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Audio effects

Godot includes several audio effects that can be added to an audio bus to alter every sound file that goes through that bus.

../../_images/audio_buses4.png

Try them all out to get a sense of how they alter sound. Here follows a short description of the available effects:

Amplify

Amplify changes the amplitude of the signal. Some care needs to be taken. Setting the level too high can make the sound clip, which is usually undesirable.

BandLimit and BandPass

These are resonant filters which block frequencies around the Cutoff point. BandPass can be used to simulate sound passing through an old telephone line or megaphone. Modulating the BandPass frequency can simulate the sound of a wah-wah guitar pedal, think of the guitar in Jimi Hendrix's Voodoo Child (Slight Return).

Capture

The Capture effect copies the audio frames of the audio bus that it is on into an internal buffer. This can be used to capture data from the microphone or to transmit audio over the network in real-time.

Chorus

The Chorus effect duplicates the incoming audio, delays the duplicate slightly and uses an LFO to continuously modulate the pitch of the duplicated signal before mixing the duplicated signal(s) and the original together again. This creates a shimmering effect and adds stereo width to the sound.

Compressor

A dynamic range compressor automatically attenuates the level of the incoming signal when its amplitude exceeds a certain threshold. The level of attenuation applied is proportional to how far the incoming audio exceeds the threshold. The compressor's Ratio parameter controls the degree of attenuation. One of the main uses of a compressor is to reduce the dynamic range of signals with very loud and quiet parts. Reducing the dynamic range of a signal can make it easier to mix.

The compressor has many uses. For example:

  • It can be used in the Master bus to compress the whole output.

  • It can be used in voice channels to ensure they sound as even as possible.

  • It can be sidechained. This means it can reduce the sound level of one signal using the level of another audio bus for threshold detection. This technique is very common in video game mixing to "duck" the level of music or sound effects when voices need to be heard.

  • It can accentuate transients by using a slower attack. This can make sound effects more punchy.

Note

If your goal is to prevent a signal from exceeding a given amplitude altogether, rather than to reduce the dynamic range of the signal, a limiter is likely a better choice than a compressor.

Delay

Adds an "echo" effect with a feedback loop. It can be used together with Reverb to simulate wide rooms, canyons, etc. where sound bounces are far apart.

Distortion

Makes the sound distorted. Godot offers several types of distortion: overdrive, tan and bit crushing. Distortion can be used to simulate sound coming through a low-quality speaker or device.

EQ

EQ is what all other equalizers inherit from. It can be extended with Custom scripts to create an equalizer with a custom number of bands.

EQ6, EQ10, EQ21

Godot provides three equalizers with different numbers of bands. An equalizer on the Master bus can be useful to cut frequencies that the device's speakers can't reproduce well (e.g. a mobile phone's speakers won't reproduce bass content well). The equalizer effect can be disabled when headphones are plugged in.

Filter

Filter is what all other filters inherit from and should not be used directly.

HighPassFilter

Cuts frequencies below a specific Cutoff frequency. HighPassFilter is used to reduce the bass content of a signal.

HighShelfFilter

Reduces all frequencies above a specific Cutoff frequency.

Limiter

A limiter is similar to a compressor, but it's less flexible and designed to prevent a signal's amplitude e