/*
 * extract_audio.c - extracts DVD audio channel from a VOB file
 * Copyright (C) 2000   Samuel Hocevar <sam@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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *                                                     
 */

/* open */
#include <fcntl.h>
/* printf */
#include <stdio.h>

int main (int argc, char *argv[])
{
        unsigned char c[65536];
	unsigned int id, type, dummy, size, useful = 0, invalid = 0;
	int data;

	fprintf(stderr,
		"usage: %s ID\nID : audio stream (0, 1, 2...)\nstdin : VOB stream\nstdout : extracted audio\n",
		argv[0]);
	
        if (argc != 2)
	{
		exit (1);
	}

	id = atoi(argv[1]) + 0xc0;

	/* read the stream - 2048 bytes each time */
	data = read(0, &c, 4);

	while (data)
	{
		if ((c[0] != 0x00) || (c[1] != 0x00) ||
			(c[2] != 0x01))
		{
			invalid++;
			c[0] = c[1];
			c[1] = c[2];
			c[2] = c[3];
			data = read(0, &(c[3]), 1);
			continue;
		}

		if( invalid )
		{
			if( useful )
			{
				fprintf(stderr, "wrote %i valid bytes\n", useful);
				useful = 0;
			}

			fprintf(stderr, "skipped %i invalid bytes\n", invalid);
			invalid = 0;
		}
		//fprintf(stderr, "OK %.2x\n", c[3]);

		/* Skip 00 00 01 BA */
		if( c[3] == 0xba )
		{
			read(0, &c, 10);
		}
		else
		{
			dummy = c[3];

			read( 0, &c, 2 );
			size = ((c[0] << 8) | c[1]);
				
			read(0, &c, size);
			if( dummy == id )
			{
				//fprintf(stderr, "size %.4x\n", size);
				dummy = 10;
				write(1, &(c[dummy]), size-dummy);
				useful += size - dummy;
			}
		}
		data = read(0, &c, 4);
	}
	fprintf(stderr, "wrote %i valid bytes\n", useful);
}