349 lines
11 KiB
Python
349 lines
11 KiB
Python
# 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.
|
|
|
|
"""Read audio files using CoreAudio on Mac OS X."""
|
|
import copy
|
|
import ctypes
|
|
import ctypes.util
|
|
import os
|
|
import sys
|
|
|
|
from .exceptions import DecodeError
|
|
from .base import AudioFile
|
|
|
|
|
|
# CoreFoundation and CoreAudio libraries along with their function
|
|
# prototypes.
|
|
|
|
def _load_framework(name):
|
|
return ctypes.cdll.LoadLibrary(ctypes.util.find_library(name))
|
|
|
|
|
|
_coreaudio = _load_framework('AudioToolbox')
|
|
_corefoundation = _load_framework('CoreFoundation')
|
|
|
|
# Convert CFStrings to C strings.
|
|
_corefoundation.CFStringGetCStringPtr.restype = ctypes.c_char_p
|
|
_corefoundation.CFStringGetCStringPtr.argtypes = [ctypes.c_void_p,
|
|
ctypes.c_int]
|
|
|
|
# Free memory.
|
|
_corefoundation.CFRelease.argtypes = [ctypes.c_void_p]
|
|
|
|
# Create a file:// URL.
|
|
_corefoundation.CFURLCreateFromFileSystemRepresentation.restype = \
|
|
ctypes.c_void_p
|
|
_corefoundation.CFURLCreateFromFileSystemRepresentation.argtypes = \
|
|
[ctypes.c_int, ctypes.c_char_p, ctypes.c_int, ctypes.c_bool]
|
|
|
|
# Get a string representation of a URL.
|
|
_corefoundation.CFURLGetString.restype = ctypes.c_void_p
|
|
_corefoundation.CFURLGetString.argtypes = [ctypes.c_void_p]
|
|
|
|
# Open an audio file for reading.
|
|
_coreaudio.ExtAudioFileOpenURL.restype = ctypes.c_int
|
|
_coreaudio.ExtAudioFileOpenURL.argtypes = [ctypes.c_void_p, ctypes.c_void_p]
|
|
|
|
# Set audio file property.
|
|
_coreaudio.ExtAudioFileSetProperty.restype = ctypes.c_int
|
|
_coreaudio.ExtAudioFileSetProperty.argtypes = \
|
|
[ctypes.c_void_p, ctypes.c_uint, ctypes.c_uint, ctypes.c_void_p]
|
|
|
|
# Get audio file property.
|
|
_coreaudio.ExtAudioFileGetProperty.restype = ctypes.c_int
|
|
_coreaudio.ExtAudioFileGetProperty.argtypes = \
|
|
[ctypes.c_void_p, ctypes.c_uint, ctypes.c_void_p, ctypes.c_void_p]
|
|
|
|
# Read from an audio file.
|
|
_coreaudio.ExtAudioFileRead.restype = ctypes.c_int
|
|
_coreaudio.ExtAudioFileRead.argtypes = \
|
|
[ctypes.c_void_p, ctypes.c_void_p, ctypes.c_void_p]
|
|
|
|
# Close/free an audio file.
|
|
_coreaudio.ExtAudioFileDispose.restype = ctypes.c_int
|
|
_coreaudio.ExtAudioFileDispose.argtypes = [ctypes.c_void_p]
|
|
|
|
|
|
# Constants used in CoreAudio.
|
|
|
|
def multi_char_literal(chars):
|
|
"""Emulates character integer literals in C. Given a string "abc",
|
|
returns the value of the C single-quoted literal 'abc'.
|
|
"""
|
|
num = 0
|
|
for index, char in enumerate(chars):
|
|
shift = (len(chars) - index - 1) * 8
|
|
num |= ord(char) << shift
|
|
return num
|
|
|
|
|
|
PROP_FILE_DATA_FORMAT = multi_char_literal('ffmt')
|
|
PROP_CLIENT_DATA_FORMAT = multi_char_literal('cfmt')
|
|
PROP_LENGTH = multi_char_literal('#frm')
|
|
AUDIO_ID_PCM = multi_char_literal('lpcm')
|
|
PCM_IS_FLOAT = 1 << 0
|
|
PCM_IS_BIG_ENDIAN = 1 << 1
|
|
PCM_IS_SIGNED_INT = 1 << 2
|
|
PCM_IS_PACKED = 1 << 3
|
|
ERROR_TYPE = multi_char_literal('typ?')
|
|
ERROR_FORMAT = multi_char_literal('fmt?')
