cysox 0.1.8

A Pythonic audio processing library wrapping libsox

cysox

A Pythonic audio processing library which uses cython to wrap libsox.

Features

• Simple API: Convert, analyze, and play audio with one-liners
• Typed Effects: 28 base effect classes with IDE autocomplete and validation
• 54 Effect Presets: Ready-to-use composite effects for voice, lo-fi, drums, mastering, and more
• Drum Loop Tools: Slice loops by BPM, create stutter effects, apply beat-synced processing
• High Performance: Direct C bindings through Cython, KissFFT-accelerated onset detection
• Zero Configuration: Auto-initialization, no manual setup required
• Cross-Platform: macOS, Linux (Windows placeholder)

Installation

Note that cysox only works on macOS and Linux.

pip install cysox

Command Line Interface

# Show version
cysox --version

# Get audio file info
cysox info audio.wav

# Convert audio files
cysox convert input.wav output.mp3
cysox convert input.wav output.wav --rate 48000 --channels 1
cysox convert input.wav output.wav -p Telephone

# Play audio
cysox play audio.wav

# Concatenate files
cysox concat intro.wav main.wav outro.wav -o full.wav

# List available effect presets
cysox preset list
cysox preset list drums          # Filter by category

# Get preset info and parameters
cysox preset info Chipmunk

# Apply a preset to audio
cysox preset apply Telephone input.wav output.wav
cysox preset apply Chipmunk input.wav output.wav --intensity=2.0

# Slice audio into segments
cysox slice drums.wav output_dir/ -n 8
cysox slice drums.wav output_dir/ --bpm 120 --beats 1
cysox slice drums.wav output_dir/ -n 4 -p DrumPunch

# Slice at detected transients (automatic beat detection)
# -t threshold (e.g. 0.3), -s sensitivity (default 1.5), -m method (default hfc)
cysox slice drums.wav output_dir/ -t 0.3
cysox slice drums.wav output_dir/ -t 0.2 -s 1.2 -m flux

# Create stutter effects
cysox stutter drums.wav stutter.wav -d 0.125 -r 8
cysox stutter drums.wav stutter.wav -s 0.5 -d 0.25 -r 4 -p GatedReverb

Quick Start

import cysox
from cysox import fx

# Get audio file info
info = cysox.info('audio.wav')
print(f"Duration: {info['duration']:.2f}s, Sample rate: {info['sample_rate']} Hz")

# Convert with effects
cysox.convert('input.wav', 'output.mp3', effects=[
    fx.Normalize(),
    fx.Reverb(reverberance=60),
    fx.Fade(fade_in=0.5, fade_out=1.0),
])

# Play audio (macOS/Linux)
cysox.play('audio.wav')

# Play with effects
cysox.play('audio.wav', effects=[fx.Volume(db=-6)])

Core Functions

cysox.info(path) -> dict

Get audio file metadata:

info = cysox.info('audio.wav')
# Returns: {
#     'path': 'audio.wav',
#     'format': 'wav',
#     'duration': 11.5,
#     'sample_rate': 44100,
#     'channels': 2,
#     'bits_per_sample': 16,
#     'samples': 507150,
#     'encoding': 'signed-integer',
# }

cysox.convert(input, output, effects=[], **options)

Convert audio files with optional effects and format options:

# Simple format conversion
cysox.convert('input.wav', 'output.mp3')

# With effects
cysox.convert('input.wav', 'output.wav', effects=[
    fx.Volume(db=3),
    fx.Bass(gain=5),
    fx.Reverb(),
])

# With format options
cysox.convert('input.wav', 'output.wav',
    sample_rate=48000,
    channels=1,
    bits=24,
)

cysox.stream(path, chunk_size=8192) -> Iterator[memoryview]

Stream audio samples for processing:

import numpy as np

for chunk in cysox.stream('large.wav', chunk_size=8192):
    arr = np.frombuffer(chunk, dtype=np.int32)
    process(arr)

cysox.play(path, effects=[])

Play audio to the default audio device:

cysox.play('audio.wav')
cysox.play('audio.wav', effects=[fx.Volume(db=-6), fx.Reverb()])

cysox.concat(inputs, output)

Concatenate multiple audio files:

cysox.concat(['intro.wav', 'main.wav', 'outro.wav'], 'full.wav')

All input files must have the same sample rate and channel count.

