mpeg4video.c

uclinux 下的vlc播放器源代码

/*****************************************************************************
 * mpeg4video.c: mpeg 4 video packetizer
 *****************************************************************************
 * Copyright (C) 2001-2006 the VideoLAN team
 * $Id: mpeg4video.c 16457 2006-08-31 20:51:12Z hartman $
 *
 * Authors: Gildas Bazin <[e-mail]>
 *          Laurent Aimar <[e-mail]>
 *          Eric Petit <[e-mail]>
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
 *****************************************************************************/

/*****************************************************************************
 * Preamble
 *****************************************************************************/
#include <stdlib.h>                                      /* malloc(), free() */

#include <vlc/vlc.h>
#include <vlc/decoder.h>
#include <vlc/sout.h>
#include <vlc/input.h>                  /* hmmm, just for INPUT_RATE_DEFAULT */

#include "vlc_bits.h"
#include "vlc_block_helper.h"

/*****************************************************************************
 * Module descriptor
 *****************************************************************************/
static int  Open ( vlc_object_t * );
static void Close( vlc_object_t * );

vlc_module_begin();
    set_category( CAT_SOUT );
    set_subcategory( SUBCAT_SOUT_PACKETIZER );
    set_description( _("MPEG4 video packetizer") );
    set_capability( "packetizer", 50 );
    set_callbacks( Open, Close );
vlc_module_end();

/****************************************************************************
 * Local prototypes
 ****************************************************************************/
static block_t *Packetize( 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];

    /*
     * Common properties
     */
    mtime_t i_interpolated_pts;
    mtime_t i_interpolated_dts;
    mtime_t i_last_ref_pts;
    mtime_t i_last_time_ref;
    mtime_t i_time_ref;
    mtime_t i_last_time;
    mtime_t i_last_timeincr;

    unsigned int i_flags;

    int         i_fps_num;
    int         i_fps_den;
    int         i_last_incr;
    int         i_last_incr_diff;

    vlc_bool_t  b_frame;

    /* Current frame being built */
    block_t    *p_frame;
    block_t    **pp_last;
};

enum {
    STATE_NOSYNC,
    STATE_NEXT_SYNC
};

static block_t *ParseMPEGBlock( decoder_t *, block_t * );
static int ParseVOL( decoder_t *, es_format_t *, uint8_t *, int );
static int ParseVOP( decoder_t *, block_t * );
static int vlc_log2( unsigned int );

#define VIDEO_OBJECT_MASK                       0x01f
#define VIDEO_OBJECT_LAYER_MASK                 0x00f

#define VIDEO_OBJECT_START_CODE                 0x100
#define VIDEO_OBJECT_LAYER_START_CODE           0x120
#define VISUAL_OBJECT_SEQUENCE_START_CODE       0x1b0
#define VISUAL_OBJECT_SEQUENCE_END_CODE         0x1b1
#define USER_DATA_START_CODE                    0x1b2
#define GROUP_OF_VOP_START_CODE                 0x1b3
#define VIDEO_SESSION_ERROR_CODE                0x1b4
#define VISUAL_OBJECT_START_CODE                0x1b5
#define VOP_START_CODE                          0x1b6
#define FACE_OBJECT_START_CODE                  0x1ba
#define FACE_OBJECT_PLANE_START_CODE            0x1bb
#define MESH_OBJECT_START_CODE                  0x1bc
#define MESH_OBJECT_PLANE_START_CODE            0x1bd
#define STILL_TEXTURE_OBJECT_START_CODE         0x1be
#define TEXTURE_SPATIAL_LAYER_START_CODE        0x1bf
#define TEXTURE_SNR_LAYER_START_CODE            0x1c0

/*****************************************************************************
 * Open: probe the packetizer and return score
 *****************************************************************************/
static int Open( vlc_object_t *p_this )
{
    decoder_t     *p_dec = (decoder_t*)p_this;
    decoder_sys_t *p_sys;

