research.m1stereo.tv/gitweb/ - melted/blob - src/modules/plus/transition_affine.c

   1 /*
   2  * transition_affine.c -- affine transformations
   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 "transition_affine.h"
  22 #include <framework/mlt.h>
  23
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <ctype.h>
  27 #include <string.h>
  28 #include <math.h>
  29
  30 /** Geometry struct.
  31 */
  32
  33 struct geometry_s
  34 {
  35         int frame;
  36         float position;
  37         float mix;
  38         int nw; // normalised width
  39         int nh; // normalised height
  40         int sw; // scaled width, not including consumer scale based upon w/nw
  41         int sh; // scaled height, not including consumer scale based upon h/nh
  42         float x;
  43         float y;
  44         float w;
  45         float h;
  46         struct geometry_s *next;
  47 };
  48
  49 /** Parse a value from a geometry string.
  50 */
  51
  52 static float parse_value( char **ptr, int normalisation, char delim, float defaults )
  53 {
  54         float value = defaults;
  55
  56         if ( *ptr != NULL && **ptr != '\0' )
  57         {
  58                 char *end = NULL;
  59                 value = strtod( *ptr, &end );
  60                 if ( end != NULL )
  61                 {
  62                         if ( *end == '%' )
  63                                 value = ( value / 100.0 ) * normalisation;
  64                         while ( *end == delim || *end == '%' )
  65                                 end ++;
  66                 }
  67                 *ptr = end;
  68         }
  69
  70         return value;
  71 }
  72
  73 /** Parse a geometry property string with the syntax X,Y:WxH:MIX. Any value can be
  74         expressed as a percentage by appending a % after the value, otherwise values are
  75         assumed to be relative to the normalised dimensions of the consumer.
  76 */
  77
  78 static void geometry_parse( struct geometry_s *geometry, struct geometry_s *defaults, char *property, int nw, int nh )
  79 {
  80         // Assign normalised width and height
  81         geometry->nw = nw;
  82         geometry->nh = nh;
  83
  84         // Assign from defaults if available
  85         if ( defaults != NULL )
  86         {
  87                 geometry->x = defaults->x;
  88                 geometry->y = defaults->y;
  89                 geometry->w = geometry->sw = defaults->w;
  90                 geometry->h = geometry->sh = defaults->h;
  91                 geometry->mix = defaults->mix;
  92                 defaults->next = geometry;
  93         }
  94         else
  95         {
  96                 geometry->mix = 100;
  97         }
  98
  99         // Parse the geomtry string
 100         if ( property != NULL && strcmp( property, "" ) )
 101         {
 102                 char *ptr = property;
 103                 geometry->x = parse_value( &ptr, nw, ',', geometry->x );
 104                 geometry->y = parse_value( &ptr, nh, ':', geometry->y );
 105                 geometry->w = geometry->sw = parse_value( &ptr, nw, 'x', geometry->w );
 106                 geometry->h = geometry->sh = parse_value( &ptr, nh, ':', geometry->h );
 107                 geometry->mix = parse_value( &ptr, 100, ' ', geometry->mix );
 108         }
 109 }
 110
 111 /** Calculate real geometry.
