git.sesse.net Git - mlt/blob - src/framework/mlt_frame.c

   1 /**
   2  * \file mlt_frame.c
   3  * \brief interface for all frame classes
   4  * \see mlt_frame_s
   5  *
   6  * Copyright (C) 2003-2009 Ushodaya Enterprises Limited
   7  * \author Charles Yates <charles.yates@pandora.be>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  22  */
  23
  24 #include "mlt_frame.h"
  25 #include "mlt_producer.h"
  26 #include "mlt_factory.h"
  27 #include "mlt_profile.h"
  28 #include "mlt_log.h"
  29
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <math.h>
  34
  35 /** Constructor for a frame.
  36 */
  37
  38 mlt_frame mlt_frame_init( mlt_service service )
  39 {
  40         // Allocate a frame
  41         mlt_frame this = calloc( sizeof( struct mlt_frame_s ), 1 );
  42
  43         if ( this != NULL )
  44         {
  45                 mlt_profile profile = mlt_service_profile( service );
  46
  47                 // Initialise the properties
  48                 mlt_properties properties = &this->parent;
  49                 mlt_properties_init( properties, this );
  50
  51                 // Set default properties on the frame
  52                 mlt_properties_set_position( properties, "_position", 0.0 );
  53                 mlt_properties_set_data( properties, "image", NULL, 0, NULL, NULL );
  54                 mlt_properties_set_int( properties, "width", profile? profile->width : 720 );
  55                 mlt_properties_set_int( properties, "height", profile? profile->height : 576 );
  56                 mlt_properties_set_int( properties, "normalised_width", profile? profile->width : 720 );
  57                 mlt_properties_set_int( properties, "normalised_height", profile? profile->height : 576 );
  58                 mlt_properties_set_double( properties, "aspect_ratio", mlt_profile_sar( NULL ) );
  59                 mlt_properties_set_data( properties, "audio", NULL, 0, NULL, NULL );
  60                 mlt_properties_set_data( properties, "alpha", NULL, 0, NULL, NULL );
  61
  62                 // Construct stacks for frames and methods
  63                 this->stack_image = mlt_deque_init( );
  64                 this->stack_audio = mlt_deque_init( );
  65                 this->stack_service = mlt_deque_init( );
  66         }
  67
  68         return this;
  69 }
  70
  71 /** Fetch the frames properties.
  72 */
  73
  74 mlt_properties mlt_frame_properties( mlt_frame this )
  75 {
  76         return this != NULL ? &this->parent : NULL;
  77 }
  78
  79 /** Check if we have a way to derive something other than a test card.
  80 */
  81
  82 int mlt_frame_is_test_card( mlt_frame this )
  83 {
  84         return mlt_deque_count( this->stack_image ) == 0 || mlt_properties_get_int( MLT_FRAME_PROPERTIES( this ), "test_image" );
  85 }
  86
  87 /** Check if we have a way to derive something other than test audio.
  88 */
  89
  90 int mlt_frame_is_test_audio( mlt_frame this )
  91 {
  92         return mlt_deque_count( this->stack_audio ) == 0 || mlt_properties_get_int( MLT_FRAME_PROPERTIES( this ), "test_audio" );
  93 }
  94
  95 /** Get the aspect ratio of the frame.
  96 */
  97
  98 double mlt_frame_get_aspect_ratio( mlt_frame this )
  99 {
 100         return mlt_properties_get_double( MLT_FRAME_PROPERTIES( this ), "aspect_ratio" );
 101 }
 102
 103 /** Set the aspect ratio of the frame.
 104 */
 105
 106 int mlt_frame_set_aspect_ratio( mlt_frame this, double value )
 107 {
 108         return mlt_properties_set_double( MLT_FRAME_PROPERTIES( this ), "aspect_ratio", value );
 109 }
 110
 111 /** Get the position of this frame.
 112 */
 113
 114 mlt_position mlt_frame_get_position( mlt_frame this )
 115 {
 116         int pos = mlt_properties_get_position( MLT_FRAME_PROPERTIES( this ), "_position" );
 117         return pos < 0 ? 0 : pos;
 118 }
 119
 120 /** Set the position of this frame.
 121 */
 122
 123 int mlt_frame_set_position( mlt_frame this, mlt_position value )
 124 {
 125         return mlt_properties_set_position( MLT_FRAME_PROPERTIES( this ), "_position", value );
 126 }
 127
 128 /** Stack a get_image callback.
