This application records microphone audio, detects silence, and transcribes speech into text using Whisper.net and NAudio. It supports multiple transcription modes: real-time, silence-aware, and WAV-file-based.
Use 16Khz Wav’s for a file feeds (FFMPEG).
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using NAudio.CoreAudioApi; using NAudio.Wave; using System; using System.Diagnostics; using System.IO; using System.Threading; using System.Threading.Tasks; using System.Windows.Forms; using Whisper.net; using Whisper.net.Ggml; using Whisper.net.Logger; //Install-Package Whisper.net.AllRuntimes //Install-Package NAudio //ffmpeg -i 111.mp3 -acodec pcm_s16le -ac 1 -ar 16000 out.wav namespace WhisperAudioToText { public partial class Form1 : Form { private WaveInEvent waveIn; private BufferedWaveProvider buffer; private WaveFileWriter writer; private string tempWavFile = Path.Combine(Path.GetTempPath(), "live.wav"); public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { //WAVToText(); //StartRealtimeIntervalWhisperAsync(); StartSilenceAwareWhisperAsync(); } private static async void WAVToText() { var ggmlType = GgmlType.Base; var modelFileName = "ggml-base.bin"; var wavFileName = @"D:\ffmpeg-7.1.1-full_build\bin\out.wav"; IDisposable whisperLogger = null; try { whisperLogger = LogProvider.AddConsoleLogging(WhisperLogLevel.Debug); if (!File.Exists(modelFileName)) { await DownloadModel(modelFileName, ggmlType); } using (var whisperFactory = WhisperFactory.FromPath(modelFileName)) using (var processor = whisperFactory.CreateBuilder() .WithLanguage("auto") .Build()) using (var fileStream = File.OpenRead(wavFileName)) { var results = processor.ProcessAsync(fileStream); var enumerator = results.GetAsyncEnumerator(); try { while (await enumerator.MoveNextAsync()) { var result = enumerator.Current; Console.WriteLine($"{result.Start}->{result.End}: {result.Text}"); } } finally { if (enumerator != null) await enumerator.DisposeAsync(); } } } finally { if (whisperLogger != null) whisperLogger.Dispose(); } } private bool _isRecording = false; private CancellationTokenSource _cancellationSource; private bool _isSilenceModeActive = false; private CancellationTokenSource _silenceToken; private const string modelFileName = "ggml-base.bin"; private async Task StartSilenceAwareWhisperAsync() { var ggmlType = GgmlType.Base; var silenceThreshold = 0.005f; var silenceDuration = TimeSpan.FromSeconds(1); //After one second of silence, process the request IDisposable whisperLogger = null; if (!File.Exists(modelFileName)) await DownloadModel(modelFileName, ggmlType); _isSilenceModeActive = true; _silenceToken = new CancellationTokenSource(); try { whisperLogger = LogProvider.AddConsoleLogging(WhisperLogLevel.None); // Disable verbose logs while (_isSilenceModeActive && !_silenceToken.IsCancellationRequested) { var waveFormat = new WaveFormat(16000, 1); var waveIn = new WaveInEvent { WaveFormat = waveFormat, BufferMilliseconds = 200 }; var chunkBuffer = new MemoryStream(); var writer = new WaveFileWriter(chunkBuffer, waveFormat); TimeSpan silenceTimer = TimeSpan.Zero; bool recordingStopped = false; EventHandler<WaveInEventArgs> dataAvailableHandler = (s, a) => { writer.Write(a.Buffer, 0, a.BytesRecorded); writer.Flush(); float maxVolume = GetMaxVolume(a.Buffer, a.BytesRecorded); if (maxVolume < silenceThreshold) { silenceTimer += TimeSpan.FromMilliseconds(waveIn.BufferMilliseconds); if (silenceTimer >= silenceDuration && !recordingStopped) { recordingStopped = true; waveIn.StopRecording(); } } else { silenceTimer = TimeSpan.Zero; } }; waveIn.DataAvailable += dataAvailableHandler; waveIn.StartRecording(); while (!recordingStopped && !