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vlc/modules/packetizer/mpegvideo.c

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/*****************************************************************************
* mpegvideo.c: parse and packetize an MPEG1/2 video stream
*****************************************************************************
* Copyright (C) 2001, 2002 VideoLAN
* $Id: mpegvideo.c,v 1.25 2003/12/07 12:11:13 gbazin Exp $
*
* Authors: Laurent Aimar <fenrir@via.ecp.fr>
* Eric Petit <titer@videolan.org>
* Gildas Bazin <gbazin@netcourrier.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
*****************************************************************************/
/*****************************************************************************
* Problem with this implementation:
*
* Although we should time-stamp each picture with a PTS, this isn't possible
* with the current implementation.
* The problem comes from the fact that for non-low-delay streams we can't
* calculate the PTS of pictures used as backward reference. Even the temporal
* reference number doesn't help here because all the pictures don't
* necessarily have the same duration (eg. 3:2 pulldown).
*
* However this doesn't really matter as far as the MPEG muxers are concerned
* because they allow having empty PTS fields. --gibalou
*****************************************************************************/
/*****************************************************************************
* Preamble
*****************************************************************************/
#include <stdlib.h> /* malloc(), free() */
#include <vlc/vlc.h>
#include <vlc/decoder.h>
#include <vlc/input.h>
#include "vlc_block_helper.h"
/*****************************************************************************
* Module descriptor
*****************************************************************************/
static int Open ( vlc_object_t * );
static void Close( vlc_object_t * );
vlc_module_begin();
set_description( _("MPEG-I/II video packetizer") );
set_capability( "packetizer", 50 );
set_callbacks( Open, Close );
vlc_module_end();
/*****************************************************************************
* Local prototypes
*****************************************************************************/
static block_t *Packetize( decoder_t *, block_t ** );
static block_t *ParseMPEGBlock( decoder_t *, block_t * );
struct decoder_sys_t
{
/*
* Input properties
*/
block_bytestream_t bytestream;
int i_state;
int i_offset;
uint8_t p_startcode[3];
/* Sequence header and extention */
block_t *p_seq;
block_t *p_ext;
/* Current frame being built */
block_t *p_frame;
vlc_bool_t b_frame_slice;
mtime_t i_pts;
mtime_t i_dts;
/* Sequence properties */
int i_frame_rate;
int i_frame_rate_base;
vlc_bool_t b_seq_progressive;
vlc_bool_t b_low_delay;
int i_aspect_ratio_info;
/* Picture properties */
int i_temporal_ref;
int i_picture_type;
int i_picture_structure;
int i_top_field_first;
int i_repeat_first_field;
int i_progressive_frame;
mtime_t i_interpolated_dts;
mtime_t i_old_duration;
mtime_t i_last_ref_pts;
/* Number of pictues since last sequence header */
int i_seq_old;
};
enum {
STATE_NOSYNC,
STATE_NEXT_SYNC
};
/*****************************************************************************
* Open:
*****************************************************************************/
static int Open( vlc_object_t *p_this )
{
decoder_t *p_dec = (decoder_t*)p_this;
decoder_sys_t *p_sys;
if( p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '1' ) &&
p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', '2' ) &&
