research.m1stereo.tv/gitweb/ - melted/blob - src/framework/mlt_frame.c

   1 /*
   2  * mlt_frame.c -- interface for all frame classes
   3  * Copyright (C) 2003-2004 Ushodaya Enterprises Limited
   4  * Author: Charles Yates <charles.yates@pandora.be>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  */
  20
  21 #include "config.h"
  22 #include "mlt_frame.h"
  23 #include "mlt_producer.h"
  24 #include "mlt_factory.h"
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28
  29 /** Constructor for a frame.
  30 */
  31
  32 mlt_frame mlt_frame_init( )
  33 {
  34         // Allocate a frame
  35         mlt_frame this = calloc( sizeof( struct mlt_frame_s ), 1 );
  36
  37         if ( this != NULL )
  38         {
  39                 // Get the normalisation
  40                 char *normalisation = mlt_environment( "MLT_NORMALISATION" );
  41
  42                 // Initialise the properties
  43                 mlt_properties properties = &this->parent;
  44                 mlt_properties_init( properties, this );
  45
  46                 // Set default properties on the frame
  47                 mlt_properties_set_position( properties, "_position", 0.0 );
  48                 mlt_properties_set_data( properties, "image", NULL, 0, NULL, NULL );
  49
  50                 if ( normalisation == NULL || strcmp( normalisation, "NTSC" ) )
  51                 {
  52                         mlt_properties_set_int( properties, "width", 720 );
  53                         mlt_properties_set_int( properties, "height", 576 );
  54                         mlt_properties_set_int( properties, "normalised_width", 720 );
  55                         mlt_properties_set_int( properties, "normalised_height", 576 );
  56                         mlt_properties_set_double( properties, "aspect_ratio", 72.0/79.0 );
  57                 }
  58                 else
  59                 {
  60                         mlt_properties_set_int( properties, "width", 720 );
  61                         mlt_properties_set_int( properties, "height", 480 );
  62                         mlt_properties_set_int( properties, "normalised_width", 720 );
  63                         mlt_properties_set_int( properties, "normalised_height", 480 );
  64                         mlt_properties_set_double( properties, "aspect_ratio", 128.0/117.0 );
  65                 }
  66
  67                 mlt_properties_set_data( properties, "audio", NULL, 0, NULL, NULL );
  68                 mlt_properties_set_data( properties, "alpha", NULL, 0, NULL, NULL );
  69
  70                 // Construct stacks for frames and methods
  71                 this->stack_get_image = mlt_deque_init( );
  72                 this->stack_frame = mlt_deque_init( );
  73                 this->stack_service = mlt_deque_init( );
  74         }
  75
  76         return this;
  77 }
  78
  79 /** Fetch the frames properties.
  80 */
  81
  82 mlt_properties mlt_frame_properties( mlt_frame this )
  83 {
  84         return &this->parent;
  85 }
  86
  87 /** Check if we have a way to derive something other than a test card.
  88 */
  89
  90 int mlt_frame_is_test_card( mlt_frame this )
  91 {
  92         return mlt_properties_get_int( mlt_frame_properties( this ), "test_image" );
  93 }
  94
  95 /** Check if we have a way to derive something than test audio.
  96 */
  97
  98 int mlt_frame_is_test_audio( mlt_frame this )
  99 {
 100         return this->get_audio == NULL || mlt_properties_get_int( mlt_frame_properties( this ), "test_audio" );
 101 }
 102
 103 /** Get the aspect ratio of the frame.
 104 */
 105
 106 double mlt_frame_get_aspect_ratio( mlt_frame this )
 107 {
 108         return mlt_properties_get_double( mlt_frame_properties( this ), "aspect_ratio" );
 109 }
 110
 111 /** Set the aspect ratio of the frame.
 112 */
 113
 114 int mlt_frame_set_aspect_ratio( mlt_frame this, double value )
 115 {
 116         return mlt_properties_set_double( mlt_frame_properties( this ), "aspect_ratio", value );
 117 }
 118
 119 /** Get the position of this frame.
