Apple Soundtrack Pro 2 - Manual (Page 301)

Chapter 9 Mixing Surround Sound 301
Note: In automation envelopes, this Position parameter is expressed as Surround Pan
X and Surround Pan Y.
 Rotation: Use this slider to alter the angle at which each signal starts out. This slider
ranges from -180 degrees to 180 degrees and affects the input signal. For example,
with no other panning, the right channel emanates from a location 45 degrees to the
right. With rotation at +65 degrees, the signal appears at 110 degrees—directly out of
the right surround speaker.
Note: This setting interacts with the position parameter when the panner mode is
not fully attenuating.
 Width: Use the Width slider to create a widened surround image. This slider is
intended primarily for stereo sources in that it spreads the left and right inputs into
adjacent channels. This creates the illusion of a widened sound stage without the
hole at the center that moving the puck rearward would create. For some movie
theaters, it may be necessary to use the Width slider to bleed the center signal in to
the left and right speakers. At 0%, all inputs go to their respective outputs. As you
drag the Width slider to the right, L and R inputs start to bleed into Ls and Rs
respectively, and to a lesser extent, L and R bleed into C, C bleeds slightly into L and
R, and Ls and Rs start to merge.
... to alter the angle from
which each signal starts.
Drag the Rotation slider...