p_dec->fmt_in.i_codec != VLC_FOURCC( 'm', 'p', 'g', 'v' ) )
{
return VLC_EGENERIC;
}
es_format_Init( &p_dec->fmt_out, VIDEO_ES, VLC_FOURCC('m','p','g','v') );
p_dec->pf_packetize = Packetize;
p_dec->p_sys = p_sys = malloc( sizeof( decoder_sys_t ) );
/* Misc init */
p_sys->i_state = STATE_NOSYNC;
p_sys->bytestream = block_BytestreamInit( p_dec );
p_sys->p_startcode[0] = 0;
p_sys->p_startcode[1] = 0;
p_sys->p_startcode[2] = 1;
p_sys->i_offset = 0;
p_sys->p_seq = NULL;
p_sys->p_ext = NULL;
p_sys->p_frame = NULL;
p_sys->b_frame_slice = VLC_FALSE;
p_sys->i_dts = p_sys->i_pts = 0;
p_sys->i_frame_rate = 1;
p_sys->i_frame_rate_base = 1;
p_sys->b_seq_progressive = VLC_TRUE;
p_sys->b_low_delay = VLC_TRUE;
p_sys->i_seq_old = 0;
p_sys->i_temporal_ref = 0;
p_sys->i_picture_type = 0;
p_sys->i_picture_structure = 0x03; /* frame */
p_sys->i_top_field_first = 0;
p_sys->i_repeat_first_field = 0;
p_sys->i_progressive_frame = 0;
p_sys->i_interpolated_dts = 0;
p_sys->i_old_duration = 0;
p_sys->i_last_ref_pts = 0;
return VLC_SUCCESS;
}
/*****************************************************************************
* Close:
*****************************************************************************/
static void Close( vlc_object_t *p_this )
{
decoder_t *p_dec = (decoder_t*)p_this;
decoder_sys_t *p_sys = p_dec->p_sys;
block_BytestreamRelease( &p_sys->bytestream );
if( p_sys->p_seq )
{
block_Release( p_sys->p_seq );
}
if( p_sys->p_ext )
{
block_Release( p_sys->p_ext );
}
if( p_sys->p_frame )
{
block_ChainRelease( p_sys->p_frame );
}
free( p_sys );
}
/*****************************************************************************
* Packetize:
*****************************************************************************/
static block_t *Packetize( decoder_t *p_dec, block_t **pp_block )
{
decoder_sys_t *p_sys = p_dec->p_sys;
block_t *p_pic;
if( pp_block == NULL || *pp_block == NULL )
{
return NULL;
}
if( (*pp_block)->b_discontinuity )
{
p_sys->i_state = STATE_NOSYNC;
if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
p_sys->p_frame = NULL;
p_sys->b_frame_slice = VLC_FALSE;
}
block_BytestreamPush( &p_sys->bytestream, *pp_block );
while( 1 )
{
switch( p_sys->i_state )
{
case STATE_NOSYNC:
if( block_FindStartcodeFromOffset( &p_sys->bytestream,
&p_sys->i_offset, p_sys->p_startcode, 3 ) == VLC_SUCCESS )
{
p_sys->i_state = STATE_NEXT_SYNC;
}
if( p_sys->i_offset )
{
block_SkipBytes( &p_sys->bytestream, p_sys->i_offset );
p_sys->i_offset = 0;
block_BytestreamFlush( &p_sys->bytestream );
}
if( p_sys->i_state != STATE_NEXT_SYNC )
{
/* Need more data */
return NULL;
}
p_sys->i_offset = 1; /* To find next startcode */
case STATE_NEXT_SYNC:
/* TODO: If p_block == NULL, flush the buffer without checking the
* next sync word */
/* Find the next startcode */
if( block_FindStartcodeFromOffset( &p_sys->bytestream,
&p_sys->i_offset, p_sys->p_startcode, 3 ) != VLC_SUCCESS )
{
/* Need more data */
return NULL;
}
/* Get the new fragment and set the pts/dts */
p_pic = block_New( p_dec, p_sys->i_offset );
p_pic->i_pts = p_sys->bytestream.p_block->i_pts;
p_pic->i_dts = p_sys->bytestream.p_block->i_dts;
block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
p_pic->i_buffer );
/* don't reuse the same timestamps several times */
if( p_pic->i_buffer >= 4 && p_pic->p_buffer[3] == 0x00 )
{
/* We have a picture start code */
p_sys->bytestream.p_block->i_pts = 0;
p_sys->bytestream.p_block->i_dts = 0;
}
p_sys->i_offset = 0;
/* Get picture if any */
if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
{
p_sys->i_state = STATE_NOSYNC;
break;
}
/* We've just started the stream, wait for the first PTS.
