1 /*****************************************************************************
2 * mpegvideo.c: parse and packetize an MPEG1/2 video stream
3 *****************************************************************************
4 * Copyright (C) 2001, 2002 the VideoLAN team
7 * Authors: Laurent Aimar <fenrir@via.ecp.fr>
8 * Eric Petit <titer@videolan.org>
9 * Gildas Bazin <gbazin@videolan.org>
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_category( CAT_SOUT );
59 set_subcategory( SUBCAT_SOUT_PACKETIZER );
60 set_description( _("MPEG-I/II video packetizer") );
61 set_capability( "packetizer", 50 );
62 set_callbacks( Open, Close );
65 /*****************************************************************************
67 *****************************************************************************/
68 static block_t *Packetize( decoder_t *, block_t ** );
69 static block_t *ParseMPEGBlock( decoder_t *, block_t * );
76 block_bytestream_t bytestream;
79 uint8_t p_startcode[3];
81 /* Sequence header and extension */
85 /* Current frame being built */
89 vlc_bool_t b_frame_slice;
93 /* Sequence properties */
95 int i_frame_rate_base;
96 vlc_bool_t b_seq_progressive;
97 vlc_bool_t b_low_delay;
98 int i_aspect_ratio_info;
101 /* Picture properties */
104 int i_picture_structure;
105 int i_top_field_first;
106 int i_repeat_first_field;
107 int i_progressive_frame;
109 mtime_t i_interpolated_dts;
110 mtime_t i_old_duration;
111 mtime_t i_last_ref_pts;
113 /* Number of pictures since last sequence header */
123 /*****************************************************************************
125 *****************************************************************************/
126 static int Open( vlc_object_t *p_this )
128 decoder_t *p_dec = (decoder_t*)p_this;
129 decoder_sys_t *p_sys;
131 if( p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '1' ) &&
132 p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '2' ) &&
133 p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', 'v' ) )
138 es_format_Init( &p_dec->fmt_out, VIDEO_ES, VLC_FOURCC('m','p','g','v') );
139 p_dec->pf_packetize = Packetize;
141 p_dec->p_sys = p_sys = malloc( sizeof( decoder_sys_t ) );
144 p_sys->i_state = STATE_NOSYNC;
145 p_sys->bytestream = block_BytestreamInit( p_dec );
146 p_sys->p_startcode[0] = 0;
147 p_sys->p_startcode[1] = 0;
148 p_sys->p_startcode[2] = 1;
153 p_sys->p_frame = NULL;
154 p_sys->pp_last = &p_sys->p_frame;
155 p_sys->b_frame_slice = VLC_FALSE;
157 p_sys->i_dts = p_sys->i_pts = 0;
159 p_sys->i_frame_rate = 1;
160 p_sys->i_frame_rate_base = 1;
161 p_sys->b_seq_progressive = VLC_TRUE;
162 p_sys->b_low_delay = VLC_TRUE;
163 p_sys->i_seq_old = 0;
165 p_sys->i_temporal_ref = 0;
166 p_sys->i_picture_type = 0;
167 p_sys->i_picture_structure = 0x03; /* frame */
168 p_sys->i_top_field_first = 0;
169 p_sys->i_repeat_first_field = 0;
170 p_sys->i_progressive_frame = 0;
173 p_sys->i_interpolated_dts = 0;
174 p_sys->i_old_duration = 0;
175 p_sys->i_last_ref_pts = 0;
180 /*****************************************************************************
182 *****************************************************************************/
183 static void Close( vlc_object_t *p_this )
185 decoder_t *p_dec = (decoder_t*)p_this;