 120 */
 121
 122 mlt_position mlt_frame_get_position( mlt_frame this )
 123 {
 124         return mlt_properties_get_position( mlt_frame_properties( this ), "_position" );
 125 }
 126
 127 /** Set the position of this frame.
 128 */
 129
 130 int mlt_frame_set_position( mlt_frame this, mlt_position value )
 131 {
 132         return mlt_properties_set_position( mlt_frame_properties( this ), "_position", value );
 133 }
 134
 135 /** Stack a get_image callback.
 136 */
 137
 138 int mlt_frame_push_get_image( mlt_frame this, mlt_get_image get_image )
 139 {
 140         return mlt_deque_push_back( this->stack_get_image, get_image );
 141 }
 142
 143 /** Pop a get_image callback.
 144 */
 145
 146 mlt_get_image mlt_frame_pop_get_image( mlt_frame this )
 147 {
 148         return mlt_deque_pop_back( this->stack_get_image );
 149 }
 150
 151 /** Push a frame.
 152 */
 153
 154 int mlt_frame_push_frame( mlt_frame this, mlt_frame that )
 155 {
 156         return mlt_deque_push_back( this->stack_frame, that );
 157 }
 158
 159 /** Pop a frame.
 160 */
 161
 162 mlt_frame mlt_frame_pop_frame( mlt_frame this )
 163 {
 164         return mlt_deque_pop_back( this->stack_frame );
 165 }
 166
 167 /** Push a service.
 168 */
 169
 170 int mlt_frame_push_service( mlt_frame this, void *that )
 171 {
 172         return mlt_deque_push_back( this->stack_service, that );
 173 }
 174
 175 /** Pop a service.
 176 */
 177
 178 void *mlt_frame_pop_service( mlt_frame this )
 179 {
 180         return mlt_deque_pop_back( this->stack_service );
 181 }
 182
 183 int mlt_frame_get_image( mlt_frame this, uint8_t **buffer, mlt_image_format *format, int *width, int *height, int writable )
 184 {
 185         mlt_properties properties = mlt_frame_properties( this );
 186         mlt_get_image get_image = mlt_frame_pop_get_image( this );
 187         mlt_producer producer = mlt_properties_get_data( properties, "test_card_producer", NULL );
 188
 189         if ( get_image != NULL )
 190         {
 191                 return get_image( this, buffer, format, width, height, writable );
 192         }
 193         else if ( mlt_properties_get_data( properties, "image", NULL ) != NULL )
 194         {
 195                 *format = mlt_image_yuv422;
 196                 *buffer = mlt_properties_get_data( properties, "image", NULL );
 197                 *width = mlt_properties_get_int( properties, "width" );
 198                 *height = mlt_properties_get_int( properties, "height" );
 199         }
 200         else if ( producer != NULL )
 201         {
 202                 mlt_frame test_frame = NULL;
 203                 mlt_service_get_frame( mlt_producer_service( producer ), &test_frame, 0 );
 204                 if ( test_frame != NULL )
 205                 {
 206                         mlt_properties test_properties = mlt_frame_properties( test_frame );
 207                         mlt_properties_set_double( test_properties, "consumer_aspect_ratio", mlt_properties_get_double( properties, "consumer_aspect_ratio" ) );
 208                         mlt_properties_set( test_properties, "rescale.interp", "nearest" );
 209                         mlt_frame_get_image( test_frame, buffer, format, width, height, writable );
 210                         mlt_properties_set_data( properties, "test_card_frame", test_frame, 0, ( mlt_destructor )mlt_frame_close, NULL );
 211                         mlt_properties_set_data( properties, "image", *buffer, *width * *height * 2, NULL, NULL );
 212                         mlt_properties_set_int( properties, "width", *width );
 213                         mlt_properties_set_int( properties, "height", *height );
 214                 }
 215                 else
 216                 {
 217                         mlt_properties_set_data( properties, "test_card_producer", NULL, 0, NULL, NULL );
 218                         mlt_frame_get_image( this, buffer, format, width, height, writable );
 219                 }
