Ambi Encoder Cartography

s3g Ambi Encoder Cartography turns one stereo input into a mapped network of as many as twenty-four virtual loudspeaker sites. The program reaches each site through an authored distribution delay, receives site-specific macro processing, travels through a configurable acoustic landscape to a movable listener, and is encoded as first- through seventh-order ACN/SN3D.

The network and acoustic landscape are separate models. Moving the listener changes loudspeaker-to-listener distance, direction, propagation time, level, and air loss. It does not rewrite the infrastructure timing that delivered the program to each loudspeaker.

The current Cartography surface includes landscape effects and expanded per-site processes within the same field, listener, and output workflow described here.

Workflow

1. Place the plugin on a stereo source track routed to a 64-channel destination, and choose the ambisonic ORDER.
2. Follow it with an ambisonic decoder.
3. Open the title-bar preset menu and audition a factory scene near the intended scale and behavior.
4. Choose SITES, LAYOUT, and MAP SCALE. The Radial, Ridge, Corridor, Grid, and Waterfront layouts initialize distinct physical and network arrangements.
5. Choose TOP to edit listener or site X/Y, or SIDE to edit X/Z. 3/4 is the inspection view. Drag an empty part of the map to orbit the camera and use - / + to change display zoom.
6. Drag the yellow listener cross and loudspeaker sites in an editable view, or enter exact coordinates with the Listener and Selected Site controls.
7. Set NETWORK DELAY, PROPAGATION TIME, and TIME REFERENCE before adding atmospheric loss.
8. On the Site Process CORE page, choose a process engine and shape Macro, Color, Memory, and Process Mix. SHRED additionally exposes Circuit, while FRACTURE exposes Processor.
9. Open the Site Process REL page to choose MACRO METRIC and shape its Spread, Deviation, Skew, and Center relationships.
10. Open the Landscape FX PATH and FIELD pages to add multipath, obstruction, infrastructure instability, refraction, movement, cross-site returns, or a distance-dependent audibility horizon. Return any landscape amount to zero for its exact bypass.
11. Add Field Listen last when the site processing should adapt to what reaches the listener.

Signal Flow

1. The shared stereo program enters the authored distribution-network timing paths. NET WEATHER can add deterministic clock wander and brief relay-level interruptions before the site feeds are formed.
2. Mid/Side, Mono, or Alternate projection forms one mono feed for each active loudspeaker site.
3. ECOLOGY can add bounded, filtered returns from other sites to those feeds, after which the selected macro engine processes them in Network, Arrival, Bearing, or Range order.
4. Independent direct acoustic paths apply listener-relative travel time. MULTIPATH adds separately delayed and directed ground and facade image paths.
5. Air and distance loss, carry, turbulence, layout-derived OCCLUSION, signed REFRACTION, and the distance-dependent HORIZON condition the arrivals. MOTION updates the effective site or listener geometry before those path relationships are calculated.
6. The direct and reflected arrivals are encoded from their current listener-relative directions into the selected ACN/SN3D order.
7. The Cube Field Listener analyzes the completed pre-output field and returns bounded control influence to later site processing.

OUT is after the listening tap, so changing final audition level does not retune the control ecology. Listener Mode changes bounded site wetness and reach; it does not recirculate output audio.

Distribution and Acoustic Maps

NETWORK DELAY spreads delivery time across the authored network order. Each site also has a bipolar SITE NETWORK TRIM. These controls represent distribution topology, buffering, relays, clock relationships, or deliberately composed infrastructure timing. Ordinary analog cable propagation is far too fast to create city-scale echoes by itself.

MAP SCALE converts one normalized map unit to meters. At PROPAGATION TIME 100%, the acoustic path uses 343 meters per second. Smaller settings compress travel time while retaining the map's distance and direction relationships.

The long acoustic taps are finite. Extreme map distances are clamped to the allocated real-time arrival horizon rather than allocating memory during playback.

Stereo Cartography

Site Processing

The Process menu retains the original automation values for CLEAN, DELAY, PITCH, SHRED, and FRACTURE, then adds BODY, SPECTRAL RELAY, and RELAY BUFFER. A 30 ms live old/new crossfade protects every engine change, including transitions to and from Clean.