186 decoder_sys_t *p_sys = p_dec->p_sys;
188 block_BytestreamRelease( &p_sys->bytestream );
192 block_Release( p_sys->p_seq );
196 block_Release( p_sys->p_ext );
200 block_ChainRelease( p_sys->p_frame );
206 /*****************************************************************************
208 *****************************************************************************/
209 static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
211 decoder_sys_t *p_sys = p_dec->p_sys;
214 if( pp_block == NULL || *pp_block == NULL )
219 if( (*pp_block)->i_flags & (BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
221 p_sys->i_state = STATE_NOSYNC;
222 if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
223 p_sys->p_frame = NULL;
224 p_sys->pp_last = &p_sys->p_frame;
225 p_sys->b_frame_slice = VLC_FALSE;
226 block_Release( *pp_block );
230 block_BytestreamPush( &p_sys->bytestream, *pp_block );
234 switch( p_sys->i_state )
238 if( block_FindStartcodeFromOffset( &p_sys->bytestream,
239 &p_sys->i_offset, p_sys->p_startcode, 3 ) == VLC_SUCCESS )
241 p_sys->i_state = STATE_NEXT_SYNC;
244 if( p_sys->i_offset )
246 block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );
248 block_BytestreamFlush( &p_sys->bytestream );
251 if( p_sys->i_state != STATE_NEXT_SYNC )
257 p_sys->i_offset = 1; /* To find next startcode */
259 case STATE_NEXT_SYNC:
260 /* TODO: If p_block == NULL, flush the buffer without checking the
263 /* Find the next startcode */
264 if( block_FindStartcodeFromOffset( &p_sys->bytestream,
265 &p_sys->i_offset, p_sys->p_startcode, 3 ) != VLC_SUCCESS )
271 /* Get the new fragment and set the pts/dts */
272 p_pic = block_New( p_dec, p_sys->i_offset );
273 block_BytestreamFlush( &p_sys->bytestream );
274 p_pic->i_pts = p_sys->bytestream.p_block->i_pts;
275 p_pic->i_dts = p_sys->bytestream.p_block->i_dts;
277 block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
280 /* don't reuse the same timestamps several times */
281 if( p_pic->i_buffer >= 4 && p_pic->p_buffer[3] == 0x00 )
283 /* We have a picture start code */
284 p_sys->bytestream.p_block->i_pts = 0;
285 p_sys->bytestream.p_block->i_dts = 0;
290 /* Get picture if any */
291 if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
293 p_sys->i_state = STATE_NOSYNC;
297 /* We've just started the stream, wait for the first PTS.
298 * We discard here so we can still get the sequence header. */
299 if( p_sys->i_dts <= 0 && p_sys->i_pts <= 0 &&
300 p_sys->i_interpolated_dts <= 0 )
302 msg_Dbg( p_dec, "need a starting pts/dts" );
303 p_sys->i_state = STATE_NOSYNC;
304 block_Release( p_pic );
308 /* When starting the stream we can have the first frame with
309 * a null DTS (i_interpolated_pts is initialized to 0) */
310 if( !p_pic->i_dts ) p_pic->i_dts = p_pic->i_pts;
312 /* So p_block doesn't get re-added several times */
313 *pp_block = block_BytestreamPop( &p_sys->bytestream );
315 p_sys->i_state = STATE_NOSYNC;
322 /*****************************************************************************
323 * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
324 *****************************************************************************/
325 static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