 220         }
 221         else
 222         {
 223                 uint8_t *p;
 224                 uint8_t *q;
 225                 int size = 0;
 226
 227                 *width = *width == 0 ? 720 : *width;
 228                 *height = *height == 0 ? 576 : *height;
 229                 size = *width * *height;
 230
 231                 mlt_properties_set_int( properties, "width", *width );
 232                 mlt_properties_set_int( properties, "height", *height );
 233
 234                 switch( *format )
 235                 {
 236                         case mlt_image_none:
 237                                 size = 0;
 238                                 *buffer = NULL;
 239                                 break;
 240                         case mlt_image_rgb24:
 241                                 size *= 3;
 242                                 size += *width * 3;
 243                                 *buffer = mlt_pool_alloc( size );
 244                                 if ( *buffer )
 245                                         memset( *buffer, 255, size );
 246                                 break;
 247                         case mlt_image_rgb24a:
 248                                 size *= 4;
 249                                 size += *width * 4;
 250                                 *buffer = mlt_pool_alloc( size );
 251                                 if ( *buffer )
 252                                         memset( *buffer, 255, size );
 253                                 break;
 254                         case mlt_image_yuv422:
 255                                 size *= 2;
 256                                 size += *width * 2;
 257                                 *buffer = mlt_pool_alloc( size );
 258                                 p = *buffer;
 259                                 q = p + size;
 260                                 while ( p != NULL && p != q )
 261                                 {
 262                                         *p ++ = 235;
 263                                         *p ++ = 128;
 264                                 }
 265                                 break;
 266                         case mlt_image_yuv420p:
 267                                 size = size * 3 / 2;
 268                                 *buffer = mlt_pool_alloc( size );
 269                                 if ( *buffer )
 270                                         memset( *buffer, 255, size );
 271                                 break;
 272                 }
 273
 274                 mlt_properties_set_data( properties, "image", *buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
 275                 mlt_properties_set_int( properties, "test_image", 1 );
 276         }
 277
 278         return 0;
 279 }
 280
 281 uint8_t *mlt_frame_get_alpha_mask( mlt_frame this )
 282 {
 283         if ( this->get_alpha_mask != NULL )
 284                 return this->get_alpha_mask( this );
 285         return NULL;
 286 }
 287
 288 int mlt_frame_get_audio( mlt_frame this, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
 289 {
 290         mlt_properties properties = mlt_frame_properties( this );
 291
 292         if ( this->get_audio != NULL )
 293         {
 294                 return this->get_audio( this, buffer, format, frequency, channels, samples );
 295         }
 296         else
 297         {
 298                 int size = 0;
 299                 *samples = *samples <= 0 ? 1920 : *samples;
 300                 *channels = *channels <= 0 ? 2 : *channels;
 301                 *frequency = *frequency <= 0 ? 48000 : *frequency;
 302                 size = *samples * *channels * sizeof( int16_t );
 303                 *buffer = mlt_pool_alloc( size );
 304                 if ( *buffer != NULL )
 305                         memset( *buffer, 0, size );
 306                 mlt_properties_set_data( properties, "audio", *buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
