LONG_DESCR

pysndfile
=========

pysndfile is a python package providing *PySndfile*, a
`Cython <http://cython.org/>`__ wrapper class around
`libsndfile <http://www.mega-nerd.com/libsndfile/>`__. PySndfile
provides methods for reading and writing a large variety of soundfile
formats on a variety of plattforms. PySndfile provides a rather complete
access to the different sound file manipulation options that are
available in libsndfile.

Due to the use of libsndfile nearly all sound file formats, (besides mp3
and derived formats) can be read and written with PySndfile.

The interface has been designed such that a rather large subset of the
functionality of libsndfile can be used, notably the reading and writing
of strings into soundfile formats that support these, and a number of
sf_commands that allow to control the way libsndfile reads and writes
the samples. One of the most important ones is the use of the clipping
command.

Transparent soundfile io with libsndfile
----------------------------------------

PySndfile has been developed in the `analysis synthesis team at
IRCAM <http://anasynth.ircam.fr/home/english>`__ mainly for research on
sound analysis and sound transformation. In this context it is essential
that the reading and writing of soundfile data is transparent.

The use of the clipping mode of libsndfile is important here because
reading and writing sound data should not change the audio samples. By
default, when clipping is off, libsndfile uses slightly different
scaling factors when reading pcm format into float samples, or when
writing float samples into pcm format. Therefore whenever a complete
read/write cycle is applied to a sound file then the audio samples may
be modified even when no processing is applied.

More precisely this will happen if

-  the sound files contains pcm format,
-  *and* the data is read into float or double,
-  *and* the audio data comes close to the maximum range such that the
   difference in scaling leads to modification.

To avoid this problem PySndfile sets clipping by default to on. If you
don't like this you can set it to off individually using the PySndfile
method set_auto_clipping(False).

Implementation
--------------

The implementation is based on a slightly modified version of the header
sndfile.hh that is distributed with libsndfile. The only modification is
the addition of a methode querying the seekable state of the open
Sndfile.

Installation
------------

via Anaconda channel roebel
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Precompiled packages are available for `Anaconda
python3 <https://anaconda.org/roebel/pysndfile>`__ under Linux (x86_64)
and Mac OS X (> 10.9). For these systems you can install pysndfile
simply by means of

.. code:: bash

   conda install -c roebel pysndfile

Unfortunately, I don't have a windows machine and therefore I cannot
provide any packages for Windows.

compile with conda build recipe
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can use the conda recipe
`here <https://github.com/roebel/conda_packages>`__. This build recipe
wil automatically download and compile libsndfile building pysndfile.

via pypi
~~~~~~~~

::

   pip install pysndfile

should install pysndfile and python dependencies. Note, that pip cannot
install libsndfile for you as it is not provided via pypi. To install
libsndfile you should be able to use the software manager of your
system. This will however only work if your software manager installs
libsndfile such that the compiler used by the setup.py script will find
it. The setup.py script will search for the dynamic library libsndfile,
as well as the include file sndfile.h, in a few standard locations,
(/usr, /usr/local, and for anaconda envrinments as well in the
exec_prefix directory of the python executable you are using). If
libsndfile is not found you may either adapt the setup.cfg file or set
the environment variable SNDFILE_INSTALL_DIR, to inform the build_ext
sub command about the location to use.

compile from sources
~~~~~~~~~~~~~~~~~~~~

Note that for compiling from sources you need to install requirements
listed in requirements.txt file before starting the compilation.
Moreover you need to install libsndfile as described in the previous
section.

If the libsndfile (header and library) is not installed in the default
compiler search path you have to specify the library and include
directories to be added to this search paths. For this you can either
set the environment variable SNDFILE_INSTALL_DIR to the installation
path or specify sndfile_libdir and sndfile_incdir in the setup.cfg file.

