1 /*****************************************************************************
2 * mpegvideo.c: parse and packetize an MPEG1/2 video stream
3 *****************************************************************************
4 * Copyright (C) 2001, 2002 VideoLAN
7 * Authors: Laurent Aimar <fenrir@via.ecp.fr>
8 * Eric Petit <titer@videolan.org>
9 * Gildas Bazin <gbazin@netcourrier.com>
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
24 *****************************************************************************/
26 /*****************************************************************************
27 * Problem with this implementation:
29 * Although we should time-stamp each picture with a PTS, this isn't possible
30 * with the current implementation.
31 * The problem comes from the fact that for non-low-delay streams we can't
32 * calculate the PTS of pictures used as backward reference. Even the temporal
33 * reference number doesn't help here because all the pictures don't
34 * necessarily have the same duration (eg. 3:2 pulldown).
36 * However this doesn't really matter as far as the MPEG muxers are concerned
37 * because they allow having empty PTS fields. --gibalou
38 *****************************************************************************/
40 /*****************************************************************************
42 *****************************************************************************/
43 #include <stdlib.h> /* malloc(), free() */
46 #include <vlc/decoder.h>
47 #include <vlc/input.h>
49 #include "vlc_block_helper.h"
51 /*****************************************************************************
53 *****************************************************************************/
54 static int Open ( vlc_object_t * );
55 static void Close( vlc_object_t * );
58 set_description( _("MPEG-I/II video packetizer") );
59 set_capability( "packetizer", 50 );
60 set_callbacks( Open, Close );
63 /*****************************************************************************
65 *****************************************************************************/
66 static block_t *Packetize( decoder_t *, block_t ** );
67 static block_t *ParseMPEGBlock( decoder_t *, block_t * );
74 block_bytestream_t bytestream;
77 uint8_t p_startcode[3];
79 /* Sequence header and extension */
83 /* Current frame being built */
87 vlc_bool_t b_frame_slice;
91 /* Sequence properties */
93 int i_frame_rate_base;
94 vlc_bool_t b_seq_progressive;
95 vlc_bool_t b_low_delay;
96 int i_aspect_ratio_info;
99 /* Picture properties */
102 int i_picture_structure;
103 int i_top_field_first;
104 int i_repeat_first_field;
105 int i_progressive_frame;
107 mtime_t i_interpolated_dts;
108 mtime_t i_old_duration;
109 mtime_t i_last_ref_pts;
111 /* Number of pictures since last sequence header */
121 /*****************************************************************************
123 *****************************************************************************/
124 static int Open( vlc_object_t *p_this )
126 decoder_t *p_dec = (decoder_t*)p_this;
127 decoder_sys_t *p_sys;
129 if( p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '1' ) &&
130 p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '2' ) &&
131 p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', 'v' ) )
136 es_format_Init( &p_dec->fmt_out, VIDEO_ES, VLC_FOURCC('m','p','g','v') );
137 p_dec->pf_packetize = Packetize;
