Game Audio in Game Engines(8)

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Questions and Answers

What occurs when the game attempts to play more sounds than the maximum number of voices in Unreal Engine?

All sounds are played simultaneously regardless of the limit.

The softest sounds will continue to play.

All sounds play as normal.

Some sounds will not play based on prioritization. (correct)

Which strategy is used to manage sound playback when the maximum number of voices is reached?

Prioritization based on assigned sound levels. (correct)

Cleaning the audio buffer of existing sounds.

Stopping all ambient sounds first.

Random playback of sounds.

Which of the following describes how sound is typically implemented in digital games?

Using MIDI playback

Via analog sound waves

Using streaming audio from the internet

Through PCM audio file playback (correct)

What is the purpose of audio culling in a game engine?

To avoid playing sounds that are too far from the listener for efficiency. Signup and view all the answers

Which of the following is NOT a feature of audio middleware?

Basic sound editing capabilities. Signup and view all the answers

What are two common sample rates used when importing audio files for playback in games?

44.1 kHz and 48 kHz Signup and view all the answers

What role does the sound designer have when using audio middleware?

To design audio content without needing programming knowledge. Signup and view all the answers

Which audio feature allows for a sound file to be played continuously without interruption?

Audio looping Signup and view all the answers

What feature in a 3D audio environment simulates sound level decrease as a listener moves away from the sound source?

Level attenuation Signup and view all the answers

How can game events impact audio middleware during gameplay?

They can trigger changes in audio parameters. Signup and view all the answers

Which audio middleware allows for complex sound playbacks, including jumping to different file locations?

Wwise. Signup and view all the answers

Which technique is commonly used for stereo panning in loudspeaker systems?

Attenuation of left and right signals Signup and view all the answers

What is a direct benefit of using audio middleware for sound playback in a game?

Sound playback can be tested without starting the game engine. Signup and view all the answers

What does HRTF stand for, and why is it used in VR systems?

Head Related Transfer Function, for binaural sound processing Signup and view all the answers

Which option does NOT typically get taken into account when simulating the position of a sound source?

Environmental noise levels Signup and view all the answers

Which audio file format is most often used in games for effective storage?

Compressed (lossy) audio files Signup and view all the answers

What does audio occlusion refer to in sound design?

Blocking or altering sound due to obstacles Signup and view all the answers

Which of the following best explains the Doppler effect in sound?

A phenomenon where the frequency of sound changes based on the listener's location Signup and view all the answers

What is the advantage of using audio mixing groups in sound design?

Allowing effects to be added to each group while managing sound levels Signup and view all the answers

What does ducking refer to in audio processing?

Lowering background sounds when a dialog is played Signup and view all the answers

What is one of the limitations regarding audio budgets in game design?

It limits the number of simultaneous voices that can be played Signup and view all the answers

Why is lossy compression used in audio files?

To decrease the file size significantly while losing some audio fidelity Signup and view all the answers

What factor significantly affects the latency of playing compressed audio files?

The compression method used such as MP3 or AAC Signup and view all the answers

What audio file format is commonly imported before any processing by the engine?

WAV Signup and view all the answers

What is a primary use case for turning off panning in audio sources?

When simulating sounds from a large space Signup and view all the answers

Why is reverb considered an expensive audio effect?

Multiple reverbs cannot operate simultaneously Signup and view all the answers

How does air affect sound transmission, particularly in relation to high frequencies?

Air absorbs high frequencies more than low ones Signup and view all the answers

What technology is used by some game engines to simulate dynamic occlusion?

Ray tracing Signup and view all the answers

In Unreal Engine 4, how is the area for applying reverb typically defined?

Using reverb volumes Signup and view all the answers

What happens to the reverb settings when transitioning between two rooms in a game?

A crossfade occurs to blend the effects Signup and view all the answers

How do directional sources like horn loudspeakers typically interact with listeners?

They apply a low-pass filter based on listener angle Signup and view all the answers

What is a notable feature of occlusion in audio simulation within gaming?

It reduces loudness of all sounds Signup and view all the answers

Study Notes

Game Audio - Sound in Game Engines

PCM audio file playback is frequently used to implement audio in modern digital games.
Audio files support a wide range of sounds and music qualities.
Every game engine has a set of unique audio features.
Game engine audio engines can either be used alone or coupled with external engines. These tools can be designed from scratch, from open-source projects, or be proprietary.
File playback features
- Start, stop, and seamlessly loop audio files.
- Import audio files with common formats (44.1kHz or 48kHz, 16bits or 24bits).
- Import audio files in compressed (lossy) formats to save space.
- Load files into RAM, or stream them from disk.
- Allow real-time adjustments of volume and pitch.

