root corrections to miracle
[melted] / 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_image = mlt_deque_init( );
72 this->stack_audio = mlt_deque_init( );
73 }
74
75 return this;
76 }
77
78 /** Fetch the frames properties.
79 */
80
81 mlt_properties mlt_frame_properties( mlt_frame this )
82 {
83 return &this->parent;
84 }
85
86 /** Check if we have a way to derive something other than a test card.
87 */
88
89 int mlt_frame_is_test_card( mlt_frame this )
90 {
91 return mlt_properties_get_int( mlt_frame_properties( this ), "test_image" );
92 }
93
94 /** Check if we have a way to derive something than test audio.
95 */
96
97 int mlt_frame_is_test_audio( mlt_frame this )
98 {
99 return this->get_audio == NULL || mlt_properties_get_int( mlt_frame_properties( this ), "test_audio" );
100 }
101
102 /** Get the aspect ratio of the frame.
103 */
104
105 double mlt_frame_get_aspect_ratio( mlt_frame this )
106 {
107 return mlt_properties_get_double( mlt_frame_properties( this ), "aspect_ratio" );
108 }
109
110 /** Set the aspect ratio of the frame.
111 */
112
113 int mlt_frame_set_aspect_ratio( mlt_frame this, double value )
114 {
115 return mlt_properties_set_double( mlt_frame_properties( this ), "aspect_ratio", value );
116 }
117
118 /** Get the position of this frame.
119 */
120
121 mlt_position mlt_frame_get_position( mlt_frame this )
122 {
123 return mlt_properties_get_position( mlt_frame_properties( this ), "_position" );
124 }
125
126 /** Set the position of this frame.
127 */
128
129 int mlt_frame_set_position( mlt_frame this, mlt_position value )
130 {
131 return mlt_properties_set_position( mlt_frame_properties( this ), "_position", value );
132 }
133
134 /** Stack a get_image callback.
135 */
136
137 int mlt_frame_push_get_image( mlt_frame this, mlt_get_image get_image )
138 {
139 return mlt_deque_push_back( this->stack_image, get_image );
140 }
141
142 /** Pop a get_image callback.
143 */
144
145 mlt_get_image mlt_frame_pop_get_image( mlt_frame this )
146 {
147 return mlt_deque_pop_back( this->stack_image );
148 }
149
150 /** Push a frame.
151 */
152
153 int mlt_frame_push_frame( mlt_frame this, mlt_frame that )
154 {
155 return mlt_deque_push_back( this->stack_image, that );
156 }
157
158 /** Pop a frame.
159 */
160
161 mlt_frame mlt_frame_pop_frame( mlt_frame this )
162 {
163 return mlt_deque_pop_back( this->stack_image );
164 }
165
166 /** Push a service.
167 */
168
169 int mlt_frame_push_service( mlt_frame this, void *that )
170 {
171 return mlt_deque_push_back( this->stack_image, that );
172 }
173
174 /** Pop a service.
175 */
176
177 void *mlt_frame_pop_service( mlt_frame this )
178 {
179 return mlt_deque_pop_back( this->stack_image );
180 }
181
182 /** Push an audio item on the stack.
183 */
184
185 int mlt_frame_push_audio( mlt_frame this, void *that )
186 {
187 return mlt_deque_push_back( this->stack_audio, that );
188 }
189
190 /** Pop an audio item from the stack
191 */
192
193 void *mlt_frame_pop_audio( mlt_frame this )
194 {
195 return mlt_deque_pop_back( this->stack_audio );
196 }
197
198 int mlt_frame_get_image( mlt_frame this, uint8_t **buffer, mlt_image_format *format, int *width, int *height, int writable )
199 {
200 mlt_properties properties = mlt_frame_properties( this );
201 mlt_get_image get_image = mlt_frame_pop_get_image( this );
202 mlt_producer producer = mlt_properties_get_data( properties, "test_card_producer", NULL );
203
204 if ( get_image != NULL )
205 {
206 return get_image( this, buffer, format, width, height, writable );
207 }
208 else if ( mlt_properties_get_data( properties, "image", NULL ) != NULL )
209 {
210 *format = mlt_image_yuv422;
211 *buffer = mlt_properties_get_data( properties, "image", NULL );
212 *width = mlt_properties_get_int( properties, "width" );
213 *height = mlt_properties_get_int( properties, "height" );
