AudioStreamPlaybackResampled in Godot – Complete Guide

Audio manipulation and effects are pivotal elements in creating immersive experiences in games and interactive media. As such, understanding how to control and manipulate audio streams is a crucial skill for developers. For those venturing into the Godot Engine, especially with its much-anticipated version 4, mastering audio functionalities can open up a world of possibilities to enhance games and applications. In this tutorial, we’ll explore the AudioStreamPlaybackResampled class, learn how it operates under the hood, and understand the power it arms a developer with. As we take a look at Godot 4’s audio capabilities, we invite learners of all levels to read on and discover the vibrant sonic landscapes that are just a line of code away.

What is AudioStreamPlaybackResampled?

AudioStreamPlaybackResampled is a class in Godot Engine 4 which serves as a foundational block for custom audio stream playback with resampling capabilities. Resampling is a process where an audio signal is converted from one sampling rate to another. This process is often necessary to ensure that audio plays back at the correct pitch and speed, regardless of the output device’s sample rate.

What is it for?

In audio processing, resampling is essential when working with sound files that may not match the system or output device’s native sampling rate. By employing the AudioStreamPlaybackResampled class, Godot developers can:

– Seamlessly adjust audio streams to match device capabilities
– Ensure synchronicity between audio and game events
– Maintain audio quality by minimizing artifacts that may occur during sample rate conversion

Why should I learn it?

Learning how to use the AudioStreamPlaybackResampled class:
– Enhances your ability to create rich audio experiences in your games and apps.
– Elevates the quality of your projects with finer control over sound playback.
– Adds a valuable skill to your repertoire, making your projects more polished and professional.
– Is an investment in your future as a game developer, as audio is an integral part of game design and user experience.

Armed with this knowledge, you’ll be able to fine-tune your audio streams and ensure they sound just right, no matter where they’re played. Let’s dive into the technical details and practical applications of this powerful audio class in the following sections.

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Creating an AudioStreamPlayer Node

Before we can manipulate audio using the AudioStreamPlaybackResampled class in Godot 4, we need to start with the basics – setting up an AudioStreamPlayer node. This node is used to play back an audio stream within a scene.

var audio_player = AudioStreamPlayer.new()
add_child(audio_player)
audio_player.stream = load("res://sounds/my_sound.ogg")

In this example, we’ve created a new AudioStreamPlayer and added it to our current scene. We then load an audio file (in this case, an OGG file), which is set as the stream that the AudioStreamPlayer will play.

Loading and Playing an Audio Stream

With the AudioStreamPlayer node in place, the next step is to load an audio stream and play it. Here’s how to do it:

audio_player.play()

The `play()` method initiates playback of the audio stream assigned to the AudioStreamPlayer. If you want to play the audio immediately as the scene starts, you could place this code within the `_ready()` function of a script attached to the node.

Implementing AudioStreamPlaybackResampled

Now, let’s use the AudioStreamPlaybackResampled class to fine-tune our audio playback with resampling.

# Assuming 'audio_player' is already an added AudioStreamPlayer node
var stream_playback = AudioStreamPlaybackResampled.new()
audio_player.stream_playback = stream_playback

Here, we create a new instance of AudioStreamPlaybackResampled and set it as the stream playback object of our audio player. This will allow us to perform resampling operations on the fly.

Adjusting Pitch and Playback Speed

One of the primary uses of resampling is to adjust the pitch and speed of audio playback. Here’s an example of how to change the pitch of the audio stream, which also alters the speed:

# Double the pitch and speed
stream_playback.pitch_scale = 2.0

# Play the audio
audio_player.play()

By setting the `pitch_scale` property to 2.0, we raise the pitch by one octave and also double the playback speed. Conversely, setting it to a value less than 1.0 will lower the pitch and slow down the playback.

Setting a Custom Playback Position

Sometimes, you may want to start playing an audio stream from a position other than the beginning. This is how you can set a custom playback position:

# Set the playback position to 5 seconds
stream_playback.seek(5.0)

# Play the audio
audio_player.play()

The `seek()` method is used to jump to a specific point in the audio stream. This can be quite useful for creating seamless audio loops or skipping to a particular section of a sound effect or piece of music.

Looping an Audio Stream

Looping audio is a common requirement for background music in games. Here’s how you can loop an audio stream with AudioStreamPlaybackResampled:

# Enable looping
stream_playback.loop = true

# Play the audio
audio_player.play()

Setting the `loop` property to `true` makes the audio stream repeat indefinitely. Make sure that the stream you want to loop is loop-friendly, without abrupt beginnings or endings.