 307                 mlt_properties_set_int( properties, "test_audio", 1 );
 308         }
 309         return 0;
 310 }
 311
 312 void mlt_frame_close( mlt_frame this )
 313 {
 314         if ( this != NULL )
 315         {
 316                 mlt_deque_close( this->stack_get_image );
 317                 mlt_deque_close( this->stack_frame );
 318                 mlt_deque_close( this->stack_service );
 319                 mlt_properties_close( &this->parent );
 320                 free( this );
 321         }
 322 }
 323
 324 /***** convenience functions *****/
 325
 326 int mlt_convert_rgb24a_to_yuv422( uint8_t *rgba, int width, int height, int stride, uint8_t *yuv, uint8_t *alpha )
 327 {
 328         int ret = 0;
 329         register int y0, y1, u0, u1, v0, v1;
 330         register int r, g, b;
 331         register uint8_t *d = yuv;
 332         register int i, j;
 333
 334         for ( i = 0; i < height; i++ )
 335         {
 336                 register uint8_t *s = rgba + ( stride * i );
 337                 for ( j = 0; j < ( width / 2 ); j++ )
 338                 {
 339                         r = *s++;
 340                         g = *s++;
 341                         b = *s++;
 342                         *alpha++ = *s++;
 343                         RGB2YUV (r, g, b, y0, u0 , v0);
 344                         r = *s++;
 345                         g = *s++;
 346                         b = *s++;
 347                         *alpha++ = *s++;
 348                         RGB2YUV (r, g, b, y1, u1 , v1);
 349                         *d++ = y0;
 350                         *d++ = (u0+u1) >> 1;
 351                         *d++ = y1;
 352                         *d++ = (v0+v1) >> 1;
 353                 }
 354                 if ( width % 2 )
 355                 {
 356                         r = *s++;
 357                         g = *s++;
 358                         b = *s++;
 359                         *alpha++ = *s++;
 360                         RGB2YUV (r, g, b, y0, u0 , v0);
 361                         *d++ = y0;
 362                         *d++ = u0;
 363                 }
 364         }
 365         return ret;
 366 }
 367
 368 int mlt_convert_rgb24_to_yuv422( uint8_t *rgb, int width, int height, int stride, uint8_t *yuv )
 369 {
 370         int ret = 0;
 371         register int y0, y1, u0, u1, v0, v1;
 372         register int r, g, b;
 373         register uint8_t *d = yuv;
 374         register int i, j;
 375
 376         for ( i = 0; i < height; i++ )
 377         {
 378                 register uint8_t *s = rgb + ( stride * i );
 379                 for ( j = 0; j < ( width / 2 ); j++ )
 380                 {
 381                         r = *s++;
 382                         g = *s++;
 383                         b = *s++;
 384                         RGB2YUV (r, g, b, y0, u0 , v0);
 385                         r = *s++;
 386                         g = *s++;
 387                         b = *s++;
 388                         RGB2YUV (r, g, b, y1, u1 , v1);
 389                         *d++ = y0;
 390                         *d++ = (u0+u1) >> 1;
 391                         *d++ = y1;
 392                         *d++ = (v0+v1) >> 1;
 393                 }
 394                 if ( width % 2 )
 395                 {
 396                         r = *s++;
 397                         g = *s++;
 398                         b = *s++;
 399                         RGB2YUV (r, g, b, y0, u0 , v0);
 400                         *d++ = y0;
 401                         *d++ = u0;
 402                 }
 403         }
 404         return ret;
 405 }
 406
 407 int mlt_convert_yuv420p_to_yuv422( uint8_t *yuv420p, int width, int height, int stride, uint8_t *yuv )
 408 {
 409         int ret = 0;
 410         register int i, j;
 411
 412         int half = width >> 1;
 413
 414         uint8_t *Y = yuv420p;
 415         uint8_t *U = Y + width * height;
 416         uint8_t *V = U + width * height / 4;
