13ec4c512a79b7a56c3e5c6e9c826636b7f715bd
[vlc.git] / modules / codec / libmpeg2.c
1 /*****************************************************************************
2  * libmpeg2.c: mpeg2 video decoder module making use of libmpeg2.
3  *****************************************************************************
4  * Copyright (C) 1999-2001 the VideoLAN team
5  * $Id$
6  *
7  * Authors: Gildas Bazin <gbazin@videolan.org>
8  *          Christophe Massiot <massiot@via.ecp.fr>
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation; either version 2 of the License, or
13  * (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18  * GNU General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
23  *****************************************************************************/
24
25 /*****************************************************************************
26  * Preamble
27  *****************************************************************************/
28 #ifdef HAVE_CONFIG_H
29 # include "config.h"
30 #endif
31
32 #include <vlc_common.h>
33 #include <vlc_plugin.h>
34 #include <vlc_vout.h>
35 #include <vlc_codec.h>
36
37 #include <mpeg2.h>
38
39 #include <vlc_codec_synchro.h>
40
41 /* Aspect ratio (ISO/IEC 13818-2 section 6.3.3, table 6-3) */
42 #define AR_SQUARE_PICTURE       1                           /* square pixels */
43 #define AR_4_3_PICTURE          2                        /* 4:3 picture (TV) */
44 #define AR_16_9_PICTURE         3              /* 16:9 picture (wide screen) */
45 #define AR_221_1_PICTURE        4                  /* 2.21:1 picture (movie) */
46
47 /*****************************************************************************
48  * decoder_sys_t : libmpeg2 decoder descriptor
49  *****************************************************************************/
50 struct decoder_sys_t
51 {
52     /*
53      * libmpeg2 properties
54      */
55     mpeg2dec_t          *p_mpeg2dec;
56     const mpeg2_info_t  *p_info;
57     bool                b_skip;
58
59     /*
60      * Input properties
61      */
62     mtime_t          i_previous_pts;
63     mtime_t          i_current_pts;
64     mtime_t          i_previous_dts;
65     mtime_t          i_current_dts;
66     int              i_current_rate;
67     picture_t *      p_picture_to_destroy;
68     bool             b_garbage_pic;
69     bool             b_after_sequence_header; /* is it the next frame after
70                                                * the sequence header ?    */
71     bool             b_slice_i;             /* intra-slice refresh stream */
72     bool             b_second_field;
73
74     bool             b_preroll;
75
76     /*
77      * Output properties
78      */
79     decoder_synchro_t *p_synchro;
80     int            i_aspect;
81     int            i_sar_num;
82     int            i_sar_den;
83     mtime_t        i_last_frame_pts;
84
85 };
86
87 /*****************************************************************************
88  * Local prototypes
89  *****************************************************************************/
90 static int  OpenDecoder( vlc_object_t * );
91 static void CloseDecoder( vlc_object_t * );
92
93 static picture_t *DecodeBlock( decoder_t *, block_t ** );
94
95 static picture_t *GetNewPicture( decoder_t *, uint8_t ** );
96 static void GetAR( decoder_t *p_dec );
97
98 /*****************************************************************************
99  * Module descriptor
100  *****************************************************************************/
101 vlc_module_begin();
102     set_description( N_("MPEG I/II video decoder (using libmpeg2)") );
103     set_capability( "decoder", 150 );
104     set_category( CAT_INPUT );
105     set_subcategory( SUBCAT_INPUT_VCODEC );
106     set_callbacks( OpenDecoder, CloseDecoder );