Host play, stop, seek, loop, and sample-offset transport boundaries receive a smooth pre-network input correction whose base duration is 6 ms, preventing one source edge from returning later as many distributed clicks. BODY extends that window according to its maximum possible wet contribution from Process Mix and Listen Amount, reaching 120 ms at a fully wet setting so the cabinet highpass and resonator do not turn a short transport ramp into a new transient. Processing restarts and resets use a separate 10 ms output bridge from silence or the preceding rendered sample; a restart also ramps any newly silent input into parked feedback memory instead of injecting a delayed edge. Transport stop does not mute or discard the landscape: the CLAP reports a conservative 90-second tail, and delay memories are invalidated without bulk-clearing large buffers on the audio thread.

The shared Macro, Color, Memory, Spread, Deviation, Skew, and Center parameters keep stable automation identities when their visible labels and audible meanings change with the engine. Selecting another engine does not overwrite their values; the selected engine reinterprets the same current point on the shared parameter surface.

BODY runs on stable physical-site lanes. A site's Macro Metric rank supplies only a target voicing coordinate, smoothed over 30 ms, so Motion, listener movement, or a metric crossing can retune that body without moving its resonator and thermal history to another loudspeaker. Disabling a site ramps its effective contribution while retaining that site identity.

FRACTURE retains the sparse 24-lane voicing map used by Spread and Center, but Logic receives a separate modulation ring made only from enabled sites in the current Macro Metric order. Each site compares against the next enabled site and the last wraps to the first, so empty macro-lane positions and disabled sites do not become silent comparison partners. A low-level carrier assist follows the current signal level and uses a stable per-lane phase; it helps identical or strongly correlated site feeds produce a changing comparison, but falls away with the signal rather than becoming an independent source.

SPECTRAL RELAY and RELAY BUFFER use a compact relationship list containing only enabled sites, so disabled points and empty ordinal gaps cannot become phantom relay sources. Their cross-site memory and capture topology follow relationship rank. When Motion, editing, a metric change, or a changed enabled-site count remaps a compact lane, the affected site's last wet sample anchors a 30 ms continuity correction into the new result instead of exposing the remap as a hard edge. Each engine keeps its own parked memory while inactive and returns only through the protected old/new crossfade.

Live level changes are protected independently of those topology rules. Process Mix follows a 15 ms smoothing time, while Site Gain, the effective audio fade behind Site Enable, and final Output follow 12 ms smoothing. Site Enable remains a discrete host parameter and map state, but its audible contribution enters and leaves continuously.

Body's derived cabinet, envelope, and resonance controls are calculated at a bounded control cadence while the signal path and relationship glide continue at audio rate. A bounded algebraic speaker-saturation curve replaces repeated general-purpose hyperbolic-tangent calls. These optimizations reduce the per-site real-time load without changing Body's physical-site state ownership or adding host latency.

Network Weather uses independently wrapped continuous oscillators for drift and relay loss, while Turbulence uses periodic smooth value noise instead of stepped random gain. Fracture's level-dependent thresholds, offsets, dither, and octave tracking follow the signal instead of assuming one fixed operating level. Crush returns exact zero after both its input and held sample are silent, and Logic's carrier assist decays with its level follower. Buffered Splice material, formant resonance, or configured Memory can still produce an intentional tail.

Fracture Splice uses a normalized segment phase, interpolated buffer reads, and a short return toward the live signal at both segment ends. Its Length and Direction choices are latched at the start of a segment, so automation does not teleport or reverse an in-progress read. Robot moves continuously from triangle through sine to a softly squared carrier rather than switching to a discontinuous square wave. Processor changes retain the 20 ms old/new crossfade and also anchor each new transition to the preceding wet sample with a smooth, decaying correction; this protects ordinary changes and rapid retargeting without erasing the individual processor histories.

SHRED conditionally displays a CIRCUIT menu with Shred, Wool, Rat, Zone A, Zone B, Fuzz I, Fuzz II, and Diode. FRACTURE instead displays a PROCESSOR menu with Relay, Crush, Splice, Logic, Void, Throat, Robot, Oct Down, Oct Up, and Oct Stack. These selectors retain independent values while hidden. Body, Spectral Relay, and Relay Buffer are independent process designs, so changing a hidden Circuit or Processor does not alter them.

