AudioClip读写

https://github.com/deadlyfingers/UnityWav

using UnityEngine;
using System.Text;
using System.IO;
using System;

/// 

/// WAV utility for recording and audio playback functions in Unity.
/// Version: 1.0 alpha 1
///
/// - Use "ToAudioClip" method for loading wav file / bytes.
/// Loads .wav (PCM uncompressed) files at 8,16,24 and 32 bits and converts data to Unity's AudioClip.
///
/// - Use "FromAudioClip" method for saving wav file / bytes.
/// Converts an AudioClip's float data into wav byte array at 16 bit.
/// 
/// 
/// For documentation and usage examples: https://github.com/deadlyfingers/UnityWav
/// 

public class WavUtility
{
    // Force save as 16-bit .wav
    const int BlockSize_16Bit = 2;

    /// 

    /// Load PCM format *.wav audio file (using Unity's Application data path) and convert to AudioClip.
    /// 
    /// The AudioClip.
    /// Local file path to .wav file
    public static AudioClip ToAudioClip(string filePath)
    {
        if (!filePath.StartsWith(Application.persistentDataPath) && !filePath.StartsWith(Application.dataPath))
        {
            Debug.LogWarning("This only supports files that are stored using Unity's Application data path. \nTo load bundled resources use 'Resources.Load(\"filename\") typeof(AudioClip)' method. \nhttps://docs.unity3d.com/ScriptReference/Resources.Load.html");
            return null;
        }
        byte[] fileBytes = File.ReadAllBytes(filePath);
        return ToAudioClip(fileBytes, 0);
    }

    public static AudioClip ToAudioClip(byte[] fileBytes, int offsetSamples = 0, string name = "wav")
    {
        //string riff = Encoding.ASCII.GetString (fileBytes, 0, 4);
        //string wave = Encoding.ASCII.GetString (fileBytes, 8, 4);
        int subchunk1 = BitConverter.ToInt32(fileBytes, 16);
        UInt16 audioFormat = BitConverter.ToUInt16(fileBytes, 20);

        // NB: Only uncompressed PCM wav files are supported.
        string formatCode = FormatCode(audioFormat);
        Debug.AssertFormat(audioFormat == 1 || audioFormat == 65534, "Detected format code '{0}' {1}, but only PCM and WaveFormatExtensable uncompressed formats are currently supported.", audioFormat, formatCode);

        UInt16 channels = BitConverter.ToUInt16(fileBytes, 22);
        int sampleRate = BitConverter.ToInt32(fileBytes, 24);
        //int byteRate = BitConverter.ToInt32 (fileBytes, 28);
        //UInt16 blockAlign = BitConverter.ToUInt16 (fileBytes, 32);
        UInt16 bitDepth = BitConverter.ToUInt16(fileBytes, 34);

        int headerOffset = 16 + 4 + subchunk1 + 4;
        int subchunk2 = BitConverter.ToInt32(fileBytes, headerOffset);
        //Debug.LogFormat ("riff={0} wave={1} subchunk1={2} format={3} channels={4} sampleRate={5} byteRate={6} blockAlign={7} bitDepth={8} headerOffset={9} subchunk2={10} filesize={11}", riff, wave, subchunk1, formatCode, channels, sampleRate, byteRate, blockAlign, bitDepth, headerOffset, subchunk2, fileBytes.Length);

        float[] data;
        switch (bitDepth)
        {
            case 8:
                data = Convert8BitByteArrayToAudioClipData(fileBytes, headerOffset, subchunk2);
                break;
            case 16:
                data = Convert16BitByteArrayToAudioClipData(fileBytes, headerOffset, subchunk2);
                break;
            case 24:
                data = Convert24BitByteArrayToAudioClipData(fileBytes, headerOffset, subchunk2);
                break;
            case 32:
                data = Convert32BitByteArrayToAudioClipData(fileBytes, headerOffset, subchunk2);
                break;
            default:
                throw new Exception(bitDepth + " bit depth is not supported.");
        }

        AudioClip audioClip = AudioClip.Create(name, data.Length, (int)channels, sampleRate, false);
        audioClip.SetData(data, 0);
        return audioClip;
    }