 129 */
 130
 131 int mlt_frame_push_get_image( mlt_frame this, mlt_get_image get_image )
 132 {
 133         return mlt_deque_push_back( this->stack_image, get_image );
 134 }
 135
 136 /** Pop a get_image callback.
 137 */
 138
 139 mlt_get_image mlt_frame_pop_get_image( mlt_frame this )
 140 {
 141         return mlt_deque_pop_back( this->stack_image );
 142 }
 143
 144 /** Push a frame.
 145 */
 146
 147 int mlt_frame_push_frame( mlt_frame this, mlt_frame that )
 148 {
 149         return mlt_deque_push_back( this->stack_image, that );
 150 }
 151
 152 /** Pop a frame.
 153 */
 154
 155 mlt_frame mlt_frame_pop_frame( mlt_frame this )
 156 {
 157         return mlt_deque_pop_back( this->stack_image );
 158 }
 159
 160 /** Push a service.
 161 */
 162
 163 int mlt_frame_push_service( mlt_frame this, void *that )
 164 {
 165         return mlt_deque_push_back( this->stack_image, that );
 166 }
 167
 168 /** Pop a service.
 169 */
 170
 171 void *mlt_frame_pop_service( mlt_frame this )
 172 {
 173         return mlt_deque_pop_back( this->stack_image );
 174 }
 175
 176 /** Push a service.
 177 */
 178
 179 int mlt_frame_push_service_int( mlt_frame this, int that )
 180 {
 181         return mlt_deque_push_back_int( this->stack_image, that );
 182 }
 183
 184 /** Pop a service.
 185 */
 186
 187 int mlt_frame_pop_service_int( mlt_frame this )
 188 {
 189         return mlt_deque_pop_back_int( this->stack_image );
 190 }
 191
 192 /** Push an audio item on the stack.
 193 */
 194
 195 int mlt_frame_push_audio( mlt_frame this, void *that )
 196 {
 197         return mlt_deque_push_back( this->stack_audio, that );
 198 }
 199
 200 /** Pop an audio item from the stack
 201 */
 202
 203 void *mlt_frame_pop_audio( mlt_frame this )
 204 {
 205         return mlt_deque_pop_back( this->stack_audio );
 206 }
 207
 208 /** Return the service stack
 209 */
 210
 211 mlt_deque mlt_frame_service_stack( mlt_frame this )
 212 {
 213         return this->stack_service;
 214 }
 215
 216 /** Replace image stack with the information provided.
 217
 218         This might prove to be unreliable and restrictive - the idea is that a transition
 219         which normally uses two images may decide to only use the b frame (ie: in the case
 220         of a composite where the b frame completely obscures the a frame).
 221
 222         The image must be writable and the destructor for the image itself must be taken
 223         care of on another frame and that frame cannot have a replace applied to it...
 224         Further it assumes that no alpha mask is in use.
 225
 226         For these reasons, it can only be used in a specific situation - when you have
 227         multiple tracks each with their own transition and these transitions are applied
 228         in a strictly reversed order (ie: highest numbered [lowest track] is processed
 229         first).
 230
 231         More reliable approach - the cases should be detected during the process phase
 232         and the upper tracks should simply not be invited to stack...
 233 */
 234
 235 void mlt_frame_replace_image( mlt_frame this, uint8_t *image, mlt_image_format format, int width, int height )
 236 {
 237         // Remove all items from the stack
 238         while( mlt_deque_pop_back( this->stack_image ) ) ;
 239
 240         // Update the information
 241         mlt_properties_set_data( MLT_FRAME_PROPERTIES( this ), "image", image, 0, NULL, NULL );
 242         mlt_properties_set_int( MLT_FRAME_PROPERTIES( this ), "width", width );
 243         mlt_properties_set_int( MLT_FRAME_PROPERTIES( this ), "height", height );
 244         mlt_properties_set_int( MLT_FRAME_PROPERTIES( this ), "format", format );
 245         this->get_alpha_mask = NULL;
 246 }
 247
 248 const char * mlt_image_format_name( mlt_image_format format )
 249 {
 250         switch ( format )
 251         {
 252                 case mlt_image_none:    return "none";
 253                 case mlt_image_rgb24:   return "rgb24";
 254                 case mlt_image_rgb24a:  return "rgb24a";
 255                 case mlt_image_yuv422:  return "yuv422";
 256                 case mlt_image_yuv420p: return "yuv420p";
 257                 case mlt_image_opengl:  return "opengl";
 258         }
 259         return "invalid";
 260 }
 261
 262 /** Get the image associated to the frame.
