context: /* (c) 2004 James Robson, http://www.arbingersys.com
  **
  ** 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.
  **
  ** ****************************
  **
  ** How to use:
  **    - libsndfile.dll must have already been compiled and be in this
  **      application's search path
  **
  **    - You must edit this file to point to the file you want to convert. Set
  **    	the following line of code (found in the Main() function further below)
  **    	to the name of a .WAV file that exists on your system.
  **		186:	string sfn = "input.wav";
  **
  **    - From a command prompt type
  **    		csc generate.cs
  **
  **    - Run the resulting executable 'generate.exe'
  **
  **
  ** Note: You will obviously need the csc compiler and the .NET runtime. I think
  ** 	 these are freely available for download from Microsoft's website
  ** 	 (part of the .NET SDK?).
  */
  
  
  using System;
  using System.Runtime.InteropServices;
  using sf_count_t = System.Int64;	//alias; see SF_INFO struct
  
  #if PLATFORM_64
  using size_t = System.UInt64;
  #else
  using size_t = System.UInt32;
  #endif
  
  
  class lsndf_example {
  
  
  //sound file formats
  	public enum lsndf_frmts {
  		SF_FORMAT_WAV			= 0x010000,		/* Microsoft WAV format (little endian). */
  		SF_FORMAT_AIFF			= 0x020000,		/* Apple/SGI AIFF format (big endian). */
  		SF_FORMAT_AU			= 0x030000,		/* Sun/NeXT AU format (big endian). */
  		SF_FORMAT_RAW			= 0x040000,		/* RAW PCM data. */
  		SF_FORMAT_PAF			= 0x050000,		/* Ensoniq PARIS file format. */
  		SF_FORMAT_SVX			= 0x060000,		/* Amiga IFF / SVX8 / SV16 format. */
  		SF_FORMAT_NIST			= 0x070000,		/* Sphere NIST format. */
  		SF_FORMAT_VOC			= 0x080000,		/* VOC files. */
  		SF_FORMAT_IRCAM			= 0x0A0000,		/* Berkeley/IRCAM/CARL */
  		SF_FORMAT_W64			= 0x0B0000,		/* Sonic Foundry's 64 bit RIFF/WAV */
  		SF_FORMAT_MAT4			= 0x0C0000,		/* Matlab (tm) V4.2 / GNU Octave 2.0 */
  		SF_FORMAT_MAT5			= 0x0D0000,		/* Matlab (tm) V5.0 / GNU Octave 2.1 */
  		SF_FORMAT_PVF			= 0x0E0000,		/* Portable Voice Format */
  		SF_FORMAT_XI			= 0x0F0000,		/* Fasttracker 2 Extended Instrument */
  		SF_FORMAT_HTK			= 0x100000,		/* HMM Tool Kit format */
  		SF_FORMAT_SDS			= 0x110000,		/* Midi Sample Dump Standard */
  
  		/* Subtypes from here on. */
  
  		SF_FORMAT_PCM_S8		= 0x0001,		/* Signed 8 bit data */
  		SF_FORMAT_PCM_16		= 0x0002,		/* Signed 16 bit data */
  		SF_FORMAT_PCM_24		= 0x0003,		/* Signed 24 bit data */
  		SF_FORMAT_PCM_32		= 0x0004,		/* Signed 32 bit data */
  
  		SF_FORMAT_PCM_U8		= 0x0005,		/* Unsigned 8 bit data (WAV and RAW only) */
  
  		SF_FORMAT_FLOAT			= 0x0006,		/* 32 bit float data */
  		SF_FORMAT_DOUBLE		= 0x0007,		/* 64 bit float data */
  
  		SF_FORMAT_ULAW			= 0x0010,		/* U-Law encoded. */
  		SF_FORMAT_ALAW			= 0x0011,		/* A-Law encoded. */
  		SF_FORMAT_IMA_ADPCM		= 0x0012,		/* IMA ADPCM. */
  		SF_FORMAT_MS_ADPCM		= 0x0013,		/* Microsoft ADPCM. */
  
  		SF_FORMAT_GSM610		= 0x0020,		/* GSM 6.10 encoding. */
  		SF_FORMAT_VOX_ADPCM		= 0x0021,		/* OKI / Dialogix ADPCM */
  
  		SF_FORMAT_G721_32		= 0x0030,		/* 32kbs G721 ADPCM encoding. */
  		SF_FORMAT_G723_24		= 0x0031,		/* 24kbs G723 ADPCM encoding. */
  		SF_FORMAT_G723_40		= 0x0032,		/* 40kbs G723 ADPCM encoding. */
  
  		SF_FORMAT_DWVW_12		= 0x0040, 		/* 12 bit Delta Width Variable Word encoding. */
  		SF_FORMAT_DWVW_16		= 0x0041, 		/* 16 bit Delta Width Variable Word encoding. */
  		SF_FORMAT_DWVW_24		= 0x0042, 		/* 24 bit Delta Width Variable Word encoding. */
  		SF_FORMAT_DWVW_N		= 0x0043, 		/* N bit Delta Width Variable Word encoding. */
  
  		SF_FORMAT_DPCM_8		= 0x0050,		/* 8 bit differential PCM (XI only) */
  		SF_FORMAT_DPCM_16		= 0x0051,		/* 16 bit differential PCM (XI only) */
  