214 }
215 else if ( producer != NULL )
216 {
217 mlt_frame test_frame = NULL;
218 mlt_service_get_frame( mlt_producer_service( producer ), &test_frame, 0 );
219 if ( test_frame != NULL )
220 {
221 mlt_properties test_properties = mlt_frame_properties( test_frame );
222 mlt_properties_set_double( test_properties, "consumer_aspect_ratio", mlt_properties_get_double( properties, "consumer_aspect_ratio" ) );
223 mlt_properties_set( test_properties, "rescale.interp", "nearest" );
224 mlt_frame_get_image( test_frame, buffer, format, width, height, writable );
225 mlt_properties_set_data( properties, "test_card_frame", test_frame, 0, ( mlt_destructor )mlt_frame_close, NULL );
226 mlt_properties_set_data( properties, "image", *buffer, *width * *height * 2, NULL, NULL );
227 mlt_properties_set_int( properties, "width", *width );
228 mlt_properties_set_int( properties, "height", *height );
229 }
230 else
231 {
232 mlt_properties_set_data( properties, "test_card_producer", NULL, 0, NULL, NULL );
233 mlt_frame_get_image( this, buffer, format, width, height, writable );
234 }
235 }
236 else
237 {
238 uint8_t *p;
239 uint8_t *q;
240 int size = 0;
241
242 *width = *width == 0 ? 720 : *width;
243 *height = *height == 0 ? 576 : *height;
244 size = *width * *height;
245
246 mlt_properties_set_int( properties, "width", *width );
247 mlt_properties_set_int( properties, "height", *height );
248 mlt_properties_set_int( properties, "aspect_ratio", 1 );
249
250 switch( *format )
251 {
252 case mlt_image_none:
253 size = 0;
254 *buffer = NULL;
255 break;
256 case mlt_image_rgb24:
257 size *= 3;
258 size += *width * 3;
259 *buffer = mlt_pool_alloc( size );
260 if ( *buffer )
261 memset( *buffer, 255, size );
262 break;
263 case mlt_image_rgb24a:
264 size *= 4;
265 size += *width * 4;
266 *buffer = mlt_pool_alloc( size );
267 if ( *buffer )
268 memset( *buffer, 255, size );
269 break;
270 case mlt_image_yuv422:
271 size *= 2;
272 size += *width * 2;
273 *buffer = mlt_pool_alloc( size );
274 p = *buffer;
275 q = p + size;
276 while ( p != NULL && p != q )
277 {
278 *p ++ = 235;
279 *p ++ = 128;
280 }
281 break;
282 case mlt_image_yuv420p:
283 size = size * 3 / 2;
284 *buffer = mlt_pool_alloc( size );
285 if ( *buffer )
286 memset( *buffer, 255, size );
287 break;
288 }
289
290 mlt_properties_set_data( properties, "image", *buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
291 mlt_properties_set_int( properties, "test_image", 1 );
292 }
293
294 return 0;
295 }
296
297 uint8_t *mlt_frame_get_alpha_mask( mlt_frame this )
298 {
299 if ( this->get_alpha_mask != NULL )
300 return this->get_alpha_mask( this );
301 return NULL;
302 }
303
304 int mlt_frame_get_audio( mlt_frame this, int16_t **buffer, mlt_audio_format *format, int *frequency, int *channels, int *samples )
305 {
306 mlt_properties properties = mlt_frame_properties( this );
307
308 if ( this->get_audio != NULL )
309 {
310 return this->get_audio( this, buffer, format, frequency, channels, samples );
311 }
312 else
313 {
314 int size = 0;
315 *samples = *samples <= 0 ? 1920 : *samples;
316 *channels = *channels <= 0 ? 2 : *channels;
317 *frequency = *frequency <= 0 ? 48000 : *frequency;
318 size = *samples * *channels * sizeof( int16_t );
319 *buffer = mlt_pool_alloc( size );
320 if ( *buffer != NULL )
321 memset( *buffer, 0, size );
322 mlt_properties_set_data( properties, "audio", *buffer, size, ( mlt_destructor )mlt_pool_release, NULL );
323 mlt_properties_set_int( properties, "test_audio", 1 );
324 }
325 return 0;
326 }
327
328 void mlt_frame_close( mlt_frame this )
329 {
330 if ( this != NULL )
331 {
332 mlt_deque_close( this->stack_image );
333 mlt_deque_close( this->stack_audio );
334 mlt_properties_close( &this->parent );
335 free( this );
336 }
337 }
338
339 /***** convenience functions *****/
340