Effects Module

The cysox.fx module provides 28 base effect classes and 54 composite presets:

Volume & Dynamics

fx.Volume(db=3)                    # Adjust volume in dB
fx.Gain(db=6)                      # Apply gain
fx.Normalize(level=-3)             # Normalize to target level

Equalization

fx.Bass(gain=5, frequency=100)     # Boost/cut bass
fx.Treble(gain=-2, frequency=3000) # Boost/cut treble
fx.Equalizer(frequency=1000, width=1.0, gain=3)

Filters

fx.HighPass(frequency=200)         # Remove low frequencies
fx.LowPass(frequency=8000)         # Remove high frequencies
fx.BandPass(frequency=1000, width=100)
fx.BandReject(frequency=60, width=10)  # Notch filter

Spatial & Reverb

fx.Reverb(reverberance=50, room_scale=100)
fx.Echo(gain_in=0.8, gain_out=0.9, delays=[100], decays=[0.5])
fx.Chorus()
fx.Flanger()

Time-Based

fx.Trim(start=1.0, end=5.0)        # Extract portion
fx.Pad(before=0.5, after=1.0)      # Add silence
fx.Speed(factor=1.5)               # Change speed (affects pitch)
fx.Tempo(factor=1.5)               # Change tempo (preserves pitch)
fx.Pitch(cents=100)                # Shift pitch (preserves tempo)
fx.Reverse()                       # Reverse audio
fx.Fade(fade_in=0.5, fade_out=1.0) # Fade in/out
fx.Repeat(count=3)                 # Repeat audio

Conversion

fx.Rate(sample_rate=48000)         # Resample
fx.Channels(channels=1)            # Change channel count
fx.Remix(out_spec=[[1, 2]])        # Custom channel mixing
fx.Dither()                        # Add dither

Composite Effects

Create reusable effect combinations:

from cysox.fx import CompositeEffect, HighPass, LowPass, Reverb, Volume

class TelephoneEffect(CompositeEffect):
    """Simulate telephone audio quality."""

    @property
    def effects(self):
        return [
            HighPass(frequency=300),
            LowPass(frequency=3400),
            Volume(db=-3),
        ]

# Use like any other effect
cysox.convert('input.wav', 'output.wav', effects=[TelephoneEffect()])

Effect Presets

The library includes 54 ready-to-use composite effect presets organized by category:

Voice Effects

fx.Chipmunk(intensity=1.8)         # High-pitched voice
fx.DeepVoice(intensity=0.6)        # Low, slowed voice
fx.Robot(intensity=70)             # Metallic robotic voice
fx.HauntedVoice(pitch_shift=5)     # Spooky ghost effect
fx.VocalClarity(presence_boost=4)  # Enhanced vocal presence
fx.Whisper()                       # Intimate whisper effect

Lo-Fi Effects

fx.Telephone(sample_rate=8000)     # Classic telephone sound
fx.AMRadio()                       # AM radio broadcast
fx.Megaphone(volume_boost=6)       # Bullhorn effect
fx.Underwater(depth=500)           # Submerged/muffled sound
fx.VinylWarmth(bass_boost=3)       # Warm vinyl aesthetic
fx.LoFiHipHop(warmth=4)            # Lo-fi hip hop style
fx.Cassette()                      # Cassette tape degradation

Spatial Effects

fx.SmallRoom(wetness=30)           # Intimate room reverb
fx.LargeHall(size=100, decay=70)   # Concert hall ambience
fx.Cathedral()                     # Church reverb
fx.Bathroom()                      # Tiled room reverb
fx.Stadium()                       # Arena with echo

