539 lines
16 KiB
Python
539 lines
16 KiB
Python
# SPDX-FileCopyrightText: 2023 Guido van Rossum <guido@cwi.nl> and others.
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#
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# SPDX-License-Identifier: PSF-2.0
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"""
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`adafruit_wave`
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================================================================================
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Read and write standard WAV-format files
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* Author(s): Jeff Epler
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Implementation Notes
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--------------------
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**Software and Dependencies:**
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* Adafruit CircuitPython firmware for the supported boards:
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https://circuitpython.org/downloads
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"""
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# pylint: disable=missing-class-docstring,redefined-outer-name,missing-function-docstring,invalid-name,import-outside-toplevel,too-many-instance-attributes,consider-using-with,no-self-use,redefined-builtin,not-callable,unused-variable,attribute-defined-outside-init,too-many-public-methods,no-else-return
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# imports
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__version__ = "0.0.0+auto.0"
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__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_wave.git"
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from collections import namedtuple
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import builtins
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import struct
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__all__ = ["open", "Error", "Wave_read", "Wave_write"]
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class Chunk:
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def __init__(self, file, align=True, bigendian=True, inclheader=False):
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self.closed = False
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self.align = align # whether to align to word (2-byte) boundaries
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if bigendian:
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strflag = ">"
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else:
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strflag = "<"
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self.file = file
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self.chunkname = file.read(4)
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if len(self.chunkname) < 4:
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raise EOFError
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try:
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self.chunksize = struct.unpack_from(strflag + "L", file.read(4))[0]
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except struct.error:
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raise EOFError from None
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if inclheader:
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self.chunksize = self.chunksize - 8 # subtract header
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self.size_read = 0
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try:
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self.offset = self.file.tell()
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except (AttributeError, OSError):
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self.seekable = False
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else:
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self.seekable = True
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def getname(self):
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"""Return the name (ID) of the current chunk."""
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return self.chunkname
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def getsize(self):
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"""Return the size of the current chunk."""
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return self.chunksize
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def close(self):
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if not self.closed:
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try:
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self.skip()
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finally:
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self.closed = True
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def isatty(self):
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if self.closed:
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raise ValueError("I/O operation on closed file")
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return False
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def seek(self, pos, whence=0):
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"""Seek to specified position into the chunk.
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Default position is 0 (start of chunk).
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If the file is not seekable, this will result in an error.
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"""
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if self.closed:
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raise ValueError("I/O operation on closed file")
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if not self.seekable:
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raise OSError("cannot seek")
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if whence == 1:
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pos = pos + self.size_read
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elif whence == 2:
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pos = pos + self.chunksize
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if pos < 0 or pos > self.chunksize:
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raise RuntimeError
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self.file.seek(self.offset + pos, 0)
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self.size_read = pos
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def tell(self):
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if self.closed:
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raise ValueError("I/O operation on closed file")
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return self.size_read
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def read(self, size=-1):
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"""Read at most size bytes from the chunk.
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If size is omitted or negative, read until the end
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of the chunk.
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"""
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if self.closed:
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raise ValueError("I/O operation on closed file")
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if self.size_read >= self.chunksize:
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return b""
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if size < 0:
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size = self.chunksize - self.size_read
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if size > self.chunksize - self.size_read:
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size = self.chunksize - self.size_read
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data = self.file.read(size)
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self.size_read = self.size_read + len(data)
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if self.size_read == self.chunksize and self.align and (self.chunksize & 1):
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dummy = self.file.read(1)
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self.size_read = self.size_read + len(dummy)
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return data
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def skip(self):
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"""Skip the rest of the chunk.
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If you are not interested in the contents of the chunk,
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this method should be called so that the file points to
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the start of the next chunk.
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"""
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if self.closed:
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raise ValueError("I/O operation on closed file")
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if self.seekable:
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try:
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n = self.chunksize - self.size_read
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# maybe fix alignment
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if self.align and (self.chunksize & 1):
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n = n + 1
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self.file.seek(n, 1)
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self.size_read = self.size_read + n
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return
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except OSError:
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pass
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while self.size_read < self.chunksize:
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n = min(8192, self.chunksize - self.size_read)
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dummy = self.read(n)
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if not dummy:
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raise EOFError
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class Error(Exception):
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pass
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WAVE_FORMAT_PCM = 0x0001
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_array_fmts = None, "b", "h", None, "i"
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_wave_params = namedtuple(
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"_wave_params", "nchannels sampwidth framerate nframes comptype compname"
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)
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class Wave_read:
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"""Used for wave files opened in read mode.
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Do not construct directly, but call `open` instead."""