self-contained extension
~~~~~~~~~~~~~~~~~~~~~~~~

Both when installing from pypi or building a wheel from source (or
sdist) the extension will need the libsndfile shared library, which must
be available at runtime.

Since version 1.4.7, it is possible to integrate libsndfile into the
extension, removing this requirement. This will greatly increase the
size of the extension, but can be useful to avoid conflicts between
different libsndfile versions or to build a self-contained wheel.

To do this, the installed libsndfile must include static libraries for
itself and its dependencies. Then define the PYSNDFILE_USE_STATIC
environment variable (either without a value or to anything except 0)
before installing or building as usual. The dependencies will be
searched using pkg-config if available, or by looking for possible
dependencies in the same directory as libsndfile itself.

In some installations of libsndfile though, the pkg-config information
is incorrect (usually a missing or misspelled dependency), which will
lead to an error when building/installing or importing. In this case,
also define the PYSNDFILE_IGNORE_PKG_CONFIG environment variable and
build/install again.

Windows
^^^^^^^

An experimental support for using pysndfile under windows has been added
since version 1.3.4. For further comments see
`here <https://github.com/roebel/pysndfile/issues/3>`__ as well as
`build
scripts <https://gist.github.com/sveinse/97411b95d36a6b8c430d4d381b620ecb>`__
provided by sveinse. Note, that I do not have any windows machine and
cannot provide any help in making this work.

Documentation
-------------

Please see the developer documentation
`here <https://pysndfile.readthedocs.io/en/latest/modules.html>`__.

Changes
-------

Version_1.4.7 (2024-12-31)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  Fix: Remove deprecated IF conditions in Cython code
-  Remove tests directory from sdist because the test is not a standard
   unittest and led to confusion
-  Extension (build): Optionally use static libraries for libsndfile to
   build a self-contained wheel or avoid runtime requirements/conflicts.
   This is done by defining the environment variable
   PYSNDFILE_USE_STATIC (and optionally PYSNDFILE_IGNORE_PKG_CONFIG)
-  Fix (build): Fixed build and installation on Windows
-  Fix (documentation): Generate ChangeLog from README.md and have
   INSTALL.txt refer to it
-  Fix (build): avoid depreciation message when using setup.cfg for
   selecting libsndfile installation to be used.
-  Extension (build): build_ext.finalize_options now communicates the
   sndfile library and include dirs that are used.

Version_1.4.6 (2024-10-11)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  Fix: Fixed setup.py to find libsndfile in standard locations such
   that pip install can be used more easily. Provide proper warning in
   case libsndfile is not found. Support using non-standard installation
   directories by means of environment variable SOUNDFILE_INSTALL_DIR.
-  Removed the requirement for --no-build-isolation in the check target
   of the Makefile

Version_1.4.5 (2024-10-10)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  Extension: support Path for filename arguments in sndio.
-  Fix: Avoid crash in sndio.write when a zero-sized array is stored
   (thanks to Frederic Cornu).
-  Fix: Makefile rule for check command, did not find the "tests"
   directory on all OS.
-  Update: setup.py now uses packaging instead of pkg_resources.

Version_1.4.4 (2022-03-11)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  Fix for win32: improved error handling for PyUnicode_AsWideCharString
   (thanks to Andrey Bienkowski)

Version_1.4.3 (2020-01-20)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  changed sndio functions to all use PySndfile as context manager. This
   fixes the problem that the sndfile remains open when an error occurs
   which may in turn lead to inconsistencies if the sndfile is tried to
   be rewritten in an exception handler.

Version_1.4.2 (2019-12-18)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed PySndfile.read_frames method to properly handle reading frames
   in parts (previous fix was incomplete)

Version_1.4.1 (2019-12-18)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  extended supported commands to change compression level when writing
   flac and ogg files
-  fixed PySndfile.read_frames and sndio.read method to properly handle
   reading frames from the middle of a file

Version_1.4.0 (2019-12-17)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  Extended PySndfile class:

   -  support use as context manager
   -  added support for wve, ogg, MPC2000 sampler and RF64 wav files
   -  added support for forcing to return 2D arrays even for mono files
   -  added method to close the file and release all resources.
   -  support reading more frames than present in the file using the
      fill_value for all values positioned after the end of the file

Version_1.3.8 (2019-10-22)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  (no changes in functionality)
-  added documentation to distributed files
-  added missing licence file to distribution
-  thanks @toddrme2178 for patches.

Version_1.3.7 (2019-08-01)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  removed cython (a build requirement) from requirements.txt
-  avoid cython warning and fix language_level in the .pyx source code
-  add and support pre-release tags in the version number
-  use hashlib to calculate the README checksum.
-  fixed support for use with python 2.7 that was broken since 1.3.4

Version_1.3.6 (2019-07-27)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed potential but undesired build dependency of pandoc
-  added link to explanation for using pysndfile under windows
-  fixed pandoc problem that does produce non ASCII chars in rst output.

Version_1.3.5 (2019-07-27)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed two copy paste bug introduced in 1.3.4 1.3.4 did in fact not
   work at all :-(
-  added a check target to the makefile that performs a complete
   built/install/test cycle to avoid problems as in 1.3.4

Version_1.3.4 (2019-07-23)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  added support for automatic installation of requirements
-  remove precompiled cython source file and rely on pip requirements to
   provide cython so that cython compilation will always be possible.
-  added experimental support for installation on win32 (thanks to Svein
   Seldal for the contributions).
-  use expanduser for replacing ~ in filenames
-  adapted cython source code to avoid all compiler warnings due to
   deprecated numpy api
-  removed use of ez_setup.py that is no longer required.

Version_1.3.3 (2019-06-01)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed missing command C_SFC_SET_SCALE_INT_FLOAT_WRITE (thanks to
   Svein Seldal for the bug report and fix)
-  better documentation of sf_string-io in sndio.read and sndio.write
-  limit size of strings to be written such that the written file can
   always be read back with libsndfile 1.0.28 (which imposes different
   constraints for different formats)
-  better error handling when number of channels exceeds channel limit
   imposed by libsndfile.
-  sndio module now exposes the dicts: fileformat_name_to_id and
   fileformat_id_to_name
-  extended sndio.read with force_2d argument that can be used to force
   the returned data array to always have 2 dimensions even for mono
   files.

Version_1.3.2 (2018-07-04)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed documentation of sndio module.

Version_1.3.1 (2018-07-04)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  Extended sndio by means of adding a enw function that allows
   retrieving embed markers from sound files. Names marker labels will
   be retrieved only for aiff files.
-  removed print out in pysndfile.get_cue_mrks(self) function.
-  fixed version number in documentation.

Version_1.3.0 (2018-07-04)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  Added support for retrieving cue points from aiff and wav files.

Version_1.2.2 (2018-06-11)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed c++-include file that was inadvertently scrambled.

Version_1.2.1 (2018-06-11)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed formatting error in long description and README.
-  setup.py to explicitly select formatting of the long description.

Version_1.2.0 (2018-06-11)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  support reading and writing sound file strings in sndio module
-  Improved documentation of module constant mappings and PySndfile
   methods.
-  Added a new method supporting to write all strings in a dictionary to
   the sound file.

Version_1.1.1 (2018-06-10)
~~~~~~~~~~~~~~~~~~~~~~~~~~

