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Cookbook

Ready-to-use recipes for common audio and MIDI processing tasks.

Recipe Overview

File Operations

  • File I/O: Common file reading and writing patterns
  • Batch Processing: Process multiple files efficiently
  • Format Detection: Detect and validate audio formats
  • Format Conversion: Convert between audio formats

Audio Processing

  • Volume Control: Normalize audio, adjust levels
  • Fades: Apply fade in/out effects
  • Resampling: Change sample rates with automatic conversion
  • Mixing: Mix multiple audio tracks
  • Slicing: Split audio into chunks
  • Concatenation: Merge multiple audio files

Real-Time Audio

  • Recording: Capture audio from input devices
  • Low-Latency Playback: Minimal latency audio output
  • Level Monitoring: Real-time audio level metering
  • Effects Processing: Apply real-time audio effects

AudioUnit Plugin Hosting

  • Plugin Discovery: Find and list available AudioUnit plugins
  • Parameter Control: Control plugin parameters and automation
  • Preset Management: Save, load, and share plugin presets
  • Audio Format Support: Process audio in multiple formats (float32/64, int16/32)
  • Plugin Chains: Create multi-effect chains with automatic routing
  • MIDI Control: Control instrument plugins with MIDI messages
  • Tempo Synchronization: Sync tempo across multiple applications
  • Beat-Accurate Timing: Schedule events on specific beats
  • AudioPlayer Sync: Synchronize audio playback with Link
  • MIDI Clock Sync: Send MIDI clock messages synchronized to Link
  • Transport Control: Control playback state across devices
  • Multi-Device Sync: Connect multiple Link-enabled applications

MIDI Processing

  • Device Discovery: Find and list MIDI sources and destinations
  • MIDI Input: Receive and process MIDI messages
  • MIDI Output: Send MIDI messages to devices
  • MIDI Routing: Route MIDI between devices and channels
  • MIDI Transformation: Transpose, scale velocity, and transform MIDI data
  • MIDI Recording: Record and playback MIDI sequences

Integration

  • NumPy Integration: Work with NumPy arrays for signal processing
  • SciPy Integration: Use SciPy for advanced DSP
  • Async I/O: Asynchronous audio file operations

Quick Reference

Common Patterns

Read audio file:

from coremusic.audio import AudioFile

with AudioFile("audio.wav") as audio:
    data, count = audio.read_packets(0, 1024)
    samples = audio.read_as_numpy()  # or the whole file at once

Load AudioUnit plugin:

from coremusic.audio.audiounit_host import AudioUnitPlugin

with AudioUnitPlugin.from_name("AUDelay") as plugin:
    plugin['Delay Time'] = 0.5
    output = plugin.process(input_data)

Create plugin chain:

from coremusic.audio.audiounit_host import AudioUnitChain

with AudioUnitChain() as chain:
    chain.add_plugin("AUHipass")
    chain.add_plugin("AUMatrixReverb")
    output = chain.process(input_data, wet_dry_mix=0.8)

Sync with Ableton Link:

from coremusic import link

session = link.LinkSession(bpm=120.0)
session.enabled = True

state = session.capture_app_session_state()
print(f"Tempo: {state.tempo:.1f} BPM")
print(f"Peers: {session.num_peers}")

session.enabled = False

Send MIDI:

from coremusic import capi
from coremusic.midi import note_on

client = capi.midi_client_create("Output")
port = capi.midi_output_port_create(client, "Out")
dest = capi.midi_destination_create(client, "Cookbook Destination")

# Send Note On
capi.midi_send_data(port, dest, note_on("C4", 100))

capi.midi_client_dispose(client)

Tips and Best Practices

Performance

  • Use chunk processing for large files
  • Pre-allocate buffers when possible
  • Minimize memory copies
  • Use appropriate buffer sizes (1024-4096 frames typical)

Resource Management

  • Always use context managers (with statements)
  • Close resources explicitly if not using context managers
  • Handle exceptions to ensure cleanup
  • Dispose of MIDI clients and ports properly

Error Handling

  • Check file existence before opening
  • Validate audio formats
  • Handle CoreAudio errors gracefully
  • Provide meaningful error messages

Thread Safety

  • AudioUnits are not thread-safe by default
  • Use locks when accessing shared resources
  • Process audio on dedicated threads
  • Avoid blocking the audio callback thread