242 lines
9.7 KiB
Python
242 lines
9.7 KiB
Python
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import json
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from pathlib import Path
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from typing import Any
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import numpy as np
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from scipy import signal
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from scipy.fft import dct
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from scipy.spatial.distance import cdist
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from app.media import decode_audio
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from app.profile_store import Profile, artifact_path
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SUPPORTED_AUDIO_SUFFIXES = {".wav", ".mp3", ".m4a", ".aac", ".flac", ".ogg"}
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def _hz_to_mel(hz: np.ndarray | float) -> np.ndarray | float:
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return 2595.0 * np.log10(1.0 + np.asarray(hz) / 700.0)
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def _mel_to_hz(mel: np.ndarray) -> np.ndarray:
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return 700.0 * (np.power(10.0, mel / 2595.0) - 1.0)
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def _mel_filterbank(sample_rate: int, n_fft: int, bands: int) -> np.ndarray:
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mel_points = np.linspace(_hz_to_mel(40.0), _hz_to_mel(sample_rate / 2), bands + 2)
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bins = np.floor((n_fft + 1) * _mel_to_hz(mel_points) / sample_rate).astype(int)
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bins = np.clip(bins, 0, n_fft // 2)
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filters = np.zeros((bands, n_fft // 2 + 1), dtype=np.float32)
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for index in range(bands):
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left, center, right = bins[index : index + 3]
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if center > left:
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filters[index, left:center] = np.linspace(0, 1, center - left, endpoint=False)
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if right > center:
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filters[index, center:right] = np.linspace(1, 0, right - center, endpoint=False)
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return filters
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def _trim_audio(samples: np.ndarray, sample_rate: int) -> np.ndarray:
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if len(samples) < sample_rate // 4:
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return samples
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frame = max(1, int(sample_rate * 0.02))
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energy = np.convolve(samples * samples, np.ones(frame) / frame, mode="same")
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threshold = max(float(np.max(energy)) * 0.0025, 1e-7)
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active = np.flatnonzero(energy >= threshold)
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if not len(active):
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return samples
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padding = int(sample_rate * 0.15)
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return samples[max(0, active[0] - padding) : min(len(samples), active[-1] + padding)]
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def feature_sequence(
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samples: np.ndarray, sample_rate: int, max_frames: int = 320
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) -> np.ndarray:
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samples = _trim_audio(samples.astype(np.float32), sample_rate)
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samples -= float(np.mean(samples))
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peak = float(np.max(np.abs(samples))) if len(samples) else 0.0
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if peak < 1e-5:
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raise ValueError("Audio contains no usable sound")
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samples /= peak
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n_fft = 512
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if len(samples) < n_fft:
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samples = np.pad(samples, (0, n_fft - len(samples)))
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_, _, stft = signal.stft(
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samples,
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fs=sample_rate,
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window="hann",
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nperseg=n_fft,
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noverlap=384,
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boundary=None,
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padded=False,
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)
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mel = _mel_filterbank(sample_rate, n_fft, 40) @ (np.abs(stft) ** 2)
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coefficients = dct(np.log(mel + 1e-8), axis=0, norm="ortho")[1:21].T
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mean = np.mean(coefficients, axis=0)
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static = mean / max(float(np.linalg.norm(mean)), 1e-5)
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normalized = (coefficients - mean) / np.maximum(np.std(coefficients, axis=0), 1e-5)
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delta = np.gradient(normalized, axis=0)
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sequence = np.concatenate(
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[normalized, delta, np.tile(static * 0.75, (len(normalized), 1))], axis=1
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).astype(np.float32)
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sequence /= np.maximum(np.linalg.norm(sequence, axis=1, keepdims=True), 1e-5)
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sequence = sequence[::2]
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if len(sequence) > max_frames:
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indices = np.linspace(0, len(sequence) - 1, max_frames).round().astype(int)
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sequence = sequence[indices]
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return sequence
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def sequence_distance(first: np.ndarray, second: np.ndarray, band_ratio: float = 0.35) -> float:
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distances = cdist(first, second, metric="cosine")
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first_length, second_length = distances.shape
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band = max(
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abs(first_length - second_length) + 2,
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int(max(first_length, second_length) * band_ratio),
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)
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previous = np.full(second_length + 1, np.inf, dtype=np.float32)
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previous[0] = 0.0
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for first_index in range(1, first_length + 1):
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current = np.full(second_length + 1, np.inf, dtype=np.float32)
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start = max(1, first_index - band)
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end = min(second_length, first_index + band)
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for second_index in range(start, end + 1):
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current[second_index] = distances[first_index - 1, second_index - 1] + min(
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current[second_index - 1],
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previous[second_index],
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previous[second_index - 1],
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)
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previous = current
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return float(previous[second_length] / (first_length + second_length))
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def _read_audio(path: Path) -> tuple[np.ndarray, int]:
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raw, sample_rate = decode_audio(path)
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return np.frombuffer(raw, dtype="<i2").astype(np.float32) / 32768.0, sample_rate
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def build_audio_profile(profile: Profile) -> dict[str, Any]:
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references = profile.directory / "references"
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labels: list[str] = []
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files: list[str] = []
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durations: list[float] = []
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sequences: list[np.ndarray] = []
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for label_dir in sorted(path for path in references.glob("*") if path.is_dir()):
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for path in sorted(label_dir.iterdir()):
