AudioEffectCompressor in Godot – Complete Guide

Welcome to this tutorial on the AudioEffectCompressor in Godot 4! As you venture into the world of game development, understanding how to manage and manipulate audio within your projects is essential. Sound plays a critical role in game immersion and experience, and having the ability to tweak it to perfection can be a game-changer. That’s where the AudioEffectCompressor comes in, and in this tutorial, we’ll learn about its features and how we can apply it to enhance our game audio in Godot.

What is the AudioEffectCompressor?

The AudioEffectCompressor is a powerful tool in Godot’s audio engine that enables you to control the dynamics of your audio. It helps in reducing the volume of loud sounds that exceed a specific threshold level, which in turn can smooth out your audio and increase its overall loudness. This effect can be very helpful in ensuring that your game’s sound is balanced and professional.

What is it for?

A compressor is often used in various scenarios within audio production. It can be found on the Master bus to provide a balanced output, on individual voice channels to make sure they are clear and consistent, or it can even be sidechained with other audio for creative effects. Sidechaining is particularly popular in gaming, where you might want the music to duck down slightly when character voices or important sound effects are played.

Why Should I Learn It?

Implementing audio compression effectively can significantly improve the aural ambiance of your game. By learning how to use the AudioEffectCompressor, you’re not only expanding your toolset but also enhancing the quality of your game. Moreover, understanding audio effects allows for more creative control and can help resolve common audio issues that can occur in game development. Whether you’re just starting your journey in game creation or looking to refine your skills, mastering audio effects is an invaluable asset.

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Setting Up the AudioEffectCompressor in Godot 4

To begin using the AudioEffectCompressor in Godot 4, you’ll first need to add it to your desired audio bus. Here’s a step-by-step code snippet on how to set this up:

var compressor =

# Now, let's add the effect to the master bus — the default bus
AudioServer.add_bus_effect(0, compressor)

Once the effect is added to the bus, you can start to configure its properties. The initial configuration might look something like this:

# Set compressor's threshold to -24dB
compressor.threshold = -24

# Set the compressor's ratio to 4:1
compressor.ratio = 4

# Set the attack time to 20ms
compressor.attack_ms = 20

# Set the release time to 250ms
compressor.release_ms = 250

This basic setup will already have a substantial impact on your audio bus, particularly in standardizing dynamic range and ensuring that no sound peaks above the set threshold.

Adjusting Compression for In-Game Sound Effects

Sound effects in games such as footsteps or weapon shots can often vary in loudness, which can disrupt the audio experience. Let’s apply the AudioEffectCompressor to individual sound effects:

# Add and setup a new bus for sound effects
var sfx_bus_index = AudioServer.get_bus_count()
AudioServer.set_bus_name(sfx_bus_index, "SoundEffects")

var sfx_compressor =
AudioServer.add_bus_effect(sfx_bus_index, sfx_compressor)

# Adjust the compressor specifically for sound effects
sfx_compressor.threshold = -18
sfx_compressor.ratio = 3
sfx_compressor.attack_ms = 10
sfx_compressor.release_ms = 150

In the above example, we’ve created a separate audio bus called “SoundEffects”, and we’ve added a compressor to it with settings that are optimized for typical in-game sound effects.

Using Compression on Music Tracks

Music tracks can also benefit from compression. It can help to even out the levels between quiet and loud parts of the track, making for a smoother listening experience.

# Add and setup a new bus for music
var music_bus_index = AudioServer.get_bus_count()
AudioServer.set_bus_name(music_bus_index, "Music")

var music_compressor =
AudioServer.add_bus_effect(music_bus_index, music_compressor)

# Adjust the compressor to enhance the musical experience
music_compressor.threshold = -20
music_compressor.ratio = 2
music_compressor.attack_ms = 30
music_compressor.release_ms = 300

The compressor settings for music usually have a lower ratio and a slightly longer attack and release time, ensuring the music breathes and maintains its natural dynamic range without cutting off any peaks too aggressively.

Sidechaining for Advanced Audio Control

In gaming, it’s common to want background music to duck out momentarily for dialogue or certain sound effects. This technique is known as sidechaining, and although a bit more complex, it’s quite possible with Godot 4 using the compressor.