341 int mlt_convert_rgb24a_to_yuv422( uint8_t *rgba, int width, int height, int stride, uint8_t *yuv, uint8_t *alpha )
342 {
343 int ret = 0;
344 register int y0, y1, u0, u1, v0, v1;
345 register int r, g, b;
346 register uint8_t *d = yuv;
347 register int i, j;
348
349 for ( i = 0; i < height; i++ )
350 {
351 register uint8_t *s = rgba + ( stride * i );
352 for ( j = 0; j < ( width / 2 ); j++ )
353 {
354 r = *s++;
355 g = *s++;
356 b = *s++;
357 *alpha++ = *s++;
358 RGB2YUV (r, g, b, y0, u0 , v0);
359 r = *s++;
360 g = *s++;
361 b = *s++;
362 *alpha++ = *s++;
363 RGB2YUV (r, g, b, y1, u1 , v1);
364 *d++ = y0;
365 *d++ = (u0+u1) >> 1;
366 *d++ = y1;
367 *d++ = (v0+v1) >> 1;
368 }
369 if ( width % 2 )
370 {
371 r = *s++;
372 g = *s++;
373 b = *s++;
374 *alpha++ = *s++;
375 RGB2YUV (r, g, b, y0, u0 , v0);
376 *d++ = y0;
377 *d++ = u0;
378 }
379 }
380 return ret;
381 }
382
383 int mlt_convert_rgb24_to_yuv422( uint8_t *rgb, int width, int height, int stride, uint8_t *yuv )
384 {
385 int ret = 0;
386 register int y0, y1, u0, u1, v0, v1;
387 register int r, g, b;
388 register uint8_t *d = yuv;
389 register int i, j;
390
391 for ( i = 0; i < height; i++ )
392 {
393 register uint8_t *s = rgb + ( stride * i );
394 for ( j = 0; j < ( width / 2 ); j++ )
395 {
396 r = *s++;
397 g = *s++;
398 b = *s++;
399 RGB2YUV (r, g, b, y0, u0 , v0);
400 r = *s++;
401 g = *s++;
402 b = *s++;
403 RGB2YUV (r, g, b, y1, u1 , v1);
404 *d++ = y0;
405 *d++ = (u0+u1) >> 1;
406 *d++ = y1;
407 *d++ = (v0+v1) >> 1;
408 }
409 if ( width % 2 )
410 {
411 r = *s++;
412 g = *s++;
413 b = *s++;
414 RGB2YUV (r, g, b, y0, u0 , v0);
415 *d++ = y0;
416 *d++ = u0;
417 }
418 }
419 return ret;
420 }
421
422 int mlt_convert_yuv420p_to_yuv422( uint8_t *yuv420p, int width, int height, int stride, uint8_t *yuv )
423 {
424 int ret = 0;
425 register int i, j;
426
427 int half = width >> 1;
428
429 uint8_t *Y = yuv420p;
430 uint8_t *U = Y + width * height;
431 uint8_t *V = U + width * height / 4;
432
433 register uint8_t *d = yuv;
434
435 for ( i = 0; i < height; i++ )
436 {
437 register uint8_t *u = U + ( i / 2 ) * ( half );
438 register uint8_t *v = V + ( i / 2 ) * ( half );
439
440 for ( j = 0; j < half; j++ )
441 {
442 *d ++ = *Y ++;
443 *d ++ = *u ++;
444 *d ++ = *Y ++;
445 *d ++ = *v ++;
446 }
447 }
448 return ret;
449 }
450
451 void mlt_resize_yuv422( uint8_t *output, int owidth, int oheight, uint8_t *input, int iwidth, int iheight )
452 {
453 // Calculate strides
454 int istride = iwidth * 2;
455 int ostride = owidth * 2;
456
457 iwidth = iwidth - ( iwidth % 4 );
458 owidth = owidth - ( owidth % 4 );
459 iheight = iheight - ( iheight % 2 );
460 oheight = oheight - ( oheight % 2 );
461
462 // Optimisation point
463 if ( iwidth == owidth && iheight == oheight )
464 memcpy( output, input, iheight * istride );
465
466 // Coordinates (0,0 is middle of output)
467 int y;
468
469 // Calculate ranges
470 int out_x_range = owidth / 2;
471 int out_y_range = oheight / 2;
472 int in_x_range = iwidth / 2 < out_x_range ? iwidth / 2 : out_x_range;
473 int in_y_range = iheight / 2 < out_y_range ? iheight / 2 : out_y_range;
474
475 // Output pointers
476 uint8_t *out_line = output;
477 uint8_t *out_ptr = out_line;
478
479 // Calculate a middle and possibly invalid pointer in the input
480 uint8_t *in_middle = input + istride * ( iheight / 2 ) + ( iwidth / 2 ) * 2;
481 int in_line = - in_y_range * istride - in_x_range * 2;
482
483 int elements;
484
485 // Fill whole section with black
486 y = out_y_range - ( iheight / 2 );
487 int blank_elements = ostride * y / 2;
488 elements = blank_elements;
489 while ( elements -- )
490 {
491 *out_line ++ = 16;
492 *out_line ++ = 128;
493 }
494
495 int active_width = 2 * iwidth;
496 int inactive_width = out_x_range - in_x_range;
497
498 // Loop for the entirety of our output height.
