/*

 * extract_a52.c

 * Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>

 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>

 *

 * This file is part of a52dec, a free ATSC A-52 stream decoder.

 * See http://liba52.sourceforge.net/ for updates.

 *

 * a52dec 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.

 *

 * a52dec 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

 */

#include "config.h"

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <errno.h>

#include <getopt.h>

#ifdef HAVE_IO_H

#include <fcntl.h>

#include <io.h>

#endif

#include <inttypes.h>

#define BUFFER_SIZE 4096

static uint8_t buffer[BUFFER_SIZE];

static FILE * in_file;

static int demux_track = 0x80;

static int demux_pid = 0;

static void print_usage (char ** argv)

{

    fprintf (stderr, "usage: %s [-s <track>] [-t <pid>] <file>\n"

	     "\t-s\tset track number (0-7 or 0x80-0x87)\n"

	     "\t-t\tuse transport stream demultiplexer, pid 0x10-0x1ffe\n",

	     argv[0]);

    exit (1);

}

static void handle_args (int argc, char ** argv)

{

    int c;

    char * s;

    while ((c = getopt (argc, argv, "s:t:")) != -1)

	switch (c) {

	case 's':

	    demux_track = strtol (optarg, &s, 16);

	    if (demux_track < 0x80)

		demux_track += 0x80;

	    if ((demux_track < 0x80) || (demux_track > 0x87) || (*s)) {

		fprintf (stderr, "Invalid track number: %s\n", optarg);

		print_usage (argv);

	    }

	    break;

	case 't':

	    demux_pid = strtol (optarg, &s, 16);

	    if ((demux_pid < 0x10) || (demux_pid > 0x1ffe) || (*s)) {

		fprintf (stderr, "Invalid pid: %s\n", optarg);

		print_usage (argv);

	    }

	    break;

	default:

	    print_usage (argv);

	}

    if (optind < argc) {

	in_file = fopen (argv[optind], "rb");

	if (!in_file) {

	    fprintf (stderr, "%s - could not open file %s\n", strerror (errno),

		     argv[optind]);

	    exit (1);

	}

    } else

	in_file = stdin;

}

#define DEMUX_PAYLOAD_START 1

static int demux (uint8_t * buf, uint8_t * end, int flags)

{

    static int mpeg1_skip_table[16] = {

	0, 0, 4, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

    };

    /*

     * the demuxer keeps some state between calls:

     * if "state" = DEMUX_HEADER, then "head_buf" contains the first

     *     "bytes" bytes from some header.

     * if "state" == DEMUX_DATA, then we need to copy "bytes" bytes

     *     of ES data before the next header.

     * if "state" == DEMUX_SKIP, then we need to skip "bytes" bytes

     *     of data before the next header.

     *

     * NEEDBYTES makes sure we have the requested number of bytes for a

     * header. If we dont, it copies what we have into head_buf and returns,

     * so that when we come back with more data we finish decoding this header.

     *

     * DONEBYTES updates "buf" to point after the header we just parsed.

     */

#define DEMUX_HEADER 0

#define DEMUX_DATA 1

#define DEMUX_SKIP 2

    static int state = DEMUX_SKIP;

    static int state_bytes = 0;

    static uint8_t head_buf[268];

    uint8_t * header;

    int bytes;

    int len;

#define NEEDBYTES(x)						\

    do {							\

	int missing;						\

								\

	missing = (x) - bytes;					\

	if (missing > 0) {					\

	    if (header == head_buf) {				\

		if (missing <= end - buf) {			\

		    memcpy (header + bytes, buf, missing);	\

		    buf += missing;				\

		    bytes = (x);				\

		} else {					\

		    memcpy (header + bytes, buf, end - buf);	\

		    state_bytes = bytes + end - buf;		\

		    return 0;					\

		}						\

	    } else {						\

		memcpy (head_buf, header, bytes);		\

		state = DEMUX_HEADER;				\

		state_bytes = bytes;				\

		return 0;					\

	    }							\

	}							\

    } while (0)

#define DONEBYTES(x)		\

    do {			\

	if (header != head_buf)	\

	    buf = header + (x);	\

    } while (0)

    if (flags & DEMUX_PAYLOAD_START)

	goto payload_start;

    switch (state) {

    case DEMUX_HEADER:

	if (state_bytes > 0) {

	    header = head_buf;

	    bytes = state_bytes;

	    goto continue_header;

	}

	break;

    case DEMUX_DATA:

	if (demux_pid || (state_bytes > end - buf)) {

	    fwrite (buf, end - buf, 1, stdout);

	    state_bytes -= end - buf;

	    return 0;

	}

	fwrite (buf, state_bytes, 1, stdout);

	buf += state_bytes;

	break;

    case DEMUX_SKIP:

	if (demux_pid || (state_bytes > end - buf)) {

	    state_bytes -= end - buf;

	    return 0;

	}

	buf += state_bytes;

	break;

    }

    while (1) {

	if (demux_pid) {

	    state = DEMUX_SKIP;

	    return 0;

	}

    payload_start:

	header = buf;

	bytes = end - buf;

    continue_header:

