:mod:!wave --- Read and write WAV files

.. module:: wave :synopsis: Provide an interface to the WAV sound format.

Source code: :source:Lib/wave.py

The :mod:!wave module provides a convenient interface to the Waveform Audio "WAVE" (or "WAV") file format.

The module supports uncompressed PCM and IEEE floating-point WAV formats.

.. versionchanged:: 3.12

Support for WAVE_FORMAT_EXTENSIBLE headers was added, provided that the extended format is KSDATAFORMAT_SUBTYPE_PCM.

.. versionchanged:: 3.15

Support for reading and writing WAVE_FORMAT_IEEE_FLOAT files was added.

The :mod:!wave module defines the following function and exception:

.. function:: open(file, mode=None)

If file is a string, a :term:path-like object or a :term:bytes-like object open the file by that name, otherwise treat it as a file-like object. mode can be:

'rb' Read only mode.

'wb' Write only mode.

Note that it does not allow read/write WAV files.

A mode of 'rb' returns a :class:Wave_read object, while a mode of 'wb' returns a :class:Wave_write object. If mode is omitted and a file-like object is passed as file, file.mode is used as the default value for mode.

If you pass in a file-like object, the wave object will not close it when its close() method is called; it is the caller's responsibility to close the file object.

The :func:.open function may be used in a :keyword:with statement. When the :keyword:!with block completes, the :meth:Wave_read.close or :meth:Wave_write.close method is called.

.. versionchanged:: 3.4 Added support for unseekable files.

.. versionchanged:: 3.15 Added support for :term:path-like objects <path-like object> and :term:bytes-like objects <bytes-like object>.

.. exception:: Error

An error raised when something is impossible because it violates the WAV specification or hits an implementation deficiency.

.. data:: WAVE_FORMAT_PCM

Format code for uncompressed PCM audio.

.. data:: WAVE_FORMAT_IEEE_FLOAT

Format code for IEEE floating-point audio.

.. data:: WAVE_FORMAT_EXTENSIBLE

Format code for WAVE extensible headers.

.. _wave-read-objects:

Wave_read Objects

.. class:: Wave_read

Read a WAV file.

Wave_read objects, as returned by :func:.open, have the following methods:

.. method:: close()

  Close the stream if it was opened by :mod:`!wave`, and make the instance
  unusable.  This is called automatically on object collection.

.. method:: getnchannels()

  Returns number of audio channels (``1`` for mono, ``2`` for stereo).

.. method:: getsampwidth()

  Returns sample width in bytes.

.. method:: getframerate()

  Returns sampling frequency.

.. method:: getnframes()

  Returns number of audio frames.

.. method:: getformat()

  Returns the frame format code.

  This is one of :data:`WAVE_FORMAT_PCM`,
  :data:`WAVE_FORMAT_IEEE_FLOAT`, or :data:`WAVE_FORMAT_EXTENSIBLE`.

.. method:: getcomptype()

  Returns compression type (``'NONE'`` is the only supported type).

.. method:: getcompname()

  Human-readable version of :meth:`getcomptype`. Usually ``'not compressed'``
  parallels ``'NONE'``.

.. method:: getparams()

  Returns a :func:`~collections.namedtuple` ``(nchannels, sampwidth,
  framerate, nframes, comptype, compname)``, equivalent to output
  of the ``get*()`` methods.

.. method:: readframes(n)

  Reads and returns at most *n* frames of audio, as a :class:`bytes` object.

.. method:: rewind()

  Rewind the file pointer to the beginning of the audio stream.

The following two methods define a term "position" which is compatible between them, and is otherwise implementation dependent.

.. method:: setpos(pos)

  Set the file pointer to the specified position.

.. method:: tell()

  Return current file pointer position.

.. _wave-write-objects:

Wave_write Objects

.. class:: Wave_write

Write a WAV file.

Wave_write objects, as returned by :func:.open.

