Glossary

A¶

ADPCM — Adaptive Differential Pulse-Code Modulation. A lossy audio compression algorithm used by the AMS codec.

Ambisonics — A full-sphere surround sound technique using spherical harmonics to encode and decode 3D sound fields.

AMIR — Amplitude HRIR file format. An optimized binary format for storing Head-Related Impulse Response data.

AMS — Amplitude Media Stream. Amplitude's custom ADPCM-compressed audio file format.

Attenuation — The reduction of sound level as distance from the source increases.

B¶

B-Format — The channel representation of an Ambisonic signal (W, X, Y, Z, etc.).

Bus — An audio mixing channel that groups sounds together for shared gain, ducking, and effects processing.

C¶

Channel — A single instance of a playing sound in the mixer. Each Play() call creates a channel.

Codec — A software component that encodes and/or decodes audio data from a specific file format.

Collection — A sound object that groups multiple sounds and selects one to play based on a scheduler.

D¶

Decoder — The part of a codec that reads compressed audio data and produces raw PCM samples.

DSP — Digital Signal Processing. Mathematical manipulation of audio signals (filters, effects, etc.).

Ducking — Automatically reducing the gain of one bus when another bus becomes active.

E¶

Encoder — The part of a codec that writes raw PCM samples into a compressed audio file.

Entity — A game object in the Amplitude engine that can emit or receive spatialized audio.

Environment — A zone in 3D space where sounds receive a specific effect (reverb, EQ, etc.).

F¶

Fader — A curve that controls how a value transitions from one point to another over time.

FlatBuffers — A binary serialization format used by Amplitude for project assets and configuration files.

H¶

HRTF — Head-Related Transfer Function. A pair of filters that capture how sound interacts with the human head and ears for 3D spatialization.

HRIR — Head-Related Impulse Response. The time-domain representation of an HRTF.

I¶

ILD — Interaural Level Difference. The difference in sound level between the two ears, used for localization.

ITD — Interaural Time Difference. The difference in arrival time of sound between the two ears, used for localization.

L¶

Listener — A point in 3D space that represents the player's ears. Audio is spatialized relative to listeners.

LZ4 — A fast lossless compression algorithm used by the ampk packager.

N¶

Node — A processing unit in the Amplimix pipeline. Nodes perform spatialization, effects, mixing, or dynamics.

P¶

Pipeline — A directed acyclic graph (DAG) of nodes that defines how audio is processed in the mixer.

R¶

Resampler — A component that converts audio from one sample rate to another.

Room — A physically modeled acoustic space with walls, materials, and dimensions that affect reverberation.

RTPC — Real-Time Parameter Control. A game value (e.g., speed, health) that dynamically controls audio properties via curves.

S¶

Sound Bank — A binary asset pack that contains multiple sounds, collections, events, and other assets.

Sound Object — A generic term for any playable asset: Sound, Collection, or SwitchContainer.

Spatialization — The process of positioning audio in 3D space using panning, HRTF, or Ambisonics.

Switch Container — A sound object that plays different audio content based on the current state of a switch.

V¶

Virtual Channel — A channel that is not actively mixed but is still tracked by the engine. Virtual channels can be promoted to real channels when resources become available.

Voice — Another term for a channel or sound instance in the mixer.