S_OK;
 457
 458                 // schedule next frame
 459                 ScheduleNextFrame(false);
 460
 461                 // step forward frames counter if underrun
 462                 if(bmdOutputFrameDisplayedLate == completed)
 463                 {
 464                         mlt_log_verbose( getConsumer(), "ScheduledFrameCompleted: bmdOutputFrameDisplayedLate == completed\n");
 465                         m_count++;
 466                 }
 467                 if(bmdOutputFrameDropped == completed)
 468                 {
 469                         mlt_log_verbose( getConsumer(), "ScheduledFrameCompleted: bmdOutputFrameDropped == completed\n");
 470                         m_count++;
 471                 }
 472
 473                 return S_OK;
 474         }
 475
 476         virtual HRESULT STDMETHODCALLTYPE ScheduledPlaybackHasStopped()
 477         {
 478                 return mlt_consumer_is_stopped( getConsumer() ) ? S_FALSE : S_OK;
 479         }
 480
 481
 482         void ScheduleNextFrame(bool preroll)
 483         {
 484                 // get the consumer
 485                 mlt_consumer consumer = getConsumer();
 486
 487                 // Get the properties
 488                 mlt_properties properties = MLT_CONSUMER_PROPERTIES( consumer );
 489
 490                 // Frame and size
 491                 mlt_frame frame = NULL;
 492
 493                 if( mlt_properties_get_int( properties, "running" ) || preroll )
 494                 {
 495                         frame = mlt_consumer_rt_frame( consumer );
 496                         if ( frame != NULL )
 497                         {
 498                                 render( frame );
 499
 500                                 mlt_events_fire( properties, "consumer-frame-show", frame, NULL );
 501
 502                                 // terminate on pause
 503                                 if (m_terminate_on_pause &&
 504                                         mlt_properties_get_double( MLT_FRAME_PROPERTIES( frame ), "_speed" ) == 0.0)
 505                                         stop();
 506
 507                                 mlt_frame_close( frame );
 508                         }
 509                 }
 510         }
 511 };
 512
 513 /** Start the consumer.
 514  */
 515
 516 static int start( mlt_consumer consumer )
 517 {
 518         // Get the properties
 519         mlt_properties properties = MLT_CONSUMER_PROPERTIES( consumer );
 520         DeckLinkConsumer* decklink = (DeckLinkConsumer*) consumer->child;
 521         return decklink->start( mlt_properties_get_int( properties, "preroll" ) ) ? 0 : 1;
 522 }
 523
 524 /** Stop the consumer.
 525  */
 526
 527 static int stop( mlt_consumer consumer )
 528 {
 529         // Get the properties
 530         DeckLinkConsumer* decklink = (DeckLinkConsumer*) consumer->child;
 531         return decklink->stop();
 532 }
 533
 534 /** Determine if the consumer is stopped.
 535  */
 536
 537 static int is_stopped( mlt_consumer consumer )
 538 {
 539         // Get the properties
 540         mlt_properties properties = MLT_CONSUMER_PROPERTIES( consumer );
 541         return !mlt_properties_get_int( properties, "running" );
 542 }
 543
 544 /** Close the consumer.
 545  */
 546
 547 static void close( mlt_consumer consumer )
 548 {
 549         // Stop the consumer
 550         mlt_consumer_stop( consumer );
 551
 552         // Close the parent
 553         consumer->close = NULL;
 554         mlt_consumer_close( consumer );
 555
 556         // Free the memory
 557         delete (DeckLinkConsumer*) consumer->child;
 558 }
 559
 560 extern "C" {
 561
 562 /** Initialise the consumer.
 563  */
 564
 565 mlt_consumer consumer_decklink_init( mlt_profile profile, mlt_service_type type, const char *id, char *arg )
 566 {
 567         // Allocate the consumer
 568         DeckLinkConsumer* decklink = new DeckLinkConsumer();
 569         mlt_consumer consumer = NULL;
 570
 571         // If allocated
 572         if ( decklink && !mlt_consumer_init( decklink->getConsumer(), decklink, profile ) )
 573         {
 574                 // If initialises without error
 575                 if ( decklink->open( arg? atoi(arg) : 0 ) )
 576                 {
 577                         consumer = decklink->getConsumer();
 578
 579                         // Setup callbacks
 580                         consumer->close = close;
 581                         consumer->start = start;
 582                         consumer->stop = stop;
 583                         consumer->is_stopped = is_stopped;
 584                         mlt_properties_set( MLT_CONSUMER_PROPERTIES(consumer), "deinterlace_method", "onefield" );
 585                 }
 586         }
 587
 588         // Return consumer
 589         return consumer;
 590 }
 591
 592 extern mlt_producer producer_decklink_init( mlt_profile profile, mlt_service_type type, const char *id, char *arg );
 593
 594 static mlt_properties metadata( mlt_service_type type, const char *id, void *data )
 595 {
 596         char file[ PATH_MAX ];
 597         const char *service_type = NULL;
 598         switch ( type )
 599         {
 600                 case consumer_type:
 601                         service_type = "consumer";
 602                         break;
 603                 case producer_type:
 604                         service_type = "producer";
 605                         break;
 606                 default:
 607                         return NULL;
 608         }
 609         snprintf( file, PATH_MAX, "%s/decklink/%s_%s.yml", mlt_environment( "MLT_DATA" ), service_type, id );
 610         return mlt_properties_parse_yaml( file );
 611 }
 612
 613 MLT_REPOSITORY
 614 {
 615         MLT_REGISTER( consumer_type, "decklink", consumer_decklink_init );
 616         MLT_REGISTER( producer_type, "decklink", producer_decklink_init );
 617         MLT_REGISTER_METADATA( consumer_type, "decklink", metadata, NULL );
 618         MLT_REGISTER_METADATA( producer_type, "decklink", metadata, NULL );
 619 }
 620
 621 } // extern C