For seekable output streams, the wave header will automatically be updated to reflect the number of frames actually written. For unseekable streams, the nframes value must be accurate when the first frame data is written. An accurate nframes value can be achieved either by calling :meth:setnframes or :meth:setparams with the number of frames that will be written before :meth:close is called and then using :meth:writeframesraw to write the frame data, or by calling :meth:writeframes with all of the frame data to be written. In the latter case :meth:writeframes will calculate the number of frames in the data and set nframes accordingly before writing the frame data.

.. versionchanged:: 3.4 Added support for unseekable files.

Wave_write objects have the following methods:

.. method:: close()

  Make sure *nframes* is correct, and close the file if it was opened by
  :mod:`!wave`.  This method is called upon object collection.  It will raise
  an exception if the output stream is not seekable and *nframes* does not
  match the number of frames actually written.

.. method:: setnchannels(n)

  Set the number of channels.

.. method:: getnchannels()

  Return the number of channels.

.. method:: setsampwidth(n)

  Set the sample width to *n* bytes.

  For :data:`WAVE_FORMAT_IEEE_FLOAT`, only 4-byte (32-bit) and
  8-byte (64-bit) sample widths are supported.

.. method:: getsampwidth()

  Return the sample width in bytes.

.. method:: setframerate(n)

  Set the frame rate to *n*.

  .. versionchanged:: 3.2
     A non-integral input to this method is rounded to the nearest
     integer.

.. method:: getframerate()

  Return the frame rate.

.. method:: setnframes(n)

  Set the number of frames to *n*.  This will be changed later if the number
  of frames actually written is different (this update attempt will
  raise an error if the output stream is not seekable).

.. method:: getnframes()

  Return the number of audio frames written so far.

.. method:: setcomptype(type, name)

  Set the compression type and description. At the moment, only compression type
  ``NONE`` is supported, meaning no compression.

.. method:: getcomptype()

  Return the compression type (``'NONE'``).

.. method:: getcompname()

  Return the human-readable compression type name.

.. method:: setformat(format)

  Set the frame format code.

  Supported values are :data:`WAVE_FORMAT_PCM` and
  :data:`WAVE_FORMAT_IEEE_FLOAT`.

  When setting :data:`WAVE_FORMAT_IEEE_FLOAT`, the sample width must be
  4 or 8 bytes.

.. method:: getformat()

  Return the current frame format code.

.. method:: setparams(tuple)

  The *tuple* should be
  ``(nchannels, sampwidth, framerate, nframes, comptype, compname, format)``,
  with values valid for the ``set*()`` methods. Sets all parameters.

  For backwards compatibility, a 6-item tuple without *format* is also
  accepted and defaults to :data:`WAVE_FORMAT_PCM`.

  For ``format=WAVE_FORMAT_IEEE_FLOAT``, *sampwidth* must be 4 or 8.

.. method:: getparams()

  Return a :func:`~collections.namedtuple`
  ``(nchannels, sampwidth, framerate, nframes, comptype, compname)``
  containing the current output parameters.

.. method:: tell()

  Return current position in the file, with the same disclaimer for the
  :meth:`Wave_read.tell` and :meth:`Wave_read.setpos` methods.

.. method:: writeframesraw(data)

  Write audio frames, without correcting *nframes*.

  .. versionchanged:: 3.4
     Any :term:`bytes-like object` is now accepted.

.. method:: writeframes(data)

  Write audio frames and make sure *nframes* is correct.  It will raise an
  error if the output stream is not seekable and the total number of frames
  that have been written after *data* has been written does not match the
  previously set value for *nframes*.

  .. versionchanged:: 3.4
     Any :term:`bytes-like object` is now accepted.

  Note that it is invalid to set any parameters after calling :meth:`writeframes`
  or :meth:`writeframesraw`, and any attempt to do so will raise
  :exc:`wave.Error`.

  For :data:`WAVE_FORMAT_IEEE_FLOAT` output, a ``fact`` chunk is written as
  required by the WAVE specification for non-PCM formats.