327 decoder_sys_t *p_sys = p_dec->p_sys;
328 block_t *p_pic = NULL;
331 * Check if previous picture is finished
333 if( ( p_sys->b_frame_slice &&
334 (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) ) &&
335 p_sys->p_seq == NULL )
337 /* We have a picture but without a sequence header we can't
339 msg_Dbg( p_dec, "waiting for sequence start" );
340 if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
341 p_sys->p_frame = NULL;
342 p_sys->pp_last = &p_sys->p_frame;
343 p_sys->b_frame_slice = VLC_FALSE;
346 else if( p_sys->b_frame_slice &&
347 (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) )
351 p_pic = block_ChainGather( p_sys->p_frame );
353 i_duration = (mtime_t)( 1000000 * p_sys->i_frame_rate_base /
354 p_sys->i_frame_rate );
356 if( !p_sys->b_seq_progressive && p_sys->i_picture_structure != 0x03 )
361 if( p_sys->b_seq_progressive )
363 if( p_sys->i_top_field_first == 0 &&
364 p_sys->i_repeat_first_field == 1 )
368 else if( p_sys->i_top_field_first == 1 &&
369 p_sys->i_repeat_first_field == 1 )
376 if( p_sys->i_picture_structure == 0x03 )
378 if( p_sys->i_progressive_frame && p_sys->i_repeat_first_field )
380 i_duration += i_duration / 2;
385 if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
387 /* Trivial case (DTS == PTS) */
388 /* Correct interpolated dts when we receive a new pts/dts */
389 if( p_sys->i_pts > 0 ) p_sys->i_interpolated_dts = p_sys->i_pts;
390 if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
394 /* Correct interpolated dts when we receive a new pts/dts */
395 if( p_sys->i_last_ref_pts > 0 )
396 p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
397 if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
399 p_sys->i_last_ref_pts = p_sys->i_pts;
402 p_pic->i_dts = p_sys->i_interpolated_dts;
404 /* Set PTS only if we have a B frame or if it comes from the stream */
405 if( p_sys->i_pts > 0 )
407 p_pic->i_pts = p_sys->i_pts;
409 else if( p_sys->i_picture_type == 0x03 )
411 p_pic->i_pts = p_pic->i_dts;
418 if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
420 /* Trivial case (DTS == PTS) */
421 p_sys->i_interpolated_dts += i_duration;
425 p_sys->i_interpolated_dts += p_sys->i_old_duration;
426 p_sys->i_old_duration = i_duration;
429 switch ( p_sys->i_picture_type )
432 p_pic->i_flags |= BLOCK_FLAG_TYPE_I;
435 p_pic->i_flags |= BLOCK_FLAG_TYPE_P;
438 p_pic->i_flags |= BLOCK_FLAG_TYPE_B;
442 p_pic->i_length = p_sys->i_interpolated_dts - p_pic->i_dts;
445 msg_Dbg( p_dec, "pic: type=%d dts="I64Fd" pts-dts="I64Fd,
446 p_sys->i_picture_type, p_pic->i_dts, p_pic->i_pts - p_pic->i_dts);
450 p_sys->p_frame = NULL;
451 p_sys->pp_last = &p_sys->p_frame;
452 p_sys->b_frame_slice = VLC_FALSE;
456 * Check info of current fragment
458 if( p_frag->p_buffer[3] == 0xb8 )
460 /* Group start code */
462 p_sys->i_seq_old > p_sys->i_frame_rate/p_sys->i_frame_rate_base )
464 /* Usefull for mpeg1: repeat sequence header every second */
465 block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_seq ) );
468 block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_ext ) );
471 p_sys->i_seq_old = 0;
474 else if( p_frag->p_buffer[3] == 0xb3 && p_frag->i_buffer >= 8 )
476 /* Sequence header code */
477 static const int code_to_frame_rate[16][2] =
