1 /*****************************************************************************
2 * mpegvideo.c: parse and packetize an MPEG1/2 video stream
3 *****************************************************************************
4 * Copyright (C) 2001, 2002 VideoLAN
5 * $Id: mpegvideo.c,v 1.30 2004/02/25 18:43:24 gbazin Exp $
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 */
85 vlc_bool_t b_frame_slice;
89 /* Sequence properties */
91 int i_frame_rate_base;
92 vlc_bool_t b_seq_progressive;
93 vlc_bool_t b_low_delay;
94 int i_aspect_ratio_info;
97 /* Picture properties */
100 int i_picture_structure;
101 int i_top_field_first;
102 int i_repeat_first_field;
103 int i_progressive_frame;
105 mtime_t i_interpolated_dts;
106 mtime_t i_old_duration;
107 mtime_t i_last_ref_pts;
109 /* Number of pictures since last sequence header */
119 /*****************************************************************************
121 *****************************************************************************/
122 static int Open( vlc_object_t *p_this )
124 decoder_t *p_dec = (decoder_t*)p_this;
125 decoder_sys_t *p_sys;
127 if( p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '1' ) &&
128 p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '2' ) &&
129 p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', 'v' ) )
134 es_format_Init( &p_dec->fmt_out, VIDEO_ES, VLC_FOURCC('m','p','g','v') );
135 p_dec->pf_packetize = Packetize;
137 p_dec->p_sys = p_sys = malloc( sizeof( decoder_sys_t ) );
140 p_sys->i_state = STATE_NOSYNC;
141 p_sys->bytestream = block_BytestreamInit( p_dec );
142 p_sys->p_startcode[0] = 0;
143 p_sys->p_startcode[1] = 0;
144 p_sys->p_startcode[2] = 1;
149 p_sys->p_frame = NULL;
150 p_sys->b_frame_slice = VLC_FALSE;
152 p_sys->i_dts = p_sys->i_pts = 0;
154 p_sys->i_frame_rate = 1;
155 p_sys->i_frame_rate_base = 1;
156 p_sys->b_seq_progressive = VLC_TRUE;
157 p_sys->b_low_delay = VLC_TRUE;
158 p_sys->i_seq_old = 0;
160 p_sys->i_temporal_ref = 0;
161 p_sys->i_picture_type = 0;
162 p_sys->i_picture_structure = 0x03; /* frame */
163 p_sys->i_top_field_first = 0;
164 p_sys->i_repeat_first_field = 0;
165 p_sys->i_progressive_frame = 0;
168 p_sys->i_interpolated_dts = 0;
169 p_sys->i_old_duration = 0;
170 p_sys->i_last_ref_pts = 0;
175 /*****************************************************************************
177 *****************************************************************************/
178 static void Close( vlc_object_t *p_this )
180 decoder_t *p_dec = (decoder_t*)p_this;
181 decoder_sys_t *p_sys = p_dec->p_sys;
183 block_BytestreamRelease( &p_sys->bytestream );
187 block_Release( p_sys->p_seq );
191 block_Release( p_sys->p_ext );
195 block_ChainRelease( p_sys->p_frame );
201 /*****************************************************************************
203 *****************************************************************************/
204 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
206 decoder_sys_t *p_sys = p_dec->p_sys;
209 if( pp_block == NULL || *pp_block == NULL )
214 if( (*pp_block)->i_flags&BLOCK_FLAG_DISCONTINUITY )
216 p_sys->i_state = STATE_NOSYNC;
217 if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
218 p_sys->p_frame = NULL;
219 p_sys->b_frame_slice = VLC_FALSE;
222 block_BytestreamPush( &p_sys->bytestream, *pp_block );
226 switch( p_sys->i_state )
230 if( block_FindStartcodeFromOffset( &p_sys->bytestream,
231 &p_sys->i_offset, p_sys->p_startcode, 3 ) == VLC_SUCCESS )
233 p_sys->i_state = STATE_NEXT_SYNC;
236 if( p_sys->i_offset )
238 block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );
240 block_BytestreamFlush( &p_sys->bytestream );
243 if( p_sys->i_state != STATE_NEXT_SYNC )
249 p_sys->i_offset = 1; /* To find next startcode */
251 case STATE_NEXT_SYNC:
252 /* TODO: If p_block == NULL, flush the buffer without checking the
255 /* Find the next startcode */
256 if( block_FindStartcodeFromOffset( &p_sys->bytestream,
257 &p_sys->i_offset, p_sys->p_startcode, 3 ) != VLC_SUCCESS )
263 /* Get the new fragment and set the pts/dts */
264 p_pic = block_New( p_dec, p_sys->i_offset );
265 p_pic->i_pts = p_sys->bytestream.p_block->i_pts;
266 p_pic->i_dts = p_sys->bytestream.p_block->i_dts;
268 block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
271 /* don't reuse the same timestamps several times */
272 if( p_pic->i_buffer >= 4 && p_pic->p_buffer[3] == 0x00 )
274 /* We have a picture start code */
275 p_sys->bytestream.p_block->i_pts = 0;
276 p_sys->bytestream.p_block->i_dts = 0;
281 /* Get picture if any */
282 if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
284 p_sys->i_state = STATE_NOSYNC;
288 /* We've just started the stream, wait for the first PTS.