    #region wav file bytes to Unity AudioClip conversion methods

    private static float[] Convert8BitByteArrayToAudioClipData(byte[] source, int headerOffset, int dataSize)
    {
        int wavSize = BitConverter.ToInt32(source, headerOffset);
        headerOffset += sizeof(int);
        Debug.AssertFormat(wavSize > 0 && wavSize == dataSize, "Failed to get valid 8-bit wav size: {0} from data bytes: {1} at offset: {2}", wavSize, dataSize, headerOffset);

        float[] data = new float[wavSize];

        sbyte maxValue = sbyte.MaxValue;

        int i = 0;
        while (i < wavSize)
        {
            data[i] = (float)source[i] / maxValue;
            ++i;
        }

        return data;
    }

    private static float[] Convert16BitByteArrayToAudioClipData(byte[] source, int headerOffset, int dataSize)
    {
        int wavSize = BitConverter.ToInt32(source, headerOffset);
        headerOffset += sizeof(int);
        Debug.AssertFormat(wavSize > 0 && wavSize == dataSize, "Failed to get valid 16-bit wav size: {0} from data bytes: {1} at offset: {2}", wavSize, dataSize, headerOffset);

        int x = sizeof(Int16); // block size = 2
        int convertedSize = wavSize / x;

        float[] data = new float[convertedSize];

        Int16 maxValue = Int16.MaxValue;

        int offset = 0;
        int i = 0;
        while (i < convertedSize)
        {
            offset = i * x + headerOffset;
            data[i] = (float)BitConverter.ToInt16(source, offset) / maxValue;
            ++i;
        }

        Debug.AssertFormat(data.Length == convertedSize, "AudioClip .wav data is wrong size: {0} == {1}", data.Length, convertedSize);

        return data;
    }

    private static float[] Convert24BitByteArrayToAudioClipData(byte[] source, int headerOffset, int dataSize)
    {
        int wavSize = BitConverter.ToInt32(source, headerOffset);
        headerOffset += sizeof(int);
        Debug.AssertFormat(wavSize > 0 && wavSize == dataSize, "Failed to get valid 24-bit wav size: {0} from data bytes: {1} at offset: {2}", wavSize, dataSize, headerOffset);

        int x = 3; // block size = 3
        int convertedSize = wavSize / x;

        int maxValue = Int32.MaxValue;

        float[] data = new float[convertedSize];

        byte[] block = new byte[sizeof(int)]; // using a 4 byte block for copying 3 bytes, then copy bytes with 1 offset

        int offset = 0;
        int i = 0;
        while (i < convertedSize)
        {
            offset = i * x + headerOffset;
            Buffer.BlockCopy(source, offset, block, 1, x);
            data[i] = (float)BitConverter.ToInt32(block, 0) / maxValue;
            ++i;
        }

        Debug.AssertFormat(data.Length == convertedSize, "AudioClip .wav data is wrong size: {0} == {1}", data.Length, convertedSize);

        return data;
    }

    private static float[] Convert32BitByteArrayToAudioClipData(byte[] source, int headerOffset, int dataSize)
    {
        int wavSize = BitConverter.ToInt32(source, headerOffset);
        headerOffset += sizeof(int);
        Debug.AssertFormat(wavSize > 0 && wavSize == dataSize, "Failed to get valid 32-bit wav size: {0} from data bytes: {1} at offset: {2}", wavSize, dataSize, headerOffset);

        int x = sizeof(float); //  block size = 4
        int convertedSize = wavSize / x;

        Int32 maxValue = Int32.MaxValue;

        float[] data = new float[convertedSize];

        int offset = 0;
        int i = 0;
        while (i < convertedSize)
        {
            offset = i * x + headerOffset;
            data[i] = (float)BitConverter.ToInt32(source, offset) / maxValue;
            ++i;
        }

        Debug.AssertFormat(data.Length == convertedSize, "AudioClip .wav data is wrong size: {0} == {1}", data.Length, convertedSize);

        return data;
    }

    #endregion

    public static byte[] FromAudioClip(AudioClip audioClip)
    {
        string file;
        return FromAudioClip(audioClip, out file, true);
    }

    public static byte[] FromAudioClip(AudioClip audioClip, out string filepath, bool saveAsFile = true, string dirname = "recordings")
    {
        MemoryStream stream = new MemoryStream();

        const int headerSize = 44;