Broadcast Effects

fx.Podcast()                       # Voice cleanup + presence
fx.RadioDJ(presence=4)             # Punchy broadcast voice
fx.Voiceover()                     # Professional VO processing
fx.Intercom()                      # PA system effect
fx.WalkieTalkie()                  # Two-way radio

Musical Effects

fx.EightiesChorus(depth=4)         # Classic 80s chorus
fx.DreamyPad()                     # Ethereal ambient texture
fx.SlowedReverb(slow_factor=0.85)  # Slowed + reverb aesthetic
fx.SlapbackEcho(delay_ms=120)      # Rockabilly short delay
fx.DubDelay(tempo_ms=375)          # Rhythmic dub delays
fx.JetFlanger()                    # Extreme flanger sweep
fx.ShoegazeWash()                  # Heavy reverb/chorus wash

Drum Loop Effects

fx.HalfTime(preserve_pitch=True)   # Slow to half speed
fx.DoubleTime(preserve_pitch=True) # Speed up to double
fx.DrumPunch(punch=4, attack=3)    # Enhance punch and attack
fx.DrumCrisp(brightness=4)         # Crisp, bright drums
fx.DrumFat(fatness=5)              # Thick, heavy drums
fx.Breakbeat()                     # Classic breakbeat processing
fx.VintageBreak()                  # Lo-fi sampled break sound
fx.DrumRoom(room_size=40)          # Natural room ambience
fx.GatedReverb()                   # 80s gated reverb
fx.DrumSlice(start=0, duration=0.5)# Extract a segment
fx.ReverseCymbal(fade_duration=0.5)# Reverse riser effect
fx.LoopReady()                     # Prepare for seamless looping

Mastering Effects

fx.BroadcastLimiter(target_level=-1)  # Broadcast-ready limiting
fx.WarmMaster(warmth=1.5)             # Warm mastering preset
fx.BrightMaster(air=2)                # Bright/airy mastering
fx.LoudnessMaster(target_level=-0.3)  # Maximum loudness

Cleanup Effects

fx.RemoveRumble(cutoff=60)         # High-pass for rumble
fx.RemoveHiss(cutoff=12000)        # Low-pass for tape hiss
fx.RemoveHum(frequency=60)         # Notch filter for hum (50/60Hz)
fx.CleanVoice()                    # Basic voice cleanup
fx.TapeRestoration()               # Restore tape recordings

Transition Effects

fx.FadeInOut(fade_in_secs=0.3, fade_out_secs=0.3)
fx.CrossfadeReady(fade_duration=0.3)

Chaining Presets

Presets can be combined with each other and base effects:

cysox.convert('input.wav', 'output.wav', effects=[
    fx.RemoveRumble(),      # Cleanup first
    fx.VinylWarmth(),       # Apply lo-fi aesthetic
    fx.SmallRoom(),         # Add room ambience
    fx.WarmMaster(),        # Final mastering
])

Drum Loop Slicing

cysox provides utilities for slicing drum loops and creating stutter effects.

cysox.slice_loop() - Split Loops into Segments

Split an audio file into multiple segment files:

import cysox
from cysox import fx

# Slice into equal parts
slices = cysox.slice_loop('drums.wav', 'output_dir/', slices=8)
# Creates: output_dir/drums_slice_000.wav through drums_slice_007.wav

# Slice by BPM (one beat per slice)
slices = cysox.slice_loop('drums.wav', 'output_dir/', bpm=120, beats_per_slice=1)

# Slice with effects applied to each segment
slices = cysox.slice_loop('drums.wav', 'output_dir/',
    slices=8,
    effects=[fx.DrumPunch()]
)

Parameters:

• path: Input audio file
• output_dir: Directory for slice files (created if needed)
• slices: Number of equal slices (default: 4)
• bpm: Calculate slice duration from BPM (overrides slices)
• beats_per_slice: Beats per slice when using BPM (default: 1)
• beat_duration: Explicit duration per slice in seconds
• threshold: Onset detection threshold 0.0-1.0 (enables automatic transient slicing)
• sensitivity: Onset detection sensitivity 1.0-3.0 (default: 1.5)
• onset_method: Detection method - 'hfc', 'flux', 'energy', or 'complex'
• output_format: Output format (default: "wav")
• effects: Effects to apply to each slice

