feat: handle large video files

index.cs

@@ -6,7 +6,6 @@
 
 using FFMpegCore;
 using FFMpegCore.Enums;
-using FFMpegCore.Pipes;
 using NAudio.Wave;
 using Whisper.net;
 using Whisper.net.Ggml;
@@ -25,44 +24,41 @@ if (File.Exists(videoPath) is false)
   return;
 }
 
-using var mp4Stream = File.OpenRead(videoPath);
+var tempWavPath = Path.Combine(Path.GetTempPath(), $"{Guid.NewGuid()}.wav");
-using var mp3Stream = new MemoryStream();
 
-await FFMpegArguments
+try
-  .FromPipeInput(new StreamPipeSource(mp4Stream))
+{
-  .OutputToPipe(
+  await FFMpegArguments
-    new StreamPipeSink(mp3Stream),
+      .FromFileInput(videoPath)
-    static o => o.DisableChannel(Channel.Video).ForceFormat("mp3")
+      .OutputToFile(tempWavPath, true, options => options
+          .DisableChannel(Channel.Video)
+          .ForceFormat("wav")
+          .WithAudioSamplingRate(16000)
       )
       .ProcessAsynchronously();
 
-mp3Stream.Position = 0;
+  using var waveReader = new WaveFileReader(tempWavPath);
-using var reader = new Mp3FileReader(mp3Stream);
-var outFormat = new WaveFormat(16000, reader.WaveFormat.Channels);
-using var resampler = new MediaFoundationResampler(reader, outFormat);
-using var waveStream = new MemoryStream();
-WaveFileWriter.WriteWavFileToStream(waveStream, resampler);
 
-waveStream.Position = 0;
+  var segmentDuration = TimeSpan.FromMinutes(2);
-using var waveReader = new WaveFileReader(waveStream);
+  var totalDuration = waveReader.TotalTime;
-var segmentDuration = TimeSpan.FromMinutes(2);
+  var numOfSegments = (int)Math.Ceiling(totalDuration.TotalSeconds / segmentDuration.TotalSeconds);
-var totalDuration = waveReader.TotalTime;
+
-var numOfSegments = (int)Math.Ceiling(totalDuration.TotalSeconds / segmentDuration.TotalSeconds);
+  using var processor = await GetProcessor();
+
+  foreach (var i in Enumerable.Range(0, numOfSegments))
+  {
+    using var segmentReader = new WaveFileReader(tempWavPath);
 
-foreach (var i in Enumerable.Range(0, numOfSegments))
-{
-  waveStream.Position = 0;
-  using var segmentReader = new WaveFileReader(waveStream);
     var segment = segmentReader.ToSampleProvider()
         .Skip(i * segmentDuration)
         .Take(segmentDuration);
 
     var segmentProvider = segment.ToWaveProvider16();
-  var segmentStream = new MemoryStream();
+    using var segmentStream = new MemoryStream();
     WaveFileWriter.WriteWavFileToStream(segmentStream, segmentProvider);
 
     segmentStream.Position = 0;
-  using var processor = await GetProcessor();
+
     var durationOffset = TimeSpan.FromSeconds(i * segmentDuration.TotalSeconds);
 
     await foreach (var result in processor.ProcessAsync(segmentStream))
@@ -71,12 +67,28 @@ foreach (var i in Enumerable.Range(0, numOfSegments))
       var endTime = result.End + durationOffset;
       Console.WriteLine($"[{startTime:hh\\:mm\\:ss} - {endTime:hh\\:mm\\:ss}]: {result.Text}");
     }
+  }
+}
+finally
+{
+  // Cleanup temporary file
+  if (File.Exists(tempWavPath))
+  {
+    try
+    {
+      File.Delete(tempWavPath);
+    }
+    catch
+    {
+      // Best effort cleanup 
+    }
+  }
 }
 
 static async Task<WhisperProcessor> GetProcessor()
 {
   using var memoryStream = new MemoryStream();
-  var model = await WhisperGgmlDownloader.Default.GetGgmlModelAsync(GgmlType.TinyEn);
+  var model = await WhisperGgmlDownloader.Default.GetGgmlModelAsync(GgmlType.BaseEn);
   await model.CopyToAsync(memoryStream);
   var whisperFactory = WhisperFactory.FromBuffer(memoryStream.ToArray());
   return whisperFactory.CreateBuilder()