3D Sound Environment

A listener is placed in the camera position.
Sound sources are positioned in the 3D environment.
Sound source levels decrease with distance.
- The attenuation level is a function of the distance between the source and the listener.
- Different algorithms can be used (linear, logarithmic, etc.).
Sound panning
- Usually a procedure involving separate attenuation values to left and right signal channels.
- The panning values depend on the listener and source angle $(\theta)$.
Binaural Audio
- HRTF (Head-Related Transfer Function) based method for headphones.
- This technique is crucial for VR, because headsets already contain headphones and users can move their heads and the location of sound sources needs to be tracked in 3D.
Occlusion
- Physical objects influence sound propagation.
- Game engines often simulate occlusion for realistic sound.
- Example: Listening to a sound inside a room while standing outside, or when a solid object obstructs the sound wave.
- Some engines use ray tracing for automated occlusion detection.

Dynamic Changes

Realtime adjustments of occlusion and reverb are necessary when part of a building is destroyed.

Reverb

Used to simulate sounds in an enclosed environment.
Typically used in buildings.
Only one reverb effect is active at a time.
Some engines use real-world scene geometry to simulate reverb.

Low-pass Filter

Air absorption of sound, more in high frequencies than low ones.
Game engines often apply these.
Frequency filter depending on distance from the sound source.

Directional Sources

Sources like horn speakers produce highly directional sound.
Engines can accurately simulate such directional audio sources.
Engine typically applies a low-pass filter and attenuation.

Time Management

Wait a set amount of time.
Processing through a curve.
Use general programming techniques.

Mixing

Mixing of different audio sources.
Mix approaches:
- Use mixer VCAs.
  - Less CPU usage.
  - No effects.
  - Use Sound Classes in Unreal Engine.
- Use mixer Groups
  - More CPU usage.
  - Supports effects, use "submixes" in Unreal Engine.

Audio Effects

Game engines can apply effects to individual sound channels or busses.

Automatic Mixing

The process of managing audio playback like "ducking" (lowering other sounds when a dialog is played)
Adding more sound effects as a player nears a source.
Adding more music based on the player emotion/stress levels.

Limitations

Budget for audio (file storage space in games)
Maximum number of concurrent sounds (audio voices).

Audio Budget

Amount of audio file storage space available.
- Example: 1 GB on a 4 GB game disc.
Lossy Audio Compression:
- Removes some components of the sound that most humans cannot hear. (example MP3, AAC, Vorbis).
- 10x Reduction in file size.
Higher CPU use for playback.
Delay before playback.
Audio Compression specifics:
- Music and dialog should be compressed (Usually longer files, so compression helps to save file size).
- Sound effects should be uncompressed (sound effects often have short playing times).
- WAV format is used for the start. The engine is responsible for compression.

Maximum Number of Voices

Sound files are loaded to RAM entirely or streamed from disk.
Real-time limitations on the amount of concurrent sound playbacks due to memory limitations.
Engine typically allows a configurable maximum number of voices playing at once.
Example: Unreal Engine default value of 32 voices.

Prioritization

Sounds are assigned priority.
If the max number of voices is hit, lower-priority sounds are stopped.
Softest sounds are stopped first.

Audio Culling

Culling is choosing which sound to play.
Sounds with low volume (attenuated based on distance to listener) are not played.

Middleware (External Tools)

Game engines provide basic audio features, but middleware can extend this.
External libraries offer support for major engines and advanced sound features.
The middleware is like a Digital Audio Workstation (DAW) for preparation of audio content.
The external tools are often combined (or built-in) with major engine projects and used to improve and provide more complex features.

Audio Programmer - Sound Designer Collaboration

Audio programmers define audio parameters for a game. (example, car speed).
These parameters affect the sound to be played.
The sound design team handles the actual implementation of these sounds.

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Description

Explore the functionality and features of audio in modern game engines. This quiz covers topics such as PCM audio playback, file formats, and the implementation of 3D sound environments. Test your knowledge on how audio is integrated and managed in gaming.