source: other-projects/fft-ddr/summer-2014/trunk/FFDDR/WavProcessor.cs@ 29750

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections;
//using NAudio.Wave;
using Exocortex.DSP;
using Newtonsoft.Json;
using System.IO;
using System.Diagnostics;

using NAudio.Wave;

namespace FFDDR
{
    static class WavProcessor
    {

        public static string[] ReadWav(string location, string wavName, int bufferSize, int numBands)
        {
            List<float[]> bandPowerList = new List<float[]>();
            TimeSpan songLength;
            
            using (WaveFileReader reader = new WaveFileReader(location + wavName + ".wav"))
            {
                songLength = reader.TotalTime;
                // Read the wav file, and save in array in segments of buffersize
                float[] buffer = new float[bufferSize];
                List<float[]> samples = new List<float[]>();
                
                while((buffer = reader.ReadNextSampleFrame()) != null){
                    samples.Add(buffer);
                }


                // Convert wav file to mono if it's stereo
                List<ComplexF> monoSamples = new List<ComplexF>();

                for (int p = 0; p < samples.Count; p++)
                {
                    ComplexF temp = new ComplexF();

                    for (int j = 0; j < reader.WaveFormat.Channels; j++)
                    {
                        temp.Re += samples[(int)p][j];

                    }
                    temp.Re = (temp.Re / (float)(reader.WaveFormat.Channels));

                    temp.Im = 0;
                    monoSamples.Add(temp);

                }

                // Construct hanning window 







                ComplexF[] monoArray = monoSamples.ToArray();
                ComplexF[] completeFFT = new ComplexF[monoArray.Length];

                int segments = samples.Count / bufferSize;

                // For each buffer
                for (int p = 0; p < segments; p++)
                {

                    //Perform fft on one buffer 
                    ComplexF[] temp = new ComplexF[bufferSize];
                    for (int j = 0; j < temp.Length; j++)
                    {
                        temp[j] = monoArray[p * bufferSize + j];
                    }
                    Fourier.FFT(temp, FourierDirection.Forward);

                    // Copy completed FFT into the final array. This isn't actually used, but it potentially could be, so I've left it in.
                    for (int j = 0; j < temp.Length; j++)
                    {
                        completeFFT[p * bufferSize + j] = temp[j];

                    }


                    //////////////////////// Create bands and calculate their power \\\\\\\\\\\\\\\\\\\\
                    // Devisor used to only get values we're interested in.
                    // default 2 (as last half of fft is a mirror). Try 4 to ignore higher frequencies. Must be power of 2 
                    int freqDevisor = 4;

                    ComplexF[] tempFinished = new ComplexF[temp.Length/freqDevisor];

                    
                    for (int j = 0; j < (temp.Length / freqDevisor); j++)
                    {
                        tempFinished[j] = temp[j];
                    }

                    int samplesPerBand = (int)Math.Floor(((float)tempFinished.Length) / (float)numBands);
                    float[] powers = new float[numBands];

                    //////////////////////// Calculate average power(intensity) for each band \\\\\\\\\\\\\\\\
                    // Note that there is a sqrt funciton performed...might be better to leave out
                    for (int d = 0; d < numBands; d++)
                    {
                        float bandAvg = 0;
                        for (int b = 0; b < samplesPerBand; b++)
                        {
                            float tempIntensity = (float)(Math.Pow((Math.Pow(tempFinished[d * samplesPerBand + b].Re, 2) + Math.Pow(tempFinished[d * samplesPerBand + b].Im, 2)),0.5));
                            bandAvg += tempIntensity;
                        }
                        bandAvg = bandAvg / samplesPerBand;
                        powers[d] = bandAvg;
                    }
                    bandPowerList.Add(powers);
                }


            }

            bool[] globalBeat = CalculateBeats(bandPowerList, songLength);

            // Convert to JSON
            string[] bandPowerJson = new string[bandPowerList.Count];
            for (int i = 0; i < bandPowerList.Count; i++)
            {
                bandPowerJson[i] = JsonConvert.SerializeObject(new WavFrame(songLength.TotalMilliseconds, bufferSize,bandPowerList[i], globalBeat[i]),Formatting.Indented); 
            }

            // Save band values into file
            File.WriteAllLines(@"C:\Users\Chris\Downloads\json.txt", bandPowerJson);

            
            // Caclulate beats

            
            return bandPowerJson;     
        }



        public static bool[] CalculateBeats(List<float[]> bands, TimeSpan songLength)
        {
            int longTermAverageSamples = 100;    

            float longAverage = 0;
            

            
            List<List<float>> bandHistoryList = new List<List<float>>();
            List<float[]> deltaHistory = new List<float[]>();
            float[] longAverageArray = new float[bands[0].Length];
            float[] beatList = new float[bands[0].Length];
            bool[] globalBeat = new bool[bands.Count];

            for (int i = 0; i < bands.Count; i++)
            {
                
                bandHistoryList.Add(new List<float>());
                int numBeats = 0;

                for (int j = 0; j < bands[0].Length; j++)
                {
                    // Populate the history with the next deltArray
                    bandHistoryList[i].Add(bands[i][j]);
                    longAverage = 0;
                    int tempValue = 0;

                    // Calculate average intensity over long term
                    for (int m = 0; (m < longTermAverageSamples) && (m < bandHistoryList[i].Count); m++)
                    {
                        longAverage += bandHistoryList[i][m];
                        tempValue = m;
                    }
                    longAverage = longAverage / (tempValue + 1);
                    if (bands[i][j] > (longAverage * 1.1f))
                    {
                        beatList[j] = 1;
                        numBeats++;
                    }
                    else
                    {
                        beatList[j] = 0;
                    }


                }

                if(numBeats > 0){
                    globalBeat[i] = true;

                }
                else
                {
                    globalBeat[i] = false;
                }
                
            }
            return globalBeat;
        }
        
    }
}