在播放nAudio时绘制.wav文件

Question

我想打开一个波形文件并播放它，同时在图表上绘制其幅度和频率响应。

我有一个函数，它接受字节数组或浮点数，并为我这样做。

我要尝试的是从上次采样时采样音频，然后将代表该时间的浮动数组传递给函数。

我正在尝试将ISampleProvider与它的read方法一起使用，但似乎无法正常工作。 第一次读取可以正常工作，但是随后的线程在后续读取时崩溃（有时在第一次读取时也崩溃）。

这就是我设置音频的方式，文件可以正常播放：

                _waveOut = new WaveOutEvent();
                _waveReader = new WaveFileReader(_cncFilePath.Substring(0, _cncFilePath.Length - 4) + "wav");
                _waveOutSampleProvider = new SampleChannel(_waveReader, true);
                _waveOut.Init(_waveOutSampleProvider);
                _waveOut.Play();

它运行在一个100毫秒的计时器上，它将在第一次滴答声中完美运行，第二个滴答声将崩溃，锁保持打开状态，所有其他调用将被备份，直到整个程序崩溃为止。

    private void WavOutChartTimeInterrupt(object waveReader)
    {
        lock (AudioLock) //todo add skipto code, use audio lock to do it.
        {
            try
            {
                var curPos = _waveOut.GetPositionTimeSpan(); //get currentPos
                if (curPos <= AudioCurrentPosition)
                {
                    AudioCurrentPosition = curPos;
                    return;
                }
                var bufferLength = (curPos - AudioCurrentPosition);
                var samplesSec = _waveOutSampleProvider.WaveFormat.SampleRate;
                var channels = _waveOut.OutputWaveFormat.Channels;
                var length = (int) (bufferLength.TotalSeconds * samplesSec * channels) % (samplesSec * channels);
                var wavOutBuffer = new float[length];
                _waveOutSampleProvider.Read(wavOutBuffer, 0, length);

                AudioCurrentPosition = curPos; //update for vCNC with where we are
            }
            catch (Exception e)
            {
                string WTF = e.StackTrace;

                throw new ArgumentException(@"Wave out buffer crashed" + e.StackTrace.ToString());
            }
        }

添加了堆栈跟踪（希望我做的正确）

at NAudio.Wave.WaveFileReader.Read(Byte[] array, Int32 offset, Int32 count)\r\n       
at NAudio.Wave.SampleProviders.Pcm16BitToSampleProvider.Read(Single[] buffer, Int32 offset, Int32 count)\r\n       
at NAudio.Wave.SampleProviders.MeteringSampleProvider.Read(Single[] buffer, Int32 offset, Int32 count)\r\n 
at NAudio.Wave.SampleProviders.VolumeSampleProvider.Read(Single[] buffer, Int32 offset, Int32 sampleCount)\r\n   
at RecordCNC.Form1.WavOutChartTimeInterrupt(Object waveReader) in C:\\Cloud\\ITRI\\Visual Studio\\RecordCNC\\RecordCNC\\Form1.cs:line 715

海丹

Answer 1

问题是我没有正确检查请求的缓冲区的长度。 缓冲区必须始终是块对齐的倍数。

    private void WavOutChartTimeInterrupt(object waveReader)
{
    lock (AudioLock) //todo add skipto code, use audio lock to do it.
    {
        try
        {
            var curPos = _waveOut.GetPositionTimeSpan(); //get currentPos
            if (curPos <= AudioCurrentPosition)
            {
                AudioCurrentPosition = curPos;
                return;
            }
            var bufferLength = (curPos - AudioCurrentPosition);
            var samplesSec = _waveOutSampleProvider.WaveFormat.SampleRate;
            var channels = _waveOut.OutputWaveFormat.Channels;
            var length = (int) (bufferLength.TotalSeconds * samplesSec * channels) % (samplesSec * channels);
            length -= length% (blockAlign / channels);  //<- THIS FIXED IT
            var wavOutBuffer = new float[length];
            _waveOutSampleProvider.Read(wavOutBuffer, 0, length);

            AudioCurrentPosition = curPos; //update for vCNC with where we are
        }
        catch (Exception e)
        {
            string WTF = e.StackTrace;

            throw new ArgumentException(@"Wave out buffer crashed" + e.StackTrace.ToString());
        }
    }