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def initfp(self, file):
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self._convert = None
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self._soundpos = 0
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self._file = Chunk(file, bigendian=0)
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if self._file.getname() != b"RIFF":
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raise Error("file does not start with RIFF id")
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if self._file.read(4) != b"WAVE":
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raise Error("not a WAVE file")
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self._fmt_chunk_read = 0
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self._data_chunk = None
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while 1:
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self._data_seek_needed = 1
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try:
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chunk = Chunk(self._file, bigendian=0)
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except EOFError:
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break
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chunkname = chunk.getname()
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if chunkname == b"fmt ":
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self._read_fmt_chunk(chunk)
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self._fmt_chunk_read = 1
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elif chunkname == b"data":
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if not self._fmt_chunk_read:
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raise Error("data chunk before fmt chunk")
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self._data_chunk = chunk
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self._nframes = chunk.chunksize // self._framesize
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self._data_seek_needed = 0
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break
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chunk.skip()
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if not self._fmt_chunk_read or not self._data_chunk:
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raise Error("fmt chunk and/or data chunk missing")
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def __init__(self, f):
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self._i_opened_the_file = None
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if isinstance(f, str):
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f = builtins.open(f, "rb")
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self._i_opened_the_file = f
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# else, assume it is an open file object already
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try:
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self.initfp(f)
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except:
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if self._i_opened_the_file:
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f.close()
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raise
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def __del__(self):
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self.close()
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def __enter__(self):
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return self
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def __exit__(self, *args):
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self.close()
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#
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# User visible methods.
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#
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def getfp(self):
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"""Get the underlying file object"""
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return self._file
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def rewind(self):
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"""Go back to the start of the audio data"""
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self._data_seek_needed = 1
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self._soundpos = 0
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def close(self):
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"""Close the file"""
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self._file = None
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file = self._i_opened_the_file
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if file:
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self._i_opened_the_file = None
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file.close()
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def tell(self):
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"""Get the current position in the audio data"""
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return self._soundpos
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def getnchannels(self):
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"""Get the number of channels (1 for mono, 2 for stereo)"""
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return self._nchannels
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def getnframes(self):
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"""Get the number of frames"""
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return self._nframes
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def getsampwidth(self):
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"""Get the sample width in bytes"""
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return self._sampwidth
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def getframerate(self):
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"""Get the sample rate in Hz"""
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return self._framerate
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def setpos(self, pos):
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"""Seek to a particular position in the audio data"""
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if pos < 0 or pos > self._nframes:
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raise Error("position not in range")
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self._soundpos = pos
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self._data_seek_needed = 1
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def readframes(self, nframes):
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"""Read frames of audio data"""
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if self._data_seek_needed:
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self._data_chunk.seek(0, 0)
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pos = self._soundpos * self._framesize
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if pos:
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self._data_chunk.seek(pos, 0)
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self._data_seek_needed = 0
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if nframes == 0:
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return b""
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data = self._data_chunk.read(nframes * self._framesize)
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if self._convert and data:
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data = self._convert(data)
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self._soundpos = self._soundpos + len(data) // (
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self._nchannels * self._sampwidth
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)
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return data
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#
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# Internal methods.
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#
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def _read_fmt_chunk(self, chunk):
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try:
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(
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wFormatTag,
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self._nchannels,
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self._framerate,
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dwAvgBytesPerSec,
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wBlockAlign,
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) = struct.unpack_from("<HHLLH", chunk.read(14))
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except struct.error:
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raise EOFError from None
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if wFormatTag == WAVE_FORMAT_PCM:
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try:
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sampwidth = struct.unpack_from("<H", chunk.read(2))[0]
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except struct.error:
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raise EOFError from None
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self._sampwidth = (sampwidth + 7) // 8
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if not self._sampwidth:
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raise Error("bad sample width")
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else:
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raise Error("unknown format: %r" % (wFormatTag,))
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if not self._nchannels:
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raise Error("bad # of channels")
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self._framesize = self._nchannels * self._sampwidth
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self._comptype = "NONE"
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self._compname = "not compressed"
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class Wave_write:
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"""Used for wave files opened in write mode.
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Do not construct directly, but call `open` instead."""
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def __init__(self, f):
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self._i_opened_the_file = None
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if isinstance(f, str):
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f = builtins.open(f, "wb")
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self._i_opened_the_file = f
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try:
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self.initfp(f)
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except:
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if self._i_opened_the_file:
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f.close()
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raise
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def initfp(self, file):
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self._file = file
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self._convert = None
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self._nchannels = 0
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self._sampwidth = 0
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self._framerate = 0
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self._nframes = 0
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self._nframeswritten = 0
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self._datawritten = 0
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self._datalength = 0
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self._headerwritten = False
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def __del__(self):
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self.close()
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def __enter__(self):
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return self
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def __exit__(self, *args):
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self.close()
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#
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# User visible methods.