this update is purely administrative, no code changes

-  moved project to IRCAM GitLab
-  moved doc to ReadTheDoc
-  fixed documentation.

Version_1.1.0 (2018-02-13)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  support returning extended sndfile info covering number of frames and
   number of channels from function sndio.get_info.

Version_1.0.0 (2017-07-26)
~~~~~~~~~~~~~~~~~~~~~~~~~~

-  Updated version number to 1.0.0:
-  pysndfile has now been used for quiet a while under python 3 and most
   problems seem to be fixed.
-  changed setup.py to avoid uploading outdated LONG_DESC file.

Version_0.2.15 (2017-07-26)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed get_sndfile_version function and tests script: adapted char
   handling to be compatible with python 3.

Version 0.2.14 (2017-07-26)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed filename display in warning messages due to invalid pointer:
   replaced char\* by std::string

Version 0.2.13 (2017-06-03)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed using "~" for representing $HOME in filenames:
-  \_pysndfile.pyx: replaced using cython getenv by os.environ to avoid
   type incompatibilities in python3

Version 0.2.12 (2017-05-11)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

-  fixed problem in sndio.read: Optionally return full information
   required to store the file using the corresponding write function
-  \_pysndfile.pyx: add constants SF_FORMAT_TYPEMASK and
   SF_FORMAT_SUBMASK, SF_FORMAT_ENDMASK to python interface Added new
   function for getting internal sf log in case of errors. Improved
   consistency of variable definitions by means of retrieving them
   automatically from sndfile.h

Version 0.2.11 (2015-05-17)
~~~~~~~~~~~~~~~~~~~~~~~~~~~

-  setup.py: fixed problem with compilers not providing the compiler
   attribute (MSVC) (Thanks to Felix Hanke for reporting the problem)
-  \_pysndfile.pyx: fixed problem when deriving from PySndfile using a
   modified list of **init** parameters in the derived class (Thanks to
   Sam Perry for the suggestion).

Version 0.2.10
~~~~~~~~~~~~~~

-  setup.py: rebuild LONG_DESC only if sdist method is used.

Version 0.2.9
~~~~~~~~~~~~~

-  Added missing files to distribution.
-  force current cythonized version to be distributed.

Version 0.2.7
~~~~~~~~~~~~~

-  Fixed typo in include directive in MANIFEST.in.

Version 0.2.5
~~~~~~~~~~~~~

-  Added missing file \_pysndfile.pyx.

Version 0.2.4
~~~~~~~~~~~~~

-  Compatibility with python 3 (thanks to Eduardo Moguillansky)
-  bug fix: ensure that vectors returned by read_frames function own
   their data.

Version 0.2.3
~~~~~~~~~~~~~

-  Use print function syntax for a print statement that was not yet
   using it.
-  Avoid newline in compiler detection message.
-  import print_function for compatibility with 2.6
-  python 3 compatibility
-  Generate error message for too high dimensional input.

Version 0.2.2
~~~~~~~~~~~~~

-  don't use SF_STR_ALBUM and SF_STR_LICENSE from sndfile.h because this
   breaks compilation for older versions.
-  don't use SF_STR_TRACKNUMBER and SF_STR_GENRE from sndfile.h because
   this breaks compilation for older versions.
-  Fixed documentation for write function.
-  Fixed typo in accessing function argument

Version 0.2.1
~~~~~~~~~~~~~

-  Initial release

Copyright
---------

Copyright (C) 2014-2024 IRCAM

Author
------

Axel Roebel

Credits
-------

-  Erik de Castro Lopo: for
   `libsndfile <http://www.mega-nerd.com/libsndfile/>`__
-  David Cournapeau: for a few ideas I gathered from
   `scikits.audiolab <http://cournape.github.io/audiolab/>`__.
-  The `Cython <http://cython.org>`__ maintainers for the efficient
   means to write interface definitions in Cython.