        // get bit depth
        UInt16 bitDepth = 16; //BitDepth (audioClip);

        // NB: Only supports 16 bit
        //Debug.AssertFormat (bitDepth == 16, "Only converting 16 bit is currently supported. The audio clip data is {0} bit.", bitDepth);

        // total file size = 44 bytes for header format and audioClip.samples * factor due to float to Int16 / sbyte conversion
        int fileSize = audioClip.samples * BlockSize_16Bit + headerSize; // BlockSize (bitDepth)

        // chunk descriptor (riff)
        WriteFileHeader(ref stream, fileSize);
        // file header (fmt)
        WriteFileFormat(ref stream, audioClip.channels, audioClip.frequency, bitDepth);
        // data chunks (data)
        WriteFileData(ref stream, audioClip, bitDepth);

        byte[] bytes = stream.ToArray();

        // Validate total bytes
        Debug.AssertFormat(bytes.Length == fileSize, "Unexpected AudioClip to wav format byte count: {0} == {1}", bytes.Length, fileSize);

        // Save file to persistant storage location
        if (saveAsFile)
        {
            filepath = string.Format("{0}/{1}/{2}.{3}", Application.persistentDataPath, dirname, DateTime.UtcNow.ToString("yyyyMMdd-HHmmss"), "wav");
            Directory.CreateDirectory(Path.GetDirectoryName(filepath));
            File.WriteAllBytes(filepath, bytes);

            Debug.Log ("Auto-saved .wav file: " + filepath);
        }
        else
        {
            filepath = null;
            Debug.Log("Save Failed!");
        }

        stream.Dispose();

        return bytes;
    }

    #region write .wav file functions

    private static int WriteFileHeader(ref MemoryStream stream, int fileSize)
    {
        int count = 0;
        int total = 12;

        // riff chunk id
        byte[] riff = Encoding.ASCII.GetBytes("RIFF");
        count += WriteBytesToMemoryStream(ref stream, riff, "ID");

        // riff chunk size
        int chunkSize = fileSize - 8; // total size - 8 for the other two fields in the header
        count += WriteBytesToMemoryStream(ref stream, BitConverter.GetBytes(chunkSize), "CHUNK_SIZE");

        byte[] wave = Encoding.ASCII.GetBytes("WAVE");
        count += WriteBytesToMemoryStream(ref stream, wave, "FORMAT");

        // Validate header
        Debug.AssertFormat(count == total, "Unexpected wav descriptor byte count: {0} == {1}", count, total);

        return count;
    }

    private static int WriteFileFormat(ref MemoryStream stream, int channels, int sampleRate, UInt16 bitDepth)
    {
        int count = 0;
        int total = 24;

        byte[] id = Encoding.ASCII.GetBytes("fmt ");
        count += WriteBytesToMemoryStream(ref stream, id, "FMT_ID");

        int subchunk1Size = 16; // 24 - 8
        count += WriteBytesToMemoryStream(ref stream, BitConverter.GetBytes(subchunk1Size), "SUBCHUNK_SIZE");

        UInt16 audioFormat = 1;
        count += WriteBytesToMemoryStream(ref stream, BitConverter.GetBytes(audioFormat), "AUDIO_FORMAT");

        UInt16 numChannels = Convert.ToUInt16(channels);
        count += WriteBytesToMemoryStream(ref stream, BitConverter.GetBytes(numChannels), "CHANNELS");

        count += WriteBytesToMemoryStream(ref stream, BitConverter.GetBytes(sampleRate), "SAMPLE_RATE");

        int byteRate = sampleRate * channels * BytesPerSample(bitDepth);
        count += WriteBytesToMemoryStream(ref stream, BitConverter.GetBytes(byteRate), "BYTE_RATE");

        UInt16 blockAlign = Convert.ToUInt16(channels * BytesPerSample(bitDepth));
        count += WriteBytesToMemoryStream(ref stream, BitConverter.GetBytes(blockAlign), "BLOCK_ALIGN");

        count += WriteBytesToMemoryStream(ref stream, BitConverter.GetBytes(bitDepth), "BITS_PER_SAMPLE");