Fracture's shared labels follow the selected Processor. For example, Macro becomes Threshold for Relay, Bits for Crush, Depth for Splice, Logic, Void, and Robot, and Mix for Throat and the octave processors. Color becomes Chatter, Rate, Length, Threshold, Recover, Vowel, Carrier, Filter, or Tone as appropriate. On the REL page, the shared SKEW parameter becomes the processor's third contextual control: Asym, Dither, Direction, Balance, Skew, Shift, Character, Track, Shape, or Balance. For Fracture this value is a global processor control rather than a first-to-last-lane skew slope; Deviation still supplies bounded lane differences. The host-facing Macro, Color, and Skew identities remain stable, so changing Processor does not break their automation.

The Site Process toolbox has two GUI pages without changing the editor size. CORE contains Engine, the conditional Circuit or Processor selector, Macro, Color, Memory, and Mix. REL contains Metric, Spread, Deviation, Skew, and Center. Switching CORE or REL changes only which controls are visible; it does not change audio, automation, or saved parameter values.

The macro lanes are not assigned by arbitrary HOA channel number. MACRO METRIC sorts the sites by one of four cartographic relationships:

• NETWORK follows the authored distribution route.
• ARRIVAL follows combined network and acoustic arrival time.
• BEARING follows angle around the listener.
• RANGE follows loudspeaker-to-listener distance.

SPREAD, SKEW, and CENTER therefore normally operate along a meaningful spatial or infrastructural axis. Fracture is the deliberate exception for SKEW: it uses that shared parameter as the selected Processor's contextual third control. DEVIATION adds stable per-lane differences without random changes on project reload.

Propagation and Auditory Distance

• AIR LOSS darkens distant paths.
• DISTANCE LOSS controls restrained geometric attenuation.
• CARRY reduces that attenuation to represent favorable or musically exaggerated reach.
• TURBULENCE adds slow, independently phased level variation at the sites.

These are perceptual composition controls rather than a calibrated weather, terrain-diffraction, or sound-pressure prediction system. See Outdoor Sound Propagation and Auditory Distance for the research context.

Landscape Effects

The seven Landscape FX controls are macro descriptions of a loudspeaker landscape rather than separate engineering simulators. Every control has an exact bypass at zero. With all seven at zero, the signal follows the original direct and stable Cartography path; latent landscape-effect filter or timing state does not color that reference. This is also the Landscape FX state used by INIT.

The Landscape FX toolbox has three GUI pages. MAP retains the drag, level, and arrival-color legend. PATH exposes Multipath, Occlusion, Net Weather, and signed Refraction. FIELD exposes Motion, Ecology, and Horizon and reminds you which established controls voice Weather and Ecology. Changing pages is only an editor view action; it does not alter audio, automation, or the saved parameter values.

Field Listener

An eight-direction Cube listener analyzes the completed pre-output field using the shared Listener Mode design. FOLLOW favors recently dominant directions, COUNTER evaluates their antipodes, and BALANCE favors less exposed regions. LISTEN AMOUNT changes site process wetness and a smaller reach term. OFF is an exact open-loop reference regardless of Listen Amount.

The yellow cross is the geometric listener position. It determines direction, distance, and propagation. Field Listen is the field's directional memory. Both can be active without being the same control.

Site Editing and Display

Click a loudspeaker to select it. In TOP, dragging a site or the yellow listener cross edits X/Y while retaining Z; in SIDE, it edits X/Z while retaining Y. 3/4 and a manually orbited view allow selection and inspection without flattening a point back onto an editing plane. Drag empty map space to orbit with the ordinary pointer gesture. The compact - / + buttons change only camera zoom, never site distance. Camera preset, manual angle, and zoom are saved with plugin state.

The Selected Site controls expose X, Y, Z, gain, network trim, and enable state. The selected-site readout reports physical distance and combined network-plus-acoustic arrival time. Node size follows recent level, node color moves from earlier cool arrivals toward later warm arrivals, and a surrounding earth-colored ring indicates layout-derived occlusion. When Motion is active, the map follows the effective animated site or listener positions while preserving the authored coordinates underneath.

Changing Layout or Sites rebuilds the corresponding authored arrangement. Save a plugin preset or project state after manual site editing; all twenty-four site records are serialized even when fewer sites are active.

Factory Presets

The title-bar preset control opens the factory bank. Factory choices preserve the current ambisonic ORDER and OUT level, rebuild their authored loudspeaker layout, and reset the selected site's gain and network trim. LOAD and SAVE manage complete user states, including manually edited site positions.

Order and Routing

The input bus is stereo and the output bus is fixed at 64 channels. ORDER activates the corresponding leading ACN/SN3D channels and clears the remainder.