Glossary

Quick definitions for terms you'll encounter when working with Orbit and ADM files.

File formats & standards

ADM: Audio Definition Model, metadata describing immersive audio components.
ADM BWF: Broadcast Wave file with ADM metadata, the standard master format for immersive audio.
BWF: Broadcast Wave Format, standardized WAV file container.
AXML: Audio XML metadata embedded in ADM BWF files.
CHNA: Channel mapping metadata in ADM BWF files.
IAMF: Immersive Audio Model and Formats, the open immersive audio format from the Alliance for Open Media. Orbit plays IAMF files and Orbit Pro exports them; see IAMF basics.
Eclipsa Audio: The consumer brand name for IAMF.
OSLS: The Orbit Speaker Layout System, an open format (.osls) describing a loudspeaker rig, up to 64 channels; see OSLS.

Bed: Channel-based audio elements that anchor the mix (e.g., dialogue, music stems).
Object: Independently positioned audio element with automation (e.g., moving effects, point sources).
Programme: The complete deliverable, containing beds and objects.
DirectSpeakers: ADM term for bed channels mapped directly to speaker positions.

7.1.4: Twelve-channel layout: eight ear-level channels (L/R/C/LFE/Ls/Rs/Lrs/Rrs) plus four overhead channels (Ltf/Rtf/Ltb/Rtb).
Binaural: Headphone rendering of spatial audio using HRTF processing.
HRTF: Head-Related Transfer Function, simulates how sound reaches your ears from different directions.
SOFA: Spatially Oriented Format for Acoustics, a standardized file format for storing HRTF measurements. Orbit supports loading custom SOFA files for personalized binaural rendering.
HOA / Ambisonics: Higher-Order Ambisonics, a scene-based format that stores the soundfield as spherical-harmonic channels rather than speaker feeds. Orbit decodes it to speakers; see Ambisonics Decode Modes.
Fold-down: Reduction of multichannel audio to stereo for compatibility.
Stereo: Two-channel audio (left and right).

LFE: Low Frequency Effects channel (subwoofer).
Automation: Time-based changes to object position, gain, or other parameters.
Timecode: The time position within the programme.
VBAP: Vector Base Amplitude Panning, distributes sound across speakers.
LBAP: Layer-Based Amplitude Panning, Orbit's default object panning mode, which pans across the layout's speaker layers. Choose LBAP or VBAP in Preferences → Spatial → Panning Mode.
Direct routing: Maps bed channels directly to their labeled speakers without panning.

QC: Quality Control, the process of verifying deliverables.
LUFS: Loudness Units relative to Full Scale, standardized loudness measurement.
True Peak: Maximum sample value after oversampling, used to prevent clipping in digital-to-analog conversion.
Integrated LUFS: Average loudness over the entire programme.
Momentary LUFS: Loudness measured over 400ms windows.
Short-term LUFS: Loudness measured over 3-second windows.