|
|
ERROR_NOT_FOUND = -43
|
|
|
|
|
|
# Check for errors in functions that return error codes.
|
|
|
|
class MacError(DecodeError):
|
|
def __init__(self, code):
|
|
if code == ERROR_TYPE:
|
|
msg = 'unsupported audio type'
|
|
elif code == ERROR_FORMAT:
|
|
msg = 'unsupported format'
|
|
else:
|
|
msg = 'error %i' % code
|
|
super().__init__(msg)
|
|
|
|
|
|
def check(err):
|
|
"""If err is nonzero, raise a MacError exception."""
|
|
if err == ERROR_NOT_FOUND:
|
|
raise OSError('file not found')
|
|
elif err != 0:
|
|
raise MacError(err)
|
|
|
|
|
|
# CoreFoundation objects.
|
|
|
|
class CFObject:
|
|
def __init__(self, obj):
|
|
if obj == 0:
|
|
raise ValueError('object is zero')
|
|
self._obj = obj
|
|
|
|
def __del__(self):
|
|
if _corefoundation:
|
|
_corefoundation.CFRelease(self._obj)
|
|
|
|
|
|
class CFURL(CFObject):
|
|
def __init__(self, filename):
|
|
if not isinstance(filename, bytes):
|
|
filename = filename.encode(sys.getfilesystemencoding())
|
|
filename = os.path.abspath(os.path.expanduser(filename))
|
|
url = _corefoundation.CFURLCreateFromFileSystemRepresentation(
|
|
0, filename, len(filename), False
|
|
)
|
|
super().__init__(url)
|
|
|
|
def __str__(self):
|
|
cfstr = _corefoundation.CFURLGetString(self._obj)
|
|
out = _corefoundation.CFStringGetCStringPtr(cfstr, 0)
|
|
# Resulting CFString does not need to be released according to docs.
|
|
return out
|
|
|
|
|
|
# Structs used in CoreAudio.
|
|
|
|
class AudioStreamBasicDescription(ctypes.Structure):
|
|
_fields_ = [
|
|
("mSampleRate", ctypes.c_double),
|
|
("mFormatID", ctypes.c_uint),
|
|
("mFormatFlags", ctypes.c_uint),
|
|
("mBytesPerPacket", ctypes.c_uint),
|
|
("mFramesPerPacket", ctypes.c_uint),
|
|
("mBytesPerFrame", ctypes.c_uint),
|
|
("mChannelsPerFrame", ctypes.c_uint),
|
|
("mBitsPerChannel", ctypes.c_uint),
|
|
("mReserved", ctypes.c_uint),
|
|
]
|
|
|
|
|
|
class AudioBuffer(ctypes.Structure):
|
|
_fields_ = [
|
|
("mNumberChannels", ctypes.c_uint),
|
|
("mDataByteSize", ctypes.c_uint),
|
|
("mData", ctypes.c_void_p),
|
|
]
|
|
|
|
|
|
class AudioBufferList(ctypes.Structure):
|
|
_fields_ = [
|
|
("mNumberBuffers", ctypes.c_uint),
|
|
("mBuffers", AudioBuffer * 1),
|
|
]
|
|
|
|
|
|
# Main functionality.
|
|
|
|
class ExtAudioFile(AudioFile):
|
|
"""A CoreAudio "extended audio file". Reads information and raw PCM
|
|
audio data from any file that CoreAudio knows how to decode.
|
|
|
|
>>> with ExtAudioFile('something.m4a') as f:
|
|
>>> print f.samplerate
|
|
>>> print f.channels
|
|
>>> print f.duration
|
|
>>> for block in f:
|
|
>>> do_something(block)
|
|
|
|
"""
|
|
def __init__(self, filename):
|
|
url = CFURL(filename)
|
|
try:
|
|
self._obj = self._open_url(url)
|
|
except:
|
|
self.closed = True
|
|
raise
|
|
del url
|
|
|
|
self.closed = False
|
|
self._file_fmt = None
|
|
self._client_fmt = None
|
|
|
|
self.setup()
|
|
|
|
@classmethod
|
|
def _open_url(cls, url):
|
|
"""Given a CFURL Python object, return an opened ExtAudioFileRef.
|
|
"""
|
|
file_obj = ctypes.c_void_p()
|
|
check(_coreaudio.ExtAudioFileOpenURL(
|
|
url._obj, ctypes.byref(file_obj)
|
|
))
|
|
return file_obj
|
|
|
|
def set_client_format(self, desc):
|
|
"""Get the client format description. This describes the
|
|
encoding of the data that the program will read from this
|
|
object.
