Harden speaker identity samples

MeetingAssistant/Speakers/AzureSpeechSpeakerIdentityMatcher.cs

@@ -15,15 +15,18 @@ public sealed class AzureSpeechSpeakerIdentityMatcher : ISpeakerIdentityMatcher
     private readonly ISpeakerIdentityDiarizationClient diarizationClient;
     private readonly SpeakerIdentificationOptions options;
     private readonly ILogger<AzureSpeechSpeakerIdentityMatcher> logger;
+    private readonly ISpeakerIdentityMatchValidator matchValidator;
 
     public AzureSpeechSpeakerIdentityMatcher(
         ISpeakerIdentityDiarizationClient diarizationClient,
         Microsoft.Extensions.Options.IOptions<MeetingAssistantOptions> options,
-        ILogger<AzureSpeechSpeakerIdentityMatcher> logger)
+        ILogger<AzureSpeechSpeakerIdentityMatcher> logger,
+        ISpeakerIdentityMatchValidator matchValidator)
     {
         this.diarizationClient = diarizationClient;
         this.options = options.Value.SpeakerIdentification;
         this.logger = logger;
+        this.matchValidator = matchValidator;
     }
 
     public async Task<SpeakerIdentityMatch?> MatchAsync(
@@ -35,6 +38,14 @@ public sealed class AzureSpeechSpeakerIdentityMatcher : ISpeakerIdentityMatcher
             return null;
         }
 
+        if (!await matchValidator.ValidateSampleAsync(request.UnknownSnippet, cancellationToken))
+        {
+            logger.LogInformation(
+                "Speaker identity matching {DiarizedSpeaker} skipped because secondary validation rejected the unknown sample",
+                request.DiarizedSpeaker);
+            return null;
+        }
+
         logger.LogInformation(
             "Speaker identity matching {DiarizedSpeaker} against {CandidateCount} candidate(s)",
             request.DiarizedSpeaker,
@@ -84,6 +95,20 @@ public sealed class AzureSpeechSpeakerIdentityMatcher : ISpeakerIdentityMatcher
                 var requiredMatches = known.Count() > 1 ? 2 : 1;
                 if (matchingSnippetCount >= requiredMatches)
                 {
+                    var validationRequest = new SpeakerIdentityMatchValidationRequest(
+                        request.DiarizedSpeaker,
+                        known.Key,
+                        request.UnknownSnippet,
+                        known.Select(segment => segment.Snippet).ToList());
+                    if (!await matchValidator.ValidateMatchAsync(validationRequest, cancellationToken))
+                    {
+                        logger.LogInformation(
+                            "Speaker identity matching {DiarizedSpeaker} rejected identity {IdentityId} after secondary validation",
+                            request.DiarizedSpeaker,
+                            known.Key);
+                        continue;
+                    }
+
                     logger.LogInformation(
                         "Speaker identity matching {DiarizedSpeaker} matched identity {IdentityId}",
                         request.DiarizedSpeaker,
@@ -99,7 +124,7 @@ public sealed class AzureSpeechSpeakerIdentityMatcher : ISpeakerIdentityMatcher
         }
         finally
         {
-            TryDelete(tempPath);
+            SpeakerCompositeWav.TryDelete(tempPath);
         }
     }
 
@@ -130,7 +155,8 @@ public sealed class AzureSpeechSpeakerIdentityMatcher : ISpeakerIdentityMatcher
 
     private CompositeLayout WriteCompositeWav(string path, SpeakerIdentityMatchRequest request)
     {
-        using var firstReader = OpenFirstReadableWave(request);
+        using var firstReader = SpeakerCompositeWav.OpenFirstReadableWave(
+            request.Candidates.SelectMany(candidate => candidate.Snippets).Append(request.UnknownSnippet));
         if (firstReader is null)
         {
             return new CompositeLayout(null, []);
@@ -145,118 +171,33 @@ public sealed class AzureSpeechSpeakerIdentityMatcher : ISpeakerIdentityMatcher
         {
             foreach (var snippet in candidate.Snippets.Where(storedSnippet => storedSnippet.Length > 0))
             {
-                var segment = AppendSnippet(writer, firstReader.WaveFormat, snippet, current);
+                var segment = SpeakerCompositeWav.AppendSnippet(writer, firstReader.WaveFormat, snippet, current);
                 if (segment is null)
                 {
                     continue;
                 }
 
