NAudio峰值体积计

Question

我正在尝试用NAudio写一个峰值音量表.我的代码与http://channel9.msdn.com/coding4fun/articles/NET-Voice-Recorder非常相似,但我的代码和链接的录音机项目都遇到了问题.

当播放恒定频率和音量的声音时,音量计最初开始于合理的水平,但随后衰减到非常小的值.我不确定为什么会这样,因为NAudioDemo中的峰值音量表不会这样做.我试图在程序中复制NAudioDemo中的代码,但是我无法找到包含峰值音量表代码的代码文件.

有人可以指导我创建峰值音量计的替代解决方案,或者帮助我确定为什么我的解决方案(以及链接中提供的解决方案)都不起作用？

public MainWindow()
    {
        int waveInDevices = WaveIn.DeviceCount;
        for (int waveInDevice = 0; waveInDevice < waveInDevices; waveInDevice++)
        {
            WaveInCapabilities deviceInfo = WaveIn.GetCapabilities(waveInDevice);
            Console.WriteLine("Device {0}: {1}, {2} channels",
                waveInDevice, deviceInfo.ProductName, deviceInfo.Channels);

            WaveIn waveIn = new WaveIn();
            waveIn.DeviceNumber = 0; //TODO: Let the user choose which device, this comes from the device numbers above
            waveIn.DataAvailable += waveIn_DataAvailable;
            int sampleRate = SAMPLE_RATE; // 8 kHz
            int channels = 1; // mono
            waveIn.WaveFormat = new WaveFormat(sampleRate, channels);
            waveIn.StartRecording();
        }
    }

    void waveIn_DataAvailable(object sender, WaveInEventArgs e)
    {
        for (int index = 0; index < e.BytesRecorded; index += 2)
        {
            short sample = (short)((e.Buffer[index + 1] << 8) |
                                    e.Buffer[index + 0]);
            float sample32 = sample / 32768f;
            ProcessSample(sample32);
        }           

    }

    void ProcessSample(float sample1)
    {
        samplenumber += 1;

        if (sample1 > maxval)
        {
            maxval = sample1;
        }

        if (sample1 < minval)
        {
            minval = sample1;
        }


        //Run updateView every few loops

        if (samplenumber > (double)SAMPLE_RATE / DISPLAY_UPDATE_RATE)
        {
            samplenumber = 0;
            updateView(); //needs to be fast!
        }
    }

    void updateView()
    {
        Console.WriteLine(maxval);
        Console.WriteLine(minval);
        progressBar1.Value = (maxval - minval)*50;

        maxval = 0;
        minval = 0;
    }

Answer 1

该文章中发生的一切是它在一个小间隔(例如20ms)内找到最大音频峰值,然后在分贝标度上绘制.要查找峰值,请检查区间中每个样本的值并选择最大值(这是SampleAggregator类正在执行的操作).要转换为分贝,请取最大值的对数基数10,然后乘以10.因此0dB是最大的,低于-96dB的任何值都是有效的静音.(实际上,回头看这篇文章,我觉得我甚至不愿意转换成分贝秤,我可能应该这样做)