Record audio output device

Program.cs

using System;
using NAudio.Lame;
using NAudio.Wave;

namespace CaptureAudio
{
    class Program
    {
        static LameMP3FileWriter _writer;

        /// <summary>
        /// Install-Package NAudio
        /// Install-Package NAudio.Lame
        /// </summary>
        static void Main(string[] args)
        {
            var filename = string.Format("rec [{0:yyyyMMddHHmmssfff}].mp3", DateTime.Now);
            using (var waveIn = new WasapiLoopbackCapture())
            using (var writer = _writer = new LameMP3FileWriter(filename, waveIn.WaveFormat, 32))
            {
                try
                {
                    waveIn.DataAvailable += Append;
                    waveIn.StartRecording();
                    Console.WriteLine("Recording. (Press any key to stop)");

                    while (!Console.KeyAvailable)
                        System.Threading.Thread.Sleep(50);
                }
                finally
                {
                    writer.Flush();
                }
            }
        }

        static void Append(object sender, WaveInEventArgs e)
        {
            if (_writer != null)
                _writer.Write(e.Buffer, 0, e.BytesRecorded);
        }
    }
}

ProgramWav.cs

using System;
using NAudio.Wave;

namespace SoundCapture
{
    class Program
    {
        static WaveFileWriter _writer;

        /// <summary>
        /// Install-Package NAudio
        /// Install-Package NAudio.Lame
        /// </summary>
        static void Main(string[] args)
        {
            var filename = $"rec [{DateTime.Now:yyyyMMddHHmmssfff}].wav";
            using (var waveIn = new WasapiLoopbackCapture())
            using (var writer = _writer = new WaveFileWriter(filename, waveIn.WaveFormat))
            {
                try
                {
                    waveIn.DataAvailable += Append;
                    waveIn.StartRecording();
                    Console.WriteLine("Recording. (Press any key to stop)");

                    while (!Console.KeyAvailable)
                        System.Threading.Thread.Sleep(50);
                }
                finally
                {
                    writer.Flush();
                }
            }
        }

        static void Append(object sender, WaveInEventArgs e)
        {
            _writer?.Write(e.Buffer, 0, e.BytesRecorded);
        }
    }
}