Add structured chirplet calibration phrase
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Meta Vens
parent
5ab8e80cf0
commit
bbb052a8ba
12 changed files with 392 additions and 136 deletions
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@ -6,10 +6,8 @@ public sealed class MimirAudioSynchronizationAnalyzer
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{
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private const int MaxWindowSamples = 48_000 * 5;
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private const int MaxLagSamples = 2_400;
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private const int ChirpletHopSamples = 64;
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private const double ChirpletDurationSeconds = 0.08;
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private const double ChirpletStartHz = 9_000.0;
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private const double ChirpletEndHz = 16_000.0;
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private const int ChirpletHopSamples = 16;
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private readonly MimirChirpletCalibrationPhrase chirpletPhrase = MimirChirpletCalibrationPhrase.Default;
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public IReadOnlyList<MimirAudioSynchronizationReport> Analyze(
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IEnumerable<MimirRollingStreamBuffer> buffers,
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@ -66,23 +64,29 @@ public sealed class MimirAudioSynchronizationAnalyzer
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continue;
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}
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var referenceSync = BuildChirpletEnergyTrace(referenceSamples.AsSpan(^compared..), referenceBlock.SampleRate);
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var candidateSync = BuildChirpletEnergyTrace(candidateSamples.AsSpan(^compared..), referenceBlock.SampleRate);
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var referenceWindow = referenceSamples.AsSpan(^compared..);
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var candidateWindow = candidateSamples.AsSpan(^compared..);
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var referenceSync = chirpletPhrase.BuildEnergyTrace(referenceWindow, referenceBlock.SampleRate, ChirpletHopSamples);
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var candidateSync = chirpletPhrase.BuildEnergyTrace(candidateWindow, referenceBlock.SampleRate, ChirpletHopSamples);
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if (referenceSync.Length < 16 || candidateSync.Length < 16)
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{
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continue;
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}
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var maxLag = Math.Min(MaxLagSamples / ChirpletHopSamples, Math.Min(referenceSync.Length, candidateSync.Length) / 2);
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var (delaySamples, confidence) = EstimateDelay(referenceSync, candidateSync, maxLag);
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delaySamples *= ChirpletHopSamples;
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var (delayHops, confidence) = EstimateDelay(referenceSync, candidateSync, maxLag);
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var fractionalDelaySamples = delayHops * ChirpletHopSamples;
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var delaySamples = (int)Math.Round(fractionalDelaySamples);
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var bandResponses = chirpletPhrase.EstimateBandResponse(candidateWindow, referenceBlock.SampleRate);
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reports.Add(new MimirAudioSynchronizationReport(
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reference.Descriptor.SourceId,
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buffer.Descriptor.SourceId,
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referenceBlock.SampleRate,
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delaySamples,
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delaySamples * 1000.0 / referenceBlock.SampleRate,
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fractionalDelaySamples,
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fractionalDelaySamples * 1000.0 / referenceBlock.SampleRate,
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confidence,
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bandResponses,
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compared,
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reference.Latest?.Sequence ?? 0,
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buffer.Latest?.Sequence ?? 0));
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@ -142,7 +146,7 @@ public sealed class MimirAudioSynchronizationAnalyzer
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var maxPositiveDelay = Math.Max(0, alignedReports.Select(report => report.DelaySamples).DefaultIfEmpty(0).Max());
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var channels = new List<MimirAlignedAudioChannel>
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{
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new(referenceSourceId, 0, 1.0),
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new(referenceSourceId, 0, 0.0, 1.0),
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};
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var samples = new List<float[]>
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{
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@ -171,7 +175,11 @@ public sealed class MimirAudioSynchronizationAnalyzer
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}
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samples.Add(TailEndingBefore(candidateSamples, frameCount, trimSamples));
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channels.Add(new MimirAlignedAudioChannel(report.SourceId, report.DelaySamples, report.Confidence));
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channels.Add(new MimirAlignedAudioChannel(
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report.SourceId,
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report.DelaySamples,
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report.FractionalDelaySamples,
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report.Confidence));
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}
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return new MimirAlignedAudioFrame(
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@ -276,81 +284,12 @@ public sealed class MimirAudioSynchronizationAnalyzer
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return output;
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}
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private static float[] BuildChirpletEnergyTrace(ReadOnlySpan<float> samples, int sampleRate)
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{
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var kernelLength = Math.Max(8, (int)Math.Round(sampleRate * ChirpletDurationSeconds));
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if (samples.Length < kernelLength)
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{
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return [];
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}
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var output = new float[1 + (samples.Length - kernelLength) / ChirpletHopSamples];
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for (var frame = 0; frame < output.Length; frame++)
