21.5. "wave" — Read and write WAV files
***************************************

**Source code:** Lib/wave.py

======================================================================

The "wave" module provides a convenient interface to the WAV sound
format. It does not support compression/decompression, but it does
support mono/stereo.

The "wave" module defines the following function and exception:

wave.open(file[, mode])

   If *file* is a string, open the file by that name, otherwise treat
   it as a seekable file-like object.  *mode* can be any of

   "'r'", "'rb'"
      Read only mode.

   "'w'", "'wb'"
      Write only mode.

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

   A *mode* of "'r'" or "'rb'" returns a "Wave_read" object, while a
   *mode* of "'w'" or "'wb'" returns a "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* (the "'b'" flag is still
   added if necessary).

   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.

wave.openfp(file, mode)

   A synonym for "open()", maintained for backwards compatibility.

exception wave.Error

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


21.5.1. Wave_read Objects
=========================

Wave_read objects, as returned by "open()", have the following
methods:

Wave_read.close()

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

Wave_read.getnchannels()

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

Wave_read.getsampwidth()

   Returns sample width in bytes.

Wave_read.getframerate()

   Returns sampling frequency.

Wave_read.getnframes()

   Returns number of audio frames.

Wave_read.getcomptype()

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

Wave_read.getcompname()

   Human-readable version of "getcomptype()". Usually "'not
   compressed'" parallels "'NONE'".

Wave_read.getparams()

   Returns a tuple "(nchannels, sampwidth, framerate, nframes,
   comptype, compname)", equivalent to output of the "get*()" methods.

Wave_read.readframes(n)

   Reads and returns at most *n* frames of audio, as a string of
   bytes.

Wave_read.rewind()

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

The following two methods are defined for compatibility with the
"aifc" module, and don’t do anything interesting.

Wave_read.getmarkers()

   Returns "None".

Wave_read.getmark(id)

   Raise an error.

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

Wave_read.setpos(pos)

   Set the file pointer to the specified position.

Wave_read.tell()

   Return current file pointer position.


21.5.2. Wave_write Objects
==========================

Wave_write objects, as returned by "open()", have the following
methods:

Wave_write.close()

   Make sure *nframes* is correct, and close the file if it was opened
   by "wave".  This method is called upon object collection.

Wave_write.setnchannels(n)

   Set the number of channels.

Wave_write.setsampwidth(n)

   Set the sample width to *n* bytes.

Wave_write.setframerate(n)

   Set the frame rate to *n*.

Wave_write.setnframes(n)

   Set the number of frames to *n*. This will be changed later if more
   frames are written.

Wave_write.setcomptype(type, name)

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

Wave_write.setparams(tuple)

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

Wave_write.tell()

   Return current position in the file, with the same disclaimer for
   the "Wave_read.tell()" and "Wave_read.setpos()" methods.

Wave_write.writeframesraw(data)

   Write audio frames, without correcting *nframes*.

Wave_write.writeframes(data)

   Write audio frames and make sure *nframes* is correct.

Note that it is invalid to set any parameters after calling
"writeframes()" or "writeframesraw()", and any attempt to do so will
raise "wave.Error".