Returns: List of created file paths

Automatic Transient Slicing

Slice loops automatically at detected transients (drum hits, etc.):

# Slice at detected onsets with default sensitivity
slices = cysox.slice_loop('drums.wav', 'output_dir/', threshold=0.3)

# More sensitive detection (catches subtle hits)
slices = cysox.slice_loop('drums.wav', 'output_dir/',
    threshold=0.2,
    sensitivity=1.2
)

# Use different detection method
slices = cysox.slice_loop('drums.wav', 'output_dir/',
    threshold=0.3,
    onset_method='flux'  # Good for tonal changes
)

cysox.onset - Direct Onset Detection

For more control, use the onset detection module directly:

from cysox import onset

# Detect onsets in a file
onsets = onset.detect('drums.wav', threshold=0.3)
print(f"Found {len(onsets)} transients")
for t in onsets:
    print(f"  {t:.3f}s")

# With custom parameters
onsets = onset.detect('drums.wav',
    threshold=0.3,      # Detection threshold (0.0-1.0)
    sensitivity=1.5,    # Peak picking sensitivity (1.0-3.0)
    min_spacing=0.05,   # Min time between onsets (seconds)
    method='hfc'        # 'hfc', 'flux', 'energy', or 'complex'
)

Detection Methods:

• hfc (default) - High-Frequency Content

  • Weights frequency bins by their index, emphasizing high frequencies
  • High frequencies are prominent in transient attacks (the "click" of a drum hit)
  • Best for: drums, percussion, plucked instruments
  • Fast and reliable for most percussive material

• flux - Spectral Flux

  • Measures the change in spectral energy between consecutive frames
  • Detects when the frequency content changes significantly
  • Best for: mixed material, melodic instruments, detecting note changes
  • Good all-around choice when HFC misses softer onsets

• energy - Energy-based

  • Simply measures the RMS energy (loudness) of each frame
  • Fastest method, minimal computation
  • Best for: very clean recordings, isolated drums, quick processing
  • May miss onsets that are spectrally distinct but similar in volume

• complex - Complex Domain

  • Analyzes both magnitude AND phase of the spectrum
  • Detects deviations from expected phase trajectories
  • Best for: maximum accuracy, subtle onsets, research applications
  • Slowest method but catches onsets other methods miss

Understanding threshold vs sensitivity:

threshold (0.0-1.0) and sensitivity (1.0-3.0) control different stages:

• threshold - Global minimum floor

  • Sets the absolute minimum level a peak must reach
  • Applied to the normalized detection function (0-1 scale)
  • Lower values = more sensitive, catches quieter transients
  • threshold=0.3 means peaks must reach at least 30% of max energy
  • Think of it as: "ignore everything below this level"

• sensitivity - Adaptive peak picking strictness

  • Controls how much a peak must exceed the local average
  • Uses a moving median filter to compute the local baseline
  • Higher values = stricter, only picks prominent peaks
  • sensitivity=1.5 means a peak must be 1.5x the local median
  • Think of it as: "how much must a peak stand out from neighbors"

Typical combinations:

• Drums with clear hits: threshold=0.3, sensitivity=1.5 (defaults)
• Subtle transients: threshold=0.2, sensitivity=1.2
• Only loud hits: threshold=0.5, sensitivity=2.0

cysox.stutter() - Create Stutter Effects

Extract a segment and repeat it:

# Basic stutter: 8x repeat of first 1/8 note at 120 BPM
cysox.stutter('drums.wav', 'stutter.wav',
    segment_duration=0.125,  # 1/8 note at 120 BPM
    repeats=8
)

# Stutter from a specific position (e.g., the snare hit)
cysox.stutter('drums.wav', 'snare_stutter.wav',
    segment_start=0.5,       # Start at 0.5 seconds
    segment_duration=0.125,
    repeats=4
)

