Grid-Based Amplitude Panning (GBAP)

GBAP calculates weights for a rectangular grid of sinks. Cursor and sink sizes determine how a source overlaps the grid; RollOff shapes the distribution. The result is control data for processes such as Matrix Spatialization, not an audio signal.

Inputs and output

Port	Value
Input Weights	List of incoming gains; System Number selects one entry
Input Multicursor	List of XY source positions
Output Weights	List of weight lists, one list per source

When Input Multicursor contains positions, they replace the internal Position control. When it is empty, GBAP calculates one weight list from Position. Each list contains Sink X # multiplied by Sink Y # weights, with X varying first.

Controls

Control	Purpose
Gain	Overall multiplier, from 0 to 1
RollOff	Shapes the weight distribution, from 0 to 24; default 6
Normalize	Scales each source’s largest weight to 1 before applying Gain and the selected input weight
Sink X # / Sink Y #	Grid dimensions, each from 1 to 12
System Number	One-based index into Input Weights
Sink Size	XY size of each sink
Cursor Size	XY size of the source’s overlap area
Position	Internal source position in the 0–1 XY area

Normalize is peak normalization, not constant-power normalization. Gain and the selected input weight are applied afterward.

System Number must select an existing Input Weights entry. Otherwise the output is zero. For a standalone spatializer, send [1] to Input Weights and set System Number to 1.

Moving a source

Drag the cursor in the grid, click a new position, or automate Position.

For external positions, connect Multi-Cursor Manager or Path Generator in XY output mode to Input Multicursor.

Applying weights to audio

For one source and four speakers:

1. Set Sink X # and Sink Y # to 2.
2. Send [1] to Input Weights and set System Number to 1.
3. Leave Input Multicursor empty and move the internal Position.
4. Connect Output Weights to Array Flattener, then connect the flattened result to Matrix Spatialization’s Weights inlet.
5. Connect a mono audio source to Matrix Spatialization’s Input. Set Audio outs to 4 and Channel offset to 0.
6. Route its audio output to the four loudspeaker channels.

For several sources, extract each nested weight list and send it to a separate Matrix Spatialization instance with the corresponding mono audio source. Flattening all source lists together does not create an audio mixing matrix.

Related processes

DBAP supports irregular speaker layouts. Multi-Cursor Manager supplies editable positions; Path Generator supplies moving positions. See Spatial audio techniques for a complete DBAP patch.

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