NAudio : 保留最后的 ex: 5s 录制的音频并随时保存

Question

我正在使用 NAudio 作为库来编写音板来管理我的音频。我想要实现的功能之一是能够连续记录一个（或多个）音频输入并能够随时保存它们。

我认为这可能的方式是保留最后一个循环缓冲区：音频输入拾取的 5 秒样本。

我还想避免将所有数据保留到开始时的状态，因为我不想过度使用内存。

我已经尝试了很多方法来解决这个问题：

使用循环缓冲区并向其提供来自 "DataAvailable" 事件的数据；
使用"Queue"和"BufferedWaveProvider"添加缓冲区数据并将其转换为样本。
我尝试使用 2 "BufferedWaveProvider" 并交替使用填充取决于哪个已满。
我还尝试使用 2 波输入和定时器来交替使用正在录音。

我尝试使用字节数组并将其用作循环缓冲区。我使用来自 "WaveInEvent" 的 "DataAvailable" 事件填充缓冲区。 "WaveInEventArgs" 有一个缓冲区，所以我将它的数据添加到循环缓冲区。

private int _start = 0, _end = 0;
private bool _filled = false;
private byte[] _buffer; // the size was set in the constructor
                        // its an equation to figure out how many samples
                        // a certain time needs.

private void _dataAvailable(object sender, WaveInEventArgs e)
{

    for (int i = 0; i < e.BytesRecorded; i++)
    {
        if (_filled)
        {
            _start = _end + 1 > _buffer.Length - 1 ? _end + 1 : 0;
        }
        if (_end > _buffer.Length - 1 && !_filled) _filled = true;
        _end = _end > _buffer.Length - 1 ? _end + 1 : 0;

        _buffer[_end] = e.Buffer[i];
    }
}

我所做的一些尝试有点奏效，但大多数时候，它们会在前 5 秒内奏效（我知道使用 "BufferredWaveProvider" 会导致该问题。我认为那部分问题在于缓冲区的开头需要一定数量的数据，一旦缓冲区开始覆盖该数据，音频播放器就不会

问题的另一个很可能的原因是我刚刚开始使用 NAudio，还没有完全理解它。

我已经被这个问题困扰了一段时间，非常感谢任何人能给我的帮助。

我还有一些代码可以添加，但我认为这个问题已经很长了。

提前致谢！

Answer 1

您 _dataAvailable 方法中的代码对我来说很陌生。我会简单地从头到尾写入字节，然后再从头开始，依此类推。然后，当您想要获取实际字节以保存它们时，创建一个从当前位置到末尾以及从开始到当前位置的新数组。检查下面的代码。

private int _pos = 0;
private bool _isFull = false;
private byte[] _buffer; // intialized in the constructor with the correct length

private void _dataAvailable(object sender, WaveInEventArgs e)
{
    for(int i = 0; i < e.BytesRecorded; ++i) {
        // save the data
        _buffer[_pos] = e.Buffer[i];
        // move the current position (advances by 1 OR resets to zero if the length of the buffer was reached)
        _pos = (_pos + 1) % _buffer.Length;
        // flag if the buffer is full (will only set it from false to true the first time that it reaches the full length of the buffer)
        _isFull |= (_pos == 0);
    }
}

public byte[] GetBytesToSave()
{
    int length = _isFull ? _buffer.Length : _pos;
    var bytesToSave = new byte[length];
    int byteCountToEnd = _isFull ? (_buffer.Length - _pos) : 0;
    if(byteCountToEnd > 0) {
        // bytes from the current position to the end
        Array.Copy(_buffer, _pos, bytesToSave, 0, byteCountToEnd);
    }
    if(_pos > 0) {
        // bytes from the start to the current position
        Array.Copy(_buffer, 0, bytesToSave, byteCountToEnd, _pos);
    }
    return bytesToSave;
}

