C# 声音强度图绘制

采集PCM音频数据

音频原来自麦克风

音频源来自录音文件

处理PCM音频数据

将PCM数据进行强度值换算

        private void UpdateVoice(double[] audio)
        {
            // 计算RMS值
            double rms = Math.Sqrt(audio.Select(x => x * x).Average());

            // 将RMS值转换为分贝值（以dBFS为单位）
            double dbfs = 20 * Math.Log10(rms);

            // 绘制数据
            volumeView.SetVolumeData(dbfs);
            volumeView.Refresh();
        }

绘制时频图

采用自定义控件的方式来绘制时频图，核心代码如下：

/// <summary>
/// 声音强度图
/// </summary>
public class SoundTimeVolumeControl : Control
{

    // 创建一个画笔
    private Pen pen = new Pen(Brushes.Blue, 1);
    public Brush TextBrush = new SolidColorBrush(Colors.Gainsboro);

    public void Refresh()
    {
        this.InvalidateVisual();
    }

    /// <summary>
    /// 最大值
    /// </summary>
    private double mMaxVolume;

    /// <summary>
    /// 最小值
    /// </summary>
    private double mMinVolume;


    // 数据源，用于存储折线图的数据
    double[] dbList = new double[256];

    public void SetVolumeData(double volume)
    {

        mMaxVolume = double.MinValue;
        mMinVolume = double.MaxValue;

        for (int i = dbList.Length - 1; i > 0; i--)
        {
            dbList[i] = dbList[i - 1];

            mMaxVolume = Math.Max(dbList[i], mMaxVolume);
            mMinVolume = Math.Min(dbList[i], mMinVolume);
        }

        dbList[0] = volume;

        mMaxVolume = Math.Max(volume, mMaxVolume);
        mMinVolume = Math.Min(volume, mMinVolume);
    }


    protected override void OnRender(DrawingContext drawingContext)
    {

        double width = this.ActualWidth;
        double height = this.ActualHeight;

        var itemWidth = width / 4;
        var itemHeight = height / 3;


        drawingContext.DrawRectangle(this.Background, null, new Rect(0, 0, width, height));
        // 画方框
        drawingContext.DrawRect(this.Foreground, 1, 1, width - 1, height - 1);

         画竖线
        //for (int i = 1; i < 4; i++)
        //{
        //    var left = i * itemWidth;
        //    drawingContext.DrawLine(this.Foreground, left, 0, left, height);
        //}

        // 画横线
        for (int i = 1; i < 3; i++)
        {
            var top = i * itemHeight;
            drawingContext.DrawLine(this.Foreground, 0, top, 3, top);

            drawingContext.DrawText(string.Format("-{0}dBFS", i * 30), this.TextBrush, 3 + 20, top, 13);
        }

        // 画折线
        if (mMaxVolume > mMinVolume)
        {
            DrawPointPath(drawingContext, width, height);
        }
    }


    private void DrawPointPath(DrawingContext drawingContext, double width, double height)
    {

        var itemHeight = height / 20;
        var itemWidth = width / dbList.Length;

        var amplitude = Math.Max(mMaxVolume - mMinVolume, 60);

        // 开始绘制路径
        StreamGeometry geometry = new StreamGeometry();
        using (StreamGeometryContext context = geometry.Open())
        {
            // 将路径移动到第一个数据点
            var x = (1 - (dbList[0] - mMinVolume) / amplitude) * 18;
            context.BeginFigure(new Point(0, x * itemHeight), false, false);

            // 添加线段连接每个数据点
            for (int i = 1; i < dbList.Length; i++)
            {
                if (dbList[i] < 0)
                {
                    x = (1 - (dbList[i] - mMinVolume) / amplitude) * 18;
                    context.LineTo(new Point(i * itemWidth, x * itemHeight), true, false);
                }
            }
        }

        // 绘制路径
        drawingContext.DrawGeometry(null, pen, geometry);
    }
}