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 p_pic->i_pts = p_sys->bytestream.p_block->i_pts;
272 p_pic->i_dts = p_sys->bytestream.p_block->i_dts;
274 /* FIXME ? Should we flush the bytestream chain before ? */
275 if( p_sys->bytestream.p_block->i_buffer ==
276 p_sys->bytestream.i_offset &&
277 p_sys->bytestream.p_block->p_next )
279 p_pic->i_pts = p_sys->bytestream.p_block->p_next->i_pts;
280 p_pic->i_dts = p_sys->bytestream.p_block->p_next->i_dts;
283 block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
286 /* don't reuse the same timestamps several times */
287 if( p_pic->i_buffer >= 4 && p_pic->p_buffer[3] == 0x00 )
289 /* We have a picture start code */
290 p_sys->bytestream.p_block->i_pts = 0;
291 p_sys->bytestream.p_block->i_dts = 0;
296 /* Get picture if any */
297 if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
299 p_sys->i_state = STATE_NOSYNC;
303 /* We've just started the stream, wait for the first PTS.
304 * We discard here so we can still get the sequence header. */
305 if( p_sys->i_dts <= 0 && p_sys->i_pts <= 0 &&
306 p_sys->i_interpolated_dts <= 0 )
308 msg_Dbg( p_dec, "need a starting pts/dts" );
309 p_sys->i_state = STATE_NOSYNC;
310 block_Release( p_pic );
314 /* When starting the stream we can have the first frame with
315 * a null DTS (i_interpolated_pts is initialized to 0) */
316 if( !p_pic->i_dts ) p_pic->i_dts = p_pic->i_pts;
318 /* So p_block doesn't get re-added several times */
319 *pp_block = block_BytestreamPop( &p_sys->bytestream );
321 p_sys->i_state = STATE_NOSYNC;
328 /*****************************************************************************
329 * ParseMPEGBlock: Re-assemble fragments into a block containing a picture
330 *****************************************************************************/
331 static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
333 decoder_sys_t *p_sys = p_dec->p_sys;
334 block_t *p_pic = NULL;
337 * Check if previous picture is finished
339 if( ( p_sys->b_frame_slice &&
340 (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) ) &&
341 p_sys->p_seq == NULL )
343 /* We have a picture but without a sequence header we can't
345 msg_Dbg( p_dec, "waiting for sequence start" );
346 if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
347 p_sys->p_frame = NULL;
348 p_sys->pp_last = &p_sys->p_frame;
349 p_sys->b_frame_slice = VLC_FALSE;
352 else if( p_sys->b_frame_slice &&
353 (p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) )
357 p_pic = block_ChainGather( p_sys->p_frame );
359 i_duration = (mtime_t)( 1000000 * p_sys->i_frame_rate_base /
360 p_sys->i_frame_rate );
362 if( !p_sys->b_seq_progressive && p_sys->i_picture_structure != 0x03 )
367 if( p_sys->b_seq_progressive )
369 if( p_sys->i_top_field_first == 0 &&
370 p_sys->i_repeat_first_field == 1 )
374 else if( p_sys->i_top_field_first == 1 &&
375 p_sys->i_repeat_first_field == 1 )
382 if( p_sys->i_picture_structure == 0x03 )
384 if( p_sys->i_progressive_frame && p_sys->i_repeat_first_field )
386 i_duration += i_duration / 2;
391 if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
393 /* Trivial case (DTS == PTS) */
394 /* Correct interpolated dts when we receive a new pts/dts */
395 if( p_sys->i_pts > 0 ) p_sys->i_interpolated_dts = p_sys->i_pts;
396 if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
400 /* Correct interpolated dts when we receive a new pts/dts */
401 if( p_sys->i_last_ref_pts > 0 )
402 p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
403 if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
405 p_sys->i_last_ref_pts = p_sys->i_pts;
408 p_pic->i_dts = p_sys->i_interpolated_dts;
410 /* Set PTS only if we have a B frame or if it comes from the stream */
411 if( p_sys->i_pts > 0 )
413 p_pic->i_pts = p_sys->i_pts;
415 else if( p_sys->i_picture_type == 0x03 )
417 p_pic->i_pts = p_pic->i_dts;
424 if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
426 /* Trivial case (DTS == PTS) */