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if path.suffix.lower() not in SUPPORTED_AUDIO_SUFFIXES:
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continue
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samples, sample_rate = _read_audio(path)
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labels.append(label_dir.name)
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files.append(path.name)
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durations.append(len(samples) / sample_rate)
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sequences.append(feature_sequence(samples, sample_rate))
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unique_labels = sorted(set(labels))
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if len(unique_labels) < 2:
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raise ValueError("At least two non-empty reference audio groups are required")
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minimum_per_label = int(profile.config.get("minimumReferencesPerLabel", 1))
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counts = {label: labels.count(label) for label in unique_labels}
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insufficient = [label for label, count in counts.items() if count < minimum_per_label]
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if insufficient:
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raise ValueError(
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f"Reference groups below minimum {minimum_per_label}: {', '.join(insufficient)}"
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)
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offsets = np.concatenate(([0], np.cumsum([len(sequence) for sequence in sequences])))
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output = artifact_path(profile)
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output.parent.mkdir(parents=True, exist_ok=True)
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np.savez_compressed(
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output,
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sequence_features=np.concatenate(sequences),
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sequence_offsets=offsets,
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labels=np.asarray(labels),
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files=np.asarray(files),
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durations=np.asarray(durations, dtype=np.float32),
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)
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manifest = output.with_name("manifest.json")
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manifest.write_text(
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json.dumps(
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{
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"profileCode": profile.code,
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"featureVersion": "mfcc-dtw-v2",
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"labelCounts": counts,
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"referenceCount": len(sequences),
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"files": files,
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},
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ensure_ascii=False,
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indent=2,
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),
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encoding="utf-8",
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)
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return {"referenceCount": len(sequences), "labelCounts": counts}
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def load_reference_sequences(profile: Profile):
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artifact = artifact_path(profile)
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if not artifact.exists():
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raise ValueError(
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f"Profile {profile.code} has no feature library; add reference audio and rebuild it"
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)
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data = np.load(artifact, allow_pickle=False)
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if "sequence_features" not in data or "sequence_offsets" not in data:
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raise ValueError(f"Profile {profile.code} uses an obsolete feature library; rebuild it")
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features = data["sequence_features"]
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offsets = data["sequence_offsets"].astype(int)
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sequences = [features[offsets[index] : offsets[index + 1]] for index in range(len(offsets) - 1)]
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return sequences, data["labels"].astype(str), data["files"].astype(str)
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def classify_sequence(
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profile: Profile,
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query: np.ndarray,
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reference_sequences: list[np.ndarray],
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labels: np.ndarray,
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files: np.ndarray,
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) -> dict[str, Any]:
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best_by_label: dict[str, dict[str, Any]] = {}
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for reference, label, file_name in zip(reference_sequences, labels, files):
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distance = sequence_distance(query, reference)
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current = best_by_label.get(label)
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if current is None or distance < current["distance"]:
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best_by_label[label] = {"distance": distance, "reference": file_name}
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ranking = sorted(best_by_label.items(), key=lambda item: item[1]["distance"])
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winner_label, winner = ranking[0]
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second_distance = ranking[1][1]["distance"] if len(ranking) > 1 else 1.0
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distance_margin = second_distance - winner["distance"]
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decision = profile.config.get("decision", {})
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maximum_distance = float(decision.get("maxDistance", 0.45))
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minimum_margin = float(decision.get("minDistanceMargin", 0.015))
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matched = winner["distance"] <= maximum_distance and distance_margin >= minimum_margin
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output_label = winner_label if matched else str(decision.get("unknownLabel", "UNKNOWN"))
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label_names = profile.config.get("labelNames", {})
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return {
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"label": output_label,
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"labelName": label_names.get(output_label, output_label),
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"matched": matched,
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"confidence": round(max(0.0, min(1.0, 1.0 - winner["distance"])), 6),
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"scores": {
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label: round(max(0.0, min(1.0, 1.0 - item["distance"])), 6)
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for label, item in ranking
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},
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"evidence": {"reference": winner["reference"] if matched else None},
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"thresholds": {
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"maxDistance": maximum_distance,
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"minDistanceMargin": minimum_margin,
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},
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}
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def classify_audio(profile: Profile, media_path: Path) -> dict[str, Any]:
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reference_sequences, labels, files = load_reference_sequences(profile)
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samples, sample_rate = _read_audio(media_path)
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maximum_seconds = float(profile.config.get("maximumAudioSeconds", 30))
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if len(samples) / sample_rate > maximum_seconds:
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raise ValueError(f"Audio duration exceeds the profile limit of {maximum_seconds:g} seconds")
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query = feature_sequence(samples, sample_rate)
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result = classify_sequence(profile, query, reference_sequences, labels, files)
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result["evidence"].update({"startMs": 0, "endMs": round(len(samples) * 1000 / sample_rate)})
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return result
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