# Stutter with effects
cysox.stutter('drums.wav', 'stutter_punchy.wav',
    segment_duration=0.25,
    repeats=4,
    effects=[fx.DrumPunch(), fx.DrumRoom()]
)

Parameters:

• path: Input audio file
• output_path: Output file path
• segment_start: Start position in seconds (default: 0)
• segment_duration: Length of segment in seconds (default: 0.125)
• repeats: Total times segment plays (default: 8)
• effects: Effects to apply after stuttering

Practical Examples

Chop an Amen Break

import cysox
from cysox import fx

# Get loop info
info = cysox.info('amen.wav')
print(f"Duration: {info['duration']:.3f}s")

# Assuming 2-bar loop at 175 BPM
bpm = 175

# Slice into individual beats
slices = cysox.slice_loop('amen.wav', 'amen_beats/', bpm=bpm)
print(f"Created {len(slices)} beat slices")

# Slice into 16th notes with breakbeat processing
slices = cysox.slice_loop('amen.wav', 'amen_16ths/',
    slices=16,
    effects=[fx.Breakbeat()]
)

# Create kick stutter fill
cysox.stutter('amen.wav', 'kick_fill.wav',
    segment_start=0,
    segment_duration=info['duration'] / 16,  # First 16th note
    repeats=16
)

Process Drum Loops

# Half-time for slow, heavy feel
cysox.convert('drums.wav', 'halftime.wav', effects=[fx.HalfTime()])

# Lo-fi vintage break sound
cysox.convert('drums.wav', 'vintage.wav', effects=[
    fx.VintageBreak(),
    fx.DrumRoom(wetness=20)
])

# 80s gated reverb snare
cysox.convert('drums.wav', 'gated.wav', effects=[fx.GatedReverb()])

# Full processing chain
cysox.convert('drums.wav', 'processed.wav', effects=[
    fx.RemoveRumble(cutoff=40),
    fx.DrumPunch(punch=5, attack=4),
    fx.DrumRoom(room_size=30, wetness=20),
    fx.BroadcastLimiter(),
])

## Low-Level API

For advanced use cases, access the full libsox bindings:

```python
from cysox import sox

# Manual initialization (high-level API handles this automatically)
sox.init()

# Open files
input_fmt = sox.Format('input.wav')
output_fmt = sox.Format('output.wav', signal=input_fmt.signal, mode='w')

# Build effects chain
chain = sox.EffectsChain(input_fmt.encoding, output_fmt.encoding)

e = sox.Effect(sox.find_effect("input"))
e.set_options([input_fmt])
chain.add_effect(e, input_fmt.signal, input_fmt.signal)

e = sox.Effect(sox.find_effect("vol"))
e.set_options(["3dB"])
chain.add_effect(e, input_fmt.signal, input_fmt.signal)

e = sox.Effect(sox.find_effect("output"))
e.set_options([output_fmt])
chain.add_effect(e, input_fmt.signal, input_fmt.signal)

# Process
chain.flow_effects()

# Cleanup
input_fmt.close()
output_fmt.close()
sox.quit()

Building from Source

macOS

brew install sox libsndfile mad libpng flac lame mpg123 libogg opus opusfile libvorbis
make
make test

Linux

sudo apt-get install libsox-dev libsndfile1-dev pkg-config
make
make test

Status

Comprehensive test suite covering all functionality. All libsox C examples ported to Python (effects chains, waveform analysis, trim, concatenation, format conversion).

Known Issues

• Memory I/O: libsox memory I/O functions have platform issues (tests skipped)
• Init/Quit Cycles: Use high-level API to avoid init/quit issues (handled automatically)

See KNOWN_LIMITATIONS.md for details.

Platform Support

• macOS: Full support
• Linux: Full support
• Windows: Placeholder (contributions welcome)

Building Documentation

pip install mkdocs-material
make docs          # Build static site
make docs-serve    # Live preview at http://localhost:8000

License

MIT

KissFFT (vendored in vendor/kissfft/) is BSD-3-Clause licensed. See vendor/kissfft/COPYING.