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/*****************************************************************************
* offsets.c: find position in an aux file
*****************************************************************************
* Copyright (C) 2009 VideoLAN
* $Id: offsets.c 10 2005-11-16 18:09:00Z cmassiot $
*
* Authors: Christophe Massiot <massiot@via.ecp.fr>
*
* 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.
*****************************************************************************/
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <sys/mman.h>
/*****************************************************************************
* Entry point
*****************************************************************************/
int main( int i_argc, char **pp_argv )
{
uint8_t *p_aux;
uint64_t i_wanted;
off_t i_offset1 = 0, i_offset2;
int i_stc_fd;
struct stat stc_stat;
uint64_t i_stc0;
if ( i_argc != 3 )
{
fprintf( stderr, "Usage: offsets <aux file> <27 MHz timestamp>\n" );
exit(EXIT_FAILURE);
}
i_wanted = strtoull( pp_argv[2], NULL, 0 );
if ( !i_wanted )
{
printf( "0\n" );
exit(EXIT_SUCCESS);
}
if ( (i_stc_fd = open( pp_argv[1], O_RDONLY )) == -1 )
{
fprintf( stderr, "unable to open %s (%s)\n", pp_argv[1],
strerror(errno) );
exit(EXIT_FAILURE);
}
if ( fstat( i_stc_fd, &stc_stat ) == -1 )
{
fprintf( stderr, "unable to stat %s (%s)\n", pp_argv[1],
strerror(errno) );
exit(EXIT_FAILURE);
}
p_aux = mmap( NULL, stc_stat.st_size, PROT_READ, MAP_SHARED,
i_stc_fd, 0 );
if ( p_aux == MAP_FAILED )
{
fprintf( stderr, "unable to mmap %s (%s)\n", pp_argv[1],
strerror(errno) );
exit(EXIT_FAILURE);
}
if ( p_aux[0] == 0x47 && p_aux[188] == 0x47 && p_aux[376] == 0x47 )
{
fprintf( stderr, "this is a TS file, not an aux file\n" );
exit(EXIT_FAILURE);
}
i_offset2 = stc_stat.st_size / sizeof(uint64_t);
i_stc0 = ((uint64_t)p_aux[0] << 56)
| ((uint64_t)p_aux[1] << 48)
| ((uint64_t)p_aux[2] << 40)
| ((uint64_t)p_aux[3] << 32)
| ((uint64_t)p_aux[4] << 24)
| ((uint64_t)p_aux[5] << 16)
| ((uint64_t)p_aux[6] << 8)
| ((uint64_t)p_aux[7] << 0);
for ( ; ; )
{
off_t i_mid_offset = (i_offset1 + i_offset2) / 2;
uint8_t *p_mid_aux = p_aux + i_mid_offset * sizeof(uint64_t);
uint64_t i_mid_stc = ((uint64_t)p_mid_aux[0] << 56)
| ((uint64_t)p_mid_aux[1] << 48)
| ((uint64_t)p_mid_aux[2] << 40)
| ((uint64_t)p_mid_aux[3] << 32)
| ((uint64_t)p_mid_aux[4] << 24)
| ((uint64_t)p_mid_aux[5] << 16)
| ((uint64_t)p_mid_aux[6] << 8)
| ((uint64_t)p_mid_aux[7] << 0);
if ( i_offset1 == i_mid_offset )
break;
if ( i_mid_stc - i_stc0 >= i_wanted )
i_offset2 = i_mid_offset;
else
i_offset1 = i_mid_offset;
}
munmap( p_aux, stc_stat.st_size );
close( i_stc_fd );
printf( "%jd\n", (intmax_t)i_offset2 );
exit(EXIT_SUCCESS);
}
|