107     add_shortcut( "libmpeg2" );
108 vlc_module_end();
109
110 /*****************************************************************************
111  * OpenDecoder: probe the decoder and return score
112  *****************************************************************************/
113 static int OpenDecoder( vlc_object_t *p_this )
114 {
115     decoder_t *p_dec = (decoder_t*)p_this;
116     decoder_sys_t *p_sys;
117     uint32_t i_accel = 0;
118
119     if( p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','v') &&
120         p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','1') &&
121         /* Pinnacle hardware-mpeg1 */
122         p_dec->fmt_in.i_codec != VLC_FOURCC('P','I','M','1') &&
123         p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','2','v') &&
124         p_dec->fmt_in.i_codec != VLC_FOURCC('m','p','g','2') &&
125         p_dec->fmt_in.i_codec != VLC_FOURCC('h','d','v','2') )
126     {
127         return VLC_EGENERIC;
128     }
129
130     /* Allocate the memory needed to store the decoder's structure */
131     if( ( p_dec->p_sys = p_sys =
132           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
133         return VLC_ENOMEM;
134
135     /* Initialize the thread properties */
136     memset( p_sys, 0, sizeof(decoder_sys_t) );
137     p_sys->p_mpeg2dec = NULL;
138     p_sys->p_synchro  = NULL;
139     p_sys->p_info     = NULL;
140     p_sys->i_current_pts  = 0;
141     p_sys->i_previous_pts = 0;
142     p_sys->i_current_dts  = 0;
143     p_sys->i_previous_dts = 0;
144     p_sys->p_picture_to_destroy = NULL;
145     p_sys->b_garbage_pic = 0;
146     p_sys->b_slice_i  = 0;
147     p_sys->b_second_field = 0;
148     p_sys->b_skip     = 0;
149     p_sys->b_preroll = false;
150
151 #if defined( __i386__ ) || defined( __x86_64__ )
152     if( vlc_CPU() & CPU_CAPABILITY_MMX )
153     {
154         i_accel |= MPEG2_ACCEL_X86_MMX;
155     }
156
157     if( vlc_CPU() & CPU_CAPABILITY_3DNOW )
158     {
159         i_accel |= MPEG2_ACCEL_X86_3DNOW;
160     }
161
162     if( vlc_CPU() & CPU_CAPABILITY_MMXEXT )
163     {
164         i_accel |= MPEG2_ACCEL_X86_MMXEXT;
165     }
166
167 #elif defined( __powerpc__ ) || defined( __ppc__ ) || defined( __ppc64__ )
168     if( vlc_CPU() & CPU_CAPABILITY_ALTIVEC )
169     {
170         i_accel |= MPEG2_ACCEL_PPC_ALTIVEC;
171     }
172
173 #else
174     /* If we do not know this CPU, trust libmpeg2's feature detection */
175     i_accel = MPEG2_ACCEL_DETECT;
176
177 #endif
178
179     /* Set CPU acceleration features */
180     mpeg2_accel( i_accel );
181
182     /* Initialize decoder */
183     p_sys->p_mpeg2dec = mpeg2_init();
184     if( p_sys->p_mpeg2dec == NULL)
185     {
186         msg_Err( p_dec, "mpeg2_init() failed" );
187         free( p_sys );
188         return VLC_EGENERIC;
189     }
190
191     p_sys->p_info = mpeg2_info( p_sys->p_mpeg2dec );
192
193     p_dec->pf_decode_video = DecodeBlock;
194
195     return VLC_SUCCESS;
196 }
197
198 /*****************************************************************************
199  * RunDecoder: the libmpeg2 decoder
200  *****************************************************************************/
201 static picture_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
202 {
203     decoder_sys_t   *p_sys = p_dec->p_sys;
204     mpeg2_state_t   state;
205     picture_t       *p_pic;
206
207     block_t *p_block;
208
209     if( !pp_block || !*pp_block ) return NULL;
210
211     p_block = *pp_block;
212
213     while( 1 )
214     {
215         state = mpeg2_parse( p_sys->p_mpeg2dec );
216
217         switch( state )
218         {
219         case STATE_BUFFER:
220             if( !p_block->i_buffer )
221             {
222                 block_Release( p_block );
223                 return NULL;
