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+
+:mod:`aifc` --- Read and write AIFF and AIFC files
+==================================================
+
+.. module:: aifc
+   :synopsis: Read and write audio files in AIFF or AIFC format.
+
+
+.. index::
+   single: Audio Interchange File Format
+   single: AIFF
+   single: AIFF-C
+
+This module provides support for reading and writing AIFF and AIFF-C files.
+AIFF is Audio Interchange File Format, a format for storing digital audio
+samples in a file.  AIFF-C is a newer version of the format that includes the
+ability to compress the audio data.
+
+**Caveat:**  Some operations may only work under IRIX; these will raise
+:exc:`ImportError` when attempting to import the :mod:`cl` module, which is only
+available on IRIX.
+
+Audio files have a number of parameters that describe the audio data. The
+sampling rate or frame rate is the number of times per second the sound is
+sampled.  The number of channels indicate if the audio is mono, stereo, or
+quadro.  Each frame consists of one sample per channel.  The sample size is the
+size in bytes of each sample.  Thus a frame consists of
+*nchannels*\**samplesize* bytes, and a second's worth of audio consists of
+*nchannels*\**samplesize*\**framerate* bytes.
+
+For example, CD quality audio has a sample size of two bytes (16 bits), uses two
+channels (stereo) and has a frame rate of 44,100 frames/second.  This gives a
+frame size of 4 bytes (2\*2), and a second's worth occupies 2\*2\*44100 bytes
+(176,400 bytes).
+
+Module :mod:`aifc` defines the following function:
+
+
+.. function:: open(file[, mode])
+
+   Open an AIFF or AIFF-C file and return an object instance with methods that are
+   described below.  The argument *file* is either a string naming a file or a file
+   object.  *mode* must be ``'r'`` or ``'rb'`` when the file must be opened for
+   reading, or ``'w'``  or ``'wb'`` when the file must be opened for writing.  If
+   omitted, ``file.mode`` is used if it exists, otherwise ``'rb'`` is used.  When
+   used for writing, the file object should be seekable, unless you know ahead of
+   time how many samples you are going to write in total and use
+   :meth:`writeframesraw` and :meth:`setnframes`.
+
+Objects returned by :func:`open` when a file is opened for reading have the
+following methods:
+
+
+.. method:: aifc.getnchannels()
+
+   Return the number of audio channels (1 for mono, 2 for stereo).
+
+
+.. method:: aifc.getsampwidth()
+
+   Return the size in bytes of individual samples.
+
+
+.. method:: aifc.getframerate()
+
+   Return the sampling rate (number of audio frames per second).
+
+
+.. method:: aifc.getnframes()
+
+   Return the number of audio frames in the file.
+
+
+.. method:: aifc.getcomptype()
+
+   Return a four-character string describing the type of compression used in the
+   audio file.  For AIFF files, the returned value is ``'NONE'``.
+
+
+.. method:: aifc.getcompname()
+
+   Return a human-readable description of the type of compression used in the audio
+   file.  For AIFF files, the returned value is ``'not compressed'``.
+
+
+.. method:: aifc.getparams()
+
+   Return a tuple consisting of all of the above values in the above order.
+
+
+.. method:: aifc.getmarkers()
+
+   Return a list of markers in the audio file.  A marker consists of a tuple of
+   three elements.  The first is the mark ID (an integer), the second is the mark
+   position in frames from the beginning of the data (an integer), the third is the
+   name of the mark (a string).
+
+
+.. method:: aifc.getmark(id)
+
+   Return the tuple as described in :meth:`getmarkers` for the mark with the given
+   *id*.
+
+
+.. method:: aifc.readframes(nframes)
+
+   Read and return the next *nframes* frames from the audio file.  The returned
+   data is a string containing for each frame the uncompressed samples of all
+   channels.
+
+
+.. method:: aifc.rewind()
+
+   Rewind the read pointer.  The next :meth:`readframes` will start from the
+   beginning.
+
+
+.. method:: aifc.setpos(pos)
+
+   Seek to the specified frame number.
+
+
+.. method:: aifc.tell()
+
+   Return the current frame number.
+
+
+.. method:: aifc.close()
+
+   Close the AIFF file.  After calling this method, the object can no longer be
+   used.
+
+Objects returned by :func:`open` when a file is opened for writing have all the
+above methods, except for :meth:`readframes` and :meth:`setpos`.  In addition
+the following methods exist.  The :meth:`get\*` methods can only be called after
+the corresponding :meth:`set\*` methods have been called.  Before the first
+:meth:`writeframes` or :meth:`writeframesraw`, all parameters except for the
+number of frames must be filled in.
+
+
+.. method:: aifc.aiff()
+
+   Create an AIFF file.  The default is that an AIFF-C file is created, unless the
+   name of the file ends in ``'.aiff'`` in which case the default is an AIFF file.
+
+
+.. method:: aifc.aifc()
+
+   Create an AIFF-C file.  The default is that an AIFF-C file is created, unless
+   the name of the file ends in ``'.aiff'`` in which case the default is an AIFF
+   file.
+
+
+.. method:: aifc.setnchannels(nchannels)
+
+   Specify the number of channels in the audio file.
+
+
+.. method:: aifc.setsampwidth(width)
+
+   Specify the size in bytes of audio samples.
+
+
+.. method:: aifc.setframerate(rate)
+
+   Specify the sampling frequency in frames per second.
+
+
+.. method:: aifc.setnframes(nframes)
+
+   Specify the number of frames that are to be written to the audio file. If this
+   parameter is not set, or not set correctly, the file needs to support seeking.
+
+
+.. method:: aifc.setcomptype(type, name)
+
+   .. index::
+      single: u-LAW
+      single: A-LAW
+      single: G.722
+
+   Specify the compression type.  If not specified, the audio data will not be
+   compressed.  In AIFF files, compression is not possible.  The name parameter
+   should be a human-readable description of the compression type, the type
+   parameter should be a four-character string.  Currently the following
+   compression types are supported: NONE, ULAW, ALAW, G722.
+
+
+.. method:: aifc.setparams(nchannels, sampwidth, framerate, comptype, compname)
+
+   Set all the above parameters at once.  The argument is a tuple consisting of the
+   various parameters.  This means that it is possible to use the result of a
+   :meth:`getparams` call as argument to :meth:`setparams`.
+
+
+.. method:: aifc.setmark(id, pos, name)
+
+   Add a mark with the given id (larger than 0), and the given name at the given
+   position.  This method can be called at any time before :meth:`close`.
+
+
+.. method:: aifc.tell()
+
+   Return the current write position in the output file.  Useful in combination
+   with :meth:`setmark`.
+
+
+.. method:: aifc.writeframes(data)
+
+   Write data to the output file.  This method can only be called after the audio
+   file parameters have been set.
+
+
+.. method:: aifc.writeframesraw(data)
+
+   Like :meth:`writeframes`, except that the header of the audio file is not
+   updated.
+
+
+.. method:: aifc.close()
+
+   Close the AIFF file.  The header of the file is updated to reflect the actual
+   size of the audio data. After calling this method, the object can no longer be
+   used.
+