        // Validate format
        Debug.AssertFormat(count == total, "Unexpected wav fmt byte count: {0} == {1}", count, total);

        return count;
    }

    private static int WriteFileData(ref MemoryStream stream, AudioClip audioClip, UInt16 bitDepth)
    {
        int count = 0;
        int total = 8;

        // Copy float[] data from AudioClip
        float[] data = new float[audioClip.samples * audioClip.channels];
        audioClip.GetData(data, 0);

        byte[] bytes = ConvertAudioClipDataToInt16ByteArray(data);

        byte[] id = Encoding.ASCII.GetBytes("data");
        count += WriteBytesToMemoryStream(ref stream, id, "DATA_ID");

        int subchunk2Size = Convert.ToInt32(audioClip.samples * BlockSize_16Bit); // BlockSize (bitDepth)
        count += WriteBytesToMemoryStream(ref stream, BitConverter.GetBytes(subchunk2Size), "SAMPLES");

        // Validate header
        Debug.AssertFormat(count == total, "Unexpected wav data id byte count: {0} == {1}", count, total);

        // Write bytes to stream
        count += WriteBytesToMemoryStream(ref stream, bytes, "DATA");

        // Validate audio data
        Debug.AssertFormat(bytes.Length == subchunk2Size, "Unexpected AudioClip to wav subchunk2 size: {0} == {1}", bytes.Length, subchunk2Size);

        return count;
    }

    private static byte[] ConvertAudioClipDataToInt16ByteArray(float[] data)
    {
        MemoryStream dataStream = new MemoryStream();

        int x = sizeof(Int16);

        Int16 maxValue = Int16.MaxValue;

        int i = 0;
        while (i < data.Length)
        {
            dataStream.Write(BitConverter.GetBytes(Convert.ToInt16(data[i] * maxValue)), 0, x);
            ++i;
        }
        byte[] bytes = dataStream.ToArray();

        // Validate converted bytes
        Debug.AssertFormat(data.Length * x == bytes.Length, "Unexpected float[] to Int16 to byte[] size: {0} == {1}", data.Length * x, bytes.Length);

        dataStream.Dispose();

        return bytes;
    }

    private static int WriteBytesToMemoryStream(ref MemoryStream stream, byte[] bytes, string tag = "")
    {
        int count = bytes.Length;
        stream.Write(bytes, 0, count);
        //Debug.LogFormat ("WAV:{0} wrote {1} bytes.", tag, count);
        return count;
    }

    #endregion

    /// 

    /// Calculates the bit depth of an AudioClip
    /// 
    /// The bit depth. Should be 8 or 16 or 32 bit.
    /// Audio clip.
    public static UInt16 BitDepth(AudioClip audioClip)
    {
        UInt16 bitDepth = Convert.ToUInt16(audioClip.samples * audioClip.channels * audioClip.length / audioClip.frequency);
        Debug.AssertFormat(bitDepth == 8 || bitDepth == 16 || bitDepth == 32, "Unexpected AudioClip bit depth: {0}. Expected 8 or 16 or 32 bit.", bitDepth);
        return bitDepth;
    }

    private static int BytesPerSample(UInt16 bitDepth)
    {
        return bitDepth / 8;
    }

    private static int BlockSize(UInt16 bitDepth)
    {
        switch (bitDepth)
        {
            case 32:
                return sizeof(Int32); // 32-bit -> 4 bytes (Int32)
            case 16:
                return sizeof(Int16); // 16-bit -> 2 bytes (Int16)
            case 8:
                return sizeof(sbyte); // 8-bit -> 1 byte (sbyte)
            default:
                throw new Exception(bitDepth + " bit depth is not supported.");
        }
    }

    private static string FormatCode(UInt16 code)
    {
        switch (code)
        {
            case 1:
                return "PCM";
            case 2:
                return "ADPCM";
            case 3:
                return "IEEE";
            case 7:
                return "μ-law";
            case 65534:
                return "WaveFormatExtensable";
            default:
                Debug.LogWarning("Unknown wav code format:" + code);
                return "";
        }
    }

}