224             }
225
226             if( (p_block->i_flags & (BLOCK_FLAG_DISCONTINUITY
227                                       | BLOCK_FLAG_CORRUPTED)) &&
228                 p_sys->p_synchro &&
229                 p_sys->p_info->sequence &&
230                 p_sys->p_info->sequence->width != (unsigned)-1 )
231             {
232                 decoder_SynchroReset( p_sys->p_synchro );
233                 if( p_sys->p_info->current_fbuf != NULL
234                     && p_sys->p_info->current_fbuf->id != NULL )
235                 {
236                     p_sys->b_garbage_pic = 1;
237                     p_pic = p_sys->p_info->current_fbuf->id;
238                 }
239                 else
240                 {
241                     uint8_t *buf[3];
242                     buf[0] = buf[1] = buf[2] = NULL;
243                     if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
244                         break;
245                     mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
246                     mpeg2_stride( p_sys->p_mpeg2dec, p_pic->p[Y_PLANE].i_pitch );
247                 }
248                 p_sys->p_picture_to_destroy = p_pic;
249
250                 if ( p_sys->b_slice_i )
251                 {
252                     decoder_SynchroNewPicture( p_sys->p_synchro,
253                         I_CODING_TYPE, 2, 0, 0, p_sys->i_current_rate,
254                         p_sys->p_info->sequence->flags & SEQ_FLAG_LOW_DELAY );
255                     decoder_SynchroDecode( p_sys->p_synchro );
256                     decoder_SynchroEnd( p_sys->p_synchro, I_CODING_TYPE, 0 );
257                 }
258             }
259
260             if( p_block->i_flags & BLOCK_FLAG_PREROLL )
261             {
262                 p_sys->b_preroll = true;
263             }
264             else if( p_sys->b_preroll )
265             {
266                 p_sys->b_preroll = false;
267                 /* Reset synchro */
268                 decoder_SynchroReset( p_sys->p_synchro );
269             }
270
271 #ifdef PIC_FLAG_PTS
272             if( p_block->i_pts )
273             {
274                 mpeg2_pts( p_sys->p_mpeg2dec, (uint32_t)p_block->i_pts );
275
276 #else /* New interface */
277             if( p_block->i_pts || p_block->i_dts )
278             {
279                 mpeg2_tag_picture( p_sys->p_mpeg2dec,
280                                    (uint32_t)p_block->i_pts,
281                                    (uint32_t)p_block->i_dts );
282 #endif
283                 p_sys->i_previous_pts = p_sys->i_current_pts;
284                 p_sys->i_current_pts = p_block->i_pts;
285                 p_sys->i_previous_dts = p_sys->i_current_dts;
286                 p_sys->i_current_dts = p_block->i_dts;
287             }
288
289             p_sys->i_current_rate = p_block->i_rate;
290
291             mpeg2_buffer( p_sys->p_mpeg2dec, p_block->p_buffer,
292                           p_block->p_buffer + p_block->i_buffer );
293
294             p_block->i_buffer = 0;
295             break;
296
297 #if MPEG2_RELEASE >= MPEG2_VERSION (0, 5, 0)
298
299         case STATE_SEQUENCE_MODIFIED:
300             GetAR( p_dec );
301             break;
302 #endif
303
304         case STATE_SEQUENCE:
305         {
306             /* Initialize video output */
307             uint8_t *buf[3];
308             buf[0] = buf[1] = buf[2] = NULL;
309
310             GetAR( p_dec );
311
312             mpeg2_custom_fbuf( p_sys->p_mpeg2dec, 1 );
313
314             /* Set the first 2 reference frames */
315             mpeg2_set_buf( p_sys->p_mpeg2dec, buf, NULL );
316
317             if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
318             {
319                 block_Release( p_block );
320                 return NULL;
321             }
