xref: /third_party/python/Doc/library/sndhdr.rst

:mod:`sndhdr` --- Determine type of sound file
==============================================

.. module:: sndhdr
   :synopsis: Determine type of a sound file.
   :deprecated:

.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>
.. Based on comments in the module source file.

**Source code:** :source:`Lib/sndhdr.py`

.. index::
   single: A-LAW
   single: u-LAW

.. deprecated-removed:: 3.11 3.13
   The :mod:`sndhdr` module is deprecated
   (see :pep:`PEP 594 <594#sndhdr>` for details and alternatives).

--------------

The :mod:`sndhdr` provides utility functions which attempt to determine the type
of sound data which is in a file.  When these functions are able to determine
what type of sound data is stored in a file, they return a
:func:`~collections.namedtuple`, containing five attributes: (``filetype``,
``framerate``, ``nchannels``, ``nframes``, ``sampwidth``). The value for *type*
indicates the data type and will be one of the strings ``'aifc'``, ``'aiff'``,
``'au'``, ``'hcom'``, ``'sndr'``, ``'sndt'``, ``'voc'``, ``'wav'``, ``'8svx'``,
``'sb'``, ``'ub'``, or ``'ul'``.  The *sampling_rate* will be either the actual
value or ``0`` if unknown or difficult to decode.  Similarly, *channels* will be
either the number of channels or ``0`` if it cannot be determined or if the
value is difficult to decode.  The value for *frames* will be either the number
of frames or ``-1``.  The last item in the tuple, *bits_per_sample*, will either
be the sample size in bits or ``'A'`` for A-LAW or ``'U'`` for u-LAW.


.. function:: what(filename)

   Determines the type of sound data stored in the file *filename* using
   :func:`whathdr`.  If it succeeds, returns a namedtuple as described above, otherwise
   ``None`` is returned.

   .. versionchanged:: 3.5
      Result changed from a tuple to a namedtuple.


.. function:: whathdr(filename)

   Determines the type of sound data stored in a file based on the file  header.
   The name of the file is given by *filename*.  This function returns a namedtuple as
   described above on success, or ``None``.

   .. versionchanged:: 3.5
      Result changed from a tuple to a namedtuple.

The following sound header types are recognized, as listed below with the return value
from :func:`whathdr`: and :func:`what`:

+------------+------------------------------------+
| Value      | Sound header format                |
+============+====================================+
| ``'aifc'`` | Compressed Audio Interchange Files |
+------------+------------------------------------+
| ``'aiff'`` | Audio Interchange Files            |
+------------+------------------------------------+
| ``'au'``   | Au Files                           |
+------------+------------------------------------+
| ``'hcom'`` | HCOM Files                         |
+------------+------------------------------------+
| ``'sndt'`` | Sndtool Sound Files                |
+------------+------------------------------------+
| ``'voc'``  | Creative Labs Audio Files          |
+------------+------------------------------------+
| ``'wav'``  | Waveform Audio File Format Files   |
+------------+------------------------------------+
| ``'8svx'`` | 8-Bit Sampled Voice Files          |
+------------+------------------------------------+
| ``'sb'``   | Signed Byte Audio Data Files       |
+------------+------------------------------------+
| ``'ub'``   | UB Files                           |
+------------+------------------------------------+
| ``'ul'``   | uLAW Audio Files                   |
+------------+------------------------------------+

.. data:: tests

   A list of functions performing the individual tests.  Each function takes two
   arguments: the byte-stream and an open file-like object. When :func:`what` is
   called with a byte-stream, the file-like object will be ``None``.

   The test function should return a string describing the image type if the test
   succeeded, or ``None`` if it failed.

Example:

.. code-block:: pycon

   >>> import sndhdr
   >>> imghdr.what('bass.wav')
   'wav'
   >>> imghdr.whathdr('bass.wav')
   'wav'