１音階ずつ２秒ごとに録った音をUnity上で切り分けるやつと、WAVファイル出力用のやつ

NoteTrim.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;

public class NoteTrim : ScriptableWizard {
    public AudioClip clip;
    public float duration = 2.0f;
    public string path = "Assets/MOTI/MusicForest/";
    public string[] notes = {
        "C1",
        "C#1",
        "D1",
        "D#1",
        "E1",
        "F1",
        "F#1",
        "G1",
        "G#1",
        "A1",
        "A#1",
        "B1",

        "C2",
        "C#2",
        "D2",
        "D#2",
        "E2",
        "F2",
        "F#2",
        "G2",
        "G#2",
        "A2",
        "A#2",
        "B2",

        "C3",
        "C#3",
        "D3",
        "D#3",
        "E3",
        "F3",
        "F#3",
        "G3",
        "G#3",
        "A3",
        "A#3",
        "B3",
        "C4",
    };

    [MenuItem("MOTI/NoteTrim")]
    static void Open() {
        DisplayWizard<NoteTrim>("NoteTrim");
    }

    void OnWizardCreate() {
        var samplingRate = clip.frequency;
        var buffer = new float[(int)(duration * samplingRate)];
        for (int noteIndex = 0; noteIndex < notes.Length; noteIndex++) {
            clip.GetData(buffer, noteIndex * buffer.Length);
            var writer = new WAVWriter(path + clip.name + " " + notes[noteIndex] + ".wav",
                1,
                samplingRate);
            writer.Write(buffer);
            writer.Close();
        }
    }
}

WAVWriter.cs

using System;
using System.IO;

public class WAVWriter {
    int numChannels;
    int samplingRate;
    int dataSize;
    BinaryWriter writer;
    const UInt16 WAVE_FORMAT_EXTENSIBLE = 0xFFFE;
    const int headerSize = 4    // "WAVE"
                            + 4    // "fmt "
                            + 40   // WAVEFORMATEXTENSIBLE
                            + 4    // "data"
                            + 4    // size of data chunk
                            ;

    public WAVWriter(string path, int numChannels, int samplingRate) {
        this.numChannels = numChannels;
        this.samplingRate = samplingRate;
        writer = new BinaryWriter(new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.Write), System.Text.Encoding.ASCII);

        WriteHeader();
    }

    enum ChannelMask : UInt32 {
        SPEAKER_FRONT_LEFT = 0x1,
        SPEAKER_FRONT_RIGHT = 0x2,
        SPEAKER_FRONT_CENTER = 0x4,
        SPEAKER_LOW_FREQUENCY = 0x8,
        SPEAKER_BACK_LEFT = 0x10,
        SPEAKER_BACK_RIGHT = 0x20,
        SPEAKER_FRONT_LEFT_OF_CENTER = 0x40,
        SPEAKER_FRONT_RIGHT_OF_CENTER = 0x80,
        SPEAKER_BACK_CENTER = 0x100,
        SPEAKER_SIDE_LEFT = 0x200,
        SPEAKER_SIDE_RIGHT = 0x400,
        SPEAKER_TOP_CENTER = 0x800,
        SPEAKER_TOP_FRONT_LEFT = 0x1000,
        SPEAKER_TOP_FRONT_CENTER = 0x2000,
        SPEAKER_TOP_FRONT_RIGHT = 0x4000,
        SPEAKER_TOP_BACK_LEFT = 0x8000,
        SPEAKER_TOP_BACK_CENTER = 0x10000,
        SPEAKER_TOP_BACK_RIGHT = 0x20000,
    }

    void WriteHeader() {
        writer.Write(System.Text.Encoding.UTF8.GetBytes("RIFF"));
        writer.Write((UInt32)headerSize);   // あとでdataSizeを足して書き込む
        writer.Write(System.Text.Encoding.UTF8.GetBytes("WAVE"));
        writer.Write(System.Text.Encoding.UTF8.GetBytes("fmt "));
        writer.Write((UInt32)40);
        writer.Write(WAVE_FORMAT_EXTENSIBLE);
        writer.Write((UInt16)numChannels);
        writer.Write((UInt32)samplingRate);
        writer.Write((UInt32)(sizeof(float) * numChannels * samplingRate));
        writer.Write((UInt16)sizeof(float));
        writer.Write((UInt16)(sizeof(float) * 8));
        writer.Write((UInt16)22);
        writer.Write((UInt16)(sizeof(float) * 8));

        ChannelMask channelMask = 0;
        switch (numChannels) {
            case 1:
                channelMask = ChannelMask.SPEAKER_FRONT_CENTER;
                break;
            case 2:
                channelMask = ChannelMask.SPEAKER_FRONT_LEFT | ChannelMask.SPEAKER_FRONT_RIGHT;
                break;
        }

        writer.Write((UInt32)channelMask);

        // KSDATAFORMAT_SUBTYPE_IEEE_FLOAT
        writer.Write((UInt32)0x00000003);
        writer.Write((UInt16)0x0000);
        writer.Write((UInt16)0x0010);
        writer.Write(new byte[] {0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71});

        writer.Write(System.Text.Encoding.UTF8.GetBytes("data"));
        writer.Write((UInt32)0);
    }

    public void Write(float[] data) {
        dataSize += data.Length * sizeof(float);

        writer.Seek(4, SeekOrigin.Begin);
        writer.Write((UInt32)(headerSize + dataSize));

        writer.Seek(64, SeekOrigin.Begin);
        writer.Write((UInt32)dataSize);

        writer.Seek(0, SeekOrigin.End);
        foreach (var sample in data) {
            writer.Write(sample);
        }
    }

    public void Close() {
        writer.Close();
    }
}