|
|
"""
|
|
assert desc.mFormatID == AUDIO_ID_PCM
|
|
check(_coreaudio.ExtAudioFileSetProperty(
|
|
self._obj, PROP_CLIENT_DATA_FORMAT, ctypes.sizeof(desc),
|
|
ctypes.byref(desc)
|
|
))
|
|
self._client_fmt = desc
|
|
|
|
def get_file_format(self):
|
|
"""Get the file format description. This describes the type of
|
|
data stored on disk.
|
|
"""
|
|
# Have cached file format?
|
|
if self._file_fmt is not None:
|
|
return self._file_fmt
|
|
|
|
# Make the call to retrieve it.
|
|
desc = AudioStreamBasicDescription()
|
|
size = ctypes.c_int(ctypes.sizeof(desc))
|
|
check(_coreaudio.ExtAudioFileGetProperty(
|
|
self._obj, PROP_FILE_DATA_FORMAT, ctypes.byref(size),
|
|
ctypes.byref(desc)
|
|
))
|
|
|
|
# Cache result.
|
|
self._file_fmt = desc
|
|
return desc
|
|
|
|
@property
|
|
def channels(self):
|
|
"""The number of channels in the audio source."""
|
|
return int(self.get_file_format().mChannelsPerFrame)
|
|
|
|
@property
|
|
def samplerate(self):
|
|
"""Gets the sample rate of the audio."""
|
|
return int(self.get_file_format().mSampleRate)
|
|
|
|
@property
|
|
def duration(self):
|
|
"""Gets the length of the file in seconds (a float)."""
|
|
return float(self.nframes) / self.samplerate
|
|
|
|
@property
|
|
def nframes(self):
|
|
"""Gets the number of frames in the source file."""
|
|
length = ctypes.c_long()
|
|
size = ctypes.c_int(ctypes.sizeof(length))
|
|
check(_coreaudio.ExtAudioFileGetProperty(
|
|
self._obj, PROP_LENGTH, ctypes.byref(size), ctypes.byref(length)
|
|
))
|
|
return length.value
|
|
|
|
def setup(self, bitdepth=16):
|
|
"""Set the client format parameters, specifying the desired PCM
|
|
audio data format to be read from the file. Must be called
|
|
before reading from the file.
|
|
"""
|
|
fmt = self.get_file_format()
|
|
newfmt = copy.copy(fmt)
|
|
|
|
newfmt.mFormatID = AUDIO_ID_PCM
|
|
newfmt.mFormatFlags = \
|
|
PCM_IS_SIGNED_INT | PCM_IS_PACKED
|
|
newfmt.mBitsPerChannel = bitdepth
|
|
newfmt.mBytesPerPacket = \
|
|
(fmt.mChannelsPerFrame * newfmt.mBitsPerChannel // 8)
|
|
newfmt.mFramesPerPacket = 1
|
|
newfmt.mBytesPerFrame = newfmt.mBytesPerPacket
|
|
self.set_client_format(newfmt)
|
|
|
|
def read_data(self, blocksize=4096):
|
|
"""Generates byte strings reflecting the audio data in the file.
|
|
"""
|
|
frames = ctypes.c_uint(blocksize // self._client_fmt.mBytesPerFrame)
|
|
buf = ctypes.create_string_buffer(blocksize)
|
|
|
|
buflist = AudioBufferList()
|
|
buflist.mNumberBuffers = 1
|
|
buflist.mBuffers[0].mNumberChannels = \
|
|
self._client_fmt.mChannelsPerFrame
|
|
buflist.mBuffers[0].mDataByteSize = blocksize
|
|
buflist.mBuffers[0].mData = ctypes.cast(buf, ctypes.c_void_p)
|
|
|
|
while True:
|
|
check(_coreaudio.ExtAudioFileRead(
|
|
self._obj, ctypes.byref(frames), ctypes.byref(buflist)
|
|
))
|
|
|
|
assert buflist.mNumberBuffers == 1
|
|
size = buflist.mBuffers[0].mDataByteSize
|
|
if not size:
|
|
break
|
|
|
|
data = ctypes.cast(buflist.mBuffers[0].mData,
|
|
ctypes.POINTER(ctypes.c_char))
|
|
blob = data[:size]
|
|
yield blob
|
|
|
|
def close(self):
|
|
"""Close the audio file and free associated memory."""
|
|
if not self.closed:
|
|
check(_coreaudio.ExtAudioFileDispose(self._obj))
|
|
self.closed = True
|
|
|
|
def __del__(self):
|
|
if _coreaudio:
|
|
self.close()
|
|
|
|
# Context manager methods.
|
|
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()
|