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14.4 sunau -- Read and write Sun AU files
The sunau module provides a convenient interface to the Sun AU sound format. Note that this module is interface-compatible with the modules aifc and wave.
An audio file consists of a header followed by the data. The fields of the header are:
| Field | Contents |
|---|---|
| magic word | The four bytes ".snd". |
| header size | Size of the header, including info, in bytes. |
| data size | Physical size of the data, in bytes. |
| encoding | Indicates how the audio samples are encoded. |
| sample rate | The sampling rate. |
| # of channels | The number of channels in the samples. |
| info | ASCII string giving a description of the audio file (padded with null bytes). |
Apart from the info field, all header fields are 4 bytes in size. They are all 32-bit unsigned integers encoded in big-endian byte order.
The sunau module defines the following functions:
- 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'- Read only mode.
'w'- Write only mode.
A mode of
'r'returns a AU_read object, while a mode of'w'or'wb'returns a AU_write object.
- openfp(file, mode)
- A synonym for open, maintained for backwards compatibility.
The sunau module defines the following exception:
- exception Error
- An error raised when something is impossible because of Sun AU specs or implementation deficiency.
The sunau module defines the following data items:
- AUDIO_FILE_MAGIC
- An integer every valid Sun AU file begins with, stored in big-endian form. This is the string ".snd" interpreted as an integer.
- AUDIO_FILE_ENCODING_MULAW_8
- AUDIO_FILE_ENCODING_LINEAR_8
- AUDIO_FILE_ENCODING_LINEAR_16
- AUDIO_FILE_ENCODING_LINEAR_24
- AUDIO_FILE_ENCODING_LINEAR_32
- AUDIO_FILE_ENCODING_ALAW_8
- Values of the encoding field from the AU header which are supported by this module.
- AUDIO_FILE_ENCODING_FLOAT
- AUDIO_FILE_ENCODING_DOUBLE
- AUDIO_FILE_ENCODING_ADPCM_G721
- AUDIO_FILE_ENCODING_ADPCM_G722
- AUDIO_FILE_ENCODING_ADPCM_G723_3
- AUDIO_FILE_ENCODING_ADPCM_G723_5
- Additional known values of the encoding field from the AU header, but which are not supported by this module.
Subsections
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Release 2.2, documentation updated on December 21, 2001.