Record ffmpeg

record.cs

public static async Task RecordAsync(Stream stream, string microphone, CancellationToken cancellationToken, Action<double> detectedSilenceCallback = null)
        {
            // do this to get audio device with a mic
            // ffmpeg -list_devices true -f dshow -i dummy
            // pick one then add it to the audio device
            // ffmpeg -f dshow -i audio="Microphone (HD Pro Webcam C920)" -ar 16000 output.wav
            using var gracefulCts = new CancellationTokenSource();
            try
            {
                // ffmpeg -f dshow -i audio="Microphone Array (Intel® Smart Sound Technology for Digital Microphones)" -ar 16000 -preset ultrafast -tune zerolatency -b 900k -f mpegts udp://127.0.0.1:9876
                var silenceEnded = 0.0;
                var cmd = Cli.Wrap("ffmpeg")
                    .WithArguments(new string[] {
                    "-f dshow",
                    $"-i audio=\"{microphone}\"",
                    "-ar 16000",
                    //"-af silencedetect=d=1.5",
                    "-af \"silencedetect=n=-30dB:d=2\"",
                    "-nostats",
                    "-f mpegts",
                    "pipe:1"
                    }, false) |
                    (PipeTarget.ToStream(stream),
                    PipeTarget.ToDelegate(buffer =>
                    {
                        Console.WriteLine(buffer);
                        if (buffer.Contains("silencedetect")
                            && detectedSilenceCallback != null)
                        {
                            //silence_end is the start of a request
                            //silence_start is when audio should be processed
                            // the difference in time should be greater than 5 seconds at least
                            if (buffer.Contains("silence_duration"))
                                silenceEnded = Convert.ToDouble(buffer.Split("silence_end:")[1].Split("|")[0].Trim());
                            else if (buffer.Contains("silence_start")) {
                                var silenceStart = Convert.ToDouble(buffer.Split("silence_start:")[1].Trim());
                                detectedSilenceCallback?.Invoke(silenceStart - silenceEnded);
                            }
                        }
                    })
                );
                await cmd.ExecuteAsync(cancellationToken, gracefulCts.Token);
            }
            catch (OperationCanceledException)
            {
                Console.WriteLine("timeout");
            }
        }