479 { 1, 1 }, /* invalid */
480 { 24000, 1001 }, { 24, 1 }, { 25, 1 }, { 30000, 1001 },
481 { 30, 1 }, { 50, 1 }, { 60000, 1001 }, { 60, 1 },
482 /* Unofficial 15fps from Xing*/
484 /* Unofficial economy rates from libmpeg3 */
485 { 5, 1001 }, { 10, 1001 }, { 12, 1001 }, { 15, 1001 },
486 { 1, 1 }, { 1, 1 } /* invalid */
489 if( p_sys->p_seq ) block_Release( p_sys->p_seq );
490 if( p_sys->p_ext ) block_Release( p_sys->p_ext );
492 p_sys->p_seq = block_Duplicate( p_frag );
493 p_sys->i_seq_old = 0;
496 p_dec->fmt_out.video.i_width =
497 ( p_frag->p_buffer[4] << 4)|(p_frag->p_buffer[5] >> 4 );
498 p_dec->fmt_out.video.i_height =
499 ( (p_frag->p_buffer[5]&0x0f) << 8 )|p_frag->p_buffer[6];
500 p_sys->i_aspect_ratio_info = p_frag->p_buffer[7] >> 4;
502 /* TODO: MPEG1 aspect ratio */
504 p_sys->i_frame_rate = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][0];
505 p_sys->i_frame_rate_base =
506 code_to_frame_rate[p_frag->p_buffer[7]&0x0f][1];
508 p_dec->fmt_out.video.i_frame_rate = p_sys->i_frame_rate;
509 p_dec->fmt_out.video.i_frame_rate_base = p_sys->i_frame_rate_base;
511 p_sys->b_seq_progressive = VLC_TRUE;
512 p_sys->b_low_delay = VLC_TRUE;
514 if ( !p_sys->b_inited )
516 msg_Dbg( p_dec, "Size %dx%d fps=%.3f",
517 p_dec->fmt_out.video.i_width, p_dec->fmt_out.video.i_height,
518 p_sys->i_frame_rate / (float)p_sys->i_frame_rate_base );
522 else if( p_frag->p_buffer[3] == 0xb5 )
524 int i_type = p_frag->p_buffer[4] >> 4;
526 /* Extention start code */
530 static const int mpeg2_aspect[16][2] =
532 {0,1}, {1,1}, {4,3}, {16,9}, {221,100},
533 {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1},
538 /* sequence extention */
539 if( p_sys->p_ext) block_Release( p_sys->p_ext );
540 p_sys->p_ext = block_Duplicate( p_frag );
542 if( p_frag->i_buffer >= 10 )
544 p_sys->b_seq_progressive =
545 p_frag->p_buffer[5]&0x08 ? VLC_TRUE : VLC_FALSE;
547 p_frag->p_buffer[9]&0x80 ? VLC_TRUE : VLC_FALSE;
550 /* Do not set aspect ratio : in case we're transcoding,
551 * transcode will take our fmt_out as a fmt_in to libmpeg2.
552 * libmpeg2.c will then believe that the user has requested
553 * a specific aspect ratio, which she hasn't. Thus in case
554 * of aspect ratio change, we're screwed. --Meuuh
557 p_dec->fmt_out.video.i_aspect =
558 mpeg2_aspect[p_sys->i_aspect_ratio_info][0] *
560 mpeg2_aspect[p_sys->i_aspect_ratio_info][1];
564 else if( i_type == 0x08 )
566 /* picture extention */
567 p_sys->i_picture_structure = p_frag->p_buffer[6]&0x03;
568 p_sys->i_top_field_first = p_frag->p_buffer[7] >> 7;
569 p_sys->i_repeat_first_field= (p_frag->p_buffer[7]>>1)&0x01;
570 p_sys->i_progressive_frame = p_frag->p_buffer[8] >> 7;
573 else if( p_frag->p_buffer[3] == 0x00 )
575 /* Picture start code */
578 if( p_frag->i_buffer >= 6 )
580 p_sys->i_temporal_ref =
581 ( p_frag->p_buffer[4] << 2 )|(p_frag->p_buffer[5] >> 6);
582 p_sys->i_picture_type = ( p_frag->p_buffer[5] >> 3 ) & 0x03;
585 p_sys->i_dts = p_frag->i_dts;
586 p_sys->i_pts = p_frag->i_pts;
588 else if( p_frag->p_buffer[3] >= 0x01 && p_frag->p_buffer[3] <= 0xaf )
590 /* Slice start code */
591 p_sys->b_frame_slice = VLC_TRUE;
594 /* Append the block */
595 block_ChainLastAppend( &p_sys->pp_last, p_frag );