  
  		/* Endian-ness options. */
  
  		SF_ENDIAN_FILE			= 0x00000000,	/* Default file endian-ness. */
  		SF_ENDIAN_LITTLE		= 0x10000000,	/* Force little endian-ness. */
  		SF_ENDIAN_BIG			= 0x20000000,	/* Force big endian-ness. */
  		SF_ENDIAN_CPU			= 0x30000000,	/* Force CPU endian-ness. */
  
  		SF_FORMAT_SUBMASK		= 0x0000FFFF,
  		SF_FORMAT_TYPEMASK		= 0x0FFF0000,
  		SF_FORMAT_ENDMASK		= 0x30000000
  	}
  
  
  //modes and other
  	public enum lsndf_tf
  	{	/* True and false */
  		SF_FALSE	= 0,
  		SF_TRUE		= 1,
  
  		/* Modes for opening files. */
  		SFM_READ	= 0x10,
  		SFM_WRITE	= 0x20,
  		SFM_RDWR	= 0x30
  	}
  
  
  //important SF_INFO structure
  	[StructLayout(LayoutKind.Sequential)]
  	public struct SF_INFO
  	{
  		public sf_count_t	frames ;		// Used to be called samples.  Changed to avoid confusion.
  		public int			samplerate ;
  		public int			channels ;
  		public int			format ;
  		public int			sections ;
  		public int			seekable ;
  	};
  
  
  //function declarations
  //Note: Not all functions have been prototyped here. Only the ones necessary to
  //	make this application work. The below code should give some clues as to
  //	how to add the rest since they have a lot of parameter and return type
  //	similarities.
  	[DllImport("libsndfile.dll")]
  	public static extern IntPtr sf_open ([MarshalAs(UnmanagedType.LPStr)] string path, int mode, ref SF_INFO sfinfo);
  
  	[DllImport("libsndfile.dll")]
  	static extern int sf_error (IntPtr sndfile);
  
  	[DllImport("libsndfile.dll")]
  	static extern IntPtr sf_strerror (IntPtr sndfile);
  
  	[DllImport("libsndfile.dll")]
  	static extern int sf_format_check (ref SF_INFO info);
  
  	[DllImport("libsndfile.dll")]
  	static extern sf_count_t sf_read_float	(IntPtr sndfile, float[] ptr, sf_count_t items);
  
  	[DllImport("libsndfile.dll")]
  	static extern sf_count_t sf_write_float	(IntPtr sndfile, float[] ptr, sf_count_t items);
  
  	[DllImport("libsndfile.dll")]
      static extern int sf_close (IntPtr sndfile);
  
  
  	public const sf_count_t BUFFER_LEN = 4096;
  
  
  //program entry
  	static void Main(  ) {
  
  
  //declarations
  		SF_INFO sfinfo = new SF_INFO();
  		float[] buffer = new float[BUFFER_LEN];
  		sf_count_t rcnt;
  
  //set the input file
  		string sfn = "input.wav";	//set to a file on YOUR system
  		//string sfn = "noexist.wav"; 	//test with non-existent file
  
  //set the output file
  		string ofn = "output.wav";
  
  //read in sound file to convert
  		IntPtr infile = sf_open (sfn, (int)lsndf_tf.SFM_READ, ref sfinfo);
  
  //exit if error was thrown
  		if ( (int)infile == 0 ) {
  			Console.WriteLine("Error opening " + sfn);
  			Console.WriteLine("Error #" + sf_error(infile));
  			return;
  		}
  
  //set the file type for the output file
  //uncomment one and only one of the statements below to change the output
  //file encoding.
  		//sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_WAV | lsndf_frmts.SF_FORMAT_PCM_U8);
  		//sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_WAV | lsndf_frmts.SF_FORMAT_PCM_16);
  		//sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_WAV | lsndf_frmts.SF_FORMAT_MS_ADPCM);
  		sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_WAV | lsndf_frmts.SF_FORMAT_IMA_ADPCM);
  		//sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_WAV | lsndf_frmts.SF_FORMAT_GSM610);
  		/* Soundforge W64. */
  		//sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_W64 | lsndf_frmts.SF_FORMAT_PCM_U8);
  		//sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_W64 | lsndf_frmts.SF_FORMAT_PCM_16);
  		//sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_W64 | lsndf_frmts.SF_FORMAT_MS_ADPCM);
  		//sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_W64 | lsndf_frmts.SF_FORMAT_IMA_ADPCM);
  		//sfinfo.format = (int)(lsndf_frmts.SF_FORMAT_W64 | lsndf_frmts.SF_FORMAT_GSM610);
  
  
  //check that SF_INFO is valid
  		if ( sf_format_check(ref sfinfo) == 0 ) {
  			Console.WriteLine("sf_format_check failed. Invalid encoding");
  			return;
  		}
  
  //open output file
  		IntPtr outfile = sf_open (ofn, (int)lsndf_tf.SFM_WRITE, ref sfinfo);
  
  //exit if error was thrown
  		if ( (int)outfile == 0 ) {
  			Console.WriteLine("Error opening " + ofn);
  			Console.WriteLine("Error #" + sf_error(outfile));
  			return;
  		}
  
  //infile -> outfile
  		Console.Write(sfn + " -> " + ofn);
  		while ( (rcnt = sf_read_float (infile, buffer, BUFFER_LEN)) > 0) {
  			Console.Write(".");
  
gt: 			sf_write_float (outfile, buffer, BUFFER_LEN);