# Assume 'music_compressor' affects the music bus
var sidechain_amount = -12 # The amount the music will dip

# Set the sidechain property - this could be linked to in-game triggers
music_compressor.sidechain = "SoundEffects"

# Set the compressor's gain reduction (ducking effect)
music_compressor.gain_reduction_db = sidechain_amount

Keep in mind that sidechaining in this context would involve triggering this effect through signals or game events, which would modify the ‘gain_reduction_db’ property according to game logic.Continuing from where we left off, let’s dive deeper into sidechaining and how you can use the AudioEffectCompressor to achieve that dynamic relationship between different audio elements.

Linking Dialogue with Background Music

Firstly, suppose you want the background music to automatically lower its volume when the in-game character is speaking. Here’s how you could adjust the `gain_reduction_db` in response to dialogue triggers:

# Imagine a function that gets called when dialogue starts
func on_dialogue_start():
    music_compressor.gain_reduction_db = -12

# And, when the dialogue ends, the music volume resets
func on_dialogue_end():
    music_compressor.gain_reduction_db = 0

These functions simulate the sidechain effect by manually adjusting the music’s compressor during dialogue sequences.

Adjusting Sidechain in Real-Time

Game scenarios often require real-time adjustment of audio dynamics. Here’s an example of adjusting sidechain levels based on game events like explosions:

# A function that triggers during an in-game explosion
func on_explosion():
    # Increase the gain reduction for a more dramatic effect
    sfx_compressor.gain_reduction_db = -20
    # Reset it after a short delay
    yield(get_tree().create_timer(0.5), "timeout")
    sfx_compressor.gain_reduction_db = -12

The `yield` allows you to create a timer which will wait for half a second before resetting the gain reduction, simulating the effect of an explosion drowning out other sounds temporarily.

Automating Sidechain with AnimationPlayer

Moreover, Godot’s built-in AnimationPlayer can be used to automate sidechain parameters over time:

# Assuming 'animation_player' is your AnimationPlayer node
var tracks = animation_player.get_animation("SidechainEffect").tracks

# Access the specific property track for gain reduction
var track_index = animation_player.find_track("AudioEffectCompressor:gain_reduction_db")
# Insert key with value -18 at time 0
animation_player.track_insert_key(track_index, 0.0, -18)
# Insert key with value 0 at time 2
animation_player.track_insert_key(track_index, 2.0, 0)

# Play the animation to automate sidechain effect"SidechainEffect")

This code will automate the reduction of the music gain when the animation is played, easing back to normal over a period of 2 seconds.

Adjusting Other Parameters for Creative Effects

The AudioEffectCompressor isn’t limited to volume control. You can also adjust other parameters for creative effects, such as making a pulsing effect for underwater or dream sequences:

# Set up compressor for a special in-game environment, e.g. underwater
underwater_compressor.threshold = -30
underwater_compressor.ratio = 6

# Adjusting makeup gain for perceived loudness
underwater_compressor.makeup_gain_db = 6

# Automate a pulsing effect with the release and threshold
animation_player.track_insert_key(release_track_index, 0.0, 150)
animation_player.track_insert_key(threshold_track_index, 0.0, -30)
animation_player.track_insert_key(release_track_index, 1.0, 500)
animation_player.track_insert_key(threshold_track_index, 1.0, -20)"UnderwaterPulse")

By creatively controlling the compressor’s threshold and release parameters, you can design a dynamic audio environment that elevates the player’s immersive experience.

Final Thoughts

Understanding and mastering the AudioEffectCompressor opens up a plethora of possibilities for in-game audio design. By manipulating various parameters and automating them in response to game events, you can create a rich, dynamic soundscape that resonates with players and enhances the gaming experience.

Remember, experimentation is key. Play around with different settings, contextually adjust them based on your game’s needs and get creative with compression to make your game soundtracks and effects come alive in the most captivating ways.In this continued exploration, we’ll delve into more advanced uses of the AudioEffectCompressor in Godot 4, giving you the knowledge to finely tune your game’s audio experience.

Dynamic Range Compression for Voiceovers

Voiceovers need to be clear and consistent throughout the game. Here’s how to compress them effectively:

# Create and set up the compressor for the voiceover bus
var vo_bus_index = AudioServer.get_bus_count()
AudioServer.set_bus_name(vo_bus_index, "VoiceOver")

var vo_compressor =
AudioServer.add_bus_effect(vo_bus_index, vo_compressor)

# Voiceover-specific compressor settings
vo_compressor.threshold = -22
vo_compressor.ratio = 3
vo_compressor.attack_ms = 15
vo_compressor.release_ms = 200

These settings will ensure that your voiceovers are audible over the background music, without compromising the clarity or quality of the voice acting.

