# `wave` — Read and write WAV files

Kod źródłowy: Lib/wave.py

The `wave` module provides a convenient interface to the Waveform Audio „WAVE” (or „WAV”) file format.

The module supports uncompressed PCM and IEEE floating-point WAV formats.

Zmienione w wersji 3.12: Support for `WAVE_FORMAT_EXTENSIBLE` headers was added, provided that the extended format is `KSDATAFORMAT_SUBTYPE_PCM`.

Zmienione w wersji 3.15: Support for reading and writing `WAVE_FORMAT_IEEE_FLOAT` files was added.

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

wave.open(file, mode=None)

  If file is a string, a path-like object or a bytes-like object open the file by that name, otherwise treat it as a file-like object. mode can be:

  `'rb'`

    Read only mode.

  `'wb'`

    Write only mode.

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

  A mode of `'rb'` returns a `Wave_read` object, while a mode of `'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.

  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.

  The `open()` function may be used in a `with` statement. When the `with` block completes, the `Wave_read.close()` or `Wave_write.close()` method is called.

  Zmienione w wersji 3.4: Added support for unseekable files.

  Zmienione w wersji 3.15: Added support for path-like objects and bytes-like objects.

exception wave.Error

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

wave.WAVE_FORMAT_PCM

  Format code for uncompressed PCM audio.

wave.WAVE_FORMAT_IEEE_FLOAT

  Format code for IEEE floating-point audio.

wave.WAVE_FORMAT_EXTENSIBLE

  Format code for WAVE extensible headers.

## Wave_read Objects

class wave.Wave_read

  Read a WAV file.

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

  close()

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

  getnchannels()

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

  getsampwidth()

    Returns sample width in bytes.

  getframerate()

    Returns sampling frequency.

  getnframes()

    Returns number of audio frames.

  getformat()

    Returns the frame format code.

    This is one of `WAVE_FORMAT_PCM`, `WAVE_FORMAT_IEEE_FLOAT`, or `WAVE_FORMAT_EXTENSIBLE`.

  getcomptype()

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

  getcompname()

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

  getparams()

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

  readframes(n)

    Reads and returns at most n frames of audio, as a `bytes` object.

  rewind()

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

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

  setpos(pos)

    Set the file pointer to the specified position.

  tell()

    Return current file pointer position.

## Wave_write Objects

class wave.Wave_write

  Write a WAV file.

  Wave_write objects, as returned by `open()`.

  For seekable output streams, the `wave` header will automatically be updated to reflect the number of frames actually written. For unseekable streams, the nframes value must be accurate when the first frame data is written. An accurate nframes value can be achieved either by calling `setnframes()` or `setparams()` with the number of frames that will be written before `close()` is called and then using `writeframesraw()` to write the frame data, or by calling `writeframes()` with all of the frame data to be written. In the latter case `writeframes()` will calculate the number of frames in the data and set nframes accordingly before writing the frame data.

  Zmienione w wersji 3.4: Added support for unseekable files.

  Wave_write objects have the following methods:

  close()

    Make sure nframes is correct, and close the file if it was opened by `wave`. This method is called upon object collection. It will raise an exception if the output stream is not seekable and nframes does not match the number of frames actually written.

  setnchannels(n)

    Set the number of channels.

  getnchannels()

    Return the number of channels.

  setsampwidth(n)

    Set the sample width to n bytes.

    For `WAVE_FORMAT_IEEE_FLOAT`, only 4-byte (32-bit) and 8-byte (64-bit) sample widths are supported.

  getsampwidth()

    Return the sample width in bytes.

  setframerate(n)

    Set the frame rate to n.

    Zmienione w wersji 3.2: A non-integral input to this method is rounded to the nearest integer.

  getframerate()

    Return the frame rate.

  setnframes(n)

    Set the number of frames to n. This will be changed later if the number of frames actually written is different (this update attempt will raise an error if the output stream is not seekable).

  getnframes()

    Return the number of audio frames written so far.

  setcomptype(type, name)

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

  getcomptype()

    Return the compression type (`'NONE'`).

  getcompname()

    Return the human-readable compression type name.

  setformat(format)

    Set the frame format code.

    Supported values are `WAVE_FORMAT_PCM` and `WAVE_FORMAT_IEEE_FLOAT`.

    When setting `WAVE_FORMAT_IEEE_FLOAT`, the sample width must be 4 or 8 bytes.

  getformat()

    Return the current frame format code.

  setparams(tuple)

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

    For backwards compatibility, a 6-item tuple without format is also accepted and defaults to `WAVE_FORMAT_PCM`.

    For `format=WAVE_FORMAT_IEEE_FLOAT`, sampwidth must be 4 or 8.

  getparams()

    Return a `namedtuple()` `(nchannels, sampwidth, framerate, nframes, comptype, compname)` containing the current output parameters.

  tell()

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

  writeframesraw(data)

    Write audio frames, without correcting nframes.

    Zmienione w wersji 3.4: Any bytes-like object is now accepted.

  writeframes(data)

    Write audio frames and make sure nframes is correct. It will raise an error if the output stream is not seekable and the total number of frames that have been written after data has been written does not match the previously set value for nframes.

    Zmienione w wersji 3.4: Any bytes-like object is now accepted.

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

    For `WAVE_FORMAT_IEEE_FLOAT` output, a `fact` chunk is written as required by the WAVE specification for non-PCM formats.