FormMicrophone.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Spectrogram.MicrophoneDemo
{
    public partial class FormMicrophone : Form
    {
        Colormap[] cmaps;

        public FormMicrophone()
        {
            InitializeComponent();

            if (NAudio.Wave.WaveIn.DeviceCount == 0)
            {
                MessageBox.Show("No audio input devices found.\n\nThis program will now exit.",
                    "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error);
                Close();
            }
            else
            {
                cbDevice.Items.Clear();
                for (int i = 0; i < NAudio.Wave.WaveIn.DeviceCount; i++)
                    cbDevice.Items.Add(NAudio.Wave.WaveIn.GetCapabilities(i).ProductName);
                cbDevice.SelectedIndex = 0;
            }

            for (int i = 9; i < 16; i++)
                cbFftSize.Items.Add($"2^{i} ({1 << i:N0})");
            cbFftSize.SelectedIndex = 1;

            cmaps = Colormap.GetColormaps();
            foreach (Colormap cmap in cmaps)
                cbColormap.Items.Add(cmap.Name);
            cbColormap.SelectedIndex = cbColormap.Items.IndexOf("Viridis");
        }

        private void Form1_Load(object sender, EventArgs e) { }
        private void cbDevice_SelectedIndexChanged(object sender, EventArgs e) => StartListening();
        private void cbFftSize_SelectedIndexChanged(object sender, EventArgs e) => StartListening();

        private SpectrogramGenerator spec;
        private Listener listener;
        private void StartListening()
        {
            int sampleRate = 6000;
            int fftSize = 1 << (9 + cbFftSize.SelectedIndex);
            int stepSize = fftSize / 20;

            pbSpectrogram.Image?.Dispose();
            pbSpectrogram.Image = null;
            listener?.Dispose();
            listener = new Listener(cbDevice.SelectedIndex, sampleRate);
            spec = new SpectrogramGenerator(sampleRate, fftSize, stepSize);
            pbSpectrogram.Height = spec.Height;

            pbScaleVert.Image?.Dispose();
            pbScaleVert.Image = spec.GetVerticalScale(pbScaleVert.Width);
            pbScaleVert.Height = spec.Height;
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            double[] newAudio = listener.GetNewAudio();
            spec.Add(newAudio, process: false);

            double multiplier = tbBrightness.Value / 20.0;

            if (spec.FftsToProcess > 0)
            {
                Stopwatch sw = Stopwatch.StartNew();
                spec.Process();
                spec.SetFixedWidth(pbSpectrogram.Width);
                Bitmap bmpSpec = new Bitmap(spec.Width, spec.Height, System.Drawing.Imaging.PixelFormat.Format32bppPArgb);
                using (var bmpSpecIndexed = spec.GetBitmap(multiplier, cbDecibels.Checked, roll: cbRoll.Checked))
                using (var gfx = Graphics.FromImage(bmpSpec))
                using (var pen = new Pen(Color.White))
                {
                    gfx.DrawImage(bmpSpecIndexed, 0, 0);
                    if (cbRoll.Checked)
                    {
                        gfx.DrawLine(pen, spec.NextColumnIndex, 0, spec.NextColumnIndex, pbSpectrogram.Height);
                    }
                }
                sw.Stop();
                pbSpectrogram.Image?.Dispose();
                pbSpectrogram.Image = bmpSpec;
                lblStatus3.Text = $"Render time: {sw.ElapsedMilliseconds:D2} ms";
                lblStatus4.Text = $"Peak (Hz): {spec.GetPeak().freqHz:N0}";
            }

            lblStatus1.Text = $"Time: {listener.TotalTimeSec:N3} sec";
            lblStatus2.Text = $"FFTs processed: {spec.FftsProcessed:N0}";
            pbAmplitude.Value = (int)(listener.AmplitudeFrac * pbAmplitude.Maximum);
        }

        private void cbColormap_SelectedIndexChanged(object sender, EventArgs e)
        {
            spec.SetColormap(cmaps[cbColormap.SelectedIndex]);
        }

        private void btnResetRoll_Click(object sender, EventArgs e)
        {
            spec.RollReset();
        }

        private void cbRoll_CheckedChanged(object sender, EventArgs e)
        {
            btnResetRoll.Enabled = cbRoll.Checked;
        }
    }
}