Add meeting assistant speech and summary automation

2026-05-21 09:55:39 +02:00
parent 1e97d2b9ff
commit 48d98d9cbb
63 changed files with 5143 additions and 151 deletions
@@ -0,0 +1,109 @@
+using NAudio.Wave;
+
+namespace MeetingAssistant.Recording;
+
+internal sealed class RollingAudioBuffer
+{
+    private readonly TimeSpan retention;
+    private readonly object gate = new();
+    private readonly Queue<TimedAudioChunk> chunks = new();
+    private TimeSpan position;
+
+    public RollingAudioBuffer(TimeSpan retention)
+    {
+        this.retention = retention > TimeSpan.Zero ? retention : TimeSpan.FromMinutes(10);
+    }
+
+    public void Append(AudioChunk chunk)
+    {
+        if (chunk.Pcm.Length == 0 || chunk.SampleRate <= 0 || chunk.Channels <= 0)
+        {
+            return;
+        }
+
+        lock (gate)
+        {
+            var start = position;
+            var end = start + chunk.Duration;
+            chunks.Enqueue(new TimedAudioChunk(start, end, chunk));
+            position = end;
+            Prune(end - retention);
+        }
+    }
+
+    public byte[] TryExtractWav(TimeSpan start, TimeSpan end)
+    {
+        if (end <= start)
+        {
+            return [];
+        }
+
+        List<TimedAudioChunk> matchingChunks;
+        lock (gate)
+        {
+            matchingChunks = chunks
+                .Where(chunk => chunk.End > start && chunk.Start < end)
+                .ToList();
+        }
+
+        if (matchingChunks.Count == 0)
+        {
+            return [];
+        }
+
+        var format = new WaveFormat(
+            matchingChunks[0].Chunk.SampleRate,
+            16,
+            matchingChunks[0].Chunk.Channels);
+        using var output = new MemoryStream();
+        using (var writer = new WaveFileWriter(output, format))
+        {
+            foreach (var timedChunk in matchingChunks)
+            {
+                if (timedChunk.Chunk.SampleRate != format.SampleRate || timedChunk.Chunk.Channels != format.Channels)
+                {
+                    continue;
+                }
+
+                var blockAlign = format.BlockAlign;
+                var copyStart = Max(start, timedChunk.Start);
+                var copyEnd = Min(end, timedChunk.End);
+                var firstFrame = (int)Math.Floor((copyStart - timedChunk.Start).TotalSeconds * format.SampleRate);
+                var afterLastFrame = (int)Math.Ceiling((copyEnd - timedChunk.Start).TotalSeconds * format.SampleRate);
+                var byteOffset = Clamp(firstFrame * blockAlign, 0, timedChunk.Chunk.Pcm.Length);
+                var byteCount = Clamp(afterLastFrame * blockAlign, byteOffset, timedChunk.Chunk.Pcm.Length) - byteOffset;
+                if (byteCount > 0)
+                {
+                    writer.Write(timedChunk.Chunk.Pcm, byteOffset, byteCount);
+                }
+            }
+        }
+
+        return output.ToArray();
+    }
+
+    private void Prune(TimeSpan cutoff)
+    {
+        while (chunks.Count > 0 && chunks.Peek().End < cutoff)
+        {
+            chunks.Dequeue();
+        }
+    }
+
+    private static TimeSpan Max(TimeSpan left, TimeSpan right)
+    {
+        return left >= right ? left : right;
+    }
+
+    private static TimeSpan Min(TimeSpan left, TimeSpan right)
+    {
+        return left <= right ? left : right;
+    }
+
+    private static int Clamp(int value, int min, int max)
+    {
+        return Math.Min(Math.Max(value, min), max);
+    }
+
+    private sealed record TimedAudioChunk(TimeSpan Start, TimeSpan End, AudioChunk Chunk);
+}