Audio Effects

Apply real-time audio effects like reverb, delay, EQ, and compression to audio buses

Overview

Godot’s audio system supports real-time audio effects that can be added to audio buses. Effects are processed in order on each bus, allowing you to create complex audio processing chains similar to professional audio software.

Effects are added to buses, not individual AudioStreamPlayer nodes. All audio routed through a bus will be processed by its effects.

Adding Effects to Buses

Programmatically Adding Effects

# Get bus index
var bus_idx = AudioServer.get_bus_index("Music")

# Create a reverb effect
var reverb = AudioEffectReverb.new()
reverb.room_size = 0.8
reverb.damping = 0.5
reverb.wet = 0.3

# Add effect to bus
AudioServer.add_bus_effect(bus_idx, reverb)

// Get bus index
int busIdx = AudioServer.GetBusIndex("Music");

// Create a reverb effect
var reverb = new AudioEffectReverb();
reverb.RoomSize = 0.8f;
reverb.Damping = 0.5f;
reverb.Wet = 0.3f;

// Add effect to bus
AudioServer.AddBusEffect(busIdx, reverb);

Managing Effects

var bus_idx = AudioServer.get_bus_index("SFX")

# Get effect count
var effect_count = AudioServer.get_bus_effect_count(bus_idx)

# Get specific effect
var effect = AudioServer.get_bus_effect(bus_idx, 0)

# Enable/disable effect
AudioServer.set_bus_effect_enabled(bus_idx, 0, false)

# Remove effect
AudioServer.remove_bus_effect(bus_idx, 0)

# Swap effect positions
AudioServer.swap_bus_effects(bus_idx, 0, 1)

Common Audio Effects

AudioEffectReverb

Adds reverb (echo/room ambience) to audio:

var reverb = AudioEffectReverb.new()
reverb.room_size = 0.8      # 0.0 to 1.0 (larger = bigger room)
reverb.damping = 0.5        # 0.0 to 1.0 (higher = more absorption)
reverb.spread = 1.0         # 0.0 to 1.0 (stereo spread)
reverb.wet = 0.3            # Effect volume (0.0 to 1.0)
reverb.dry = 1.0            # Original signal volume
reverb.predelay_msec = 20.0 # Pre-delay in milliseconds

var bus_idx = AudioServer.get_bus_index("Ambient")
AudioServer.add_bus_effect(bus_idx, reverb)

Use Cases:

• Simulating room acoustics
• Adding depth to music
• Environmental audio (caves, halls, outdoors)

AudioEffectDelay

Creates echo/delay effects:

var delay = AudioEffectDelay.new()
delay.dry = 1.0

# Configure tap 1 (first echo)
delay.tap1_active = true
delay.tap1_delay_ms = 300.0  # 300ms delay
delay.tap1_level_db = -6.0   # Volume of first echo
delay.tap1_pan = -0.2        # Slight left pan

# Configure tap 2 (second echo)
delay.tap2_active = true
delay.tap2_delay_ms = 600.0
delay.tap2_level_db = -12.0
delay.tap2_pan = 0.2         # Slight right pan

# Feedback creates repeating echoes
delay.feedback_active = true
delay.feedback_delay_ms = 400.0
delay.feedback_level_db = -6.0

var bus_idx = AudioServer.get_bus_index("SFX")
AudioServer.add_bus_effect(bus_idx, delay)

Use Cases:

• Rhythmic delays
• Space/sci-fi effects
• Doubling instruments

AudioEffectEQ

Equalizer for frequency control (6-band, 10-band, or 21-band):

# 10-band EQ
var eq = AudioEffectEQ10.new()

# Boost bass (31 Hz)
eq.set_band_gain_db(0, 3.0)

# Cut low-mids (125 Hz)
eq.set_band_gain_db(2, -2.0)

# Boost presence (4000 Hz)
eq.set_band_gain_db(7, 2.0)

var bus_idx = AudioServer.get_bus_index("Music")
AudioServer.add_bus_effect(bus_idx, eq)

Available EQ Types:

• AudioEffectEQ6 - 6 bands (32, 100, 320, 1000, 3200, 10000 Hz)
• AudioEffectEQ10 - 10 bands
• AudioEffectEQ21 - 21 bands (most precise)

Use Cases:

• Shaping tone of music/SFX
• Removing unwanted frequencies
• Mixing multiple audio sources

AudioEffectCompressor

Dynamic range compression:

var compressor = AudioEffectCompressor.new()
compressor.threshold = -20.0     # dB threshold to start compression
compressor.ratio = 4.0           # Compression ratio (4:1)
compressor.gain = 0.0            # Makeup gain
compressor.attack_us = 20.0      # Attack time in microseconds
compressor.release_ms = 250.0    # Release time in milliseconds
compressor.mix = 1.0             # Wet/dry mix

var bus_idx = AudioServer.get_bus_index("Master")
AudioServer.add_bus_effect(bus_idx, compressor)

Use Cases:

• Controlling dynamic range
• Preventing audio clipping
• “Gluing” mix elements together
• Making quiet sounds more audible

AudioEffectLimiter

Prevents audio from exceeding a threshold:

var limiter = AudioEffectLimiter.new()
limiter.ceiling_db = -0.3        # Maximum output level
limiter.threshold_db = -10.0     # When limiting starts
limiter.soft_clip_db = -1.0      # Soft clipping threshold
limiter.soft_clip_ratio = 10.0   # Soft clipping ratio

var bus_idx = AudioServer.get_bus_index("Master")
AudioServer.add_bus_effect(bus_idx, limiter)

Always add a limiter to the Master bus to prevent audio clipping and distortion.

