【Unity Epitome】音频模块：加载、转换、剪切、混音、合并

GitHub项目：Epitome.Audio音频模块

WWW类外部加载音乐文件

使用delegate委托：音频加载完成进行回调

namespace Epitome
{
    public delegate void AudioClipLoadFinish(AudioClip clip);

    public static class AudioLoad
    {
        public static IEnumerator Load(string url, AudioClipLoadFinish finish)
        {
            WWW www = new WWW("file://" + url);
            yield return www;
            finish(www.GetAudioClip());
        }
    }
}

使用案列：

public AudioSource accompany;

private void Start()
{
	// 加载音频
	StartCoroutine(AudioLoad.Load("filepath", AudioClipLoadFinish));
}
    
public void AudioClipLoadFinish(AudioClip clip)
{
	accompany.clip = clip;
	accompany.Paly();
}

NAudio介绍

NAudio是Mark Heath编写的开源.NET音频库
GitHub：NAudio项目
NAudio是个相对成熟、开源的C#音频开发工具，它包含录音、播放录音、格式转换、混音调整等功能。

基于NAudio音频文件格式转换

namespace Epitome
{
    public static class AudioConverter
    {
        /// 

        /// MP3文件转WAV文件
        /// 
        /// MP3文件读取路径
        /// WAV文件保存路径
        public static void MP3TurnWAV(string filePath, string savePath)
        {
            using (FileStream stream = File.Open(filePath, FileMode.Open))
            {
                Mp3FileReader reader = new Mp3FileReader(stream);
                WaveFileWriter.CreateWaveFile(savePath, reader);
            }
        }

        public static void MP3TurnWAV(string filePath, string savePath, List<string> fileNames)
        {
            List<string> strs = Project.DirectoryAllFileNames(filePath, new List<string>() { "mp3" });

            if (strs != null)
            {
                string targetFilePath, saveFilePath;
                for (int j = 0; j < strs.Count; j++)
                {
                    targetFilePath = filePath + "/" + strs[j];
                    saveFilePath = savePath + "/" + strs[j].Substring(0, strs[j].Length - 3) + "wav";
                    MP3TurnWAV(targetFilePath, saveFilePath);
                }
#if UNITY_EDITOR
                AssetDatabase.Refresh();
#endif
            }
        }
	}
}

使用案列：
EditorExtension.GetSelectionPath：获取编辑器选择的目标路径，获取该路径下的MP3音频文件
通过拼接音频文件路径，调用MP3TurnWAV生成WAV音频文件

/// 

/// MP3文件转WAV文件
/// 
[MenuItem("Epitome/Audio/MP3TurnWAV")]
[MenuItem("Assets/Epitome/Audio/MP3TurnWAV")]
private static void MP3TurnWAV()
{
    List<string> paths = EditorExtension.GetSelectionPath();
    for (int i = 0; i < paths.Count; i++)
    {
        if (Directory.Exists(paths[i]))
        {
            string rootPath = ProjectPath.GetDataPath.Substring(0, ProjectPath.GetDataPath.Length - 6);

            DirectoryInfo info = new DirectoryInfo(rootPath + paths[i]);

            string savePath = info.FullName + "_WAV";

            Project.CreateDirectory(savePath);

            List<string> strs = Project.DirectoryAllFileNames(info.FullName, new List<string>() { "mp3" });

            AudioConverter.MP3TurnWAV(info.FullName, savePath, strs);
        }
    }
}

音频剪切

/// 

/// 剪切空白部分
/// 
public static AudioClip CutBlankSection(AudioClip audioClip, int time, int samplingRate)
{
    float[] samples_one = new float[audioClip.samples];

    audioClip.GetData(samples_one, 0);

    float[] samples_two = new float[time * samplingRate];

    Array.Copy(samples_one, 0, samples_two, 0, time * samplingRate);

    AudioClip newAudioClip = AudioClip.Create(audioClip.name, samplingRate * time, 1, samplingRate, false);
    newAudioClip.SetData(samples_two, 0);

    return newAudioClip;
}

audioLength//秒单位
frequency = 44100;
AudioClip audioClip = AudioClips.CutBlankSection(recording.clip, audioLength, frequency);

基于NAudio音频剪切

/// 

/// 修剪Wav文件
/// 
/// 修剪文件路径
/// 保存文件路径
/// 开始间隔
/// 结束间隔
public static void TrimWavFile(string filePath, string savePath, TimeSpan cutFromStart, TimeSpan cutFromEnd)
{
    using (WaveFileReader reader = new WaveFileReader(filePath))
    {
        using (WaveFileWriter writer = new WaveFileWriter(savePath, reader.WaveFormat))
        {
            int bytesPerMillisecond = reader.WaveFormat.AverageBytesPerSecond / 1000;

            int startPos = (int)cutFromStart.TotalMilliseconds * bytesPerMillisecond;
            startPos = startPos - startPos % reader.WaveFormat.BlockAlign;

            int endBytes = (int)cutFromEnd.TotalMilliseconds * bytesPerMillisecond;
            endBytes = endBytes - endBytes % reader.WaveFormat.BlockAlign;
            int endPos = (int)reader.Length - endBytes;

            TrimWavFile(reader, writer, startPos, endPos);
        }
    }
}

/// 

/// 修剪Wav文件
/// 
private static void TrimWavFile(WaveFileReader reader, WaveFileWriter writer, int startPos, int endPos)
{
    reader.Position = startPos;
    byte[] buffer = new byte[1024];
    while (reader.Position < endPos)
    {
        int bytesRequired = (int)(endPos - reader.Position);
        if (bytesRequired > 0)
        {
            int bytesToRead = Math.Min(bytesRequired, buffer.Length);
            int bytesRead = reader.Read(buffer, 0, bytesToRead);
            if (bytesRead > 0)
            {
                writer.Write(buffer, 0, bytesRead);
            }
        }
    }
}

基于NAudio音频混合（混音）

namespace Epitome
{
    public static class AudioMixer
    {
        /// 

        /// 音频混合（混音）
        /// 
        /// 音频文件路径
        /// 音频文件路径
        /// 混合音频文件路径
        public static void AudioMixing(string filePath1, string filePath2,string mixedPath)
        {
            using (var reader1 = new AudioFileReader(filePath1))
            using (var reader2 = new AudioFileReader(filePath2))
            {
                var mixer = new MixingSampleProvider(new[] { reader1, reader2 });
                WaveFileWriter.CreateWaveFile16(mixedPath, mixer);
            }
        }
    }
}

使用案列：

// 伴奏混合原声
AudioMixer.AudioMixing(accompanyClipPath, originalPath, finalPath);

音频合并

/// 

/// 合并音频
/// 
public static AudioClip MergeAudio(int interval, params AudioClip[] clips)
{
    if (clips == null || clips.Length == 0)
        return null;

    int channels = clips[0].channels;
    int frequency = clips[0].frequency;

    using (MemoryStream memoryStream = new MemoryStream())
    {
        for (int i = 0; i < clips.Length; i++)
        {
            if (clips[i] == null)
                continue;

            clips[i].LoadAudioData();

            var buffer = clips[i].GetData();

            memoryStream.Write(buffer, 0, buffer.Length);

            if (clips.Length - 1 == i)
                continue;

            byte[] byteClips = new byte[clips[i].frequency * clips[i].channels * 4 * interval];//合并音频间的间隔
            memoryStream.Write(byteClips, 0, byteClips.Length);
        }

        var bytes = memoryStream.ToArray();

        var result = AudioClip.Create("Merge", bytes.Length / 4 / channels, channels, 44100, false);

        result.SetData(bytes);

        return result;
    }
}