/*
** mpganaly.c - Program to analyse MPEG audio files
**
** File created:  6/16/2000
** Last revision: 8/10/2000
**
** Copyright (C) 2000	Sean R. Wells <swells@gmu.edu>
**
** 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
**
*/

#include <stdio.h>
#include "mp3_data.h"

#define DEBUG_LONG

int FindBitrate ( int version, int layer, int value );
int FindSamplingRate ( float version, int value );
int FindFrameSize ( mpeg_info header );
int ReadHeader ( unsigned int frame_value, mpeg_info *header );

int ReadMPEG ( register FILE *infile )
{
  unsigned int frame_value;
  int i;
  mpeg_info header;
  float check_ver;
  int check_lay;
  int check_bit;
  int ch = 0;
  int byte_count = 0;

  InitializeStruct ( &header );

  while ( ch != EOF ) {
    frame_value = 0;
    /* Find frame sync */

    for ( ch = getc ( infile ), byte_count++, frame_value =
	 ( frame_value << 8 ) +	ch;
        ( ( ch != EOF ) && ( ( ( frame_value >> 21 ) & 0x07ff ) != 0x07ff ) );
        ch = getc ( infile ), frame_value = ( frame_value << 8 ) + ch ,
        byte_count++ );
    if ( ch == EOF ) {
      return ( 0 );
    }

    ReadHeader ( frame_value, &header );

    if ( byte_count < 8 ) {
      check_ver = header.MPEG_ver;
      check_lay = header.MPEG_lay;
      check_bit = header.MPEG_bitrate;
  printf ( "Version = %1.1f	Layer = %d	Bitrate = %d\n",
            check_ver, check_lay, check_bit );
    }

    /* Check for a valid header (these values /shouldn't/ change) */
    if ( ( header.MPEG_ver == check_ver ) &&
         ( header.MPEG_lay == check_lay ) &&
         ( header.MPEG_bitrate == check_bit ) ) {
#ifdef DEBUG_LONG
  printf ( "MPEG Version = %1.1f\n", header.MPEG_ver );
  printf ( "MPEG Layer = %d\n", header.MPEG_lay );
  printf ( "MPEG Protection = %s\n", header.MPEG_prot );
  printf ( "MPEG Bitrate = %d bps\n", header.MPEG_bitrate );
  printf ( "MPEG Sampling rate = %d Hz\n", header.MPEG_samp_rate );
  printf ( "MPEG Padding bit = %d\n", header.MPEG_pad_bit );
  printf ( "MPEG Channel mode = %s\n", header.MPEG_chan_mode );
  printf ( "MPEG Mode extension = %d\n", header.MPEG_mode_ext );
  printf ( "MPEG Copyright = %s\n", header.MPEG_copyright );
  printf ( "MPEG Copy = %s\n", header.MPEG_copy );
  printf ( "MPEG Emphasis = %d\n", header.MPEG_emphasis );
  printf ( "MPEG Frame size = %d\n\n", header.MPEG_frame_size );
  printf ( "MPEG Frame count = %d\n", header.MPEG_frame_count );
  printf ( "MPEG Byte count = %d\n\n", byte_count );
#endif
      for ( i = 0; i < header.MPEG_frame_size - ( 4 + header.MPEG_pad_bit);
	    i++	) {
        ch = getc ( infile );
        byte_count++;
        if ( ch == EOF ) {
	  return ( 0 );
        }
      }

      header.MPEG_frame_count++;
    }
  }

  printf ( "MPEG Version = %1.1f\n", header.MPEG_ver );
  printf ( "MPEG Layer = %d\n", header.MPEG_lay );
  printf ( "MPEG Protection = %s\n", header.MPEG_prot );
  printf ( "MPEG Bitrate = %d bps\n", header.MPEG_bitrate );
  printf ( "MPEG Sampling rate = %d Hz\n", header.MPEG_samp_rate );
  printf ( "MPEG Padding bit = %d\n", header.MPEG_pad_bit );
  printf ( "MPEG Channel mode = %s\n", header.MPEG_chan_mode );
  printf ( "MPEG Mode extension = %d\n", header.MPEG_mode_ext );
  printf ( "MPEG Copyright = %s\n", header.MPEG_copyright );
  printf ( "MPEG Copy = %s\n", header.MPEG_copy );
  printf ( "MPEG Emphasis = %d\n", header.MPEG_emphasis );
  printf ( "MPEG Frame size = %d\n\n", header.MPEG_frame_size );
  printf ( "MPEG Frame count = %d\n\n", header.MPEG_frame_count );

  return ( 0 );
}

int main ( argc, argv )
	   int argc;
	   char	**argv;
{
  register FILE *infile;

  if ( argc < 2 ) {
    fprintf ( stderr, "mpganaly version 1.0b Copyright (C) 2000 Sean R. Wells");
    fprintf ( stderr, "\nUsage: mpganaly <filename>\n" );
    return ( 0 );
  }

  infile = fopen ( argv[1], "rb" );
  if ( !infile ) {
    fprintf ( stderr, "ERROR - Could not open input file.\n" );
    return ( 0 );
  }

  ReadMPEG ( infile );
  fclose ( infile );

  return ( 0 );
}