AudioEffectFilter

Frequency filters (low-pass, high-pass, band-pass, notch):

# Low-pass filter (removes high frequencies)
var lpf = AudioEffectLowPassFilter.new()
lpf.cutoff_hz = 2000.0           # Frequency cutoff
lpf.resonance = 0.5              # Resonance at cutoff

# High-pass filter (removes low frequencies)
var hpf = AudioEffectHighPassFilter.new()
hpf.cutoff_hz = 200.0
hpf.resonance = 0.7

# Band-pass filter (allows only a frequency range)
var bpf = AudioEffectBandPassFilter.new()
bpf.cutoff_hz = 1000.0
bpf.resonance = 0.8

var bus_idx = AudioServer.get_bus_index("Radio")
AudioServer.add_bus_effect(bus_idx, lpf)
AudioServer.add_bus_effect(bus_idx, hpf)

Use Cases:

• Radio/telephone effects
• Underwater effects (low-pass)
• Rumble removal (high-pass)
• Creative sound design

AudioEffectDistortion

Adds harmonic distortion:

var distortion = AudioEffectDistortion.new()
distortion.mode = AudioEffectDistortion.MODE_OVERDRIVE
distortion.drive = 0.8           # 0.0 to 1.0
distortion.pre_gain = 0.0        # Pre-amplification in dB
distortion.post_gain = 0.0       # Post-amplification in dB

var bus_idx = AudioServer.get_bus_index("Guitar")
AudioServer.add_bus_effect(bus_idx, distortion)

Distortion Modes:

• MODE_CLIP - Hard clipping
• MODE_ATAN - Soft saturation
• MODE_LOFI - Lo-fi bit crushing
• MODE_OVERDRIVE - Tube-like overdrive
• MODE_WAVESHAPE - Wave shaping

AudioEffectChorus

Thickens sound by creating multiple slightly detuned copies:

var chorus = AudioEffectChorus.new()
chorus.dry = 1.0
chorus.wet = 0.5

# Configure voice 1
chorus.voice_1_delay_ms = 15.0
chorus.voice_1_rate_hz = 0.8
chorus.voice_1_depth_ms = 2.0
chorus.voice_1_level_db = 0.0

# Configure voice 2
chorus.voice_2_delay_ms = 20.0
chorus.voice_2_rate_hz = 1.2
chorus.voice_2_depth_ms = 3.0
chorus.voice_2_level_db = 0.0

var bus_idx = AudioServer.get_bus_index("Synth")
AudioServer.add_bus_effect(bus_idx, chorus)

AudioEffectPhaser

Creates sweeping, swirling effects:

var phaser = AudioEffectPhaser.new()
phaser.range_min_hz = 440.0
phaser.range_max_hz = 1600.0
phaser.rate_hz = 0.5
phaser.feedback = 0.7
phaser.depth = 1.0

var bus_idx = AudioServer.get_bus_index("Synth")
AudioServer.add_bus_effect(bus_idx, phaser)

Effect Chains

Effects are processed in the order they’re added:

var bus_idx = AudioServer.get_bus_index("Vocal")

# 1. EQ to shape tone
var eq = AudioEffectEQ10.new()
eq.set_band_gain_db(0, -3.0)  # Reduce bass
AudioServer.add_bus_effect(bus_idx, eq)

# 2. Compressor to control dynamics
var comp = AudioEffectCompressor.new()
comp.threshold = -15.0
comp.ratio = 3.0
AudioServer.add_bus_effect(bus_idx, comp)

# 3. Reverb for ambience
var reverb = AudioEffectReverb.new()
reverb.room_size = 0.6
reverb.wet = 0.2
AudioServer.add_bus_effect(bus_idx, reverb)

Effect order matters! Generally: EQ → Dynamics (Compressor) → Time-based (Delay/Reverb).

Analyzing Audio

AudioEffectSpectrumAnalyzer

Analyze frequency content for visualizations:

var spectrum = AudioEffectSpectrumAnalyzer.new()
spectrum.buffer_length = 2.0  # Analysis window
spectrum.fft_size = AudioEffectSpectrumAnalyzer.FFT_SIZE_2048

var bus_idx = AudioServer.get_bus_index("Master")
AudioServer.add_bus_effect(bus_idx, spectrum)

# In _process():
func _process(delta):
    var effect = AudioServer.get_bus_effect_instance(bus_idx, 0)
    var magnitude = effect.get_magnitude_for_frequency_range(200, 400)
    # Use magnitude for visualization

AudioEffectCapture

Capture audio for recording or processing:

var capture = AudioEffectCapture.new()
capture.buffer_length = 0.1

var bus_idx = AudioServer.get_bus_index("Record")
AudioServer.add_bus_effect(bus_idx, capture)

# Retrieve audio data
func get_audio_data():
    var effect = AudioServer.get_bus_effect_instance(bus_idx, 0) as AudioEffectCapture
    var frames = effect.get_frames_available()
    return effect.get_buffer(frames)

Best Practices

Use buses wisely

Create separate buses for different audio categories (Music, SFX, Voice) and apply appropriate effects to each.

Mind CPU usage

Effects consume CPU. Use them judiciously, especially on mobile platforms. Disable effects when not needed.

Test on target hardware

Effect performance varies across platforms. Always test on your target devices.

Use subtle settings

Less is often more. Start with subtle effect settings and increase gradually.

Bypass for debugging

Use set_bus_bypass_effects() to temporarily disable all effects on a bus for troubleshooting.

See Also

Audio Overview

Learn about AudioServer and bus architecture

Audio Streams

Understand audio formats and playback