.s3gimprint Format

.s3gimprint is the interchange format between the s3g-mc Imprint Sketch browser utility and s3g Processor Ambi Imprint 64ch. It is UTF-8 JSON with a dedicated extension so a runtime imprint remains distinct from an editable Imprint Sketch project.

The format is sample-rate independent. Times are stored in milliseconds or seconds and frequencies in hertz. Processor Ambi Imprint compiles the descriptor into FIR kernels at the host sample rate.

Version 1

The root object contains:

• format: s3g-ambi-imprint
• version: 1
• ambisonics: ACN/SN3D and reference-order metadata
• spectral_bands_hz: exactly eight band centers
• space: optional generalized family, seed, topology, polygon, ceiling profile, connected regions, portals, openness, and acoustic estimates
• room: compatibility dimensions, top-view polygon, and optional connected-region/opening provenance
• listener_position_m: listener XYZ position
• direction_layout and direction_count
• duration_s: requested response duration
• profiles: one to eight directional response descriptors

Each profile contains its input AED direction, source position, quadrature weight, direct arrival, discrete early reflections, and late response. The late response includes eight-band absorption and RT60 values, diffusion, spread, damping, level, and a deterministic seed. Processor Ambi Imprint derives processing from these resolved profiles; generalized geometry remains useful provenance and drives the orbitable GUI scene rather than a realtime geometry simulation.

Optional display metadata includes the primary XY polygon, an XZ ceiling profile, and a connected-volume graph. space.regions records each region polygon, base elevation, height, family, attachment, and parent. space.portals records the connection endpoints, 3D center and orientation, opening shape, dimensions, area, transmission estimate, and outline. This permits wall, overhead, beneath, and stacked regions without changing the resolved audio contract.

An optional echo_paths object records the requested and resolved structure, geometry-derived interval, path points, prominence, persistence, and regularity. Coupled paths may traverse more than one portal and region. Resolved echo events are ordinary entries in early_reflections, with optional path and bounce identifiers for provenance. Readers derive sound from the resolved profiles; the optional provenance does not change version 1 response decoding.

Runtime Limits

Processor Ambi Imprint version 1 accepts one to eight profiles and up to 128 early events per profile. Realtime responses are limited to four seconds even when the authoring file retains a longer duration. The plugin reports 1024 samples of latency and embeds the imported JSON in CLAP project state.

Imprint Sketch material curves are creative acoustic estimates. They support procedural sound design and repeatable spatial response construction; they are not measured architectural coefficients.

Choosing the Correct File

Load the exported .s3gimprint runtime descriptor in Processor Ambi Imprint, not the editable Imprint Sketch .json project. Exporting requires no s3g-field conversion step. To reuse a legacy s3g-ir-room-sketch project, import it into Imprint Sketch and export a new .s3gimprint file.