 417
 418         register uint8_t *d = yuv;
 419
 420         for ( i = 0; i < height; i++ )
 421         {
 422                 register uint8_t *u = U + ( i / 2 ) * ( half );
 423                 register uint8_t *v = V + ( i / 2 ) * ( half );
 424
 425                 for ( j = 0; j < half; j++ )
 426                 {
 427                         *d ++ = *Y ++;
 428                         *d ++ = *u ++;
 429                         *d ++ = *Y ++;
 430                         *d ++ = *v ++;
 431                 }
 432         }
 433         return ret;
 434 }
 435
 436 void mlt_resize_yuv422( uint8_t *output, int owidth, int oheight, uint8_t *input, int iwidth, int iheight )
 437 {
 438         // Calculate strides
 439         int istride = iwidth * 2;
 440         int ostride = owidth * 2;
 441
 442         iwidth = iwidth - ( iwidth % 4 );
 443         owidth = owidth - ( owidth % 4 );
 444         iheight = iheight - ( iheight % 2 );
 445         oheight = oheight - ( oheight % 2 );
 446
 447         // Optimisation point
 448         if ( iwidth == owidth && iheight == oheight )
 449                 memcpy( output, input, iheight * istride );
 450
 451         // Coordinates (0,0 is middle of output)
 452         int y;
 453
 454         // Calculate ranges
 455         int out_x_range = owidth / 2;
 456         int out_y_range = oheight / 2;
 457         int in_x_range = iwidth / 2 < out_x_range ? iwidth / 2 : out_x_range;
 458         int in_y_range = iheight / 2 < out_y_range ? iheight / 2 : out_y_range;
 459
 460         // Output pointers
 461         uint8_t *out_line = output;
 462         uint8_t *out_ptr = out_line;
 463
 464         // Calculate a middle and possibly invalid pointer in the input
 465         uint8_t *in_middle = input + istride * ( iheight / 2 ) + ( iwidth / 2 ) * 2;
 466         int in_line = - in_y_range * istride - in_x_range * 2;
 467
 468         int elements;
 469
 470         // Fill whole section with black
 471         y = out_y_range - ( iheight / 2 );
 472         int blank_elements = ostride * y / 2;
 473         elements = blank_elements;
 474         while ( elements -- )
 475         {
 476                 *out_line ++ = 16;
 477                 *out_line ++ = 128;
 478         }
 479
 480         int active_width = 2 * iwidth;
 481         int inactive_width = out_x_range - in_x_range;
 482
 483         // Loop for the entirety of our output height.
 484         while ( iheight -- )
 485         {
 486         // Start at the beginning of the line
 487         out_ptr = out_line;
 488
 489                 // Fill the outer part with black
 490                 elements = inactive_width;
 491                 while ( elements -- )
 492                 {
 493                         *out_ptr ++ = 16;
 494                         *out_ptr ++ = 128;
 495                 }
 496
 497                 // We're in the input range for this row.
 498                 memcpy( out_ptr, in_middle + in_line, active_width );
 499                 out_ptr += active_width;
 500
 501                 // Fill the outer part with black
 502                 elements = inactive_width;
 503                 while ( elements -- )
 504                 {
 505                         *out_ptr ++ = 16;
 506                         *out_ptr ++ = 128;
 507                 }
 508
 509                 // Move to next input line
 510                 in_line += istride;
 511
 512         // Move to next output line
 513         out_line += ostride;
 514         }
 515
 516         // Fill whole section with black
 517         elements = blank_elements;
 518         while ( elements -- )
 519         {
 520                 *out_line ++ = 16;
 521                 *out_line ++ = 128;
 522         }
 523 }
 524
 525 /** A resizing function for yuv422 frames - this does not rescale, but simply
 526         resizes. It assumes yuv422 images available on the frame so use with care.
