Amplitude panning using vector bases

Abstract

This chapter describes Ville Pulkki’s famous vector-base amplitude panning (VBAP) as the most robust and generic algorithm of amplitude panning that works on nearly any surrounding loudspeaker layout. VBAP activates the smallest-possible number of loudspeakers, which gives a directionally robust auditory event localization for virtual sound sources, but it can also cause fluctuations in width and coloration for moving sources. Multiple-direction amplitude panning (MDAP) proposed by Pulkki is a modification that increases the number of activated loudspeakers. In this way, more direction-independence is achieved at the cost of an increased perceived source width and reduced localization accuracy at off-center positions. As vector-base panning methods rely on convex hull triangulation, irregular loudspeaker layouts yielding degenerate vector bases can become a problem. Imaginary loudspeaker insertion and downmix is shown as robust method improving the behavior, in particular for smaller surround-with-height loudspeaker layouts. The chapter concludes with some practical examples using free software tools that accomplish amplitude panning on vector bases.