Adaptive Compression for Dynamic Scenes

Your game might feature scenes with varying levels of action which would require adaptive compression for the sound effects bus:

var is_action_scene = false  # Assume this reflects the current game state

# Check the scene's state and adapt the SFX compressor settings
func update_sfx_compression():
    if is_action_scene:
        sfx_compressor.threshold = -10
        sfx_compressor.ratio = 8
        sfx_compressor.attack_ms = 5
        sfx_compressor.release_ms = 100
        sfx_compressor.threshold = -18
        sfx_compressor.ratio = 4
        sfx_compressor.attack_ms = 10
        sfx_compressor.release_ms = 150

# Call this function whenever the game state changes

Adjusting the compressor’s settings based on the current scene can help keep the audio well-balanced regardless of the on-screen action.

Creating an Atmospheric Ambiance

Atmospheric sounds, like wind or ocean waves, can also benefit from compression for a consistent ambient soundscape:

var ambient_compressor =
ambient_compressor.threshold = -15
ambient_compressor.ratio = 1.8
ambient_compressor.attack_ms = 50
ambient_compressor.release_ms = 500

# Assign the compressor to the ambient sound bus
var ambient_bus_index = AudioServer.get_bus_count()
AudioServer.set_bus_name(ambient_bus_index, "Ambient")
AudioServer.add_bus_effect(ambient_bus_index, ambient_compressor)

Setting a softer compression ratio and longer release times helps maintain the natural ebb and flow of ambient sounds, avoiding the effect of “pumping” which can be distracting.

Enhancing UI Sounds with Subtle Compression

UI sounds, such as clicks and notifications, are enhanced with subtle compression to maintain presence without overwhelming:

# Configure a compressor specifically for UI sounds
var ui_compressor =
ui_compressor.threshold = -20
ui_compressor.ratio = 1.5
ui_compressor.attack_ms = 10
ui_compressor.release_ms = 100

# Apply the effect to the UI bus
var ui_bus_index = AudioServer.get_bus_count()
AudioServer.set_bus_name(ui_bus_index, "UI")
AudioServer.add_bus_effect(ui_bus_index, ui_compressor)

A light compression on UI sounds ensures they blend smoothly into the game without becoming too intrusive, especially during gameplay.

Utilizing Compression for Looped Sound Effects

Looped effects, like engine hums or background machinery, can sometimes have noticeable seams when they restart their loop. Compression can be used to smooth these transitions:

# Set up a dedicated compressor for looped sounds
var loop_compressor =
loop_compressor.threshold = -10
loop_compressor.ratio = 3
loop_compressor.attack_ms = 10
loop_compressor.release_ms = 300

# Bind the compressor to the loop effects bus
var loop_bus_index = AudioServer.get_bus_count()
AudioServer.set_bus_name(loop_bus_index, "LoopEffects")
AudioServer.add_bus_effect(loop_bus_index, loop_compressor)

By doing so, the compressor will evenly apply gain reduction across the loop, minimizing the disruption when the sound effect restarts.

These examples showcase how the AudioEffectCompressor can be integrated into various aspects of your game audio. By tailoring the parameters to suit the specific needs of voiceovers, action scenes, ambient sounds, UI elements, and looped audio, you can ensure a cohesive and engaging auditory environment that augments the player’s experience. Remember, each game’s needs will differ, so it’s essential to test your audio in the context of the gameplay and tweak the compressors accordingly to achieve the best result.

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In this tutorial, we’ve taken a deep dive into the dynamic world of audio effects with Godot 4’s AudioEffectCompressor. As you’ve seen, the right audio settings can make the difference between a good game and a great one. The subtle art of compression can elevate your game’s immersion factor, keep the player engaged, and ensure your soundscapes are as vivid and responsive as your visuals. The possibilities are endless, and now with these skills under your belt, the soundscape of your next game project is bound to captivate your audience.

Don’t stop here — continue to elevate your game development prowess with our comprehensive Godot Game Development Mini-Degree. You’re just a click away from unlocking a treasure trove of knowledge that will help you become the game developer you’ve always aspired to be. Join us at Zenva, and let’s make your game development dreams a reality!

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