In the next section, we will delve into more advanced examples and learn how to utilize the full potential of the AudioStreamPlaybackResampled class. Stay tuned to elevate your audio game to the next level.

Manipulating Audio in Real-Time

Let’s look at how you can manipulate audio streams in real-time to interact with player actions or environmental triggers. For instance, altering the volume based on the player’s proximity to a sound source.

# This example assumes you have a method to calculate the distance
# between the player and the sound source

var distance_to_player = get_distance_to_player()

# Set volume based on distance
var volume_db = -20 - (distance_to_player * 2)
audio_player.set_volume_db(volume_db)

Here, we’re setting the volume in decibels based on the distance to the player. The further the player is from the source, the quieter the sound.

Applying Effects to Audio Streams

Applying audio effects can massively enhance the feel of a game. In Godot, you can use the AudioEffectPitchShift class in combination with AudioStreamPlaybackResampled to apply a pitch shift effect without changing playback speed.

# Create the pitch shift effect
var pitch_shift_effect = AudioEffectPitchShift.new()
pitch_shift_effect.pitch_scale = 1.5 # Pitch is scaled by a factor of 1.5

# Add effect to an AudioBus
var bus_idx = AudioServer.get_bus_index("Effects")
AudioServer.add_bus_effect(bus_idx, pitch_shift_effect)

# Assign our audio player to the 'Effects' bus
audio_player.bus = "Effects"

In the example above, we created a new pitch shift effect, scaled the pitch by 1.5 times its original pitch (without affecting the playback speed), added it to an ‘Effects’ bus, and then assigned our audio player to use that bus.

Fading Audio In and Out

Audio fading is commonly used to smoothly introduce or exit audio streams. Below is a simple way to fade out an audio stream over time:

# Fade out over two seconds
var fade_time = 2.0
var steps = 10
var fade_out_vol_step = audio_player.volume_db / steps

for i in range(steps + 1):
    yield(get_tree().create_timer(fade_time / steps), "timeout")
    audio_player.volume_db -= fade_out_vol_step

This script gradually decreases the volume of `audio_player` to achieve a fade-out effect. The `yield` statement creates a delay equal to a fraction of the total fade time before the volume is decreased by a step.

Syncing Audio with Game Actions

For making audio feedback feel more natural, you might want to sync audio with specific game actions. This can be done by using the `play()` method with an additional positional argument.

# Play a 'jump' sound effect when the player jumps
func _on_player_jump():
    var jump_sound = load("res://sounds/jump_sound.ogg")
    audio_player.stream = jump_sound
    audio_player.play(0.0) # Play immediately at position 0

In this snippet, `_on_player_jump` is a hypothetical callback function for a player jump event. The function ensures that the ‘jump’ sound effect plays instantly with zero delay.

Handling Audio Playback Completion

There might be situations where you want to execute code after an audio stream has finished playing. Godot provides you with a built-in signal, `finished`, which is emitted when playback ends.

# Connect to the 'finished' signal
audio_player.connect("finished", self, "_on_audio_finished")

# Callback function for when the audio finishes playing
func _on_audio_finished():
    print("Audio playback has finished.")

After the audio player finishes playing the current stream, `_on_audio_finished` is called, indicating that playback has completed. This could be used to trigger other events or tidy up the scene.

By understanding and harnessing these code examples, you’re well on your way to adding professional, dynamic audio to your Godot projects. Don’t be afraid to experiment with these features to discover what works best for your specific game or application. Remember, engaging audio is key to creating an immersive experience for your players.In this continuation, we’ll provide more advanced examples and cover additional use cases, such as creating 3D audio effects, handling multiple audio streams, and working with audio analysis.

Creating 3D Audio Effects

3D audio effects can give a sense of space and direction to sounds in a game, making the audio experience much more realistic. Godot has an `AudioStreamPlayer3D` node designed for spatial sound effects.

var audio_player_3d = AudioStreamPlayer3D.new()
audio_player_3d.stream = load("res://sounds/space_sound.ogg")
add_child(audio_player_3d)
audio_player_3d.play()

This creates an audio player for 3D sounds. The sound will seem like it’s coming from the position of the `AudioStreamPlayer3D` node within the 3D world. This can enhance the realism of environmental sounds or effects tied to game objects.

