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# 21.5. `wave` — Read and write WAV files

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, other 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).

`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, 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. This method is called upon deletion.

`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`.

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