322
323             mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
324             mpeg2_stride( p_sys->p_mpeg2dec, p_pic->p[Y_PLANE].i_pitch );
325
326             /* This picture will never go through display_picture. */
327             p_pic->date = 0;
328
329             /* For some reason, libmpeg2 will put this pic twice in
330              * discard_picture. This can be considered a bug in libmpeg2. */
331             p_dec->pf_picture_link( p_dec, p_pic );
332
333             if( p_sys->p_synchro )
334             {
335                 decoder_SynchroRelease( p_sys->p_synchro );
336             }
337             p_sys->p_synchro = decoder_SynchroInit( p_dec,
338                 (uint32_t)((uint64_t)1001000000 * 27 /
339                 p_sys->p_info->sequence->frame_period) );
340             p_sys->b_after_sequence_header = 1;
341         }
342         break;
343
344         case STATE_PICTURE_2ND:
345             p_sys->b_second_field = 1;
346             break;
347
348         case STATE_PICTURE:
349         {
350             uint8_t *buf[3];
351             mtime_t i_pts, i_dts;
352             buf[0] = buf[1] = buf[2] = NULL;
353
354             if ( p_sys->b_after_sequence_header &&
355                  ((p_sys->p_info->current_picture->flags &
356                        PIC_MASK_CODING_TYPE) == PIC_FLAG_CODING_TYPE_P) )
357             {
358                 /* Intra-slice refresh. Simulate a blank I picture. */
359                 msg_Dbg( p_dec, "intra-slice refresh stream" );
360                 decoder_SynchroNewPicture( p_sys->p_synchro,
361                     I_CODING_TYPE, 2, 0, 0, p_sys->i_current_rate,
362                     p_sys->p_info->sequence->flags & SEQ_FLAG_LOW_DELAY );
363                 decoder_SynchroDecode( p_sys->p_synchro );
364                 decoder_SynchroEnd( p_sys->p_synchro, I_CODING_TYPE, 0 );
365                 p_sys->b_slice_i = 1;
366             }
367             p_sys->b_after_sequence_header = 0;
368
369 #ifdef PIC_FLAG_PTS
370             i_pts = p_sys->p_info->current_picture->flags & PIC_FLAG_PTS ?
371                 ( ( p_sys->p_info->current_picture->pts ==
372                     (uint32_t)p_sys->i_current_pts ) ?
373                   p_sys->i_current_pts : p_sys->i_previous_pts ) : 0;
374             i_dts = 0;
375
376             /* Hack to handle demuxers which only have DTS timestamps */
377             if( !i_pts && !p_block->i_pts && p_block->i_dts > 0 )
378             {
379                 if( p_sys->p_info->sequence->flags & SEQ_FLAG_LOW_DELAY ||
380                     (p_sys->p_info->current_picture->flags &
381                       PIC_MASK_CODING_TYPE) == PIC_FLAG_CODING_TYPE_B )
382                 {
383                     i_pts = p_block->i_dts;
384                 }
385             }
386             p_block->i_pts = p_block->i_dts = 0;
387             /* End hack */
388
389 #else /* New interface */
390
391             i_pts = p_sys->p_info->current_picture->flags & PIC_FLAG_TAGS ?
392                 ( ( p_sys->p_info->current_picture->tag ==
393                     (uint32_t)p_sys->i_current_pts ) ?
394                   p_sys->i_current_pts : p_sys->i_previous_pts ) : 0;
395             i_dts = p_sys->p_info->current_picture->flags & PIC_FLAG_TAGS ?
396                 ( ( p_sys->p_info->current_picture->tag2 ==
397                     (uint32_t)p_sys->i_current_dts ) ?
398                   p_sys->i_current_dts : p_sys->i_previous_dts ) : 0;
399 #endif
400
401             /* If nb_fields == 1, it is a field picture, and it will be
402              * followed by another field picture for which we won't call
403              * decoder_SynchroNewPicture() because this would have other
404              * problems, so we take it into account here.