499 while ( iheight -- )
500 {
501 // Start at the beginning of the line
502 out_ptr = out_line;
503
504 // Fill the outer part with black
505 elements = inactive_width;
506 while ( elements -- )
507 {
508 *out_ptr ++ = 16;
509 *out_ptr ++ = 128;
510 }
511
512 // We're in the input range for this row.
513 memcpy( out_ptr, in_middle + in_line, active_width );
514 out_ptr += active_width;
515
516 // Fill the outer part with black
517 elements = inactive_width;
518 while ( elements -- )
519 {
520 *out_ptr ++ = 16;
521 *out_ptr ++ = 128;
522 }
523
524 // Move to next input line
525 in_line += istride;
526
527 // Move to next output line
528 out_line += ostride;
529 }
530
531 // Fill whole section with black
532 elements = blank_elements;
533 while ( elements -- )
534 {
535 *out_line ++ = 16;
536 *out_line ++ = 128;
537 }
538 }
539
540 /** A resizing function for yuv422 frames - this does not rescale, but simply
541 resizes. It assumes yuv422 images available on the frame so use with care.
542 */
543
544 uint8_t *mlt_frame_resize_yuv422( mlt_frame this, int owidth, int oheight )
545 {
546 // Get properties
547 mlt_properties properties = mlt_frame_properties( this );
548
549 // Get the input image, width and height
550 uint8_t *input = mlt_properties_get_data( properties, "image", NULL );
551 int iwidth = mlt_properties_get_int( properties, "width" );
552 int iheight = mlt_properties_get_int( properties, "height" );
553
554 // If width and height are correct, don't do anything
555 if ( iwidth != owidth || iheight != oheight )
556 {
557 // Create the output image
558 uint8_t *output = mlt_pool_alloc( owidth * ( oheight + 1 ) * 2 );
559
560 // Call the generic resize
561 mlt_resize_yuv422( output, owidth, oheight, input, iwidth, iheight );
562
563 // Now update the frame
564 mlt_properties_set_data( properties, "image", output, owidth * ( oheight + 1 ) * 2, ( mlt_destructor )mlt_pool_release, NULL );
565 mlt_properties_set_int( properties, "width", owidth );
566 mlt_properties_set_int( properties, "height", oheight );
567
568 // Return the output
569 return output;
570 }
571 // No change, return input
572 return input;
573 }
574
575 /** A rescaling function for yuv422 frames - low quality, and provided for testing
576 only. It assumes yuv422 images available on the frame so use with care.
577 */
578
579 uint8_t *mlt_frame_rescale_yuv422( mlt_frame this, int owidth, int oheight )
580 {
581 // Get properties
582 mlt_properties properties = mlt_frame_properties( this );
583
584 // Get the input image, width and height
585 uint8_t *input = mlt_properties_get_data( properties, "image", NULL );
586 int iwidth = mlt_properties_get_int( properties, "width" );
587 int iheight = mlt_properties_get_int( properties, "height" );
588
589 // If width and height are correct, don't do anything
590 if ( iwidth != owidth || iheight != oheight )
591 {
592 // Create the output image
593 uint8_t *output = mlt_pool_alloc( owidth * ( oheight + 1 ) * 2 );
594
595 // Calculate strides
596 int istride = iwidth * 2;
597 int ostride = owidth * 2;
598
599 iwidth = iwidth - ( iwidth % 4 );
600
601 // Derived coordinates
602 int dy, dx;
603
604 // Calculate ranges
605 int out_x_range = owidth / 2;
606 int out_y_range = oheight / 2;
607 int in_x_range = iwidth / 2;
608 int in_y_range = iheight / 2;
609
610 // Output pointers
611 register uint8_t *out_line = output;
612 register uint8_t *out_ptr;
613
614 // Calculate a middle pointer
615 uint8_t *in_middle = input + istride * in_y_range + in_x_range * 2;
616 uint8_t *in_line;
617
618 // Generate the affine transform scaling values
619 register int scale_width = ( iwidth << 16 ) / owidth;
620 register int scale_height = ( iheight << 16 ) / oheight;
621 register int base = 0;
622
623 int outer = out_x_range * scale_width;
624 int bottom = out_y_range * scale_height;
625
626 // Loop for the entirety of our output height.