 527 */
 528
 529 uint8_t *mlt_frame_resize_yuv422( mlt_frame this, int owidth, int oheight )
 530 {
 531         // Get properties
 532         mlt_properties properties = mlt_frame_properties( this );
 533
 534         // Get the input image, width and height
 535         uint8_t *input = mlt_properties_get_data( properties, "image", NULL );
 536         int iwidth = mlt_properties_get_int( properties, "width" );
 537         int iheight = mlt_properties_get_int( properties, "height" );
 538
 539         // If width and height are correct, don't do anything
 540         if ( iwidth != owidth || iheight != oheight )
 541         {
 542                 // Create the output image
 543                 uint8_t *output = mlt_pool_alloc( owidth * ( oheight + 1 ) * 2 );
 544
 545                 // Call the generic resize
 546                 mlt_resize_yuv422( output, owidth, oheight, input, iwidth, iheight );
 547
 548                 // Now update the frame
 549                 mlt_properties_set_data( properties, "image", output, owidth * ( oheight + 1 ) * 2, ( mlt_destructor )mlt_pool_release, NULL );
 550                 mlt_properties_set_int( properties, "width", owidth );
 551                 mlt_properties_set_int( properties, "height", oheight );
 552
 553                 // Return the output
 554                 return output;
 555         }
 556         // No change, return input
 557         return input;
 558 }
 559
 560 /** A rescaling function for yuv422 frames - low quality, and provided for testing
 561         only. It assumes yuv422 images available on the frame so use with care.
 562 */
 563
 564 uint8_t *mlt_frame_rescale_yuv422( mlt_frame this, int owidth, int oheight )
 565 {
 566         // Get properties
 567         mlt_properties properties = mlt_frame_properties( this );
 568
 569         // Get the input image, width and height
 570         uint8_t *input = mlt_properties_get_data( properties, "image", NULL );
 571         int iwidth = mlt_properties_get_int( properties, "width" );
 572         int iheight = mlt_properties_get_int( properties, "height" );
 573
 574         // If width and height are correct, don't do anything
 575         if ( iwidth != owidth || iheight != oheight )
 576         {
 577                 // Create the output image
 578                 uint8_t *output = mlt_pool_alloc( owidth * ( oheight + 1 ) * 2 );
 579
 580                 // Calculate strides
 581                 int istride = iwidth * 2;
 582                 int ostride = owidth * 2;
 583
 584                 iwidth = iwidth - ( iwidth % 4 );
 585
 586                 // Derived coordinates
 587                 int dy, dx;
 588
 589         // Calculate ranges
 590         int out_x_range = owidth / 2;
 591         int out_y_range = oheight / 2;
 592         int in_x_range = iwidth / 2;
 593         int in_y_range = iheight / 2;
 594
 595         // Output pointers
 596         register uint8_t *out_line = output;
 597         register uint8_t *out_ptr;
 598
 599         // Calculate a middle pointer
 600         uint8_t *in_middle = input + istride * in_y_range + in_x_range * 2;
 601         uint8_t *in_line;
 602
 603                 // Generate the affine transform scaling values
 604                 register int scale_width = ( iwidth << 16 ) / owidth;
 605                 register int scale_height = ( iheight << 16 ) / oheight;
 606                 register int base = 0;
 607
 608                 int outer = out_x_range * scale_width;
 609                 int bottom = out_y_range * scale_height;
 610
 611         // Loop for the entirety of our output height.
 612         for ( dy = - bottom; dy < bottom; dy += scale_height )
 613         {
 614                 // Start at the beginning of the line
 615                 out_ptr = out_line;
 616
 617                 // Pointer to the middle of the input line
 618                 in_line = in_middle + ( dy >> 16 ) * istride;
 619
 620                 // Loop for the entirety of our output row.
