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Spatial Objects

On a stereo output the SPATIAL tab has no audible effect. On an output of more than two channels (up to 16), ANTIVERB renders to every output, and this tab decides where each part of the sound sits. The speaker rig itself is covered in Speaker Layout.

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Panning

Panning is VBAP (vector-base amplitude panning), with MDAP spread for wider, smoother phantom images.1 Each element of the reverb gets its own direction and its own set of speaker gains:
  • every tap of the densifier’s cascade,
  • every early reflection (42 in all, in groups at 0°, 15° and 30° of elevation),
  • every delay line of the late tail (16 to 128),
  • and each input channel of the Dry object.
On a rig with height speakers the directions are panned across triangles of speakers covering the sphere; on a flat rig (stereo, quad, 5.1, 7.1 or a ring) they are panned between neighbouring pairs by azimuth, and elevation has no effect. The gains are recalculated only when a control changes.

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SPATIAL ROUTING Header

When the host bus has more outputs than the rig has speakers, the header shows how many outputs are unmapped; those outputs stay silent. When the rig has more speakers than the bus has outputs, the header reads N speakers have no output, and those speakers get no signal.

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INPUT

shape sets the layout a multichannel input’s channels sit in before the objects place them. The readout beside it shows the channel count and the shape in use (for example (6 ch · 5.1)). Up to 8 input channels are placed, and an LFE input channel is routed to the Sub outputs and never panned. With no Sub in the rig, the LFE input is not played.

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OBJECTS

ANTIVERB has four objects, one per part of the sound: Dry (◇), Density (△), Reflections (○) and Space (▭). Each object is placed independently of the others. The table’s columns are az, el, wid, spr and a power switch. For Density and Space, spread acts twice: it fans the taps or lines out around each channel’s direction, and it widens each one’s image.

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Layout-Aware Spread

ANTIVERB treats an output of two channels or fewer as stereo and anything wider as surround. Dry starts at 0 % spread on both. Density, Reflections and Space start at 30 % on stereo and 100 % on surround. When the output width changes from one class to the other, ANTIVERB moves any of those three spreads still at the old class’s default to the new one. The change is one undo step. DEFAULTS in the LAYOUT header resets azimuth, elevation, width and spread of all four objects to the current class’s defaults. See Speaker Layout.

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FIELD

The field controls turn and tilt all four objects together, Dry included. In MINIMAL the FIELD card shows rotation and the Width macro, which moves the four object widths together.

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ROUTING

Open [+] ROUTING (EXPERT view).

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LISTENER

Open [+] LISTENER (EXPERT view). The listener position is the point every direction and every speaker distance is measured from. Dragging the listener marker in the rig view moves X and Y.

Footnotes

  1. V. Pulkki, “Virtual Sound Source Positioning Using Vector Base Amplitude Panning”, Journal of the Audio Engineering Society 45(6), 1997; V. Pulkki, “Uniform spreading of amplitude panned virtual sources”, Proc. IEEE WASPAA, 1999. ↩