 112 */
 113
 114 static void geometry_calculate( struct geometry_s *output, struct geometry_s *in, float position )
 115 {
 116         // Search in for position
 117         struct geometry_s *out = in->next;
 118
 119         if ( position >= 1.0 )
 120         {
 121                 int section = floor( position );
 122                 position -= section;
 123                 if ( section % 2 == 1 )
 124                         position = 1.0 - position;
 125         }
 126
 127         while ( out->next != NULL )
 128         {
 129                 if ( position >= in->position && position < out->position )
 130                         break;
 131
 132                 in = out;
 133                 out = in->next;
 134         }
 135
 136         position = ( position - in->position ) / ( out->position - in->position );
 137
 138         // Calculate this frames geometry
 139         if ( in->frame != out->frame - 1 )
 140         {
 141                 output->nw = in->nw;
 142                 output->nh = in->nh;
 143                 output->x = in->x + ( out->x - in->x ) * position;
 144                 output->y = in->y + ( out->y - in->y ) * position;
 145                 output->w = in->w + ( out->w - in->w ) * position;
 146                 output->h = in->h + ( out->h - in->h ) * position;
 147                 output->mix = in->mix + ( out->mix - in->mix ) * position;
 148         }
 149         else
 150         {
 151                 output->nw = out->nw;
 152                 output->nh = out->nh;
 153                 output->x = out->x;
 154                 output->y = out->y;
 155                 output->w = out->w;
 156                 output->h = out->h;
 157                 output->mix = out->mix;
 158         }
 159 }
 160
 161 void transition_destroy_keys( void *arg )
 162 {
 163         struct geometry_s *ptr = arg;
 164         struct geometry_s *next = NULL;
 165
 166         while ( ptr != NULL )
 167         {
 168                 next = ptr->next;
 169                 free( ptr );
 170                 ptr = next;
 171         }
 172 }
 173
 174 static struct geometry_s *transition_parse_keys( mlt_transition this,  int normalised_width, int normalised_height )
 175 {
 176         // Loop variable for property interrogation
 177         int i = 0;
 178
 179         // Get the properties of the transition
 180         mlt_properties properties = mlt_transition_properties( this );
 181
 182         // Get the in and out position
 183         mlt_position in = mlt_transition_get_in( this );
 184         mlt_position out = mlt_transition_get_out( this );
 185
 186         // Create the start
 187         struct geometry_s *start = calloc( 1, sizeof( struct geometry_s ) );
 188
 189         // Create the end (we always need two entries)
 190         struct geometry_s *end = calloc( 1, sizeof( struct geometry_s ) );
 191
 192         // Pointer
 193         struct geometry_s *ptr = start;
 194
 195         // Parse the start property
 196         geometry_parse( start, NULL, mlt_properties_get( properties, "start" ), normalised_width, normalised_height );
 197
 198         // Parse the keys in between
 199         for ( i = 0; i < mlt_properties_count( properties ); i ++ )
 200         {
 201                 // Get the name of the property
 202                 char *name = mlt_properties_get_name( properties, i );
 203
 204                 // Check that it's valid
 205                 if ( !strncmp( name, "key[", 4 ) )
 206                 {
 207                         // Get the value of the property
 208                         char *value = mlt_properties_get_value( properties, i );
 209
 210                         // Determine the frame number
 211                         int frame = atoi( name + 4 );
 212
 213                         // Determine the position
 214                         float position = 0;
 215
 216                         if ( frame >= 0 && frame < ( out - in ) )
 217                                 position = ( float )frame / ( float )( out - in + 1 );
 218                         else if ( frame < 0 && - frame < ( out - in ) )
 219                                 position = ( float )( out - in + frame ) / ( float )( out - in + 1 );
 220
 221                         // For now, we'll exclude all keys received out of order
 222                         if ( position > ptr->position )
 223                         {
 224                                 // Create a new geometry
 225                                 struct geometry_s *temp = calloc( 1, sizeof( struct geometry_s ) );
 226
 227                                 // Parse and add to the list
 228                                 geometry_parse( temp, ptr, value, normalised_width, normalised_height );
 229
 230                                 // Assign the position and frame
 231                                 temp->frame = frame;