139 p_dec->p_sys = p_sys = malloc( sizeof( decoder_sys_t ) );
142 p_sys->i_state = STATE_NOSYNC;
143 p_sys->bytestream = block_BytestreamInit( p_dec );
144 p_sys->p_startcode[0] = 0;
145 p_sys->p_startcode[1] = 0;
146 p_sys->p_startcode[2] = 1;
151 p_sys->p_frame = NULL;
152 p_sys->pp_last = &p_sys->p_frame;
153 p_sys->b_frame_slice = VLC_FALSE;
155 p_sys->i_dts = p_sys->i_pts = 0;
157 p_sys->i_frame_rate = 1;
158 p_sys->i_frame_rate_base = 1;
159 p_sys->b_seq_progressive = VLC_TRUE;
160 p_sys->b_low_delay = VLC_TRUE;
161 p_sys->i_seq_old = 0;
163 p_sys->i_temporal_ref = 0;
164 p_sys->i_picture_type = 0;
165 p_sys->i_picture_structure = 0x03; /* frame */
166 p_sys->i_top_field_first = 0;
167 p_sys->i_repeat_first_field = 0;
168 p_sys->i_progressive_frame = 0;
171 p_sys->i_interpolated_dts = 0;
172 p_sys->i_old_duration = 0;
173 p_sys->i_last_ref_pts = 0;
178 /*****************************************************************************
180 *****************************************************************************/
181 static void Close( vlc_object_t *p_this )
183 decoder_t *p_dec = (decoder_t*)p_this;
184 decoder_sys_t *p_sys = p_dec->p_sys;
186 block_BytestreamRelease( &p_sys->bytestream );
190 block_Release( p_sys->p_seq );
194 block_Release( p_sys->p_ext );
198 block_ChainRelease( p_sys->p_frame );
204 /*****************************************************************************
206 *****************************************************************************/
207 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
209 decoder_sys_t *p_sys = p_dec->p_sys;
212 if( pp_block == NULL || *pp_block == NULL )
217 if( (*pp_block)->i_flags & BLOCK_FLAG_DISCONTINUITY )
219 p_sys->i_state = STATE_NOSYNC;
220 if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
221 p_sys->p_frame = NULL;
222 p_sys->pp_last = &p_sys->p_frame;
223 p_sys->b_frame_slice = VLC_FALSE;
224 block_Release( *pp_block );
228 block_BytestreamPush( &p_sys->bytestream, *pp_block );
232 switch( p_sys->i_state )
236 if( block_FindStartcodeFromOffset( &p_sys->bytestream,
237 &p_sys->i_offset, p_sys->p_startcode, 3 ) == VLC_SUCCESS )
239 p_sys->i_state = STATE_NEXT_SYNC;
242 if( p_sys->i_offset )
244 block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );
246 block_BytestreamFlush( &p_sys->bytestream );
249 if( p_sys->i_state != STATE_NEXT_SYNC )
255 p_sys->i_offset = 1; /* To find next startcode */
257 case STATE_NEXT_SYNC:
258 /* TODO: If p_block == NULL, flush the buffer without checking the
261 /* Find the next startcode */
262 if( block_FindStartcodeFromOffset( &p_sys->bytestream,
263 &p_sys->i_offset, p_sys->p_startcode, 3 ) != VLC_SUCCESS )
269 /* Get the new fragment and set the pts/dts */
270 p_pic = block_New( p_dec, p_sys->i_offset );
271 block_BytestreamFlush( &p_sys->bytestream );
272 p_pic->i_pts = p_sys->bytestream.p_block->i_pts;
273 p_pic->i_dts = p_sys->bytestream.p_block->i_dts;
275 block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
278 /* don't reuse the same timestamps several times */
279 if( p_pic->i_buffer >= 4 && p_pic->p_buffer[3] == 0x00 )
281 /* We have a picture start code */
282 p_sys->bytestream.p_block->i_pts = 0;
283 p_sys->bytestream.p_block->i_dts = 0;
288 /* Get picture if any */
289 if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
291 p_sys->i_state = STATE_NOSYNC;
295 /* We've just started the stream, wait for the first PTS.
