using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace Spectrogram.Tests

{

public static class AudioFile

{

/// <summary>

/// Use NAudio to read the contents of a WAV file.

/// </summary>

public static (double[] audio, int sampleRate) ReadWAV(string filePath, double multiplier = 16_000)

{

using var afr = new NAudio.Wave.AudioFileReader(filePath);

int sampleRate = afr.WaveFormat.SampleRate;

int bytesPerSample = afr.WaveFormat.BitsPerSample / 8;

int sampleCount = (int)afr.Length / bytesPerSample;

int channelCount = afr.WaveFormat.Channels;

var audio = new List<double>(sampleCount);

var buffer = new float[sampleRate * channelCount];

int samplesRead = 0;

while ((samplesRead = afr.Read(buffer, 0, buffer.Length)) > 0)

audio.AddRange(buffer.Take(samplesRead).Select(x => x * multiplier));

return (audio.ToArray(), sampleRate);

}

/// <summary>

/// Use MP3Sharp to read the contents of an MP3 file.

/// </summary>

public static double[] ReadMP3(string filePath, int bufferSize = 4096)

{

List<double> audio = new List<double>();

MP3Sharp.MP3Stream stream = new MP3Sharp.MP3Stream(filePath);

byte[] buffer = new byte[bufferSize];

int bytesReturned = 1;

while (bytesReturned > 0)

{

bytesReturned = stream.Read(buffer, 0, bufferSize);

for (int i = 0; i < bytesReturned / 2 - 1; i += 2)

audio.Add(BitConverter.ToInt16(buffer, i * 2));

}

stream.Close();

return audio.ToArray();

}

}

}