 232                                 temp->position = position;
 233
 234                                 // Allow the next to be appended after this one
 235                                 ptr = temp;
 236                         }
 237                         else
 238                         {
 239                                 fprintf( stderr, "Key out of order - skipping %s\n", name );
 240                         }
 241                 }
 242         }
 243
 244         // Parse the end
 245         geometry_parse( end, ptr, mlt_properties_get( properties, "end" ), normalised_width, normalised_height );
 246         if ( out > 0 )
 247                 end->position = ( float )( out - in ) / ( float )( out - in + 1 );
 248         else
 249                 end->position = 1;
 250
 251         // Assign to properties to ensure we get destroyed
 252         mlt_properties_set_data( properties, "geometries", start, 0, transition_destroy_keys, NULL );
 253
 254         return start;
 255 }
 256
 257 struct geometry_s *composite_calculate( struct geometry_s *result, mlt_transition this, mlt_frame a_frame, float position )
 258 {
 259         // Get the properties from the transition
 260         mlt_properties properties = mlt_transition_properties( this );
 261
 262         // Get the properties from the frame
 263         mlt_properties a_props = mlt_frame_properties( a_frame );
 264
 265         // Structures for geometry
 266         struct geometry_s *start = mlt_properties_get_data( properties, "geometries", NULL );
 267
 268         // Now parse the geometries
 269         if ( start == NULL )
 270         {
 271                 // Obtain the normalised width and height from the a_frame
 272                 int normalised_width = mlt_properties_get_int( a_props, "normalised_width" );
 273                 int normalised_height = mlt_properties_get_int( a_props, "normalised_height" );
 274
 275                 // Parse the transitions properties
 276                 start = transition_parse_keys( this, normalised_width, normalised_height );
 277         }
 278
 279         // Do the calculation
 280         geometry_calculate( result, start, position );
 281
 282         return start;
 283 }
 284
 285 typedef struct
 286 {
 287         float matrix[3][3];
 288 }
 289 affine_t;
 290
 291 static void affine_init( float this[3][3] )
 292 {
 293         this[0][0] = 1;
 294         this[0][1] = 0;
 295         this[0][2] = 0;
 296         this[1][0] = 0;
 297         this[1][1] = 1;
 298         this[1][2] = 0;
 299         this[2][0] = 0;
 300         this[2][1] = 0;
 301         this[2][2] = 1;
 302 }
 303
 304 // Multiply two this affine transform with that
 305 static void affine_multiply( float this[3][3], float that[3][3] )
 306 {
 307         float output[3][3];
 308         int i;
 309         int j;
 310
 311         for ( i = 0; i < 3; i ++ )
 312                 for ( j = 0; j < 3; j ++ )
 313                         output[i][j] = this[i][0] * that[j][0] + this[i][1] * that[j][1] + this[i][2] * that[j][2];
 314
 315         this[0][0] = output[0][0];
 316         this[0][1] = output[0][1];
 317         this[0][2] = output[0][2];
 318         this[1][0] = output[1][0];
 319         this[1][1] = output[1][1];
 320         this[1][2] = output[1][2];
 321         this[2][0] = output[2][0];
 322         this[2][1] = output[2][1];
 323         this[2][2] = output[2][2];
 324 }
 325
 326 // Rotate by a given angle
 327 static void affine_rotate( float this[3][3], float angle )
 328 {
 329         float affine[3][3];
 330         affine[0][0] = cos( angle * M_PI / 180 );
 331         affine[0][1] = 0 - sin( angle * M_PI / 180 );
 332         affine[0][2] = 0;
 333         affine[1][0] = sin( angle * M_PI / 180 );
 334         affine[1][1] = cos( angle * M_PI / 180 );
 335         affine[1][2] = 0;
 336         affine[2][0] = 0;
 337         affine[2][1] = 0;
 338         affine[2][2] = 1;
 339         affine_multiply( this, affine );
 340 }
 341
 342 static void affine_rotate_y( float this[3][3], float angle )
 343 {
 344         float affine[3][3];
 345         affine[0][0] = cos( angle * M_PI / 180 );
 346         affine[0][1] = 0;
 347         affine[0][2] = 0 - sin( angle * M_PI / 180 );
 348         affine[1][0] = 0;
 349         affine[1][1] = 1;
 350         affine[1][2] = 0;
 351         affine[2][0] = sin( angle * M_PI / 180 );
 352         affine[2][1] = 0;
 353         affine[2][2] = cos( angle * M_PI / 180 );
 354         affine_multiply( this, affine );
 355 }
 356
 357 static void affine_rotate_z( float this[3][3], float angle )
 358 {
 359         float affine[3][3];
 360         affine[0][0] = 1;
 361         affine[0][1] = 0;
 362         affine[0][2] = 0;
 363         affine[1][0] = 0;
 364         affine[1][1] = cos( angle * M_PI / 180 );
