Spaces:
Running
Running
File size: 4,322 Bytes
ddb9253 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 |
# This file is part of audioread.
# Copyright 2011, Adrian Sampson.
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
"""Uses standard-library modules to read AIFF, AIFF-C, and WAV files."""
import aifc
import audioop
import struct
import sunau
import wave
from .exceptions import DecodeError
from .base import AudioFile
# Produce two-byte (16-bit) output samples.
TARGET_WIDTH = 2
# Python 3.4 added support for 24-bit (3-byte) samples.
SUPPORTED_WIDTHS = (1, 2, 3, 4)
class UnsupportedError(DecodeError):
"""File is not an AIFF, WAV, or Au file."""
class BitWidthError(DecodeError):
"""The file uses an unsupported bit width."""
def byteswap(s):
"""Swaps the endianness of the bytestring s, which must be an array
of shorts (16-bit signed integers). This is probably less efficient
than it should be.
"""
assert len(s) % 2 == 0
parts = []
for i in range(0, len(s), 2):
chunk = s[i:i + 2]
newchunk = struct.pack('<h', *struct.unpack('>h', chunk))
parts.append(newchunk)
return b''.join(parts)
class RawAudioFile(AudioFile):
"""An AIFF, WAV, or Au file that can be read by the Python standard
library modules ``wave``, ``aifc``, and ``sunau``.
"""
def __init__(self, filename):
self._fh = open(filename, 'rb')
try:
self._file = aifc.open(self._fh)
except aifc.Error:
# Return to the beginning of the file to try the next reader.
self._fh.seek(0)
else:
self._needs_byteswap = True
self._check()
return
try:
self._file = wave.open(self._fh)
except wave.Error:
self._fh.seek(0)
pass
else:
self._needs_byteswap = False
self._check()
return
try:
self._file = sunau.open(self._fh)
except sunau.Error:
self._fh.seek(0)
pass
else:
self._needs_byteswap = True
self._check()
return
# None of the three libraries could open the file.
self._fh.close()
raise UnsupportedError()
def _check(self):
"""Check that the files' parameters allow us to decode it and
raise an error otherwise.
"""
if self._file.getsampwidth() not in SUPPORTED_WIDTHS:
self.close()
raise BitWidthError()
def close(self):
"""Close the underlying file."""
self._file.close()
self._fh.close()
@property
def channels(self):
"""Number of audio channels."""
return self._file.getnchannels()
@property
def samplerate(self):
"""Sample rate in Hz."""
return self._file.getframerate()
@property
def duration(self):
"""Length of the audio in seconds (a float)."""
return float(self._file.getnframes()) / self.samplerate
def read_data(self, block_samples=1024):
"""Generates blocks of PCM data found in the file."""
old_width = self._file.getsampwidth()
while True:
data = self._file.readframes(block_samples)
if not data:
break
# Make sure we have the desired bitdepth and endianness.
data = audioop.lin2lin(data, old_width, TARGET_WIDTH)
if self._needs_byteswap and self._file.getcomptype() != 'sowt':
# Big-endian data. Swap endianness.
data = byteswap(data)
yield data
# Context manager.
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.close()
return False
# Iteration.
def __iter__(self):
return self.read_data()
|