405              * This kind of sucks, but I didn't think better. --Meuuh
406              */
407             decoder_SynchroNewPicture( p_sys->p_synchro,
408                 p_sys->p_info->current_picture->flags & PIC_MASK_CODING_TYPE,
409                 p_sys->p_info->current_picture->nb_fields == 1 ? 2 :
410                 p_sys->p_info->current_picture->nb_fields, i_pts, i_dts,
411                 p_sys->i_current_rate,
412                 p_sys->p_info->sequence->flags & SEQ_FLAG_LOW_DELAY );
413
414             if( !p_dec->b_pace_control && !p_sys->b_preroll &&
415                 !(p_sys->b_slice_i
416                    && ((p_sys->p_info->current_picture->flags
417                          & PIC_MASK_CODING_TYPE) == P_CODING_TYPE))
418                    && !decoder_SynchroChoose( p_sys->p_synchro,
419                               p_sys->p_info->current_picture->flags
420                                 & PIC_MASK_CODING_TYPE,
421                               /*p_sys->p_vout->render_time*/ 0 /*FIXME*/,
422                               p_sys->p_info->sequence->flags & SEQ_FLAG_LOW_DELAY ) )
423             {
424                 mpeg2_skip( p_sys->p_mpeg2dec, 1 );
425                 p_sys->b_skip = 1;
426                 decoder_SynchroTrash( p_sys->p_synchro );
427                 mpeg2_set_buf( p_sys->p_mpeg2dec, buf, NULL );
428             }
429             else
430             {
431                 mpeg2_skip( p_sys->p_mpeg2dec, 0 );
432                 p_sys->b_skip = 0;
433                 decoder_SynchroDecode( p_sys->p_synchro );
434
435                 if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
436                 {
437                     block_Release( p_block );
438                     return NULL;
439                 }
440
441                 mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
442         mpeg2_stride( p_sys->p_mpeg2dec, p_pic->p[Y_PLANE].i_pitch );
443             }
444         }
445         break;
446
447         case STATE_END:
448         case STATE_SLICE:
449             p_pic = NULL;
450             if( p_sys->p_info->display_fbuf
451                 && p_sys->p_info->display_fbuf->id )
452             {
453                 p_pic = (picture_t *)p_sys->p_info->display_fbuf->id;
454
455                 decoder_SynchroEnd( p_sys->p_synchro,
456                             p_sys->p_info->display_picture->flags
457                              & PIC_MASK_CODING_TYPE,
458                             p_sys->b_garbage_pic );
459                 p_sys->b_garbage_pic = 0;
460
461                 if ( p_sys->p_picture_to_destroy != p_pic )
462                 {
463                     p_pic->date = decoder_SynchroDate( p_sys->p_synchro );
464                 }
465                 else
466                 {
467                     p_sys->p_picture_to_destroy = NULL;
468                     p_pic->date = 0;
469                 }
470             }
471
472             if( p_sys->p_info->discard_fbuf &&
473                 p_sys->p_info->discard_fbuf->id )
474             {
475                 p_dec->pf_picture_unlink( p_dec,
476                                           p_sys->p_info->discard_fbuf->id );
477             }
478
479             /* For still frames */
480             if( state == STATE_END && p_pic ) p_pic->b_force = true;
481
482             if( p_pic )
483             {
484                 /* Avoid frames with identical timestamps.
485                  * Especially needed for still frames in DVD menus. */
486                 if( p_sys->i_last_frame_pts == p_pic->date ) p_pic->date++;
487                 p_sys->i_last_frame_pts = p_pic->date;
488
489                 return p_pic;
490             }
491
492             break;
493
494         case STATE_INVALID:
495         {
496             uint8_t *buf[3];
497             buf[0] = buf[1] = buf[2] = NULL;
498
499             msg_Warn( p_dec, "invalid picture encountered" );
500             if ( ( p_sys->p_info->current_picture == NULL ) ||
501                ( ( p_sys->p_info->current_picture->flags &
502                    PIC_MASK_CODING_TYPE) != B_CODING_TYPE ) )
503             {
504                 if( p_sys->p_synchro ) decoder_SynchroReset( p_sys->p_synchro );
505             }
506             mpeg2_skip( p_sys->p_mpeg2dec, 1 );
507             p_sys->b_skip = 1;
508