 365         affine[1][2] = sin( angle * M_PI / 180 );
 366         affine[2][0] = 0;
 367         affine[2][1] = - sin( angle * M_PI / 180 );
 368         affine[2][2] = cos( angle * M_PI / 180 );
 369         affine_multiply( this, affine );
 370 }
 371
 372 static void affine_scale( float this[3][3], float sx, float sy )
 373 {
 374         float affine[3][3];
 375         affine[0][0] = sx;
 376         affine[0][1] = 0;
 377         affine[0][2] = 0;
 378         affine[1][0] = 0;
 379         affine[1][1] = sy;
 380         affine[1][2] = 0;
 381         affine[2][0] = 0;
 382         affine[2][1] = 0;
 383         affine[2][2] = 1;
 384         affine_multiply( this, affine );
 385 }
 386
 387 // Shear by a given value
 388 static void affine_shear( float this[3][3], float shear_x, float shear_y, float shear_z )
 389 {
 390         float affine[3][3];
 391         affine[0][0] = 1;
 392         affine[0][1] = tan( shear_x * M_PI / 180 );
 393         affine[0][2] = 0;
 394         affine[1][0] = tan( shear_y * M_PI / 180 );
 395         affine[1][1] = 1;
 396         affine[1][2] = tan( shear_z * M_PI / 180 );
 397         affine[2][0] = 0;
 398         affine[2][1] = 0;
 399         affine[2][2] = 1;
 400         affine_multiply( this, affine );
 401 }
 402
 403 static void affine_offset( float this[3][3], int x, int y )
 404 {
 405         this[0][2] += x;
 406         this[1][2] += y;
 407 }
 408
 409 // Obtain the mapped x coordinate of the input
 410 static inline double MapX( float this[3][3], int x, int y )
 411 {
 412         return this[0][0] * x + this[0][1] * y + this[0][2];
 413 }
 414
 415 // Obtain the mapped y coordinate of the input
 416 static inline double MapY( float this[3][3], int x, int y )
 417 {
 418         return this[1][0] * x + this[1][1] * y + this[1][2];
 419 }
 420
 421 static inline double MapZ( float this[3][3], int x, int y )
 422 {
 423         return this[2][0] * x + this[2][1] * y + this[2][2];
 424 }
 425
 426 #define MAX( x, y ) x > y ? x : y
 427 #define MIN( x, y ) x < y ? x : y
 428
 429 static void affine_max_output( float this[3][3], float *w, float *h )
 430 {
 431         int tlx = MapX( this, -720, 576 );
 432         int tly = MapY( this, -720, 576 );
 433         int trx = MapX( this, 720, 576 );
 434         int try = MapY( this, 720, 576 );
 435         int blx = MapX( this, -720, -576 );
 436         int bly = MapY( this, -720, -576 );
 437         int brx = MapX( this, 720, -576 );
 438         int bry = MapY( this, 720, -576 );
 439
 440         int max_x;
 441         int max_y;
 442         int min_x;
 443         int min_y;
 444
 445         max_x = MAX( tlx, trx );
 446         max_x = MAX( max_x, blx );
 447         max_x = MAX( max_x, brx );
 448
 449         min_x = MIN( tlx, trx );
 450         min_x = MIN( min_x, blx );
 451         min_x = MIN( min_x, brx );
 452
 453         max_y = MAX( tly, try );
 454         max_y = MAX( max_y, bly );
 455         max_y = MAX( max_y, bry );
 456
 457         min_y = MIN( tly, try );
 458         min_y = MIN( min_y, bly );
 459         min_y = MIN( min_y, bry );
 460
 461         *w = ( float )( max_x - min_x + 1 ) / 1440.0;
 462         *h = ( float )( max_y - min_y + 1 ) / 1152.0;
 463 }
 464
 465 #define IN_RANGE( v, r )        ( v >= - r / 2 && v < r / 2 )
 466
 467 /** Get the image.
 468 */
 469
 470 static int transition_get_image( mlt_frame a_frame, uint8_t **image, mlt_image_format *format, int *width, int *height, int writable )
 471 {
 472         // Get the b frame from the stack
 473         mlt_frame b_frame = mlt_frame_pop_frame( a_frame );
 474
 475         // Get the transition object
 476         mlt_transition this = mlt_frame_pop_service( a_frame );
 477
 478         // Get the properties of the transition
 479         mlt_properties properties = mlt_transition_properties( this );
 480
 481         // Get the properties of the a frame
 482         mlt_properties a_props = mlt_frame_properties( a_frame );
 483
 484         // Get the properties of the b frame
 485         mlt_properties b_props = mlt_frame_properties( b_frame );
 486
 487         // Image, format, width, height and image for the b frame
 488         uint8_t *b_image = NULL;
 489         mlt_image_format b_format = mlt_image_yuv422;
 490         int b_width;
 491         int b_height;
 492
 493         // Get the unique name to retrieve the frame position
 494         char *name = mlt_properties_get( properties, "_unique_id" );
 495
 496         // Assign the current position to the name
 497         mlt_position position =  mlt_properties_get_position( a_props, name );
 498         mlt_position in = mlt_properties_get_position( properties, "in" );
 499         mlt_position out = mlt_properties_get_position( properties, "out" );
 500
 501         // Structures for geometry
 502         struct geometry_s *start = mlt_properties_get_data( properties, "geometries", NULL );