 263 */
 264
 265 int mlt_frame_get_image( mlt_frame this, uint8_t **buffer, mlt_image_format *format, int *width, int *height, int writable )
 266 {
 267         mlt_properties properties = MLT_FRAME_PROPERTIES( this );
 268         mlt_get_image get_image = mlt_frame_pop_get_image( this );
 269         mlt_producer producer = mlt_properties_get_data( properties, "test_card_producer", NULL );
 270         mlt_image_format requested_format = *format;
 271         int error = 0;
 272
 273         if ( get_image )
 274         {
 275                 mlt_properties_set_int( properties, "image_count", mlt_properties_get_int( properties, "image_count" ) - 1 );
 276                 mlt_position position = mlt_frame_get_position( this );
 277                 error = get_image( this, buffer, format, width, height, writable );
 278                 mlt_properties_set_int( properties, "width", *width );
 279                 mlt_properties_set_int( properties, "height", *height );
 280                 mlt_properties_set_int( properties, "format", *format );
 281                 mlt_frame_set_position( this, position );
 282                 if ( this->convert_image )
 283                         this->convert_image( this, buffer, format, requested_format );
 284         }
 285         else if ( mlt_properties_get_data( properties, "image", NULL ) )
 286         {
 287                 *format = mlt_properties_get_int( properties, "format" );
 288                 *buffer = mlt_properties_get_data( properties, "image", NULL );
 289                 *width = mlt_properties_get_int( properties, "width" );
 290                 *height = mlt_properties_get_int( properties, "height" );
 291                 if ( this->convert_image )
 292                         this->convert_image( this, buffer, format, requested_format );
 293         }
 294         else if ( producer )
 295         {
 296                 mlt_frame test_frame = NULL;
 297                 mlt_service_get_frame( MLT_PRODUCER_SERVICE( producer ), &test_frame, 0 );
 298                 if ( test_frame )
 299                 {
 300                         mlt_properties test_properties = MLT_FRAME_PROPERTIES( test_frame );
 301                         mlt_properties_set_double( test_properties, "consumer_aspect_ratio", mlt_properties_get_double( properties, "consumer_aspect_ratio" ) );
 302                         mlt_properties_set( test_properties, "rescale.interp", mlt_properties_get( properties, "rescale.interp" ) );
 303                         mlt_frame_get_image( test_frame, buffer, format, width, height, writable );
 304                         mlt_properties_set_data( properties, "test_card_frame", test_frame, 0, ( mlt_destructor )mlt_frame_close, NULL );
 305                         mlt_properties_set_double( properties, "aspect_ratio", mlt_frame_get_aspect_ratio( test_frame ) );
 306 //                      mlt_properties_set_data( properties, "image", *buffer, *width * *height * 2, NULL, NULL );
 307 //                      mlt_properties_set_int( properties, "width", *width );
 308 //                      mlt_properties_set_int( properties, "height", *height );
 309 //                      mlt_properties_set_int( properties, "format", *format );
 310                 }
 311                 else
 312                 {
 313                         mlt_properties_set_data( properties, "test_card_producer", NULL, 0, NULL, NULL );
 314                         mlt_frame_get_image( this, buffer, format, width, height, writable );
 315                 }
 316         }
 317         else
 318         {
 319                 register uint8_t *p;
 320                 register uint8_t *q;
 321                 int size = 0;
 322
 323                 *width = *width == 0 ? 720 : *width;
 324                 *height = *height == 0 ? 576 : *height;
 325                 size = *width * *height;
 326
 327                 mlt_properties_set_int( properties, "format", *format );
 328                 mlt_properties_set_int( properties, "width", *width );
 329                 mlt_properties_set_int( properties, "height", *height );
 330                 mlt_properties_set_int( properties, "aspect_ratio", 0 );
 331
 332                 switch( *format )
 333                 {
 334                         case mlt_image_none:
 335                                 size = 0;
 336                                 *buffer = NULL;
 337                                 break;
 338                         case mlt_image_rgb24:
 339                                 size *= 3;
 340                                 size += *width * 3;
 341                                 *buffer = mlt_pool_alloc( size );
 342                                 if ( *buffer )
 343                                         memset( *buffer, 255, size );
 344                                 break;
 345                         case mlt_image_rgb24a:
 346                         case mlt_image_opengl:
 347                                 size *= 4;
 348                                 size += *width * 4;
 349                                 *buffer = mlt_pool_alloc( size );
 350                                 if ( *buffer )
 351                                         memset( *buffer, 255, size );
 352                                 break;
 353                         case mlt_image_yuv422:
 354                                 size *= 2;
 355                                 size += *width * 2;
