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packetizer_helper.h：源码内容
							/*****************************************************************************
 * packetizer.h: Packetizer helpers
 *****************************************************************************
 * Copyright (C) 2009 Laurent Aimar
 * $Id: 1c6e67b205a9fa0e40c2e4e641f074fcfc70c3bd $
 *
 * Authors: Laurent Aimar <fenrir _AT_ videolan _DOT_ org>
 *
 * 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.
 *****************************************************************************/
#ifndef _PACKETIZER_H
#define _PACKETIZER_H 1
#include <vlc_block.h>
enum
{
    STATE_NOSYNC,
    STATE_NEXT_SYNC
};
typedef void (*packetizer_reset_t)( void *p_private, bool b_broken );
typedef block_t *(*packetizer_parse_t)( void *p_private, bool *pb_ts_used, block_t * );
typedef int (*packetizer_validate_t)( void *p_private, block_t * );
typedef struct
{
    int i_state;
    block_bytestream_t bytestream;
    size_t i_offset;
    bool   b_flushing;
    int i_startcode;
    const uint8_t *p_startcode;
    int i_au_prepend;
    const uint8_t *p_au_prepend;
    void *p_private;
    packetizer_reset_t    pf_reset;
    packetizer_parse_t    pf_parse;
    packetizer_validate_t pf_validate;
} packetizer_t;
static inline void packetizer_Init( packetizer_t *p_pack,
                                    const uint8_t *p_startcode, int i_startcode,
                                    const uint8_t *p_au_prepend, int i_au_prepend,
                                    packetizer_reset_t pf_reset,
                                    packetizer_parse_t pf_parse,
                                    packetizer_validate_t pf_validate,
                                    void *p_private )
{
    p_pack->i_state = STATE_NOSYNC;
    p_pack->bytestream = block_BytestreamInit();
    p_pack->i_offset = 0;
    p_pack->b_flushing = false;
    p_pack->i_au_prepend = i_au_prepend;
    p_pack->p_au_prepend = p_au_prepend;
    p_pack->i_startcode = i_startcode;
    p_pack->p_startcode = p_startcode;
    p_pack->pf_reset = pf_reset;
    p_pack->pf_parse = pf_parse;
    p_pack->pf_validate = pf_validate;
    p_pack->p_private = p_private;
}
static inline void packetizer_Clean( packetizer_t *p_pack )
{
    block_BytestreamRelease( &p_pack->bytestream );
}
static inline block_t *packetizer_Packetize( packetizer_t *p_pack, block_t **pp_block )
{
    if( !pp_block || !*pp_block )
        return NULL;
    if( (*pp_block)->i_flags&(BLOCK_FLAG_DISCONTINUITY|BLOCK_FLAG_CORRUPTED) )
    {
        const bool b_broken = ( (*pp_block)->i_flags&BLOCK_FLAG_CORRUPTED ) != 0;
        if( b_broken )
        {
            p_pack->i_state = STATE_NOSYNC;
            block_BytestreamEmpty( &p_pack->bytestream );
            p_pack->i_offset = 0;
        }
        p_pack->pf_reset( p_pack->p_private, b_broken );
        block_Release( *pp_block );
        return NULL;
    }
    block_BytestreamPush( &p_pack->bytestream, *pp_block );
    for( ;; )
    {
        bool b_used_ts;
        block_t *p_pic;
        switch( p_pack->i_state )
        {
        case STATE_NOSYNC:
            /* Find a startcode */
            if( !block_FindStartcodeFromOffset( &p_pack->bytestream, &p_pack->i_offset,
                                                p_pack->p_startcode, p_pack->i_startcode ) )
                p_pack->i_state = STATE_NEXT_SYNC;
            if( p_pack->i_offset )
            {
                block_SkipBytes( &p_pack->bytestream, p_pack->i_offset );
                p_pack->i_offset = 0;
                block_BytestreamFlush( &p_pack->bytestream );
            }
            if( p_pack->i_state != STATE_NEXT_SYNC )
                return NULL; /* Need more data */
            p_pack->i_offset = 1; /* To find next startcode */
        case STATE_NEXT_SYNC:
            /* Find the next startcode */
            if( block_FindStartcodeFromOffset( &p_pack->bytestream, &p_pack->i_offset,
                                               p_pack->p_startcode, p_pack->i_startcode ) )
            {
                if( !p_pack->b_flushing || !p_pack->bytestream.p_chain )
                    return NULL; /* Need more data */
                /* When flusing and we don't find a startcode, suppose that
                 * the data extend up to the end */
                block_ChainProperties( p_pack->bytestream.p_chain,
                                       NULL, &p_pack->i_offset, NULL );
                p_pack->i_offset -= p_pack->bytestream .i_offset;
                if( p_pack->i_offset <= (size_t)p_pack->i_startcode )
                    return NULL;
            }
            block_BytestreamFlush( &p_pack->bytestream );
            /* Get the new fragment and set the pts/dts */
            block_t *p_block_bytestream = p_pack->bytestream.p_block;
            p_pic = block_New( p_dec, p_pack->i_offset + p_pack->i_au_prepend );
            p_pic->i_pts = p_block_bytestream->i_pts;
            p_pic->i_dts = p_block_bytestream->i_dts;
            block_GetBytes( &p_pack->bytestream, &p_pic->p_buffer[p_pack->i_au_prepend],
                            p_pic->i_buffer - p_pack->i_au_prepend );
            if( p_pack->i_au_prepend > 0 )
                memcpy( p_pic->p_buffer, p_pack->p_au_prepend, p_pack->i_au_prepend );
            p_pack->i_offset = 0;
            /* Parse the NAL */
            p_pic = p_pack->pf_parse( p_pack->p_private, &b_used_ts, p_pic );
            if( b_used_ts )
            {
                p_block_bytestream->i_dts = -1;
                p_block_bytestream->i_pts = -1;
            }
            if( !p_pic )
            {
                p_pack->i_state = STATE_NOSYNC;
                break;
            }
            if( p_pack->pf_validate( p_pack->p_private, p_pic ) )
            {
                p_pack->i_state = STATE_NOSYNC;
                block_Release( p_pic );
                break;
            }
            /* So p_block doesn't get re-added several times */
            *pp_block = block_BytestreamPop( &p_pack->bytestream );
            p_pack->i_state = STATE_NOSYNC;
            return p_pic;
        }
    }
}
static inline void packetizer_Header( packetizer_t *p_pack,
                                      const uint8_t *p_header, int i_header )
{
    block_t *p_init = block_Alloc( i_header );
    if( !p_init )
        return;
    memcpy( p_init->p_buffer, p_header, i_header );
    p_pack->b_flushing = true;
    block_t *p_pic;
    while( ( p_pic = packetizer_Packetize( p_pack, &p_init ) ) )
        block_Release( p_pic ); /* Should not happen (only sequence header) */
    p_pack->i_state = STATE_NOSYNC;
    block_BytestreamEmpty( &p_pack->bytestream );
    p_pack->i_offset = 0;
    p_pack->b_flushing = false;
}
#endif

						