FireDrillSystem_GuiGang_WYSYGL/Assets/FFmpeg/FFmpegDemo/FFmpegRECHelpers/RecAudio/RecAudio.cs

using System;
using System.IO;
using System.Collections.Generic;
using UnityEngine;

public enum RecAudioSource
{
    Mic,
    System,
    None
}

public interface IRecAudio 
{
    void StartRecording();
    void StopRecording(string savePath);
}

public static class SavWav
{
    const int HEADER_SIZE = 44;

    public static void Save(string path, AudioClip clip)
    {
        // Make sure directory exists if user is saving to sub dir.
        Directory.CreateDirectory(Path.GetDirectoryName(path));

        using (var fileStream = CreateEmpty(path))
        {
            ConvertAndWrite(fileStream, clip);

            WriteHeader(fileStream, clip);
        }
    }

    public static AudioClip TrimSilence(AudioClip clip, float min)
    {
        var samples = new float[clip.samples];

        clip.GetData(samples, 0);

        return TrimSilence(new List<float>(samples), min, clip.channels, clip.frequency);
    }

    public static AudioClip TrimSilence(List<float> samples, float min, int channels, int hz)
    {
        int i;

        for (i = 0; i < samples.Count; i++)
        {
            if (Mathf.Abs(samples[i]) > min)
            {
                break;
            }
        }

        samples.RemoveRange(0, i);

        for (i = samples.Count - 1; i > 0; i--)
        {
            if (Mathf.Abs(samples[i]) > min)
            {
                break;
            }
        }

        samples.RemoveRange(i, samples.Count - i);

        var clip = AudioClip.Create("TempClip", samples.Count, channels, hz, false);

        clip.SetData(samples.ToArray(), 0);

        return clip;
    }

    static FileStream CreateEmpty(string filepath)
    {
        var fileStream = new FileStream(filepath, FileMode.Create);
        byte emptyByte = new byte();

        for (int i = 0; i < HEADER_SIZE; i++) //preparing the header
        {
            fileStream.WriteByte(emptyByte);
        }

        return fileStream;
    }

    static void ConvertAndWrite(FileStream fileStream, AudioClip clip)
    {
        var samples = new float[clip.samples];

        clip.GetData(samples, 0);

        Int16[] intData = new Int16[samples.Length];
        //converting in 2 float[] steps to Int16[], //then Int16[] to Byte[]

        Byte[] bytesData = new Byte[samples.Length * 2];
        //bytesData array is twice the size of
        //dataSource array because a float converted in Int16 is 2 bytes.

        int rescaleFactor = 32767; //to convert float to Int16

        for (int i = 0; i < samples.Length; i++)
        {
            intData[i] = (short)(samples[i] * rescaleFactor);
            Byte[] byteArr = new Byte[2];
            byteArr = BitConverter.GetBytes(intData[i]);
            byteArr.CopyTo(bytesData, i * 2);
        }

        fileStream.Write(bytesData, 0, bytesData.Length);
    }

    static void WriteHeader(FileStream fileStream, AudioClip clip)
    {
        var hz = clip.frequency;
        var channels = clip.channels;
        var samples = clip.samples;

        fileStream.Seek(0, SeekOrigin.Begin);

        Byte[] riff = System.Text.Encoding.UTF8.GetBytes("RIFF");
        fileStream.Write(riff, 0, 4);

        Byte[] chunkSize = BitConverter.GetBytes(fileStream.Length - 8);
        fileStream.Write(chunkSize, 0, 4);

        Byte[] wave = System.Text.Encoding.UTF8.GetBytes("WAVE");
        fileStream.Write(wave, 0, 4);

        Byte[] fmt = System.Text.Encoding.UTF8.GetBytes("fmt ");
        fileStream.Write(fmt, 0, 4);

        Byte[] subChunk1 = BitConverter.GetBytes(16);
        fileStream.Write(subChunk1, 0, 4);

        //UInt16 two = 2;
        UInt16 one = 1;

        Byte[] audioFormat = BitConverter.GetBytes(one);
        fileStream.Write(audioFormat, 0, 2);

        Byte[] numChannels = BitConverter.GetBytes(channels);
        fileStream.Write(numChannels, 0, 2);

        Byte[] sampleRate = BitConverter.GetBytes(hz);
        fileStream.Write(sampleRate, 0, 4);

        Byte[] byteRate = BitConverter.GetBytes(hz * channels * 2); // sampleRate * bytesPerSample*number of channels, here 44100*2*2
        fileStream.Write(byteRate, 0, 4);

        UInt16 blockAlign = (ushort)(channels * 2);
        fileStream.Write(BitConverter.GetBytes(blockAlign), 0, 2);

        UInt16 bps = 16;
        Byte[] bitsPerSample = BitConverter.GetBytes(bps);
        fileStream.Write(bitsPerSample, 0, 2);

        Byte[] datastring = System.Text.Encoding.UTF8.GetBytes("data");
        fileStream.Write(datastring, 0, 4);

        Byte[] subChunk2 = BitConverter.GetBytes(samples * channels * 2);
        fileStream.Write(subChunk2, 0, 4);
    }
}