<?php
    /* 
     * WavForge PHP WAV Generation Class
     * Version 0.2 Beta
     * Created by sk89q
     * http://www.therisenrealm.com
     *
     * Copyright (c) 2004, sk89q
     * All rights reserved.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions are
     * met:
     *
     * Redistributions of source code must retain the above copyright notice,
     * this list of conditions and the following disclaimer.
     * 
     * Redistributions in binary form must reproduce the above copyright
     * notice, this list of conditions and the following disclaimer in the
     * documentation and/or other materials provided with the distribution.
     * 
     * Neither the name of sk89q nor the names of its contributors may be
     * used to endorse or promote products derived from this software
     * without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    */

    class WavForge
    {
        // Public
        var $channels = 2;
        var $sample_rate = 44100;
        var $bits_per_sample = 16;
        
        // Private
        var $samples = 0;
        var $output;
        
        function output_wav()
        {
            return $this->output_header() . $this->output;
        }
        
        function write_wav( $filename, $mode = 'w' )
        {
            if( $fp = fopen( $filename, $mode ) )
            {
                fwrite( $fp, $this->output_header() . $this->output );
                fclose( $fp );
                return true;
            }
            else
            {
                return false;
            }
        }
        
        function output_header()
        {
            $subchunk_2_size = $this->samples * $this->channels * $this->bits_per_sample / 8;
            
            $header .= pack( 'N*', 0x52494646 ); // ChunkID [0,4] RIFF
            $header .= pack( 'V*', $subchunk_2_size + 36 ); // ChunkSize [0,4]
            $header .= pack( 'N*', 0x57415645 ); // Format [8,4] WAVE
            $header .= pack( 'N*', 0x666d7420 ); // Subchunk1ID [12,4] fmt
            $header .= pack( 'V*', 16 ); // Subchunk1Size [16,4] 16 for PCM
            $header .= pack( 'v*', 1 ); // AudioFormat [20,2] 1 for PCM
            $header .= pack( 'v*', $this->channels ); // NumChannels [22,2] 1 for mono, 2 for stereo
            $header .= pack( 'V*', $this->sample_rate ); // SampleRate [24,4]
            $header .= pack( 'V*', $this->sample_rate * $this->channels * $this->bits_per_sample / 8 ); // ByteRate [28,4] SampleRate * NumChannels * BitsPerSample / 8
            $header .= pack( 'v*', $this->channels * $this->bits_per_sample / 8 ); // BlockAlign [32,2] NumChannels * BitsPerSample / 8
            $header .= pack( 'v*', $this->bits_per_sample ); // BitsPerSample [34,2]
            $header .= pack( 'N*', 0x64617461 ); // Subchunk1ID [36,4] data
            $header .= pack( 'V*', $subchunk_2_size ); // Subchunk2Size [40,4]
            
            return $header;
        }
        
        function synth_sine( $frequency, $volume, $seconds )
        {
            for( $i = 0; $i < $seconds * $this->sample_rate; $i++ )
            {
                for( $c = 0; $c < $this->channels; $c++ )
                {
                    $this->output .= pack( 'v*', (double) ( $volume * sin( 2 * 3.14159265358979 * $i * $frequency / $this->sample_rate ) ) );
                }
                $this->samples++;
            }
        }
    }
?>