	NEEDBYTES (4);

	if (header[0] || header[1] || (header[2] != 1)) {

	    if (demux_pid) {

		state = DEMUX_SKIP;

		return 0;

	    } else if (header != head_buf) {

		buf++;

		goto payload_start;

	    } else {

		header[0] = header[1];

		header[1] = header[2];

		header[2] = header[3];

		bytes = 3;

		goto continue_header;

	    }

	}

	if (demux_pid && (header[3] != 0xbd)) {

	    fprintf (stderr, "bad stream id %x\n", header[3]);

	    exit (1);

	}

	switch (header[3]) {

	case 0xb9:	/* program end code */

	    /* DONEBYTES (4); */

	    /* break;         */

	    return 1;

	case 0xba:	/* pack header */

	    NEEDBYTES (12);

	    if ((header[4] & 0xc0) == 0x40) {	/* mpeg2 */

		NEEDBYTES (14);

		len = 14 + (header[13] & 7);

		NEEDBYTES (len);

		DONEBYTES (len);

		/* header points to the mpeg2 pack header */

	    } else if ((header[4] & 0xf0) == 0x20) {	/* mpeg1 */

		DONEBYTES (12);

		/* header points to the mpeg1 pack header */

	    } else {

		fprintf (stderr, "weird pack header\n");

		exit (1);

	    }

	    break;

	case 0xbd:	/* private stream 1 */

	    NEEDBYTES (7);

	    if ((header[6] & 0xc0) == 0x80) {	/* mpeg2 */

		NEEDBYTES (9);

		len = 10 + header[8];

		NEEDBYTES (len);

		/* header points to the mpeg2 pes header */

	    } else {	/* mpeg1 */

		len = 7;

		while ((header-1)[len] == 0xff) {

		    len++;

		    NEEDBYTES (len);

		    if (len == 23) {

			fprintf (stderr, "too much stuffing\n");

			break;

		    }

		}

		if (((header-1)[len] & 0xc0) == 0x40) {

		    len += 2;

		    NEEDBYTES (len);

		}

		len += mpeg1_skip_table[(header - 1)[len] >> 4] + 1;

		NEEDBYTES (len);

		/* header points to the mpeg1 pes header */

	    }

	    if ((!demux_pid) && ((header-1)[len] != demux_track)) {

		DONEBYTES (len);

		bytes = 6 + (header[4] << 8) + header[5] - len;

		if (bytes <= 0)

		    continue;

		goto skip;

	    }

	    len += 3;

	    NEEDBYTES (len);

	    DONEBYTES (len);

	    bytes = 6 + (header[4] << 8) + header[5] - len;

	    if (demux_pid || (bytes > end - buf)) {

		fwrite (buf, end - buf, 1, stdout);

		state = DEMUX_DATA;

		state_bytes = bytes - (end - buf);

		return 0;

	    } else if (bytes <= 0)

		continue;

	    fwrite (buf, bytes, 1, stdout);

	    buf += bytes;

	    break;

	default:

	    if (header[3] < 0xb9) {

		fprintf (stderr,

			 "looks like a video stream, not system stream\n");

		exit (1);

	    } else {

		NEEDBYTES (6);

		DONEBYTES (6);

		bytes = (header[4] << 8) + header[5];

	    skip:

		if (bytes > end - buf) {

		    state = DEMUX_SKIP;

		    state_bytes = bytes - (end - buf);

		    return 0;

		}

		buf += bytes;

	    }

	}

    }

}

static void ps_loop (void)

{

    uint8_t * end;

    do {

	end = buffer + fread (buffer, 1, BUFFER_SIZE, in_file);

	if (demux (buffer, end, 0))

	    break;	/* hit program_end_code */

    } while (end == buffer + BUFFER_SIZE);

}

static void ts_loop (void)

{

#define PACKETS (BUFFER_SIZE / 188)

    uint8_t * buf;

    uint8_t * data;

    uint8_t * end;

    int packets;

    int i;

    int pid;

    do {

	packets = fread (buffer, 188, PACKETS, in_file);

	for (i = 0; i < packets; i++) {

	    buf = buffer + i * 188;

	    end = buf + 188;

	    if (buf[0] != 0x47) {

		fprintf (stderr, "bad sync byte\n");

		exit (1);

	    }

	    pid = ((buf[1] << 8) + buf[2]) & 0x1fff;

	    if (pid != demux_pid)

		continue;

	    data = buf + 4;

	    if (buf[3] & 0x20) {	/* buf contains an adaptation field */

		data = buf + 5 + buf[4];

		if (data > end)

		    continue;

	    }

	    if (buf[3] & 0x10)

		demux (data, end, (buf[1] & 0x40) ? DEMUX_PAYLOAD_START : 0);

	}

    } while (packets == PACKETS);

}

int main (int argc, char ** argv)

{

#ifdef HAVE_IO_H

    setmode (fileno (stdout), O_BINARY);

#endif

    handle_args (argc, argv);

    if (demux_pid)

	ts_loop ();

    else

	ps_loop ();

    return 0;

}