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wave.rst

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

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


.. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>

Source code: :source:`Lib/wave.py`

The :mod:`wave` module provides a convenient interface to the Waveform Audio "WAVE" (or "WAV") file format. Only uncompressed PCM encoded wave files are supported.

.. versionchanged:: 3.12

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

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

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

   If *file* is a string, 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.


.. exception:: Error

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

Wave_read Objects

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:: 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 are defined for compatibility with the old :mod:`!aifc` module, and don't do anything interesting.

.. method:: getmarkers()

   Returns ``None``.

   .. deprecated-removed:: 3.13 3.15
      The method only existed for compatibility with the :mod:`!aifc` module
      which has been removed in Python 3.13.



.. method:: getmark(id)

   Raise an error.

   .. deprecated-removed:: 3.13 3.15
      The method only existed for compatibility with the :mod:`!aifc` module
      which has been removed in Python 3.13.

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

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:: setsampwidth(n)

   Set the sample width to *n* 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:: 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:: setcomptype(type, name)

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



.. method:: setparams(tuple)

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