627 for ( dy = - bottom; dy < bottom; dy += scale_height )
628 {
629 // Start at the beginning of the line
630 out_ptr = out_line;
631
632 // Pointer to the middle of the input line
633 in_line = in_middle + ( dy >> 16 ) * istride;
634
635 // Loop for the entirety of our output row.
636 for ( dx = - outer; dx < outer; dx += scale_width )
637 {
638 base = dx >> 15;
639 base &= 0xfffffffe;
640 *out_ptr ++ = *( in_line + base );
641 base &= 0xfffffffc;
642 *out_ptr ++ = *( in_line + base + 1 );
643 dx += scale_width;
644 base = dx >> 15;
645 base &= 0xfffffffe;
646 *out_ptr ++ = *( in_line + base );
647 base &= 0xfffffffc;
648 *out_ptr ++ = *( in_line + base + 3 );
649 }
650
651 // Move to next output line
652 out_line += ostride;
653 }
654
655 // Now update the frame
656 mlt_properties_set_data( properties, "image", output, owidth * ( oheight + 1 ) * 2, ( mlt_destructor )mlt_pool_release, NULL );
657 mlt_properties_set_int( properties, "width", owidth );
658 mlt_properties_set_int( properties, "height", oheight );
659
660 // Return the output
661 return output;
662 }
663
664 // No change, return input
665 return input;
666 }
667
668 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 )
669 {
670 int ret = 0;
671 int16_t *src, *dest;
672 int frequency_src = *frequency, frequency_dest = *frequency;
673 int channels_src = *channels, channels_dest = *channels;
674 int samples_src = *samples, samples_dest = *samples;
675 int i, j;
676 double d = 0, s = 0;
677
678 mlt_frame_get_audio( this, &dest, format, &frequency_dest, &channels_dest, &samples_dest );
679 //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" ) );
680 mlt_frame_get_audio( that, &src, format, &frequency_src, &channels_src, &samples_src );
681 //fprintf( stderr, "mix: frame src samples %d channels %d\n", samples_src, channels_src );
682
683 if ( channels_src > 6 )
684 channels_src = 0;
685 if ( channels_dest > 6 )
686 channels_dest = 0;
687 if ( samples_src > 4000 )
688 samples_src = 0;
689 if ( samples_dest > 4000 )
690 samples_dest = 0;
691
692 // determine number of samples to process
693 *samples = samples_src < samples_dest ? samples_src : samples_dest;
694 *channels = channels_src < channels_dest ? channels_src : channels_dest;
695 *buffer = dest;
696 *frequency = frequency_dest;
697
698 // Compute a smooth ramp over start to end
699 float weight = weight_start;
700 float weight_step = ( weight_end - weight_start ) / *samples;
701
702 // Mixdown
703 for ( i = 0; i < *samples; i++ )
704 {
705 for ( j = 0; j < *channels; j++ )
706 {
707 if ( j < channels_dest )
708 d = (double) dest[ i * channels_dest + j ];
709 if ( j < channels_src )
710 s = (double) src[ i * channels_src + j ];
711 dest[ i * channels_dest + j ] = s * weight + d * ( 1.0 - weight );
712 }
713 weight += weight_step;
714 }
715
716 return ret;
717 }
718
719 int mlt_sample_calculator( float fps, int frequency, int64_t position )
720 {
721 int samples = 0;
722
723 if ( fps > 29 && fps <= 30 )
724 {
725 samples = frequency / 30;
726
727 switch ( frequency )
728 {
729 case 48000:
730 if ( position % 5 != 0 )
731 samples += 2;
732 break;
733 case 44100:
734 if ( position % 300 == 0 )
735 samples = 1471;
736 else if ( position % 30 == 0 )
737 samples = 1470;
738 else if ( position % 2 == 0 )
739 samples = 1472;
740 else
741 samples = 1471;
742 break;
743 case 32000:
744 if ( position % 30 == 0 )
745 samples = 1068;
746 else if ( position % 29 == 0 )
747 samples = 1067;
748 else if ( position % 4 == 2 )
749 samples = 1067;
750 else
751 samples = 1068;
752 break;
753 default:
754 samples = 0;
755 }
756 }
757 else if ( fps != 0 )
758 {
759 samples = frequency / fps;
760 }
761
762 return samples;
763 }