ossaudiodev Module¶

⚠️ REMOVED IN PYTHON 3.13: The ossaudiodev module was deprecated in Python 3.11 and removed in Python 3.13.

The ossaudiodev module provides access to OSS (Open Sound System) audio devices on Linux and FreeBSD: opening /dev/dsp for playback or recording, and /dev/mixer for volume control.

Throughout, n is the number of bytes transferred.

Complexity Reference¶

Module¶

Operation	Time	Space	Notes
`open(mode)`	O(1) + syscall	O(1)	Opens `/dev/dsp`; mode is `"r"`, `"w"`, or `"rw"`
`open(device, mode)`	O(1) + syscall	O(1)	Explicit device path
`openmixer(device=None)`	O(1) + syscall	O(1)	Opens `/dev/mixer`

Audio Device¶

Operation	Time	Space	Notes
`read(size)`	O(n) + blocks	O(n)	Blocks until `size` bytes are captured
`write(data)`	O(n) + blocks	O(1)	Blocks until the buffer accepts the data
`writeall(data)`	O(n) + blocks	O(1)	Loops until everything is written
`setparameters(format, nchannels, samplerate)`	O(1) + syscall	O(1)	Configure the device
`setfmt(format)`	O(1) + syscall	O(1)	Sample format only
`channels(n)`	O(1) + syscall	O(1)	Channel count only
`speed(rate)`	O(1) + syscall	O(1)	Sample rate only
`bufsize()`	O(1) + syscall	O(1)	Buffer size in samples
`obufcount()`	O(1) + syscall	O(1)	Samples queued for playback
`obuffree()`	O(1) + syscall	O(1)	Space remaining in the buffer
`sync()`	O(1) + blocks	O(1)	Waits for the buffer to drain
`reset()`	O(1) + syscall	O(1)	Discards buffered audio
`close()`	O(1) + syscall	O(1)	Release the device

Mixer Device¶

Operation	Time	Space	Notes
`controls()`	O(1) + syscall	O(1)	Bitmask of supported controls
`get(control)`	O(1) + syscall	O(1)	Current volume
`set(control, (left, right))`	O(1) + syscall	O(1)	Set volume
`stereocontrols()`	O(1) + syscall	O(1)	Which controls are stereo

The data-transfer calls are linear in bytes; everything else is a constant-time ioctl. The dominant cost in practice is blocking on the device, not CPU work.

Playing Audio¶

import ossaudiodev

# O(1) to open and configure
dsp = ossaudiodev.open("w")
try:
    dsp.setparameters(ossaudiodev.AFMT_S16_LE, 2, 44100)
    dsp.writeall(pcm_bytes)   # O(n), blocks until fully written
    dsp.sync()                # blocks until the buffer drains
finally:
    dsp.close()

Recording Audio¶

import ossaudiodev

dsp = ossaudiodev.open("r")
try:
    dsp.setparameters(ossaudiodev.AFMT_S16_LE, 1, 16000)
    # O(n) per chunk; blocks until the samples are captured
    chunks = [dsp.read(4096) for _ in range(100)]
finally:
    dsp.close()

audio = b"".join(chunks)   # O(total bytes)

Avoiding Underruns¶

write() blocks when the device buffer is full. To keep a real-time loop responsive, check the free space first:

import ossaudiodev

dsp = ossaudiodev.open("w")
dsp.setparameters(ossaudiodev.AFMT_S16_LE, 2, 44100)

# O(1) - only write what fits, never block
free = dsp.obuffree()
if free >= len(chunk):
    dsp.write(chunk)

Removed in Python 3.13

There is no standard-library replacement. OSS itself is largely superseded by ALSA and PulseAudio on Linux; use a third-party binding for those.

Linux and FreeBSD only

The module was never available on Windows or macOS, and requires the OSS device nodes to be present.

Version Notes¶

Python 3.11: deprecated (PEP 594)
Python 3.13: removed
Before 3.13: available only on platforms with OSS device support
All versions: transfer calls are linear in bytes; control calls are constant-time ioctls