 356                                 *buffer = mlt_pool_alloc( size );
 357                                 p = *buffer;
 358                                 q = p + size;
 359                                 while ( p != NULL && p != q )
 360                                 {
 361                                         *p ++ = 235;
 362                                         *p ++ = 128;
 363                                 }
 364                                 break;
 365                         case mlt_image_yuv420p:
 366                                 size = size * 3 / 2;
 367                                 *buffer = mlt_pool_alloc( size );
 368                                 if ( *buffer )
 369                                         memset( *buffer, 255, size );
 370                                 break;
 371                 }
 372
 373                 mlt_properties_set_data( properties, "image", *buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
 374                 mlt_properties_set_int( properties, "test_image", 1 );
 375         }
 376
 377         mlt_properties_set_int( properties, "scaled_width", *width );
 378         mlt_properties_set_int( properties, "scaled_height", *height );
 379
 380         return error;
 381 }
 382
 383 uint8_t *mlt_frame_get_alpha_mask( mlt_frame this )
 384 {
 385         uint8_t *alpha = NULL;
 386         if ( this != NULL )
 387         {
 388                 if ( this->get_alpha_mask != NULL )
 389                         alpha = this->get_alpha_mask( this );
 390                 if ( alpha == NULL )
 391                         alpha = mlt_properties_get_data( &this->parent, "alpha", NULL );
 392                 if ( alpha == NULL )
 393                 {
 394                         int size = mlt_properties_get_int( &this->parent, "scaled_width" ) * mlt_properties_get_int( &this->parent, "scaled_height" );
 395                         alpha = mlt_pool_alloc( size );
 396                         memset( alpha, 255, size );
 397                         mlt_properties_set_data( &this->parent, "alpha", alpha, size, mlt_pool_release, NULL );
 398                 }
 399         }
 400         return alpha;
 401 }
 402
 403 int mlt_frame_get_audio( mlt_frame this, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
 404 {
 405         mlt_get_audio get_audio = mlt_frame_pop_audio( this );
 406         mlt_properties properties = MLT_FRAME_PROPERTIES( this );
 407         int hide = mlt_properties_get_int( properties, "test_audio" );
 408
 409         if ( hide == 0 && get_audio != NULL )
 410         {
 411                 mlt_position position = mlt_frame_get_position( this );
 412                 get_audio( this, buffer, format, frequency, channels, samples );
 413                 mlt_frame_set_position( this, position );
 414         }
 415         else if ( mlt_properties_get_data( properties, "audio", NULL ) )
 416         {
 417                 *buffer = mlt_properties_get_data( properties, "audio", NULL );
 418                 *frequency = mlt_properties_get_int( properties, "audio_frequency" );
 419                 *channels = mlt_properties_get_int( properties, "audio_channels" );
 420                 *samples = mlt_properties_get_int( properties, "audio_samples" );
 421         }
 422         else
 423         {
 424                 int size = 0;
 425                 *samples = *samples <= 0 ? 1920 : *samples;
 426                 *channels = *channels <= 0 ? 2 : *channels;
 427                 *frequency = *frequency <= 0 ? 48000 : *frequency;
 428                 size = *samples * *channels * sizeof( int16_t );
 429                 *buffer = mlt_pool_alloc( size );
 430                 if ( *buffer != NULL )
 431                         memset( *buffer, 0, size );
 432                 mlt_properties_set_data( properties, "audio", *buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
 433                 mlt_properties_set_int( properties, "test_audio", 1 );
 434         }
 435
 436         mlt_properties_set_int( properties, "audio_frequency", *frequency );
 437         mlt_properties_set_int( properties, "audio_channels", *channels );
 438         mlt_properties_set_int( properties, "audio_samples", *samples );
 439
 440         if ( mlt_properties_get( properties, "meta.volume" ) )
 441         {
 442                 double value = mlt_properties_get_double( properties, "meta.volume" );
 443
 444                 if ( value == 0.0 )
 445                 {
 446                         memset( *buffer, 0, *samples * *channels * 2 );
 447                 }
 448                 else if ( value != 1.0 )
 449                 {
 450                         int total = *samples * *channels;
 451                         int16_t *p = *buffer;
 452                         while ( total -- )
 453                         {
 454                                 *p = *p * value;
 455                                 p ++;
 456                         }
 457                 }
 458
 459                 mlt_properties_set( properties, "meta.volume", NULL );
 460         }
 461
 462         return 0;
 463 }
 464
 465 unsigned char *mlt_frame_get_waveform( mlt_frame this, int w, int h )
 466 {
 467         int16_t *pcm = NULL;
 468         mlt_properties properties = MLT_FRAME_PROPERTIES( this );
 469         mlt_audio_format format = mlt_audio_pcm;
 470         int frequency = 32000; // lower frequency available?