509             if( p_sys->p_info->current_fbuf &&
510                 p_sys->p_info->current_fbuf->id )
511             {
512                 p_sys->b_garbage_pic = 1;
513                 p_pic = p_sys->p_info->current_fbuf->id;
514             }
515             else if( !p_sys->p_info->sequence )
516             {
517                 break;
518             }
519             else
520             {
521                 if( (p_pic = GetNewPicture( p_dec, buf )) == NULL )
522                     break;
523                 mpeg2_set_buf( p_sys->p_mpeg2dec, buf, p_pic );
524                 mpeg2_stride( p_sys->p_mpeg2dec, p_pic->p[Y_PLANE].i_pitch );
525             }
526             p_sys->p_picture_to_destroy = p_pic;
527
528             memset( p_pic->p[0].p_pixels, 0,
529                     p_sys->p_info->sequence->width
530                      * p_sys->p_info->sequence->height );
531             memset( p_pic->p[1].p_pixels, 0x80,
532                     p_sys->p_info->sequence->width
533                      * p_sys->p_info->sequence->height / 4 );
534             memset( p_pic->p[2].p_pixels, 0x80,
535                     p_sys->p_info->sequence->width
536                      * p_sys->p_info->sequence->height / 4 );
537
538             if( p_sys->b_slice_i )
539             {
540                 decoder_SynchroNewPicture( p_sys->p_synchro,
541                         I_CODING_TYPE, 2, 0, 0, p_sys->i_current_rate,
542                         p_sys->p_info->sequence->flags & SEQ_FLAG_LOW_DELAY );
543                 decoder_SynchroDecode( p_sys->p_synchro );
544                 decoder_SynchroEnd( p_sys->p_synchro, I_CODING_TYPE, 0 );
545             }
546             break;
547         }
548
549         default:
550             break;
551         }
552     }
553
554     /* Never reached */
555     return NULL;
556 }
557
558 /*****************************************************************************
559  * CloseDecoder: libmpeg2 decoder destruction
560  *****************************************************************************/
561 static void CloseDecoder( vlc_object_t *p_this )
562 {
563     decoder_t *p_dec = (decoder_t *)p_this;
564     decoder_sys_t *p_sys = p_dec->p_sys;
565
566     if( p_sys->p_synchro ) decoder_SynchroRelease( p_sys->p_synchro );
567
568     if( p_sys->p_mpeg2dec ) mpeg2_close( p_sys->p_mpeg2dec );
569
570     free( p_sys );
571 }
572
573 /*****************************************************************************
574  * GetNewPicture: Get a new picture from the vout and set the buf struct
575  *****************************************************************************/
576 static picture_t *GetNewPicture( decoder_t *p_dec, uint8_t **pp_buf )
577 {
578     decoder_sys_t *p_sys = p_dec->p_sys;
579     picture_t *p_pic;
580
581     p_dec->fmt_out.video.i_width = p_sys->p_info->sequence->width;
582     p_dec->fmt_out.video.i_visible_width =
583         p_sys->p_info->sequence->picture_width;
584     p_dec->fmt_out.video.i_height = p_sys->p_info->sequence->height;
585     p_dec->fmt_out.video.i_visible_height =
586         p_sys->p_info->sequence->picture_height;
587     p_dec->fmt_out.video.i_aspect = p_sys->i_aspect;
588     p_dec->fmt_out.video.i_sar_num = p_sys->i_sar_num;
589     p_dec->fmt_out.video.i_sar_den = p_sys->i_sar_den;
590
591     if( p_sys->p_info->sequence->frame_period > 0 )
592     {
593         p_dec->fmt_out.video.i_frame_rate =
594             (uint32_t)( (uint64_t)1001000000 * 27 /
595                         p_sys->p_info->sequence->frame_period );
596         p_dec->fmt_out.video.i_frame_rate_base = 1001;
597     }
598
599     p_dec->fmt_out.i_codec =
600         ( p_sys->p_info->sequence->chroma_height <
601           p_sys->p_info->sequence->height ) ?
602         VLC_FOURCC('I','4','2','0') : VLC_FOURCC('I','4','2','2');
603
604     /* Get a new picture */
605     p_pic = p_dec->pf_vout_buffer_new( p_dec );
606
607     if( p_pic == NULL ) return NULL;
608
609     p_pic->b_progressive = p_sys->p_info->current_picture != NULL ?
610         p_sys->p_info->current_picture->flags & PIC_FLAG_PROGRESSIVE_FRAME : 1;
611     p_pic->b_top_field_first = p_sys->p_info->current_picture != NULL ?
612         p_sys->p_info->current_picture->flags & PIC_FLAG_TOP_FIELD_FIRST : 1;
613     p_pic->i_nb_fields = p_sys->p_info->current_picture != NULL ?