296 * We discard here so we can still get the sequence header. */
297 if( p_sys->i_dts <= 0 && p_sys->i_pts <= 0 &&
298 p_sys->i_interpolated_dts <= 0 )
300 msg_Dbg( p_dec, "need a starting pts/dts" );
301 p_sys->i_state = STATE_NOSYNC;
302 block_Release( p_pic );
306 /* When starting the stream we can have the first frame with
307 * a null DTS (i_interpolated_pts is initialized to 0) */
308 if( !p_pic->i_dts ) p_pic->i_dts = p_pic->i_pts;
310 /* So p_block doesn't get re-added several times */
311 *pp_block = block_BytestreamPop( &p_sys->bytestream );
313 p_sys->i_state = STATE_NOSYNC;
320 /*****************************************************************************
321 * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
322 *****************************************************************************/
323 static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
325 decoder_sys_t *p_sys = p_dec->p_sys;
326 block_t *p_pic = NULL;
329 * Check if previous picture is finished
331 if( ( p_sys->b_frame_slice &&
332 (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) ) &&
333 p_sys->p_seq == NULL )
335 /* We have a picture but without a sequence header we can't
337 msg_Dbg( p_dec, "waiting for sequence start" );
338 if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
339 p_sys->p_frame = NULL;
340 p_sys->pp_last = &p_sys->p_frame;
341 p_sys->b_frame_slice = VLC_FALSE;
344 else if( p_sys->b_frame_slice &&
345 (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) )
349 p_pic = block_ChainGather( p_sys->p_frame );
351 i_duration = (mtime_t)( 1000000 * p_sys->i_frame_rate_base /
352 p_sys->i_frame_rate );
354 if( !p_sys->b_seq_progressive && p_sys->i_picture_structure != 0x03 )
359 if( p_sys->b_seq_progressive )
361 if( p_sys->i_top_field_first == 0 &&
362 p_sys->i_repeat_first_field == 1 )
366 else if( p_sys->i_top_field_first == 1 &&
367 p_sys->i_repeat_first_field == 1 )
374 if( p_sys->i_picture_structure == 0x03 )
376 if( p_sys->i_progressive_frame && p_sys->i_repeat_first_field )
378 i_duration += i_duration / 2;
383 if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
385 /* Trivial case (DTS == PTS) */
386 /* Correct interpolated dts when we receive a new pts/dts */
387 if( p_sys->i_pts > 0 ) p_sys->i_interpolated_dts = p_sys->i_pts;
388 if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
392 /* Correct interpolated dts when we receive a new pts/dts */
393 if( p_sys->i_last_ref_pts > 0 )
394 p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
395 if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
397 p_sys->i_last_ref_pts = p_sys->i_pts;
400 p_pic->i_dts = p_sys->i_interpolated_dts;
402 /* Set PTS only if we have a B frame or if it comes from the stream */
403 if( p_sys->i_pts > 0 )
405 p_pic->i_pts = p_sys->i_pts;
407 else if( p_sys->i_picture_type == 0x03 )
409 p_pic->i_pts = p_pic->i_dts;
416 if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
418 /* Trivial case (DTS == PTS) */
419 p_sys->i_interpolated_dts += i_duration;
423 p_sys->i_interpolated_dts += p_sys->i_old_duration;
424 p_sys->i_old_duration = i_duration;
427 switch ( p_sys->i_picture_type )
430 p_pic->i_flags |= BLOCK_FLAG_TYPE_I;
433 p_pic->i_flags |= BLOCK_FLAG_TYPE_P;
436 p_pic->i_flags |= BLOCK_FLAG_TYPE_B;
440 p_pic->i_length = p_sys->i_interpolated_dts - p_pic->i_dts;
443 msg_Dbg( p_dec, "pic: type=%d dts="I64Fd" pts-dts="I64Fd,
444 p_sys->i_picture_type, p_pic->i_dts, p_pic->i_pts - p_pic->i_dts);
