7 Ardour's VBAP panner is currently in development, and its semantics may
8 change in the near future, possibly affecting your mixes. Please do not
9 rely on it for important production work while the dust settles.
13 <dfn><abbr title="Vector-base Amplitude Panning">VBAP</abbr></dfn>
14 is a versatile and straightforward method to pan a source around over an
15 arbitrary number of speakers on a horizontal polygon or a 3D surface,
16 even if the speaker layout is highly irregular.
19 <h2>Basic concepts</h2>
22 VBAP was developed by Ville Pulkki at Aalto University, Helsinki, in 2001.
23 It works by distributing the signal to the speakers nearest to the desired
24 direction with appropriate weightings, aiming to create a maximally sharp
25 phantom source by using as few speakers as possible:
29 <li>one speaker, if the desired direction coincides with a speaker
31 <li>two speakers, if the desired direction is on the line between two
33 <li>and three speakers in the general 3D case.</li>
37 Thus, if you move the panner onto a speaker, you can be sure that only
38 this speaker will get any signal. This is handy when you need precise
43 The drawback of VBAP is that a moving source will constantly change its
44 apparent sharpness, as it transitions between the three states mentioned
49 A <dfn>horizontal</dfn> VBAP panner has one parameter, the <dfn>azimuth
50 angle</dfn>. A <dfn>full-sphere</dfn> panner offers an additional
51 <dfn>elevation angle</dfn> control.
55 More elaborate implementations of VBAP also include a
56 <dfn>spread</dfn> parameter, which will distribute the signal over a
57 greater number of speakers in order to maintain constant (but no longer
58 maximal) sharpness, regardless of position. Ardour's VBAP panner does not
59 currently include this feature.
62 <h2>Speaker layout</h2>
65 Each VBAP panner is specific to its <dfn>speaker layout</dfn>
66 — the panner has
67 to "know" about the precise location of all the speakers. A complete VBAP
68 implementation must therefore include the possibility to define this
72 <img src="/images/VBAP-panner-5.png" class="small right" alt="The VBAP
73 panner with 5 outputs"/>
76 Ardour currently uses a simplified approach: if a track or bus has more
77 than two output channels (which implies stereo), it assumes that you
78 have N speakers distributed in a regular N-gon. That means that for
79 irregular layouts such as 5.1 or 7.1, the direction you dial in will
80 differ a bit from the actual auditory result, but you can still achieve
81 any desired spatialisation.
84 <h3>Experimental 3D VBAP</h3>
86 <img src="/images/VBAP-panner-10.png" class="small right" alt="The VBAP
87 panner with 10 outputs, in experimental 3D mode"/>
90 For tracks with 10 outputs, Ardour will currently assume a 3-dimensional
91 speaker layout corresponding to Auro-3D 10.1, which is a horizontal 5.1
92 system, four elevated speakers above L, R, Ls, and Rs, and an additional
93 "voice-of-god" speaker at the zenith.
98 <img src="/images/VBAP-panner-4in5.png" class="small right" alt="The VBAP
99 panner in 4 in, 5 out mode"/>
102 For tracks and busses with more than one input, Ardour will (for now) assume that
103 you wish to distribute the inputs symmetrically along the latitude around
104 the panner direction. The width parameter controls the opening angle of
105 the distribution sector.