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108 lines
3.2 KiB
Python
108 lines
3.2 KiB
Python
# Copyright (C) 2006 Lukas Lalinsky
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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"""OptimFROG audio streams with APEv2 tags.
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OptimFROG is a lossless audio compression program. Its main goal is to
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reduce at maximum the size of audio files, while permitting bit
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identical restoration for all input. It is similar with the ZIP
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compression, but it is highly specialized to compress audio data.
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Only versions 4.5 and higher are supported.
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For more information, see http://www.losslessaudio.org/
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"""
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__all__ = ["OptimFROG", "Open", "delete"]
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import struct
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from ._util import convert_error, endswith
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from mutagen import StreamInfo
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from mutagen.apev2 import APEv2File, error, delete
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SAMPLE_TYPE_BITS = {
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0: 8,
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1: 8,
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2: 16,
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3: 16,
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4: 24,
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5: 24,
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6: 32,
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7: 32,
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}
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class OptimFROGHeaderError(error):
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pass
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class OptimFROGInfo(StreamInfo):
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"""OptimFROGInfo()
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OptimFROG stream information.
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Attributes:
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channels (`int`): number of audio channels
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length (`float`): file length in seconds, as a float
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sample_rate (`int`): audio sampling rate in Hz
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bits_per_sample (`int`): the audio sample size
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encoder_info (`mutagen.text`): encoder version, e.g. "5.100"
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"""
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@convert_error(IOError, OptimFROGHeaderError)
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def __init__(self, fileobj):
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"""Raises OptimFROGHeaderError"""
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header = fileobj.read(76)
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if len(header) != 76 or not header.startswith(b"OFR "):
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raise OptimFROGHeaderError("not an OptimFROG file")
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data_size = struct.unpack("<I", header[4:8])[0]
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if data_size != 12 and data_size < 15:
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raise OptimFROGHeaderError("not an OptimFROG file")
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(total_samples, total_samples_high, sample_type, self.channels,
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self.sample_rate) = struct.unpack("<IHBBI", header[8:20])
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total_samples += total_samples_high << 32
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self.channels += 1
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self.bits_per_sample = SAMPLE_TYPE_BITS.get(sample_type)
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if self.sample_rate:
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self.length = float(total_samples) / (self.channels *
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self.sample_rate)
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else:
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self.length = 0.0
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if data_size >= 15:
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encoder_id = struct.unpack("<H", header[20:22])[0]
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version = str((encoder_id >> 4) + 4500)
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self.encoder_info = "%s.%s" % (version[0], version[1:])
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else:
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self.encoder_info = ""
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def pprint(self):
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return u"OptimFROG, %.2f seconds, %d Hz" % (self.length,
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self.sample_rate)
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class OptimFROG(APEv2File):
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"""OptimFROG(filething)
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Attributes:
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info (`OptimFROGInfo`)
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tags (`mutagen.apev2.APEv2`)
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"""
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_Info = OptimFROGInfo
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@staticmethod
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def score(filename, fileobj, header):
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filename = filename.lower()
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return (header.startswith(b"OFR") + endswith(filename, b".ofr") +
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endswith(filename, b".ofs"))
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Open = OptimFROG
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