Claude (homelab agent)andClaude Opus 5.5
56eb5af0ff
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
38 lines
1.4 KiB
Python
38 lines
1.4 KiB
Python
"""MPEG Layer III duration without external tools."""
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_BR1 = [0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320]
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_BR2 = [0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160]
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_SR = {3: [44100, 48000, 32000], 2: [22050, 24000, 16000], 0: [11025, 12000, 8000]}
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def mp3_duration(path):
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"""Duration of an MPEG Layer III file by walking frame headers (works for VBR)."""
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with open(path, "rb") as fh:
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data = fh.read()
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i = 0
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if data[:3] == b"ID3" and len(data) >= 10:
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i = 10 + ((data[6] & 0x7f) << 21 | (data[7] & 0x7f) << 14 | (data[8] & 0x7f) << 7 | (data[9] & 0x7f))
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samples = 0.0
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first = True
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n = len(data)
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while i + 4 <= n:
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h = int.from_bytes(data[i:i + 4], "big")
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ver, layer, bri, sri = (h >> 19) & 3, (h >> 17) & 3, (h >> 12) & 15, (h >> 10) & 3
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if (h >> 21) & 0x7ff != 0x7ff or ver == 1 or layer != 1 or bri in (0, 15) or sri == 3:
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i += 1
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continue
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sr = _SR[ver][sri]
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pad = (h >> 9) & 1
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if ver == 3:
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flen, spf = 144000 * _BR1[bri] // sr + pad, 1152
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else:
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flen, spf = 72000 * _BR2[bri] // sr + pad, 576
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if first:
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first = False
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if b"Xing" in data[i:i + 64] or b"Info" in data[i:i + 64]:
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i += flen
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continue
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samples += spf / sr
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i += flen
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return samples
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