    switch( p_dec->fmt_in.i_codec )
    {
        case VLC_FOURCC( 'm', '4', 's', '2'):
        case VLC_FOURCC( 'M', '4', 'S', '2'):
        case VLC_FOURCC( 'm', 'p', '4', 's'):
        case VLC_FOURCC( 'M', 'P', '4', 'S'):
        case VLC_FOURCC( 'm', 'p', '4', 'v'):
        case VLC_FOURCC( 'M', 'P', '4', 'V'):
        case VLC_FOURCC( 'D', 'I', 'V', 'X'):
        case VLC_FOURCC( 'd', 'i', 'v', 'x'):
        case VLC_FOURCC( 'X', 'V', 'I', 'D'):
        case VLC_FOURCC( 'X', 'v', 'i', 'D'):
        case VLC_FOURCC( 'x', 'v', 'i', 'd'):
        case VLC_FOURCC( 'D', 'X', '5', '0'):
        case VLC_FOURCC( 'd', 'x', '5', '0'):
        case VLC_FOURCC( 0x04, 0,   0,   0):
        case VLC_FOURCC( '3', 'I', 'V', '2'):
        case VLC_FOURCC( 'm', '4', 'c', 'c'):
        case VLC_FOURCC( 'M', '4', 'C', 'C'):
            break;

        default:
            return VLC_EGENERIC;
    }

    /* Allocate the memory needed to store the decoder's structure */
    if( ( p_dec->p_sys = p_sys = malloc( sizeof(decoder_sys_t) ) ) == NULL )
    {
        msg_Err( p_dec, "out of memory" );
        return VLC_EGENERIC;
    }
    memset( p_sys, 0, 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_frame = NULL;
    p_sys->pp_last = &p_sys->p_frame;

    /* Setup properties */
    es_format_Copy( &p_dec->fmt_out, &p_dec->fmt_in );
    p_dec->fmt_out.i_codec = VLC_FOURCC( 'm', 'p', '4', 'v' );

    if( p_dec->fmt_in.i_extra )
    {
        /* We have a vol */
        p_dec->fmt_out.i_extra = p_dec->fmt_in.i_extra;
        p_dec->fmt_out.p_extra = malloc( p_dec->fmt_in.i_extra );
        memcpy( p_dec->fmt_out.p_extra, p_dec->fmt_in.p_extra,
                p_dec->fmt_in.i_extra );

        msg_Dbg( p_dec, "opening with vol size: %d", p_dec->fmt_in.i_extra );
        ParseVOL( p_dec, &p_dec->fmt_out,
                  p_dec->fmt_out.p_extra, p_dec->fmt_out.i_extra );
    }
    else
    {
        /* No vol, we'll have to look for one later on */
        p_dec->fmt_out.i_extra = 0;
        p_dec->fmt_out.p_extra = 0;
    }

    /* Set callback */
    p_dec->pf_packetize = Packetize;

    return VLC_SUCCESS;
}

/*****************************************************************************
 * Close: clean up the packetizer
 *****************************************************************************/
static void Close( vlc_object_t *p_this )
{
    decoder_t *p_dec = (decoder_t*)p_this;

    block_BytestreamRelease( &p_dec->p_sys->bytestream );
    if( p_dec->p_sys->p_frame ) block_ChainRelease( p_dec->p_sys->p_frame );
    free( p_dec->p_sys );
}

/****************************************************************************
 * Packetize: the whole thing
 ****************************************************************************/
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;
    mtime_t       i_pts, i_dts;

    if( pp_block == NULL || *pp_block == NULL ) return NULL;

    if( (*pp_block)->i_flags & BLOCK_FLAG_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->pp_last = &p_sys->p_frame;
        block_Release( *pp_block );
        return NULL;
    }

    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 );
            block_BytestreamFlush( &p_sys->bytestream );
            p_pic->i_pts = i_pts = p_sys->bytestream.p_block->i_pts;
            p_pic->i_dts = i_dts = p_sys->bytestream.p_block->i_dts;
            p_pic->i_rate = p_sys->bytestream.p_block->i_rate;

            block_GetBytes( &p_sys->bytestream, p_pic->p_buffer,
                            p_pic->i_buffer );

            p_sys->i_offset = 0;

            /* Get picture if any */
            if( !( p_pic = ParseMPEGBlock( p_dec, p_pic ) ) )
            {
                p_sys->i_state = STATE_NOSYNC;
                break;
            }

            /* don't reuse the same timestamps several times */
            if( i_pts == p_sys->bytestream.p_block->i_pts &&
                i_dts == p_sys->bytestream.p_block->i_dts )
            {
                p_sys->bytestream.p_block->i_pts = 0;
                p_sys->bytestream.p_block->i_dts = 0;
            }

            /* 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_interpolated_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;
            }