289 * We discard here so we can still get the sequence header. */
290 if( p_sys->i_dts <= 0 && p_sys->i_pts <= 0 &&
291 p_sys->i_interpolated_dts <= 0 )
293 msg_Dbg( p_dec, "need a starting pts/dts" );
294 p_sys->i_state = STATE_NOSYNC;
295 block_Release( p_pic );
299 /* When starting the stream we can have the first frame with
300 * a null DTS (i_interpolated_pts is initialized to 0) */
301 if( !p_pic->i_dts ) p_pic->i_dts = p_pic->i_pts;
303 /* So p_block doesn't get re-added several times */
304 *pp_block = block_BytestreamPop( &p_sys->bytestream );
306 p_sys->i_state = STATE_NOSYNC;
313 /*****************************************************************************
314 * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
315 *****************************************************************************/
316 static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
318 decoder_sys_t *p_sys = p_dec->p_sys;
319 block_t *p_pic = NULL;
322 * Check if previous picture is finished
324 if( ( p_sys->b_frame_slice &&
325 (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) ) &&
326 p_sys->p_seq == NULL )
328 /* We have a picture but without a sequence header we can't
330 msg_Dbg( p_dec, "waiting for sequence start" );
331 if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
332 p_sys->p_frame = NULL;
333 p_sys->b_frame_slice = VLC_FALSE;
336 else if( p_sys->b_frame_slice &&
337 (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) )
341 p_pic = block_ChainGather( p_sys->p_frame );
343 i_duration = (mtime_t)( 1000000 * p_sys->i_frame_rate_base /
344 p_sys->i_frame_rate );
346 if( !p_sys->b_seq_progressive && p_sys->i_picture_structure != 0x03 )
351 if( p_sys->b_seq_progressive )
353 if( p_sys->i_top_field_first == 0 &&
354 p_sys->i_repeat_first_field == 1 )
358 else if( p_sys->i_top_field_first == 1 &&
359 p_sys->i_repeat_first_field == 1 )
366 if( p_sys->i_picture_structure == 0x03 )
368 if( p_sys->i_progressive_frame && p_sys->i_repeat_first_field )
370 i_duration += i_duration / 2;
375 if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
377 /* Trivial case (DTS == PTS) */
378 /* Correct interpolated dts when we receive a new pts/dts */
379 if( p_sys->i_pts > 0 ) p_sys->i_interpolated_dts = p_sys->i_pts;
380 if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
384 /* Correct interpolated dts when we receive a new pts/dts */
385 if( p_sys->i_last_ref_pts > 0 )
386 p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
387 if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
389 p_sys->i_last_ref_pts = p_sys->i_pts;
392 p_pic->i_dts = p_sys->i_interpolated_dts;
394 /* Set PTS only if we have a B frame or if it comes from the stream */
395 if( p_sys->i_pts > 0 )
397 p_pic->i_pts = p_sys->i_pts;
399 else if( p_sys->i_picture_type == 0x03 )
401 p_pic->i_pts = p_pic->i_dts;
408 if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
410 /* Trivial case (DTS == PTS) */
411 p_sys->i_interpolated_dts += i_duration;
415 p_sys->i_interpolated_dts += p_sys->i_old_duration;
416 p_sys->i_old_duration = i_duration;
419 p_pic->i_length = p_sys->i_interpolated_dts - p_pic->i_dts;
422 msg_Dbg( p_dec, "pic: type=%d dts="I64Fd" pts-dts="I64Fd,
423 p_sys->i_picture_type, p_pic->i_dts, p_pic->i_pts - p_pic->i_dts);
427 p_sys->p_frame = NULL;
428 p_sys->b_frame_slice = VLC_FALSE;