_silenceToken.IsCancellationRequested) await Task.Delay(100); waveIn.DataAvailable -= dataAvailableHandler; writer.Flush(); byte[] audioData = chunkBuffer.ToArray(); writer.Dispose(); waveIn.Dispose(); if (IsSilent(audioData)) { //Debug.WriteLine("[Skipped silent chunk]"); continue; } // Transcribe in background using a dedicated processor _ = Task.Run(async () => { try { using (var whisperFactory = WhisperFactory.FromPath(modelFileName)) using (var taskProcessor = whisperFactory.CreateBuilder() .WithLanguage("auto") .Build()) using (var memoryStream = new MemoryStream(audioData)) { var results = taskProcessor.ProcessAsync(memoryStream); var enumerator = results.GetAsyncEnumerator(); try { while (await enumerator.MoveNextAsync()) { var result = enumerator.Current; Debug.WriteLine($"{DateTime.Now} {result.Start}->{result.End}: {result.Text}"); } } finally { await enumerator.DisposeAsync(); } } } catch (Exception ex) { Debug.WriteLine("Transcription Task Error: " + ex.Message); } }); } } finally { whisperLogger?.Dispose(); } } private bool IsSilent(byte[] buffer) { if (buffer == null || buffer.Length <= 44) return true; // Skip the first 44 bytes (WAV header) int offset = 44; double sumSquares = 0; int samples = (buffer.Length - offset) / 2; for (int i = offset; i < buffer.Length; i += 2) { short sample = BitConverter.ToInt16(buffer, i); double normalized = sample / 32768.0; sumSquares += normalized * normalized; } double rms = Math.Sqrt(sumSquares / samples); // Debug: Show RMS & first few bytes (optional) if (false) { Debug.WriteLine("RMS: " + rms.ToString("F6")); for (int i = 0; i < Math.Min(16, buffer.Length); i++) Debug.Write(buffer[i].ToString("X2") + " "); Debug.WriteLine(""); } // Silence if RMS is very low return rms < 0.001; } private float GetMaxVolume(byte[] buffer, int bytesRecorded) { float max = 0; for (int i = 0; i < bytesRecorded; i += 2) { short sample = BitConverter.ToInt16(buffer, i); float amplitude = Math.Abs(sample / 32768f); if (amplitude > max) max = amplitude; } return max; } private async Task StartRealtimeIntervalWhisperAsync() { var modelFileName = "ggml-base.bin"; var ggmlType = GgmlType.Base; IDisposable whisperLogger = null; try { whisperLogger = LogProvider.AddConsoleLogging(WhisperLogLevel.Warning); if (!File.Exists(modelFileName)) { await DownloadModel(modelFileName, ggmlType); } _isRecording = true; _cancellationSource = new CancellationTokenSource(); using (var whisperFactory = WhisperFactory.FromPath(modelFileName)) using (var processor = whisperFactory.CreateBuilder() .WithLanguage("auto") .Build()) { while (_isRecording && !_cancellationSource.IsCancellationRequested) { string chunkPath = Path.Combine(Path.GetTempPath(), "chunk_" + Guid.NewGuid().ToString("N") + ".wav"); await RecordChunkAsync(chunkPath, durationMs: 5000); using (var fileStream = File.OpenRead(chunkPath)) { var results = processor.ProcessAsync(fileStream); var enumerator = results.GetAsyncEnumerator(); try { while (await enumerator.MoveNextAsync()) { var result = enumerator.Current; Debug.WriteLine(result.Start + "->" + result.End + ": " + result.Text); } } finally { if (enumerator != null) await enumerator.DisposeAsync(); } } File.Delete(chunkPath); } } } finally { whisperLogger?.Dispose(); } } private async Task RecordChunkAsync(string filePath, int durationMs) { var waveFormat = new WaveFormat(16000, 1); var waveIn = new WaveInEvent { WaveFormat = waveFormat, BufferMilliseconds = 250 }; var buffer = new BufferedWaveProvider(waveFormat); var writer = new WaveFileWriter(filePath, waveFormat); waveIn.DataAvailable += (s, a) => { buffer.AddSamples(a.Buffer, 0, a.BytesRecorded); writer.Write(a.Buffer, 0, a.BytesRecorded); writer.Flush(); }; waveIn.StartRecording(); await Task.Delay(durationMs); waveIn.StopRecording(); writer.Dispose(); waveIn.Dispose(); } private void StopRealtimeWhisper() { _isRecording = false; _cancellationSource?.Cancel(); } private static async Task DownloadModel(string fileName, GgmlType ggmlType) { Console.WriteLine($"Downloading Model {fileName}"); using (var modelStream = await WhisperGgmlDownloader.Default.GetGgmlModelAsync(ggmlType)) using (var fileWriter = File.OpenWrite(fileName)) { await modelStream.CopyToAsync(fileWriter); } } } } |