Answer 2

如果其他人想做类似的事情，我将离开整个 class。想怎么用就怎么用。

using System;
using NAudio.Wave;
using System.Diagnostics;

public class AudioRecorder
{
    public WaveInEvent MyWaveIn;
    public readonly double RecordTime;

    private WaveOutEvent _wav = new WaveOutEvent();
    private bool _isFull = false;
    private int _pos = 0;
    private byte[] _buffer;
    private bool _isRecording = false;

    /// <summary>
    /// Creates a new recorder with a buffer
    /// </summary>
    /// <param name="recordTime">Time to keep in buffer (in seconds)</param>
    public AudioRecorder(double recordTime)
    {
        RecordTime = recordTime;
        MyWaveIn = new WaveInEvent();
        MyWaveIn.DataAvailable += DataAvailable;
        _buffer = new byte[(int)(MyWaveIn.WaveFormat.AverageBytesPerSecond * RecordTime)];
    }

    /// <summary>
    /// Starts recording
    /// </summary>
    public void StartRecording()
    {
        if (!_isRecording)
        {
            try
            {
                MyWaveIn.StartRecording();
            }
            catch (InvalidOperationException)
            {
                Debug.WriteLine("Already recording!");
            }
        }

        _isRecording = true;
    }

    /// <summary>
    /// Stops recording
    /// </summary>
    public void StopRecording()
    {
        MyWaveIn.StopRecording();
        _isRecording = false;
    }

    /// <summary>
    /// Play currently recorded data
    /// </summary>
    public void PlayRecorded() 
    {
        if (_wav.PlaybackState == PlaybackState.Stopped)
        {
            var buff = new BufferedWaveProvider(MyWaveIn.WaveFormat);
            var bytes = GetBytesToSave();
            buff.AddSamples(bytes, 0, bytes.Length);
            _wav.Init(buff);
            _wav.Play();
        }

    }

    /// <summary>
    /// Stops replay
    /// </summary>
    public void StopReplay()
    {
        if (_wav != null) _wav.Stop();
    }

    /// <summary>
    /// Save to disk
    /// </summary>
    /// <param name="fileName"></param>
    public void Save(string fileName)
    {
        var writer = new WaveFileWriter(fileName, MyWaveIn.WaveFormat);
        var buff = GetBytesToSave();
        writer.Write(buff, 0 , buff.Length);
        writer.Flush();
    }


    private void DataAvailable(object sender, WaveInEventArgs e)
    {

        for (int i = 0; i < e.BytesRecorded; ++i)
        {
            // save the data
            _buffer[_pos] = e.Buffer[i];
            // move the current position (advances by 1 OR resets to zero if the length of the buffer was reached)
            _pos = (_pos + 1) % _buffer.Length;
            // flag if the buffer is full (will only set it from false to true the first time that it reaches the full length of the buffer)
            _isFull |= (_pos == 0);
        }
    }

    public byte[] GetBytesToSave()
    {
        int length = _isFull ? _buffer.Length : _pos;
        var bytesToSave = new byte[length];
        int byteCountToEnd = _isFull ? (_buffer.Length - _pos) : 0;
        if (byteCountToEnd > 0)
        {
            // bytes from the current position to the end
            Array.Copy(_buffer, _pos, bytesToSave, 0, byteCountToEnd);
        }
        if (_pos > 0)
        {
            // bytes from the start to the current position
            Array.Copy(_buffer, 0, bytesToSave, byteCountToEnd, _pos);
        }
        return bytesToSave;
    }

    /// <summary>
    /// Starts recording if WaveIn stopped
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    private void Stopped(object sender, StoppedEventArgs e)
    {
        Debug.WriteLine("Recording stopped!");
        if (e.Exception != null) Debug.WriteLine(e.Exception.Message);
        if (_isRecording)
        {
            MyWaveIn.StartRecording();
        }
    }
}

NAudio : 保留最后的 ex: 5s 录制的音频并随时保存

NAudio : Keeping last ex: 5s of recorded audio and save it anytime

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