22.4. 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=None)¶ If file is a string, 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 aWave_read
object, while a mode of'wb'
returns aWave_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 awith
statement. When thewith
block completes, theWave_read.close()
orWave_write.close()
method is called.Distinto en la versión 3.4: Added support for unseekable files.
-
exception
wave.
Error
¶ An error raised when something is impossible because it violates the WAV specification or hits an implementation deficiency.
22.4.1. 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
namedtuple()
(nchannels, sampwidth, framerate, nframes, comptype, compname)
, equivalent to output of theget*()
methods.
-
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.
22.4.2. Wave_write Objects¶
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.
Wave_write objects, as returned by open()
, have the following methods:
Distinto en la versión 3.4: Added support for unseekable files.
-
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. It will raise an exception if the output stream is not seekable and nframes does not match the number of frames actually written.
-
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.
Distinto en la versión 3.2: A non-integral input to this method is rounded to the nearest integer.
-
Wave_write.
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).
-
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 theset*()
methods. Sets all parameters.
-
Wave_write.
tell
()¶ Return current position in the file, with the same disclaimer for the
Wave_read.tell()
andWave_read.setpos()
methods.
-
Wave_write.
writeframesraw
(data)¶ Write audio frames, without correcting nframes.
Distinto en la versión 3.4: Any bytes-like object is now accepted.
-
Wave_write.
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.
Distinto en la versión 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
.