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#
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def setnchannels(self, nchannels):
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"""Set the number of channels (1 for mono, 2 for stereo)"""
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if self._datawritten:
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raise Error("cannot change parameters after starting to write")
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if nchannels < 1:
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raise Error("bad # of channels")
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self._nchannels = nchannels
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def getnchannels(self):
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"""Get the number of channels (1 for mono, 2 for stereo)"""
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if not self._nchannels:
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raise Error("number of channels not set")
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return self._nchannels
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def setsampwidth(self, sampwidth):
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"""Set the sample width in bytes"""
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if self._datawritten:
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raise Error("cannot change parameters after starting to write")
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if sampwidth < 1 or sampwidth > 4:
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raise Error("bad sample width")
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self._sampwidth = sampwidth
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def getsampwidth(self):
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"""Get the sample width in bytes"""
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if not self._sampwidth:
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raise Error("sample width not set")
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return self._sampwidth
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def setframerate(self, framerate):
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"""Set the sample rate in Hz"""
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if self._datawritten:
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raise Error("cannot change parameters after starting to write")
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if framerate <= 0:
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raise Error("bad frame rate")
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self._framerate = int(round(framerate))
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def getframerate(self):
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"""Get the sample rate in Hz"""
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if not self._framerate:
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raise Error("frame rate not set")
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return self._framerate
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def setnframes(self, nframes):
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if self._datawritten:
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raise Error("cannot change parameters after starting to write")
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self._nframes = nframes
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def getnframes(self):
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return self._nframeswritten
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def setparams(self, params):
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"""Set all parameters at once"""
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nchannels, sampwidth, framerate, nframes, comptype, compname = params
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if self._datawritten:
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raise Error("cannot change parameters after starting to write")
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self.setnchannels(nchannels)
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self.setsampwidth(sampwidth)
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self.setframerate(framerate)
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self.setnframes(nframes)
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def tell(self):
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"""Get the current position in the audio data"""
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return self._nframeswritten
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def writeframesraw(self, data):
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"""Write data to the file without updating the header"""
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if not isinstance(data, (bytes, bytearray)):
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data = memoryview(data).cast("B")
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self._ensure_header_written(len(data))
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nframes = len(data) // (self._sampwidth * self._nchannels)
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if self._convert:
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data = self._convert(data)
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self._file.write(data)
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self._datawritten += len(data)
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self._nframeswritten = self._nframeswritten + nframes
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def writeframes(self, data):
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"""Write data to the file and update the header if needed"""
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self.writeframesraw(data)
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if self._datalength != self._datawritten:
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self._patchheader()
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def close(self):
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"""Close the file"""
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try:
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if self._file:
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self._ensure_header_written(0)
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if self._datalength != self._datawritten:
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self._patchheader()
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self._file.flush()
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finally:
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self._file = None
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file = self._i_opened_the_file
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if file:
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self._i_opened_the_file = None
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file.close()
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#
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# Internal methods.
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#
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def _ensure_header_written(self, datasize):
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if not self._headerwritten:
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if not self._nchannels:
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raise Error("# channels not specified")
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if not self._sampwidth:
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raise Error("sample width not specified")
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if not self._framerate:
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raise Error("sampling rate not specified")
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self._write_header(datasize)
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def _write_header(self, initlength):
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assert not self._headerwritten
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self._file.write(b"RIFF")
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if not self._nframes:
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self._nframes = initlength // (self._nchannels * self._sampwidth)
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self._datalength = self._nframes * self._nchannels * self._sampwidth
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try:
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self._form_length_pos = self._file.tell()
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except (AttributeError, OSError):
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self._form_length_pos = None
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self._file.write(
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struct.pack(
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"<L4s4sLHHLLHH4s",
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36 + self._datalength,
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b"WAVE",
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b"fmt ",
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16,
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WAVE_FORMAT_PCM,
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self._nchannels,
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self._framerate,
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self._nchannels * self._framerate * self._sampwidth,
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self._nchannels * self._sampwidth,
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self._sampwidth * 8,
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b"data",
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)
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)
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if self._form_length_pos is not None:
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self._data_length_pos = self._file.tell()
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self._file.write(struct.pack("<L", self._datalength))
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self._headerwritten = True
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def _patchheader(self):
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assert self._headerwritten
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if self._datawritten == self._datalength:
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return
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curpos = self._file.tell()
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self._file.seek(self._form_length_pos, 0)
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self._file.write(struct.pack("<L", 36 + self._datawritten))
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self._file.seek(self._data_length_pos, 0)
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self._file.write(struct.pack("<L", self._datawritten))
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self._file.seek(curpos, 0)
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self._datalength = self._datawritten
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def open(f, mode=None): # pylint: disable=redefined-builtin
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"""Open a wave file in reading (default) or writing (``mode="w"``) mode.
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The argument may be a filename or an open file.
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In reading mode, returns a `Wave_read` object.
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In writing mode, returns a `Wave_write` object.
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"""
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if mode is None:
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if hasattr(f, "mode"):
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mode = f.mode
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else:
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mode = "rb"
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if mode in ("r", "rb"):
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return Wave_read(f)
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elif mode in ("w", "wb"):
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return Wave_write(f)
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else:
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raise Error("mode must be 'r', 'rb', 'w', or 'wb'")
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