aifc
— Read and write AIFF and AIFC filesSource code: Lib/aifc.py
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 AIFF-C is a newer version of the format that includes the ability to compress the audio data.
Note
Some operations may only work under IRIX; these will raise ImportError
when attempting to import the 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 aifc
defines the following function:
aifc.
open
(file[, mode])'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 writeframesraw()
and setnframes()
.Objects returned by open()
when a file is opened for reading have the
following methods:
aifc.
getnchannels
()aifc.
getsampwidth
()aifc.
getframerate
()aifc.
getnframes
()aifc.
getcomptype
()'NONE'
.aifc.
getcompname
()'not compressed'
.aifc.
getparams
()aifc.
getmarkers
()aifc.
getmark
(id)getmarkers()
for the mark with the given id.aifc.
readframes
(nframes)aifc.
rewind
()readframes()
will start from the beginning.aifc.
setpos
(pos)aifc.
tell
()aifc.
close
()Objects returned by open()
when a file is opened for writing have all the
above methods, except for readframes()
and setpos()
. In addition
the following methods exist. The get*()
methods can only be called after
the corresponding set*()
methods have been called. Before the first
writeframes()
or writeframesraw()
, all parameters except for the
number of frames must be filled in.
aifc.
aiff
()'.aiff'
in which case the default is an AIFF file.aifc.
aifc
()'.aiff'
in which case the default is an AIFF file.aifc.
setnchannels
(nchannels)aifc.
setsampwidth
(width)aifc.
setframerate
(rate)aifc.
setnframes
(nframes)aifc.
setcomptype
(type, name)aifc.
setparams
(nchannels, sampwidth, framerate, comptype, compname)getparams()
call as argument to setparams()
.aifc.
setmark
(id, pos, name)close()
.aifc.
tell
()setmark()
.aifc.
writeframes
(data)aifc.
writeframesraw
(data)writeframes()
, except that the header of the audio file is not updated.aifc.
close
()