* We discard here so we can still get the sequence header. */
if( p_sys->i_dts <= 0 && p_sys->i_pts <= 0 &&
p_sys->i_interpolated_dts <= 0 )
{
msg_Dbg( p_dec, "need a starting pts/dts" );
p_sys->i_state = STATE_NOSYNC;
block_Release( p_pic );
break;
}
/* So p_block doesn't get re-added several times */
*pp_block = block_BytestreamPop( &p_sys->bytestream );
p_sys->i_state = STATE_NOSYNC;
return p_pic;
}
}
}
/*****************************************************************************
* ParseMPEGBlock: Re-assemble fragments into a block containing a picture
*****************************************************************************/
static block_t *ParseMPEGBlock( decoder_t *p_dec, block_t *p_frag )
{
decoder_sys_t *p_sys = p_dec->p_sys;
block_t *p_pic = NULL;
/*
* Check if previous picture is finished
*/
if( ( p_sys->b_frame_slice &&
(p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) ) &&
p_sys->p_seq == NULL )
{
/* We have a picture but without a sequence header we can't
* do anything */
msg_Dbg( p_dec, "waiting for sequence start" );
if( p_sys->p_frame ) block_ChainRelease( p_sys->p_frame );
p_sys->p_frame = NULL;
p_sys->b_frame_slice = VLC_FALSE;
}
else if( p_sys->b_frame_slice &&
(p_frag->p_buffer[3] == 0x00 || p_frag->p_buffer[3] > 0xaf) )
{
mtime_t i_duration;
p_pic = block_ChainGather( p_sys->p_frame );
i_duration = (mtime_t)( 1000000 * p_sys->i_frame_rate_base /
p_sys->i_frame_rate );
if( !p_sys->b_seq_progressive && p_sys->i_picture_structure != 0x03 )
{
i_duration /= 2;
}
if( p_sys->b_seq_progressive )
{
if( p_sys->i_top_field_first == 0 &&
p_sys->i_repeat_first_field == 1 )
{
i_duration *= 2;
}
else if( p_sys->i_top_field_first == 1 &&
p_sys->i_repeat_first_field == 1 )
{
i_duration *= 3;
}
}
else
{
if( p_sys->i_picture_structure == 0x03 )
{
if( p_sys->i_progressive_frame && p_sys->i_repeat_first_field )
{
i_duration += i_duration / 2;
}
}
}
if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
{
/* Trivial case (DTS == PTS) */
/* Correct interpolated dts when we receive a new pts/dts */
if( p_sys->i_pts > 0 ) p_sys->i_interpolated_dts = p_sys->i_pts;
if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
}
else
{
/* Correct interpolated dts when we receive a new pts/dts */
if( p_sys->i_last_ref_pts > 0 )
p_sys->i_interpolated_dts = p_sys->i_last_ref_pts;
if( p_sys->i_dts > 0 ) p_sys->i_interpolated_dts = p_sys->i_dts;
p_sys->i_last_ref_pts = p_sys->i_pts;
}
p_pic->i_dts = p_sys->i_interpolated_dts;
/* Set PTS only if we have a B frame or if it comes from the stream */
if( p_sys->i_pts > 0 )
{
p_pic->i_pts = p_sys->i_pts;
}
else if( p_sys->i_picture_type == 0x03 )
{
p_pic->i_pts = p_pic->i_dts;
}
else
{
p_pic->i_pts = 0;
}
if( p_sys->b_low_delay || p_sys->i_picture_type == 0x03 )
{
/* Trivial case (DTS == PTS) */
p_sys->i_interpolated_dts += i_duration;
}
else
{
p_sys->i_interpolated_dts += p_sys->i_old_duration;
p_sys->i_old_duration = i_duration;
}
p_pic->i_length = p_sys->i_interpolated_dts - p_pic->i_dts;
#if 0
msg_Dbg( p_dec, "pic: type=%d dts="I64Fd" pts-dts="I64Fd,
p_sys->i_picture_type, p_pic->i_dts, p_pic->i_pts - p_pic->i_dts);
#endif
/* Reset context */
p_sys->p_frame = NULL;
p_sys->b_frame_slice = VLC_FALSE;
}
/*
* Check info of current fragment