427 p_sys->i_interpolated_dts += i_duration;
431 p_sys->i_interpolated_dts += p_sys->i_old_duration;
432 p_sys->i_old_duration = i_duration;
435 switch ( p_sys->i_picture_type )
438 p_pic->i_flags |= BLOCK_FLAG_TYPE_I;
441 p_pic->i_flags |= BLOCK_FLAG_TYPE_P;
444 p_pic->i_flags |= BLOCK_FLAG_TYPE_B;
448 p_pic->i_length = p_sys->i_interpolated_dts - p_pic->i_dts;
451 msg_Dbg( p_dec, "pic: type=%d dts="I64Fd" pts-dts="I64Fd,
452 p_sys->i_picture_type, p_pic->i_dts, p_pic->i_pts - p_pic->i_dts);
456 p_sys->p_frame = NULL;
457 p_sys->pp_last = &p_sys->p_frame;
458 p_sys->b_frame_slice = VLC_FALSE;
462 * Check info of current fragment
464 if( p_frag->p_buffer[3] == 0xb8 )
466 /* Group start code */
468 p_sys->i_seq_old > p_sys->i_frame_rate/p_sys->i_frame_rate_base )
470 /* Usefull for mpeg1: repeat sequence header every second */
471 block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_seq ) );
474 block_ChainLastAppend( &p_sys->pp_last, block_Duplicate( p_sys->p_ext ) );
477 p_sys->i_seq_old = 0;
480 else if( p_frag->p_buffer[3] == 0xb3 && p_frag->i_buffer >= 8 )
482 /* Sequence header code */
483 static const int code_to_frame_rate[16][2] =
485 { 1, 1 }, /* invalid */
486 { 24000, 1001 }, { 24, 1 }, { 25, 1 }, { 30000, 1001 },
487 { 30, 1 }, { 50, 1 }, { 60000, 1001 }, { 60, 1 },
488 /* Unofficial 15fps from Xing*/
490 /* Unofficial economy rates from libmpeg3 */
491 { 5, 1001 }, { 10, 1001 }, { 12, 1001 }, { 15, 1001 },
492 { 1, 1 }, { 1, 1 } /* invalid */
495 if( p_sys->p_seq ) block_Release( p_sys->p_seq );
496 if( p_sys->p_ext ) block_Release( p_sys->p_ext );
498 p_sys->p_seq = block_Duplicate( p_frag );
499 p_sys->i_seq_old = 0;
502 p_dec->fmt_out.video.i_width =
503 ( p_frag->p_buffer[4] << 4)|(p_frag->p_buffer[5] >> 4 );
504 p_dec->fmt_out.video.i_height =
505 ( (p_frag->p_buffer[5]&0x0f) << 8 )|p_frag->p_buffer[6];
506 p_sys->i_aspect_ratio_info = p_frag->p_buffer[7] >> 4;
508 /* TODO: MPEG1 aspect ratio */
510 p_sys->i_frame_rate = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][0];
511 p_sys->i_frame_rate_base =
512 code_to_frame_rate[p_frag->p_buffer[7]&0x0f][1];
514 p_sys->b_seq_progressive = VLC_TRUE;
515 p_sys->b_low_delay = VLC_TRUE;
517 if ( !p_sys->b_inited )
519 msg_Dbg( p_dec, "Size %dx%d fps=%.3f",
520 p_dec->fmt_out.video.i_width, p_dec->fmt_out.video.i_height,
521 p_sys->i_frame_rate / (float)p_sys->i_frame_rate_base );
525 else if( p_frag->p_buffer[3] == 0xb5 )
527 int i_type = p_frag->p_buffer[4] >> 4;
529 /* Extention start code */
532 static const int mpeg2_aspect[16][2] =
534 {0,1}, {1,1}, {4,3}, {16,9}, {221,100},
535 {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1},
539 /* sequence extention */
540 if( p_sys->p_ext) block_Release( p_sys->p_ext );
541 p_sys->p_ext = block_Duplicate( p_frag );
543 if( p_frag->i_buffer >= 10 )
545 p_sys->b_seq_progressive =
546 p_frag->p_buffer[5]&0x08 ? VLC_TRUE : VLC_FALSE;
548 p_frag->p_buffer[9]&0x80 ? VLC_TRUE : VLC_FALSE;
551 p_dec->fmt_out.video.i_aspect =
552 mpeg2_aspect[p_sys->i_aspect_ratio_info][0] *
554 mpeg2_aspect[p_sys->i_aspect_ratio_info][1];
557 else if( i_type == 0x08 )
559 /* picture extention */
560 p_sys->i_picture_structure = p_frag->p_buffer[6]&0x03;
561 p_sys->i_top_field_first = p_frag->p_buffer[7] >> 7;
562 p_sys->i_repeat_first_field= (p_frag->p_buffer[7]>>1)&0x01;
563 p_sys->i_progressive_frame = p_frag->p_buffer[8] >> 7;
566 else if( p_frag->p_buffer[3] == 0x00 )
568 /* Picture start code */
571 if( p_frag->i_buffer >= 6 )
573 p_sys->i_temporal_ref =
574 ( p_frag->p_buffer[4] << 2 )|(p_frag->p_buffer[5] >> 6);
575 p_sys->i_picture_type = ( p_frag->p_buffer[5] >> 3 ) & 0x03;
578 p_sys->i_dts = p_frag->i_dts;
579 p_sys->i_pts = p_frag->i_pts;
581 else if( p_frag->p_buffer[3] >= 0x01 && p_frag->p_buffer[3] <= 0xaf )
583 /* Slice start code */
584 p_sys->b_frame_slice = VLC_TRUE;
587 /* Append the block */
588 block_ChainLastAppend( &p_sys->pp_last, p_frag );