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{
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var offset = frame * ChirpletHopSamples;
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var real = 0.0;
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var imag = 0.0;
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var energy = 0.0;
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for (var index = 0; index < kernelLength; index++)
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{
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var normalized = kernelLength <= 1 ? 1.0 : index / (double)(kernelLength - 1);
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var time = index / (double)sampleRate;
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var envelope = 0.5 - 0.5 * Math.Cos(2.0 * Math.PI * normalized);
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var phase = 2.0 * Math.PI * (ChirpletStartHz * time + 0.5 * (ChirpletEndHz - ChirpletStartHz) * time * normalized);
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var sample = samples[offset + index] * envelope;
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real += sample * Math.Cos(phase);
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imag -= sample * Math.Sin(phase);
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energy += sample * sample;
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}
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var magnitude = Math.Sqrt(real * real + imag * imag);
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output[frame] = energy > 1.0e-12 ? (float)(magnitude / Math.Sqrt(energy)) : 0.0f;
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}
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return ContrastNormalize(output);
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}
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private static float[] ContrastNormalize(float[] samples)
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{
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if (samples.Length == 0)
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{
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return samples;
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}
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var mean = 0.0;
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for (var index = 0; index < samples.Length; index++)
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{
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mean += samples[index];
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}
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mean /= samples.Length;
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var variance = 0.0;
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for (var index = 0; index < samples.Length; index++)
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{
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var centered = samples[index] - mean;
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variance += centered * centered;
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}
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var deviation = Math.Sqrt(variance / samples.Length);
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if (deviation <= 1.0e-12)
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{
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return samples;
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}
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var output = new float[samples.Length];
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for (var index = 0; index < samples.Length; index++)
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{
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var z = (samples[index] - mean) / deviation;
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output[index] = z > 0.0 ? (float)(z * z) : 0.0f;
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}
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return output;
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}
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private static (int DelaySamples, double Confidence) EstimateDelay(ReadOnlySpan<float> reference, ReadOnlySpan<float> candidate, int maxLag)
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private static (double DelaySamples, double Confidence) EstimateDelay(ReadOnlySpan<float> reference, ReadOnlySpan<float> candidate, int maxLag)
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{
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var bestLag = 0;
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var best = double.NegativeInfinity;
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var previous = double.NegativeInfinity;
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var next = double.NegativeInfinity;
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for (var lag = -maxLag; lag <= maxLag; lag++)
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{
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var score = NormalizedCorrelation(reference, candidate, lag);
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@ -361,7 +300,34 @@ public sealed class MimirAudioSynchronizationAnalyzer
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}
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}
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return (bestLag, Math.Max(0.0, Math.Min(1.0, best)));
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if (bestLag > -maxLag)
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{
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previous = NormalizedCorrelation(reference, candidate, bestLag - 1);
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}
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if (bestLag < maxLag)
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{
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next = NormalizedCorrelation(reference, candidate, bestLag + 1);
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}
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var offset = ParabolicPeakOffset(previous, best, next);
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return (bestLag + offset, Math.Max(0.0, Math.Min(1.0, best)));
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}
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private static double ParabolicPeakOffset(double left, double center, double right)
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{
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if (!double.IsFinite(left) || !double.IsFinite(center) || !double.IsFinite(right))
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{
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return 0.0;
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}
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var denominator = left - 2.0 * center + right;
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if (Math.Abs(denominator) <= 1.0e-12)
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{
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return 0.0;
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}
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return Math.Clamp(0.5 * (left - right) / denominator, -0.5, 0.5);
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}
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private static double NormalizedCorrelation(ReadOnlySpan<float> reference, ReadOnlySpan<float> candidate, int lag)
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