 503         struct geometry_s result;
 504
 505         // Now parse the geometries
 506         if ( start == NULL )
 507         {
 508                 // Obtain the normalised width and height from the a_frame
 509                 int normalised_width = mlt_properties_get_int( a_props, "normalised_width" );
 510                 int normalised_height = mlt_properties_get_int( a_props, "normalised_height" );
 511
 512                 // Parse the transitions properties
 513                 start = transition_parse_keys( this, normalised_width, normalised_height );
 514         }
 515
 516         // Fetch the a frame image
 517         mlt_frame_get_image( a_frame, image, format, width, height, 1 );
 518
 519         // Calculate the region now
 520         composite_calculate( &result, this, a_frame, ( float )( position ) / ( out - in + 1 ) );
 521
 522         // Fetch the b frame image
 523         result.w = ( int )( result.w * *width / result.nw );
 524         result.h = ( int )( result.h * *height / result.nh );
 525         result.x = ( int )( result.x * *width / result.nw );
 526         result.y = ( int )( result.y * *height / result.nh );
 527         result.w -= ( int )abs( result.w ) % 2;
 528         result.x -= ( int )abs( result.x ) % 2;
 529         b_width = result.w;
 530         b_height = result.h;
 531
 532         if ( !strcmp( mlt_properties_get( a_props, "rescale.interp" ), "none" ) )
 533         {
 534                 mlt_properties_set( b_props, "rescale.interp", "nearest" );
 535                 mlt_properties_set_double( b_props, "consumer_aspect_ratio", mlt_properties_get_double( a_props, "aspect_ratio" ) );
 536         }
 537         else
 538         {
 539                 mlt_properties_set( b_props, "rescale.interp", mlt_properties_get( a_props, "rescale.interp" ) );
 540                 mlt_properties_set_double( b_props, "consumer_aspect_ratio", mlt_properties_get_double( a_props, "consumer_aspect_ratio" ) );
 541         }
 542
 543         mlt_properties_set( b_props, "distort", mlt_properties_get( properties, "distort" ) );
 544         mlt_frame_get_image( b_frame, &b_image, &b_format, &b_width, &b_height, 0 );
 545         result.w = b_width;
 546         result.h = b_height;
 547
 548         // Check that both images are of the correct format and process
 549         if ( *format == mlt_image_yuv422 && b_format == mlt_image_yuv422 )
 550         {
 551                 register int x, y;
 552                 register int dx, dy;
 553                 double dz;
 554                 float sw, sh;
 555
 556                 // Get values from the transition
 557                 float fix_rotate_x = mlt_properties_get_double( properties, "fix_rotate_x" );
 558                 float fix_rotate_y = mlt_properties_get_double( properties, "fix_rotate_y" );
 559                 float fix_rotate_z = mlt_properties_get_double( properties, "fix_rotate_z" );
 560                 float rotate_x = mlt_properties_get_double( properties, "rotate_x" );
 561                 float rotate_y = mlt_properties_get_double( properties, "rotate_y" );
 562                 float rotate_z = mlt_properties_get_double( properties, "rotate_z" );
 563                 float fix_shear_x = mlt_properties_get_double( properties, "fix_shear_x" );
 564                 float fix_shear_y = mlt_properties_get_double( properties, "fix_shear_y" );
 565                 float fix_shear_z = mlt_properties_get_double( properties, "fix_shear_z" );
 566                 float shear_x = mlt_properties_get_double( properties, "shear_x" );
 567                 float shear_y = mlt_properties_get_double( properties, "shear_y" );
 568                 float shear_z = mlt_properties_get_double( properties, "shear_z" );
 569                 float ox = mlt_properties_get_double( properties, "ox" );
 570                 float oy = mlt_properties_get_double( properties, "oy" );
 571                 int scale = mlt_properties_get_int( properties, "scale" );
 572
 573                 uint8_t *p = *image;
 574                 uint8_t *q = *image;
 575
 576                 int cx = result.x + ( b_width >> 1 );
 577                 int cy = result.y + ( b_height >> 1 );
 578
 579                 int lower_x = 0 - cx;
 580                 int upper_x = *width - cx;
 581                 int lower_y = 0 - cy;
 582                 int upper_y = *height - cy;
 583
 584                 int b_stride = b_width << 1;
 585                 int a_stride = *width << 1;
 586                 int x_offset = ( int )result.w >> 1;
 587                 int y_offset = ( int )result.h >> 1;
 588
 589                 uint8_t *alpha = mlt_frame_get_alpha_mask( b_frame );
 590                 float mix;
 591
 592                 affine_t affine;
 593                 affine_init( affine.matrix );