448 p_sys->p_frame = NULL;
449 p_sys->pp_last = &p_sys->p_frame;
450 p_sys->b_frame_slice = VLC_FALSE;
454 * Check info of current fragment
456 if( p_frag->p_buffer[3] == 0xb8 )
458 /* Group start code */
460 p_sys->i_seq_old > p_sys->i_frame_rate/p_sys->i_frame_rate_base )
462 /* Usefull for mpeg1: repeat sequence header every second */
463 block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_seq ) );
466 block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_ext ) );
469 p_sys->i_seq_old = 0;
472 else if( p_frag->p_buffer[3] == 0xb3 && p_frag->i_buffer >= 8 )
474 /* Sequence header code */
475 static const int code_to_frame_rate[16][2] =
477 { 1, 1 }, /* invalid */
478 { 24000, 1001 }, { 24, 1 }, { 25, 1 }, { 30000, 1001 },
479 { 30, 1 }, { 50, 1 }, { 60000, 1001 }, { 60, 1 },
480 /* Unofficial 15fps from Xing*/
482 /* Unofficial economy rates from libmpeg3 */
483 { 5, 1001 }, { 10, 1001 }, { 12, 1001 }, { 15, 1001 },
484 { 1, 1 }, { 1, 1 } /* invalid */
487 if( p_sys->p_seq ) block_Release( p_sys->p_seq );
488 if( p_sys->p_ext ) block_Release( p_sys->p_ext );
490 p_sys->p_seq = block_Duplicate( p_frag );
491 p_sys->i_seq_old = 0;
494 p_dec->fmt_out.video.i_width =
495 ( p_frag->p_buffer[4] << 4)|(p_frag->p_buffer[5] >> 4 );
496 p_dec->fmt_out.video.i_height =
497 ( (p_frag->p_buffer[5]&0x0f) << 8 )|p_frag->p_buffer[6];
498 p_sys->i_aspect_ratio_info = p_frag->p_buffer[7] >> 4;
500 /* TODO: MPEG1 aspect ratio */
502 p_sys->i_frame_rate = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][0];
503 p_sys->i_frame_rate_base =
504 code_to_frame_rate[p_frag->p_buffer[7]&0x0f][1];
506 p_sys->b_seq_progressive = VLC_TRUE;
507 p_sys->b_low_delay = VLC_TRUE;
509 if ( !p_sys->b_inited )
511 msg_Dbg( p_dec, "Size %dx%d fps=%.3f",
512 p_dec->fmt_out.video.i_width, p_dec->fmt_out.video.i_height,
513 p_sys->i_frame_rate / (float)p_sys->i_frame_rate_base );
517 else if( p_frag->p_buffer[3] == 0xb5 )
519 int i_type = p_frag->p_buffer[4] >> 4;
521 /* Extention start code */
524 static const int mpeg2_aspect[16][2] =
526 {0,1}, {1,1}, {4,3}, {16,9}, {221,100},
527 {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1},
531 /* sequence extention */
532 if( p_sys->p_ext) block_Release( p_sys->p_ext );
533 p_sys->p_ext = block_Duplicate( p_frag );
535 if( p_frag->i_buffer >= 10 )
537 p_sys->b_seq_progressive =
538 p_frag->p_buffer[5]&0x08 ? VLC_TRUE : VLC_FALSE;
540 p_frag->p_buffer[9]&0x80 ? VLC_TRUE : VLC_FALSE;
543 p_dec->fmt_out.video.i_aspect =
544 mpeg2_aspect[p_sys->i_aspect_ratio_info][0] *
546 mpeg2_aspect[p_sys->i_aspect_ratio_info][1];
549 else if( i_type == 0x08 )
551 /* picture extention */
552 p_sys->i_picture_structure = p_frag->p_buffer[6]&0x03;
553 p_sys->i_top_field_first = p_frag->p_buffer[7] >> 7;
554 p_sys->i_repeat_first_field= (p_frag->p_buffer[7]>>1)&0x01;
555 p_sys->i_progressive_frame = p_frag->p_buffer[8] >> 7;
558 else if( p_frag->p_buffer[3] == 0x00 )
560 /* Picture start code */
563 if( p_frag->i_buffer >= 6 )
565 p_sys->i_temporal_ref =
566 ( p_frag->p_buffer[4] << 2 )|(p_frag->p_buffer[5] >> 6);
567 p_sys->i_picture_type = ( p_frag->p_buffer[5] >> 3 ) & 0x03;
570 p_sys->i_dts = p_frag->i_dts;
571 p_sys->i_pts = p_frag->i_pts;
573 else if( p_frag->p_buffer[3] >= 0x01 && p_frag->p_buffer[3] <= 0xaf )
575 /* Slice start code */
576 p_sys->b_frame_slice = VLC_TRUE;
579 /* Append the block */
580 block_ChainLastAppend( &p_sys->pp_last, p_frag );