87 lines
2.5 KiB
Python
87 lines
2.5 KiB
Python
# This file is part of audioread.
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# Copyright 2011, Adrian Sampson.
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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"""Decode MPEG audio files with MAD (via pymad)."""
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import mad
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from . import DecodeError
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from .base import AudioFile
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class UnsupportedError(DecodeError):
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"""The file is not readable by MAD."""
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class MadAudioFile(AudioFile):
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"""MPEG audio file decoder using the MAD library."""
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def __init__(self, filename):
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self.fp = open(filename, 'rb')
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self.mf = mad.MadFile(self.fp)
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if not self.mf.total_time(): # Indicates a failed open.
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self.fp.close()
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raise UnsupportedError()
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def close(self):
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if hasattr(self, 'fp'):
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self.fp.close()
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if hasattr(self, 'mf'):
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del self.mf
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def read_blocks(self, block_size=4096):
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"""Generates buffers containing PCM data for the audio file.
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"""
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while True:
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out = self.mf.read(block_size)
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if not out:
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break
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yield bytes(out)
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@property
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def samplerate(self):
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"""Sample rate in Hz."""
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return self.mf.samplerate()
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@property
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def duration(self):
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"""Length of the audio in seconds (a float)."""
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return float(self.mf.total_time()) / 1000
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@property
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def channels(self):
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"""The number of channels."""
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if self.mf.mode() == mad.MODE_SINGLE_CHANNEL:
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return 1
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elif self.mf.mode() in (mad.MODE_DUAL_CHANNEL,
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mad.MODE_JOINT_STEREO,
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mad.MODE_STEREO):
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return 2
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else:
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# Other mode?
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return 2
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def __del__(self):
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self.close()
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# Iteration.
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def __iter__(self):
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return self.read_blocks()
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# Context manager.
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def __enter__(self):
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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self.close()
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return False
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