614         p_sys->p_info->current_picture->nb_fields : 2;
615
616     p_dec->pf_picture_link( p_dec, p_pic );
617
618     pp_buf[0] = p_pic->p[0].p_pixels;
619     pp_buf[1] = p_pic->p[1].p_pixels;
620     pp_buf[2] = p_pic->p[2].p_pixels;
621
622     return p_pic;
623 }
624
625 /*****************************************************************************
626  * GetAR: Get aspect ratio
627  *****************************************************************************/
628 static void GetAR( decoder_t *p_dec )
629 {
630     decoder_sys_t *p_sys = p_dec->p_sys;
631
632     /* Check whether the input gave a particular aspect ratio */
633     if( p_dec->fmt_in.video.i_aspect )
634     {
635         p_sys->i_aspect = p_dec->fmt_in.video.i_aspect;
636         if( p_sys->i_aspect <= AR_221_1_PICTURE )
637         switch( p_sys->i_aspect )
638         {
639         case AR_4_3_PICTURE:
640             p_sys->i_aspect = VOUT_ASPECT_FACTOR * 4 / 3;
641             p_sys->i_sar_num = p_sys->p_info->sequence->picture_height * 4;
642             p_sys->i_sar_den = p_sys->p_info->sequence->picture_width * 3;
643             break;
644         case AR_16_9_PICTURE:
645             p_sys->i_aspect = VOUT_ASPECT_FACTOR * 16 / 9;
646             p_sys->i_sar_num = p_sys->p_info->sequence->picture_height * 16;
647             p_sys->i_sar_den = p_sys->p_info->sequence->picture_width * 9;
648             break;
649         case AR_221_1_PICTURE:
650             p_sys->i_aspect = VOUT_ASPECT_FACTOR * 221 / 100;
651             p_sys->i_sar_num = p_sys->p_info->sequence->picture_height * 221;
652             p_sys->i_sar_den = p_sys->p_info->sequence->picture_width * 100;
653             break;
654         case AR_SQUARE_PICTURE:
655             p_sys->i_aspect = VOUT_ASPECT_FACTOR *
656                            p_sys->p_info->sequence->picture_width /
657                            p_sys->p_info->sequence->picture_height;
658             p_sys->i_sar_num = p_sys->i_sar_den = 1;
659             break;
660         }
661     }
662     else
663     {
664         /* Use the value provided in the MPEG sequence header */
665         if( p_sys->p_info->sequence->pixel_height > 0 )
666         {
667             p_sys->i_aspect =
668                 ((uint64_t)p_sys->p_info->sequence->picture_width) *
669                 p_sys->p_info->sequence->pixel_width *
670                 VOUT_ASPECT_FACTOR /
671                 p_sys->p_info->sequence->picture_height /
672                 p_sys->p_info->sequence->pixel_height;
673             p_sys->i_sar_num = p_sys->p_info->sequence->pixel_width;
674             p_sys->i_sar_den = p_sys->p_info->sequence->pixel_height;
675         }
676         else
677         {
678             /* Invalid aspect, assume 4:3.
679              * This shouldn't happen and if it does it is a bug
680              * in libmpeg2 (likely triggered by an invalid stream) */
681             p_sys->i_aspect = VOUT_ASPECT_FACTOR * 4 / 3;
682             p_sys->i_sar_num = p_sys->p_info->sequence->picture_height * 4;
683             p_sys->i_sar_den = p_sys->p_info->sequence->picture_width * 3;
684         }
685     }
686
687     msg_Dbg( p_dec, "%dx%d (display %d,%d), aspect %d, sar %i:%i, %u.%03u fps",
688              p_sys->p_info->sequence->picture_width,
689              p_sys->p_info->sequence->picture_height,
690              p_sys->p_info->sequence->display_width,
691              p_sys->p_info->sequence->display_height,
692              p_sys->i_aspect, p_sys->i_sar_num, p_sys->i_sar_den,
693              (uint32_t)((uint64_t)1001000000 * 27 /
694                  p_sys->p_info->sequence->frame_period / 1001),
695              (uint32_t)((uint64_t)1001000000 * 27 /
696                  p_sys->p_info->sequence->frame_period % 1001) );
697 }