 471         int channels = 2;
 472         double fps = mlt_profile_fps( NULL );
 473         int samples = mlt_sample_calculator( fps, frequency, mlt_frame_get_position( this ) );
 474
 475         // Get the pcm data
 476         mlt_frame_get_audio( this, &pcm, &format, &frequency, &channels, &samples );
 477
 478         // Make an 8-bit buffer large enough to hold rendering
 479         int size = w * h;
 480         unsigned char *bitmap = ( unsigned char* )mlt_pool_alloc( size );
 481         if ( bitmap != NULL )
 482                 memset( bitmap, 0, size );
 483         mlt_properties_set_data( properties, "waveform", bitmap, size, ( mlt_destructor )mlt_pool_release, NULL );
 484
 485         // Render vertical lines
 486         int16_t *ubound = pcm + samples * channels;
 487         int skip = samples / w - 1;
 488         int i, j, k;
 489
 490         // Iterate sample stream and along x coordinate
 491         for ( i = 0; i < w && pcm < ubound; i++ )
 492         {
 493                 // pcm data has channels interleaved
 494                 for ( j = 0; j < channels; j++ )
 495                 {
 496                         // Determine sample's magnitude from 2s complement;
 497                         int pcm_magnitude = *pcm < 0 ? ~(*pcm) + 1 : *pcm;
 498                         // The height of a line is the ratio of the magnitude multiplied by
 499                         // half the vertical resolution
 500                         int height = ( int )( ( double )( pcm_magnitude ) / 32768 * h / 2 );
 501                         // Determine the starting y coordinate - left channel above center,
 502                         // right channel below - currently assumes 2 channels
 503                         int displacement = ( h / 2 ) - ( 1 - j ) * height;
 504                         // Position buffer pointer using y coordinate, stride, and x coordinate
 505                         unsigned char *p = &bitmap[ i + displacement * w ];
 506
 507                         // Draw vertical line
 508                         for ( k = 0; k < height; k++ )
 509                                 p[ w * k ] = 0xFF;
 510
 511                         pcm++;
 512                 }
 513                 pcm += skip * channels;
 514         }
 515
 516         return bitmap;
 517 }
 518
 519 mlt_producer mlt_frame_get_original_producer( mlt_frame this )
 520 {
 521         if ( this != NULL )
 522                 return mlt_properties_get_data( MLT_FRAME_PROPERTIES( this ), "_producer", NULL );
 523         return NULL;
 524 }
 525
 526 void mlt_frame_close( mlt_frame this )
 527 {
 528         if ( this != NULL && mlt_properties_dec_ref( MLT_FRAME_PROPERTIES( this ) ) <= 0 )
 529         {
 530                 mlt_deque_close( this->stack_image );
 531                 mlt_deque_close( this->stack_audio );
 532                 while( mlt_deque_peek_back( this->stack_service ) )
 533                         mlt_service_close( mlt_deque_pop_back( this->stack_service ) );
 534                 mlt_deque_close( this->stack_service );
 535                 mlt_properties_close( &this->parent );
 536                 free( this );
 537         }
 538 }
 539
 540 /***** convenience functions *****/
 541
 542 int mlt_frame_mix_audio( mlt_frame this, mlt_frame that, float weight_start, float weight_end, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
 543 {
 544         int ret = 0;
 545         int16_t *src, *dest;
 546         int frequency_src = *frequency, frequency_dest = *frequency;
 547         int channels_src = *channels, channels_dest = *channels;
 548         int samples_src = *samples, samples_dest = *samples;
 549         int i, j;
 550         double d = 0, s = 0;
 551
 552         mlt_frame_get_audio( that, &src, format, &frequency_src, &channels_src, &samples_src );
 553         mlt_frame_get_audio( this, &dest, format, &frequency_dest, &channels_dest, &samples_dest );
 554
 555         int silent = mlt_properties_get_int( MLT_FRAME_PROPERTIES( this ), "silent_audio" );
 556         mlt_properties_set_int( MLT_FRAME_PROPERTIES( this ), "silent_audio", 0 );