 594                 affine_rotate( affine.matrix, fix_rotate_x + rotate_x * ( position - in ) );
 595                 affine_rotate_y( affine.matrix, fix_rotate_y + rotate_y * ( position - in ) );
 596                 affine_rotate_z( affine.matrix, fix_rotate_z + rotate_z * ( position - in ) );
 597                 affine_shear( affine.matrix,
 598                                           fix_shear_x + shear_x * ( position - in ),
 599                                           fix_shear_y + shear_y * ( position - in ),
 600                                           fix_shear_z + shear_z * ( position - in ) );
 601                 affine_offset( affine.matrix, ox, oy );
 602
 603                 if ( scale )
 604                 {
 605                         affine_max_output( affine.matrix, &sw, &sh );
 606                         affine_scale( affine.matrix, sw, sh );
 607                 }
 608
 609                 lower_x -= ( lower_x & 1 );
 610                 upper_x -= ( upper_x & 1 );
 611
 612                 q = *image;
 613
 614                 dz = MapZ( affine.matrix, 0, 0 );
 615
 616                 for ( y = lower_y; y < upper_y; y ++ )
 617                 {
 618                         p = q;
 619
 620                         for ( x = lower_x; x < upper_x; x ++ )
 621                         {
 622                                 dx = MapX( affine.matrix, x, y ) / dz + x_offset;
 623                                 dy = MapY( affine.matrix, x, y ) / dz + y_offset;
 624
 625                                 if ( dx >= 0 && dx < b_width && dy >=0 && dy < b_height )
 626                                 {
 627                                         if ( alpha == NULL )
 628                                         {
 629                                                 dx += dx & 1;
 630                                                 *p ++ = *( b_image + dy * b_stride + ( dx << 1 ) );
 631                                                 *p ++ = *( b_image + dy * b_stride + ( dx << 1 ) + ( ( x & 1 ) << 1 ) + 1 );
 632                                         }
 633                                         else
 634                                         {
 635                                                 mix = ( float )*( alpha + dy * b_width + dx ) / 255.0;
 636                                                 dx += dx & 1;
 637                                                 *p = *p * ( 1 - mix ) + mix * *( b_image + dy * b_stride + ( dx << 1 ) );
 638                                                 p ++;
 639                                                 *p = *p * ( 1 - mix ) + mix * *( b_image + dy * b_stride + ( dx << 1 ) + ( ( x & 1 ) << 1 ) + 1 );
 640                                                 p ++;
 641                                         }
 642                                 }
 643                                 else
 644                                 {
 645                                         p += 2;
 646                                 }
 647                         }
 648
 649                         q += a_stride;
 650                 }
 651         }
 652
 653         return 0;
 654 }
 655
 656 /** Affine transition processing.
 657 */
 658
 659 static mlt_frame transition_process( mlt_transition transition, mlt_frame a_frame, mlt_frame b_frame )
 660 {
 661         // Get a unique name to store the frame position
 662         char *name = mlt_properties_get( mlt_transition_properties( transition ), "_unique_id" );
 663
 664         // Assign the current position to the name
 665         mlt_properties a_props = mlt_frame_properties( a_frame );
 666         mlt_properties_set_position( a_props, name, mlt_frame_get_position( a_frame ) );
 667
 668         // Push the transition on to the frame
 669         mlt_frame_push_service( a_frame, transition );
 670
 671         // Push the b_frame on to the stack
 672         mlt_frame_push_frame( a_frame, b_frame );
 673
 674         // Push the transition method
 675         mlt_frame_push_get_image( a_frame, transition_get_image );
 676
 677         return a_frame;
 678 }
 679
 680 /** Constructor for the filter.
 681 */
 682
 683 mlt_transition transition_affine_init( char *arg )
 684 {
 685         mlt_transition transition = mlt_transition_new( );
 686         if ( transition != NULL )
 687         {
 688                 mlt_properties_set_int( mlt_transition_properties( transition ), "sx", 1 );
 689                 mlt_properties_set_int( mlt_transition_properties( transition ), "sy", 1 );
 690                 mlt_properties_set( mlt_transition_properties( transition ), "distort", NULL );
 691                 mlt_properties_set( mlt_transition_properties( transition ), "start", "0,0:100%x100%" );
 692                 transition->process = transition_process;
 693         }
 694         return transition;
 695 }