 621                 for ( dx = - outer; dx < outer; dx += scale_width )
 622                 {
 623                                 base = dx >> 15;
 624                                 base &= 0xfffffffe;
 625                                 *out_ptr ++ = *( in_line + base );
 626                                 base &= 0xfffffffc;
 627                                 *out_ptr ++ = *( in_line + base + 1 );
 628                                 dx += scale_width;
 629                                 base = dx >> 15;
 630                                 base &= 0xfffffffe;
 631                                 *out_ptr ++ = *( in_line + base );
 632                                 base &= 0xfffffffc;
 633                                 *out_ptr ++ = *( in_line + base + 3 );
 634                 }
 635
 636                 // Move to next output line
 637                 out_line += ostride;
 638         }
 639
 640                 // Now update the frame
 641                 mlt_properties_set_data( properties, "image", output, owidth * ( oheight + 1 ) * 2, ( mlt_destructor )mlt_pool_release, NULL );
 642                 mlt_properties_set_int( properties, "width", owidth );
 643                 mlt_properties_set_int( properties, "height", oheight );
 644
 645                 // Return the output
 646                 return output;
 647         }
 648
 649         // No change, return input
 650         return input;
 651 }
 652
 653 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 )
 654 {
 655         int ret = 0;
 656         int16_t *src, *dest;
 657         int frequency_src = *frequency, frequency_dest = *frequency;
 658         int channels_src = *channels, channels_dest = *channels;
 659         int samples_src = *samples, samples_dest = *samples;
 660         int i, j;
 661         double d = 0, s = 0;
 662
 663         mlt_frame_get_audio( this, &dest, format, &frequency_dest, &channels_dest, &samples_dest );
 664         //fprintf( stderr, "mix: frame dest samples %d channels %d position %lld\n", samples_dest, channels_dest, mlt_properties_get_position( mlt_frame_properties( this ), "_position" ) );
 665         mlt_frame_get_audio( that, &src, format, &frequency_src, &channels_src, &samples_src );
 666         //fprintf( stderr, "mix: frame src  samples %d channels %d\n", samples_src, channels_src );
 667
 668         if ( channels_src > 6 )
 669                 channels_src = 0;
 670         if ( channels_dest > 6 )
 671                 channels_dest = 0;
 672         if ( samples_src > 4000 )
 673                 samples_src = 0;
 674         if ( samples_dest > 4000 )
 675                 samples_dest = 0;
 676
 677         // determine number of samples to process
 678         *samples = samples_src < samples_dest ? samples_src : samples_dest;
 679         *channels = channels_src < channels_dest ? channels_src : channels_dest;
 680         *buffer = dest;
 681         *frequency = frequency_dest;
 682
 683         // Compute a smooth ramp over start to end
 684         float weight = weight_start;
 685         float weight_step = ( weight_end - weight_start ) / *samples;
 686
 687         // Mixdown
 688         for ( i = 0; i < *samples; i++ )
 689         {
 690                 for ( j = 0; j < *channels; j++ )
 691                 {
 692                         if ( j < channels_dest )
 693                                 d = (double) dest[ i * channels_dest + j ];
 694                         if ( j < channels_src )
 695                                 s = (double) src[ i * channels_src + j ];
 696                         dest[ i * channels_dest + j ] = s * weight + d * ( 1.0 - weight );
 697                 }
 698                 weight += weight_step;
 699         }
 700
 701         return ret;
 702 }
 703
 704 int mlt_sample_calculator( float fps, int frequency, int64_t position )
 705 {
 706         int samples = 0;
 707
 708         if ( fps > 29 && fps <= 30 )
 709         {
 710                 samples = frequency / 30;
 711
 712                 switch ( frequency )
 713                 {
 714                         case 48000:
 715                                 if ( position % 5 != 0 )
 716                                         samples += 2;
 717                                 break;
 718                         case 44100:
 719                                 if ( position % 300 == 0 )
 720                                         samples = 1471;
 721                                 else if ( position % 30 == 0 )
 722                                         samples = 1470;
 723                                 else if ( position % 2 == 0 )
 724                                         samples = 1472;
 725                                 else
 726                                         samples = 1471;
 727                                 break;
 728                         case 32000:
 729                                 if ( position % 30 == 0 )
 730                                         samples = 1068;
 731                                 else if ( position % 29 == 0 )
 732                                         samples = 1067;
 733                                 else if ( position % 4 == 2 )
 734                                         samples = 1067;
 735                                 else
 736                                         samples = 1068;
 737                                 break;
 738                         default:
 739                                 samples = 0;
 740                 }
 741         }
 742         else if ( fps != 0 )
 743         {
 744                 samples = frequency / fps;
 745         }
 746
 747         return samples;
 748 }