如何使用 NAudio 将声音文件加载到内存中并在以后使用？

Question

我每秒播放 5 次相同的声音文件（在它们之间随机选择），而且我总是加载到内存中，所以程序使用了大量内存。我怎样才能将声音文件加载到内存中，然后从那里开始呢？我正在使用 NAudio。当前代码：

var sound = "sounds/test.mp3";
using (var audioFile = new AudioFileReader(sound))
using (var outputDevice = new WaveOutEvent())
{
    outputDevice.Init(audioFile);
    outputDevice.Play();
    while (outputDevice.PlaybackState == PlaybackState.Playing)
    {
        Thread.Sleep(1000);
    }
    threadStop();
}

Answer 1

如果您删除 using 块，则 audioFile 和 outputDevice 将不会被丢弃。然后您可以将它们保留在内存中，每次播放音频时都会使用相同的引用。

对于 using 个块，您正在重复实例化其内存可能不会立即释放的 NAudio 对象。

var sound = "sounds/test.mp3";
var audioFile = new AudioFileReader(sound);
var outputDevice = new WaveOutEvent();
outputDevice.Init(audioFile);
outputDevice.Play();
while (outputDevice.PlaybackState == PlaybackState.Playing)
{
    Thread.Sleep(1000);
}
threadStop();

Answer 2

我使用 article 中的代码解决了整个问题。它使用 MixingSampleProvider。我将声音加载到名为 CachedSound 的自定义 class 中。然后我使用另一个 class 播放它们：AudioPlaybackEngine。它处理混音器，我使用 CachedSoundSampleProvider class 读取缓存的声音。

代码如下所示：

class AudioPlaybackEngine : IDisposable
{
    private readonly IWavePlayer outputDevice;
    private readonly MixingSampleProvider mixer;

    public AudioPlaybackEngine(int sampleRate = 44100, int channelCount = 2)
    {
        outputDevice = new WaveOutEvent();
        mixer = new MixingSampleProvider(WaveFormat.CreateIeeeFloatWaveFormat(sampleRate, channelCount));
        mixer.ReadFully = true;
        outputDevice.Init(mixer);
        outputDevice.Play();
    }

    public void PlaySound(string fileName)
    {
        var input = new AudioFileReader(fileName);
        AddMixerInput(new AutoDisposeFileReader(input));
    }

    private ISampleProvider ConvertToRightChannelCount(ISampleProvider input)
    {
        if (input.WaveFormat.Channels == mixer.WaveFormat.Channels)
        {
            return input;
        }
        if (input.WaveFormat.Channels == 1 && mixer.WaveFormat.Channels == 2)
        {
            return new MonoToStereoSampleProvider(input);
        }
        throw new NotImplementedException("Not yet implemented this channel count conversion");
    }

    public void PlaySound(CachedSound sound)
    {
        AddMixerInput(new CachedSoundSampleProvider(sound));
    }

    private void AddMixerInput(ISampleProvider input)
    {
        mixer.AddMixerInput(ConvertToRightChannelCount(input));
    }

    public void Dispose()
    {
        outputDevice.Dispose();
    }

    public static readonly AudioPlaybackEngine Instance = new AudioPlaybackEngine(44100, 2);
}

class CachedSound
{
    public float[] AudioData { get; private set; }
    public WaveFormat WaveFormat { get; private set; }
    public CachedSound(string audioFileName)
    {
        using (var audioFileReader = new AudioFileReader(audioFileName))
        {
            // TODO: could add resampling in here if required
            WaveFormat = audioFileReader.WaveFormat;
            var wholeFile = new List<float>((int)(audioFileReader.Length / 4));
            var readBuffer= new float[audioFileReader.WaveFormat.SampleRate * audioFileReader.WaveFormat.Channels];
            int samplesRead;
            while((samplesRead = audioFileReader.Read(readBuffer,0,readBuffer.Length)) > 0)
            {
                wholeFile.AddRange(readBuffer.Take(samplesRead));
            }
            AudioData = wholeFile.ToArray();
        }
    }
}

class CachedSoundSampleProvider : ISampleProvider
{
    private readonly CachedSound cachedSound;
    private long position;

    public CachedSoundSampleProvider(CachedSound cachedSound)
    {
        this.cachedSound = cachedSound;
    }

    public int Read(float[] buffer, int offset, int count)
    {
        var availableSamples = cachedSound.AudioData.Length - position;
        var samplesToCopy = Math.Min(availableSamples, count);
        Array.Copy(cachedSound.AudioData, position, buffer, offset, samplesToCopy);
        position += samplesToCopy;
        return (int)samplesToCopy;
    }

    public WaveFormat WaveFormat { get { return cachedSound.WaveFormat; } }
}

// This class automatically disposes the file reader that it contains.
class AutoDisposeFileReader : ISampleProvider
{
    private readonly AudioFileReader reader;
    private bool isDisposed;
    public AutoDisposeFileReader(AudioFileReader reader)
    {
        this.reader = reader;
        this.WaveFormat = reader.WaveFormat;
    }

    public int Read(float[] buffer, int offset, int count)
    {
        if (isDisposed)
            return 0;
        int read = reader.Read(buffer, offset, count);
        if (read == 0)
        {
            reader.Dispose();
            isDisposed = true;
        }
        return read;
    }

    public WaveFormat WaveFormat { get; private set; }
}

如何使用 NAudio 将声音文件加载到内存中并在以后使用？

How can I load a sound file into memory using NAudio and use it later?

c#

multithreading

memory-management

file

naudio