 557         if ( silent )
 558                 memset( dest, 0, samples_dest * channels_dest * sizeof( int16_t ) );
 559
 560         silent = mlt_properties_get_int( MLT_FRAME_PROPERTIES( that ), "silent_audio" );
 561         mlt_properties_set_int( MLT_FRAME_PROPERTIES( that ), "silent_audio", 0 );
 562         if ( silent )
 563                 memset( src, 0, samples_src * channels_src * sizeof( int16_t ) );
 564
 565         if ( channels_src > 6 )
 566                 channels_src = 0;
 567         if ( channels_dest > 6 )
 568                 channels_dest = 0;
 569         if ( samples_src > 4000 )
 570                 samples_src = 0;
 571         if ( samples_dest > 4000 )
 572                 samples_dest = 0;
 573
 574         // determine number of samples to process
 575         *samples = samples_src < samples_dest ? samples_src : samples_dest;
 576         *channels = channels_src < channels_dest ? channels_src : channels_dest;
 577         *buffer = dest;
 578         *frequency = frequency_dest;
 579
 580         // Compute a smooth ramp over start to end
 581         float weight = weight_start;
 582         float weight_step = ( weight_end - weight_start ) / *samples;
 583
 584         if ( src == dest )
 585         {
 586                 *samples = samples_src;
 587                 *channels = channels_src;
 588                 *buffer = src;
 589                 *frequency = frequency_src;
 590                 return ret;
 591         }
 592
 593         // Mixdown
 594         for ( i = 0; i < *samples; i++ )
 595         {
 596                 for ( j = 0; j < *channels; j++ )
 597                 {
 598                         if ( j < channels_dest )
 599                                 d = (double) dest[ i * channels_dest + j ];
 600                         if ( j < channels_src )
 601                                 s = (double) src[ i * channels_src + j ];
 602                         dest[ i * channels_dest + j ] = s * weight + d * ( 1.0 - weight );
 603                 }
 604                 weight += weight_step;
 605         }
 606
 607         return ret;
 608 }
 609
 610 // Replacement for broken mlt_frame_audio_mix - this filter uses an inline low pass filter
 611 // to allow mixing without volume hacking
 612 int mlt_frame_combine_audio( mlt_frame this, mlt_frame that, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
 613 {
 614         int ret = 0;
 615         int16_t *src, *dest;
 616         int frequency_src = *frequency, frequency_dest = *frequency;
 617         int channels_src = *channels, channels_dest = *channels;
 618         int samples_src = *samples, samples_dest = *samples;
 619         int i, j;
 620         double vp[ 6 ];
 621         double b_weight = 1.0;
 622
 623         if ( mlt_properties_get_int( MLT_FRAME_PROPERTIES( this ), "meta.mixdown" ) )
 624                 b_weight = 1.0 - mlt_properties_get_double( MLT_FRAME_PROPERTIES( this ), "meta.volume" );
 625
 626         mlt_frame_get_audio( that, &src, format, &frequency_src, &channels_src, &samples_src );
 627         mlt_frame_get_audio( this, &dest, format, &frequency_dest, &channels_dest, &samples_dest );
 628
 629         int silent = mlt_properties_get_int( MLT_FRAME_PROPERTIES( this ), "silent_audio" );
 630         mlt_properties_set_int( MLT_FRAME_PROPERTIES( this ), "silent_audio", 0 );
 631         if ( silent )
 632                 memset( dest, 0, samples_dest * channels_dest * sizeof( int16_t ) );
 633
 634         silent = mlt_properties_get_int( MLT_FRAME_PROPERTIES( that ), "silent_audio" );
 635         mlt_properties_set_int( MLT_FRAME_PROPERTIES( that ), "silent_audio", 0 );
 636         if ( silent )
 637                 memset( src, 0, samples_src * channels_src * sizeof( int16_t ) );
 638
 639         if ( src == dest )
 640         {
 641                 *samples = samples_src;
 642                 *channels = channels_src;
 643                 *buffer = src;
 644                 *frequency = frequency_src;
 645                 return ret;
 646         }
 647
 648         // determine number of samples to process