-                knownSegments.Add(new KnownCompositeSegment(candidate.IdentityId, segment.Value));
+                knownSegments.Add(new KnownCompositeSegment(candidate.IdentityId, segment.Value, snippet));
                 current = segment.Value.End + silence;
-                WriteSilence(writer, firstReader.WaveFormat, silence);
+                SpeakerCompositeWav.WriteSilence(writer, firstReader.WaveFormat, silence);
             }
         }
 
-        var unknownSegment = AppendSnippet(writer, firstReader.WaveFormat, request.UnknownSnippet, current);
+        var unknownSegment = SpeakerCompositeWav.AppendSnippet(
+            writer,
+            firstReader.WaveFormat,
+            request.UnknownSnippet,
+            current);
         return new CompositeLayout(unknownSegment, knownSegments);
     }
 
-    private static WaveFileReader? OpenFirstReadableWave(SpeakerIdentityMatchRequest request)
-    {
-        foreach (var bytes in request.Candidates.SelectMany(candidate => candidate.Snippets).Append(request.UnknownSnippet))
-        {
-            if (bytes.Length == 0)
-            {
-                continue;
-            }
-
-            try
-            {
-                return new WaveFileReader(new MemoryStream(bytes));
-            }
-            catch (FormatException)
-            {
-            }
-        }
-
-        return null;
-    }
-
-    private static TimeSegment? AppendSnippet(
-        WaveFileWriter writer,
-        WaveFormat targetFormat,
-        byte[] snippet,
-        TimeSpan start)
-    {
-        if (snippet.Length == 0)
-        {
-            return null;
-        }
-
-        using var reader = new WaveFileReader(new MemoryStream(snippet));
-        if (!WaveFormatsMatch(reader.WaveFormat, targetFormat))
-        {
-            throw new InvalidDataException("Speaker identity snippets must use the same WAV format.");
-        }
-
-        reader.CopyTo(writer);
-        return new TimeSegment(start, start + reader.TotalTime);
-    }
-
-    private static void WriteSilence(WaveFileWriter writer, WaveFormat format, TimeSpan duration)
-    {
-        if (duration <= TimeSpan.Zero)
-        {
-            return;
-        }
-
-        var bytes = new byte[(int)(format.AverageBytesPerSecond * duration.TotalSeconds)];
-        writer.Write(bytes, 0, bytes.Length);
-    }
-
     private static string? FindBestSpeaker(TimeSegment segment, IReadOnlyList<TranscriptionSegment> segments)
     {
-        var bestOverlap = 0d;
-        string? bestSpeaker = null;
-        foreach (var transcriptSegment in segments)
-        {
-            var overlap = Math.Min(segment.End.TotalSeconds, transcriptSegment.End.TotalSeconds)
-                - Math.Max(segment.Start.TotalSeconds, transcriptSegment.Start.TotalSeconds);
-            if (overlap > bestOverlap)
-            {
-                bestOverlap = overlap;
-                bestSpeaker = transcriptSegment.Speaker;
-            }
-        }
-
-        return bestSpeaker;
-    }
-
-    private static bool WaveFormatsMatch(WaveFormat left, WaveFormat right)
-    {
-        return left.Encoding == right.Encoding
-            && left.SampleRate == right.SampleRate
-            && left.Channels == right.Channels
-            && left.BitsPerSample == right.BitsPerSample;
-    }
-
-    private static void TryDelete(string path)
-    {
-        try
-        {
-            if (File.Exists(path))
-            {
-                File.Delete(path);
-            }
-        }
-        catch (IOException)
-        {
-        }
+        return SpeakerCompositeWav.FindBestSpeaker(segment, segments);
     }
 
     private sealed record CompositeLayout(TimeSegment? UnknownSegment, IReadOnlyList<KnownCompositeSegment> KnownSegments);
 
-    private sealed record KnownCompositeSegment(int IdentityId, TimeSegment Segment);
+    private sealed record KnownCompositeSegment(int IdentityId, TimeSegment Segment, byte[] Snippet);
 
-    private readonly record struct TimeSegment(TimeSpan Start, TimeSpan End);
 }