Handling Multiple Audio Streams

At times, you might want to handle more than one audio stream simultaneously, such as background music and sound effects. Here’s how to manage multiple streams:

var bgm_player = AudioStreamPlayer.new()
var sfx_player = AudioStreamPlayer.new()

bgm_player.stream = load("res://music/background_music.ogg")
sfx_player.stream = load("res://sounds/explosion_sound.ogg")

add_child(bgm_player)
add_child(sfx_player)

bgm_player.play()  # Start background music
sfx_player.play()  # Play sound effect

Each `AudioStreamPlayer` can play a different sound. You can control them independently, allowing you to, for example, stop sound effects during a cutscene while keeping the background music playing.

Customizing Audio Buses

Godot uses a sophisticated audio bus system that allows you to group and process sounds together. You can create an audio bus for special effects and change its properties.

# Create an effects bus and add a reverb effect
var effects_bus_index = AudioServer.get_bus_index("Effects")
var reverb_effect = AudioEffectReverb.new()

AudioServer.add_bus_effect(effects_bus_index, reverb_effect)

# Set the reverb properties
reverb_effect.room_size = 0.8
reverb_effect.damping = 0.5
reverb_effect.wet = 0.6

# Assign audio stream to the effects bus
audio_player.bus = "Effects"

This sets up a reverb effect on the ‘Effects’ bus and configures its properties for the desired sound. The `audio_player` is routed through this bus, applying the reverb to its stream.

Working with Audio Analysis

You may want to analyze audio for visualizations or gameplay mechanics. Here’s how you can access the raw sample data of an audio stream for analysis:

# Get the audio stream's raw sample data
var pcm = AudioServer.get_stream_peak_volume_left_db()

This line of code retrieves the peak volume of the left channel of the currently playing stream. You can use this data to create visualizations like waveforms or volume meters.

Adjusting Equalization

Adjusting the equalizer settings can help you shape the sound of your audio streams, emphasizing or reducing certain frequencies:

# Create an equalizer effect with three bands
var eq = AudioEffectEQ.new()
eq.bands[0].gain = -10 # Reduce low frequencies
eq.bands[1].gain = 5   # Boost mid frequencies
eq.bands[2].gain = -5  # Reduce high frequencies

var eq_bus_index = AudioServer.get_bus_index("Equalizer")
AudioServer.add_bus_effect(eq_bus_index, eq)

# Assign the audio player to the Equalizer bus
audio_player.bus = "Equalizer"

With these samples of functionalities, you can begin to see the depth of control Godot 4 offers in audio manipulation. Feel free to combine these examples and tweak settings to create the audio environment that best serves your project.

By exploring these more advanced features and integrating them into your projects, you’re equipped to create a truly engaging and interactive audio experience. Remember, audio isn’t just a background element; used effectively, it can significantly enhance storytelling and gameplay in your Godot creations.

Continue Your Game Development Journey

Delving into the intricacies of audio in Godot 4 is just the beginning of your game development journey. As you expand your knowledge and skills within this powerful engine, consider exploring deeper into the rich features Godot has to offer. To keep learning and broaden your game development expertise, we encourage you to enroll in our Godot Game Development Mini-Degree. This thorough collection of courses guides you through building games using both 2D and 3D assets, mastering the GDScript programming language, and more.

Our Mini-Degree is tailored to accommodate learners at any stage, whether you’re just starting out or expanding your existing skills. Projects and quizzes throughout the courses will solidify your knowledge and help you create a polished portfolio. Upon completion, you’ll receive certificates that can open new doors for you in the ever-growing game development industry.

If you’re eager to explore a wider range of topics or wish to handpick individual classes, our comprehensive selection of Godot courses is at your disposal. With Zenva, your learning experience is flexible, accessible, and always moving forward. Dive in and let us help you turn your game development aspirations into reality!

Conclusion

Mastering audio in the Godot Engine is a vital step towards professional and compelling game design. The practical applications of the AudioStreamPlaybackResampled class, along with Godot 4’s comprehensive audio manipulation tools, empower you to take your game’s auditory experience to new heights. Whether you’re syncing footsteps on different terrains or crafting an enveloping background score, the control is in your hands to create an unforgettable soundscape.

Don’t stop here—your journey as a game developer is full of exciting learning opportunities. Take your next big step by joining our Godot Game Development Mini-Degree, where each course is a building block towards mastering the art of game creation. With every audio stream you tweak and every line of code you write, you’re not just building games; you’re building your future in the gaming industry. Let the power of sound amplify your game development career with Zenva. Start today!

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