 649         *samples = samples_src < samples_dest ? samples_src : samples_dest;
 650         *channels = channels_src < channels_dest ? channels_src : channels_dest;
 651         *buffer = dest;
 652         *frequency = frequency_dest;
 653
 654         for ( j = 0; j < *channels; j++ )
 655                 vp[ j ] = ( double )dest[ j ];
 656
 657         double Fc = 0.5;
 658         double B = exp(-2.0 * M_PI * Fc);
 659         double A = 1.0 - B;
 660         double v;
 661
 662         for ( i = 0; i < *samples; i++ )
 663         {
 664                 for ( j = 0; j < *channels; j++ )
 665                 {
 666                         v = ( double )( b_weight * dest[ i * channels_dest + j ] + src[ i * channels_src + j ] );
 667                         v = v < -32767 ? -32767 : v > 32768 ? 32768 : v;
 668                         vp[ j ] = dest[ i * channels_dest + j ] = ( int16_t )( v * A + vp[ j ] * B );
 669                 }
 670         }
 671
 672         return ret;
 673 }
 674
 675 /* Will this break when mlt_position is converted to double? -Zach */
 676 int mlt_sample_calculator( float fps, int frequency, int64_t position )
 677 {
 678         int samples = 0;
 679
 680         if ( ( int )( fps * 100 ) == 2997 )
 681         {
 682                 samples = frequency / 30;
 683
 684                 switch ( frequency )
 685                 {
 686                         case 48000:
 687                                 if ( position % 5 != 0 )
 688                                         samples += 2;
 689                                 break;
 690                         case 44100:
 691                                 if ( position % 300 == 0 )
 692                                         samples = 1471;
 693                                 else if ( position % 30 == 0 )
 694                                         samples = 1470;
 695                                 else if ( position % 2 == 0 )
 696                                         samples = 1472;
 697                                 else
 698                                         samples = 1471;
 699                                 break;
 700                         case 32000:
 701                                 if ( position % 30 == 0 )
 702                                         samples = 1068;
 703                                 else if ( position % 29 == 0 )
 704                                         samples = 1067;
 705                                 else if ( position % 4 == 2 )
 706                                         samples = 1067;
 707                                 else
 708                                         samples = 1068;
 709                                 break;
 710                         default:
 711                                 samples = 0;
 712                 }
 713         }
 714         else if ( fps != 0 )
 715         {
 716                 samples = frequency / fps;
 717         }
 718
 719         return samples;
 720 }
 721
 722 int64_t mlt_sample_calculator_to_now( float fps, int frequency, int64_t frame )
 723 {
 724         int64_t samples = 0;
 725
 726         // TODO: Correct rules for NTSC and drop the * 100 hack
 727         if ( ( int )( fps * 100 ) == 2997 )
 728         {
 729                 samples = ( ( double )( frame * frequency ) / 30 );
 730                 switch( frequency )
 731                 {
 732                         case 48000:
 733                                 samples += 2 * ( frame / 5 );
 734                                 break;
 735                         case 44100:
 736                                 samples += frame + ( frame / 2 ) - ( frame / 30 ) + ( frame / 300 );
 737                                 break;
 738                         case 32000:
 739                                 samples += ( 2 * frame ) - ( frame / 4 ) - ( frame / 29 );
 740                                 break;
 741                 }
 742         }
 743         else if ( fps != 0 )
 744         {
 745                 samples = ( ( frame * frequency ) / ( int )fps );
 746         }
 747
 748         return samples;
 749 }