WorkIndicator/AudioWatcher.cs

using NAudio.CoreAudioApi;
using NAudio.CoreAudioApi.Interfaces;
using System.Collections.Generic;
using System.Linq;
using Serilog;

namespace WorkIndicator;

internal class AudioWatcher : IMMNotificationClient
{
    private readonly ILogger _logger = Log.ForContext<AudioWatcher>();
    private readonly MMDeviceEnumerator _deviceEnumerator = new();
    private readonly Dictionary<string, AudioDevice> _inputDevices = new();

    public delegate void MicrophoneInUseChangedDelegate(bool microphoneInUse);

    public event MicrophoneInUseChangedDelegate MicrophoneInUseChanged;

    public void Start()
    {
        _logger.Information("Start");

        _deviceEnumerator.RegisterEndpointNotificationCallback(this);

        _logger.Information("Getting capture devices");

        var captureDevices = _deviceEnumerator.EnumerateAudioEndPoints(DataFlow.Capture, DeviceState.Active);

        foreach (var captureDevice in captureDevices)
        {
            _logger.Information("Capture device: {name}", captureDevice.DeviceFriendlyName);

            HandleAddedDevice(captureDevice);
        }
    }

    private void HandleAddedDevice(MMDevice captureDevice)
    {
        _logger.Information("Device added: {name}", captureDevice.DeviceFriendlyName);

        var audioDevice = new AudioDevice(captureDevice);
        audioDevice.AudioSessionsChanged += AudioDevice_AudioSessionsChanged;

        _inputDevices[captureDevice.ID] = audioDevice;

        MicrophoneInUseChanged?.Invoke(MicrophoneInUse());
    }

    private void AudioDevice_AudioSessionsChanged()
    {
        MicrophoneInUseChanged?.Invoke(MicrophoneInUse());
    }

    private void HandleRemovedDevice(string deviceId)
    {
        _logger.Information("Device removed: {id}", deviceId);

        _inputDevices.Remove(deviceId);

        MicrophoneInUseChanged?.Invoke(MicrophoneInUse());
    }

    public void Stop()
    {
        _logger.Information("Stop");

        _deviceEnumerator.UnregisterEndpointNotificationCallback(this);
        _deviceEnumerator.Dispose();
    }

    public bool MicrophoneInUse()
    {
        var totalActiveSessionCount = _inputDevices.Sum(i => i.Value.ActiveSessionCount);

        return totalActiveSessionCount > 0;
    }

    void IMMNotificationClient.OnDeviceStateChanged(string deviceId, DeviceState newState)
    {
        _logger.Information("OnDeviceStateChanged: {deviceId} {newState}", deviceId, newState);
    }

    void IMMNotificationClient.OnDeviceAdded(string deviceId)
    {
        _logger.Information("OnDeviceAdded: {deviceId}", deviceId);

        var device = _deviceEnumerator.GetDevice(deviceId);

        if (device.DataFlow is DataFlow.Capture or DataFlow.All)
        {
            HandleAddedDevice(device);
        }
    }

    void IMMNotificationClient.OnDeviceRemoved(string deviceId)
    {
        _logger.Information("OnDeviceRemoved: {deviceId}", deviceId);

        HandleRemovedDevice(deviceId);
    }

    void IMMNotificationClient.OnDefaultDeviceChanged(DataFlow flow, Role role, string defaultDeviceId)
    {
        _logger.Information("OnDefaultDeviceChanged: {defaultDeviceId} {flow} {role}", defaultDeviceId, flow, role);
    }

    void IMMNotificationClient.OnPropertyValueChanged(string pwstrDeviceId, PropertyKey key)
    {
        _logger.Debug("OnPropertyValueChanged: {deviceId} {propertyId}", pwstrDeviceId, key.propertyId);
    }
}