zhukang
1c7abd81d1
- 310 registry:skill items, 1528 files, 7 categories (hub tags) - registry.json generated by @kortix/registry buildRegistry - nested SKILL.md in sn-da-* renamed SUBSKILL.md (no phantom skills) - provenance + licenses: SOURCES.md
28 lines
951 B
Python
28 lines
951 B
Python
#!/usr/bin/env python3
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"""Find time offset of a short clip within a longer source via FFT cross-correlation.
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Usage: audio_align.py CLIP_PCM SRC_PCM SRC_WINDOW_OFFSET_S
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Both files must be int16 mono PCM at 8000 Hz.
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SRC_WINDOW_OFFSET_S is the absolute time of the start of SRC_PCM in the original source.
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Stdout: absolute offset (seconds) of CLIP_PCM start within the original source.
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"""
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import numpy as np, sys
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SR = 8000
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clip = np.fromfile(sys.argv[1], dtype=np.int16).astype(np.float32)
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src = np.fromfile(sys.argv[2], dtype=np.int16).astype(np.float32)
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window_off = float(sys.argv[3])
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clip = (clip - clip.mean()) / (clip.std() + 1e-9)
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src = (src - src.mean()) / (src.std() + 1e-9)
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n = len(src) + len(clip)
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p = 1
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while p < n: p *= 2
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S = np.fft.rfft(src, p)
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C = np.fft.rfft(clip[::-1], p)
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corr = np.fft.irfft(S * C, p)[:n-1]
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peak = int(np.argmax(corr))
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offset_in_window = (peak - (len(clip) - 1)) / SR
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print(f"{window_off + offset_in_window:.3f}")
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