*/
if( p_frag->p_buffer[3] == 0xb8 )
{
/* Group start code */
if( p_sys->p_seq &&
p_sys->i_seq_old > p_sys->i_frame_rate/p_sys->i_frame_rate_base )
{
/* Usefull for mpeg1: repeat sequence header every second */
block_ChainAppend( &p_sys->p_frame,
block_Duplicate( p_sys->p_seq ) );
if( p_sys->p_ext )
{
block_ChainAppend( &p_sys->p_frame,
block_Duplicate( p_sys->p_ext ) );
}
p_sys->i_seq_old = 0;
}
}
else if( p_frag->p_buffer[3] == 0xb3 && p_frag->i_buffer >= 8 )
{
/* Sequence header code */
static const int code_to_frame_rate[16][2] =
{
{ 1, 1 }, /* invalid */
{ 24000, 1001 }, { 24, 1 }, { 25, 1 }, { 30000, 1001 },
{ 30, 1 }, { 50, 1 }, { 60000, 1001 }, { 60, 1 },
/* Unofficial 15fps from Xing*/
{ 15, 1001 },
/* Unofficial economy rates from libmpeg3 */
{ 5, 1001 }, { 10, 1001 }, { 12, 1001 }, { 15, 1001 },
{ 1, 1 }, { 1, 1 } /* invalid */
};
if( p_sys->p_seq ) block_Release( p_sys->p_seq );
if( p_sys->p_ext ) block_Release( p_sys->p_ext );
p_sys->p_seq = block_Duplicate( p_frag );
p_sys->i_seq_old = 0;
p_sys->p_ext = NULL;
p_dec->fmt_out.video.i_width =
( p_frag->p_buffer[4] << 4)|(p_frag->p_buffer[5] >> 4 );
p_dec->fmt_out.video.i_height =
( (p_frag->p_buffer[5]&0x0f) << 8 )|p_frag->p_buffer[6];
p_sys->i_aspect_ratio_info = p_frag->p_buffer[7] >> 4;
/* TODO: MPEG1 aspect ratio */
p_sys->i_frame_rate = code_to_frame_rate[p_frag->p_buffer[7]&0x0f][0];
p_sys->i_frame_rate_base =
code_to_frame_rate[p_frag->p_buffer[7]&0x0f][1];
p_sys->b_seq_progressive = VLC_TRUE;
p_sys->b_low_delay = VLC_TRUE;
#if 0
msg_Dbg( p_dec, "Size %dx%d fps=%.3f",
p_dec->fmt_out.video.i_width, p_dec->fmt_out.video.i_height,
p_sys->i_frame_rate / (float)p_sys->i_frame_rate_base );
#endif
}
else if( p_frag->p_buffer[3] == 0xb5 )
{
int i_type = p_frag->p_buffer[4] >> 4;
/* Extention start code */
if( i_type == 0x01 )
{
static const int mpeg2_aspect[16][2] =
{
{0,1}, {1,1}, {4,3}, {16,9}, {221,100},
{0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1}, {0,1},
{0,1}, {0,1}
};
/* sequence extention */
if( p_sys->p_ext) block_Release( p_sys->p_ext );
p_sys->p_ext = block_Duplicate( p_frag );
if( p_frag->i_buffer >= 10 )
{
p_sys->b_seq_progressive =
p_frag->p_buffer[5]&0x08 ? VLC_TRUE : VLC_FALSE;
p_sys->b_low_delay =
p_frag->p_buffer[9]&0x80 ? VLC_TRUE : VLC_FALSE;
}
p_dec->fmt_out.video.i_aspect =
mpeg2_aspect[p_sys->i_aspect_ratio_info][0] *
VOUT_ASPECT_FACTOR /
mpeg2_aspect[p_sys->i_aspect_ratio_info][1];
}
else if( i_type == 0x08 )
{
/* picture extention */
p_sys->i_picture_structure = p_frag->p_buffer[6]&0x03;
p_sys->i_top_field_first = p_frag->p_buffer[7] >> 7;
p_sys->i_repeat_first_field= (p_frag->p_buffer[7]>>1)&0x01;
p_sys->i_progressive_frame = p_frag->p_buffer[8] >> 7;
}
}
else if( p_frag->p_buffer[3] == 0x00 )
{
/* Picture start code */
p_sys->i_seq_old++;
if( p_frag->i_buffer >= 6 )
{
p_sys->i_temporal_ref =
( p_frag->p_buffer[4] << 2 )|(p_frag->p_buffer[5] >> 6);
p_sys->i_picture_type = ( p_frag->p_buffer[5] >> 3 ) & 0x03;
}
p_sys->i_dts = p_frag->i_dts;
p_sys->i_pts = p_frag->i_pts;
}
else if( p_frag->p_buffer[3] >= 0x01 && p_frag->p_buffer[3] <= 0xaf )
{
/* Slice start code */
p_sys->b_frame_slice = VLC_TRUE;
}
/* Append the block */
block_ChainAppend( &p_sys->p_frame, p_frag );
return p_pic;
}