432 * Check info of current fragment
434 if( p_frag->p_buffer[3] == 0xb8 )
436 /* Group start code */
438 p_sys->i_seq_old > p_sys->i_frame_rate/p_sys->i_frame_rate_base )
440 /* Usefull for mpeg1: repeat sequence header every second */
441 block_ChainAppend( &p_sys->p_frame,
442 block_Duplicate( p_sys->p_seq ) );
445 block_ChainAppend( &p_sys->p_frame,
446 block_Duplicate( p_sys->p_ext ) );
449 p_sys->i_seq_old = 0;
452 else if( p_frag->p_buffer[3] == 0xb3 && p_frag->i_buffer >= 8 )
454 /* Sequence header code */
455 static const int code_to_frame_rate[16][2] =
457 { 1, 1 }, /* invalid */
458 { 24000, 1001 }, { 24, 1 }, { 25, 1 }, { 30000, 1001 },
459 { 30, 1 }, { 50, 1 }, { 60000, 1001 }, { 60, 1 },
460 /* Unofficial 15fps from Xing*/
462 /* Unofficial economy rates from libmpeg3 */
463 { 5, 1001 }, { 10, 1001 }, { 12, 1001 }, { 15, 1001 },
464 { 1, 1 }, { 1, 1 } /* invalid */
467 if( p_sys->p_seq ) block_Release( p_sys->p_seq );
468 if( p_sys->p_ext ) block_Release( p_sys->p_ext );
470 p_sys->p_seq = block_Duplicate( p_frag );
471 p_sys->i_seq_old = 0;
474 p_dec->fmt_out.video.i_width =
475 ( p_frag->p_buffer[4] << 4)|(p_frag->p_buffer[5] >> 4 );
476 p_dec->fmt_out.video.i_height =
477 ( (p_frag->p_buffer[5]&0x0f) << 8 )|p_frag->p_buffer[6];
478 p_sys->i_aspect_ratio_info = p_frag->p_buffer[7] >> 4;
480 /* TODO: MPEG1 aspect ratio */
482 p_sys->i_frame_rate = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][0];
483 p_sys->i_frame_rate_base =
484 code_to_frame_rate[p_frag->p_buffer[7]&0x0f][1];
486 p_sys->b_seq_progressive = VLC_TRUE;
487 p_sys->b_low_delay = VLC_TRUE;
489 if ( !p_sys->b_inited )
491 msg_Dbg( p_dec, "Size %dx%d fps=%.3f",
492 p_dec->fmt_out.video.i_width, p_dec->fmt_out.video.i_height,
493 p_sys->i_frame_rate / (float)p_sys->i_frame_rate_base );
497 else if( p_frag->p_buffer[3] == 0xb5 )
499 int i_type = p_frag->p_buffer[4] >> 4;
501 /* Extention start code */
504 static const int mpeg2_aspect[16][2] =
506 {0,1}, {1,1}, {4,3}, {16,9}, {221,100},
507 {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1},
511 /* sequence extention */
512 if( p_sys->p_ext) block_Release( p_sys->p_ext );
513 p_sys->p_ext = block_Duplicate( p_frag );
515 if( p_frag->i_buffer >= 10 )
517 p_sys->b_seq_progressive =
518 p_frag->p_buffer[5]&0x08 ? VLC_TRUE : VLC_FALSE;
520 p_frag->p_buffer[9]&0x80 ? VLC_TRUE : VLC_FALSE;
523 p_dec->fmt_out.video.i_aspect =
524 mpeg2_aspect[p_sys->i_aspect_ratio_info][0] *
526 mpeg2_aspect[p_sys->i_aspect_ratio_info][1];
529 else if( i_type == 0x08 )
531 /* picture extention */
532 p_sys->i_picture_structure = p_frag->p_buffer[6]&0x03;
533 p_sys->i_top_field_first = p_frag->p_buffer[7] >> 7;
534 p_sys->i_repeat_first_field= (p_frag->p_buffer[7]>>1)&0x01;
535 p_sys->i_progressive_frame = p_frag->p_buffer[8] >> 7;
538 else if( p_frag->p_buffer[3] == 0x00 )
540 /* Picture start code */
543 if( p_frag->i_buffer >= 6 )
545 p_sys->i_temporal_ref =
546 ( p_frag->p_buffer[4] << 2 )|(p_frag->p_buffer[5] >> 6);
547 p_sys->i_picture_type = ( p_frag->p_buffer[5] >> 3 ) & 0x03;
550 p_sys->i_dts = p_frag->i_dts;
551 p_sys->i_pts = p_frag->i_pts;
553 else if( p_frag->p_buffer[3] >= 0x01 && p_frag->p_buffer[3] <= 0xaf )
555 /* Slice start code */
556 p_sys->b_frame_slice = VLC_TRUE;
559 /* Append the block */
560 block_ChainAppend( &p_sys->p_frame, p_frag );