Synchronic : Using Synchronic : Synchronic Playback Performance Mode : Synchronic Playback Order

Synchronic Playback Order
Order determines the sequence in which the slices of the selected sound are played back. Synchronic provides several options for Playback Order: Off, One Slice, Reverse, Diverge, Random, Step, Span, Straddle.
 
Off
Plays the sound slices in their original sequence. Each slice increments from the previous one until the end of the sound is reached, and then continues to loop from the starting slice.
One Slice
Plays back and loops only the selected Start slice.
Reverse
Plays the original sequence of slices in reverse order. Each slice plays in the specified direction (see Synchronic Playback Direction), but order of slices is reversed.
Diverge
Plays the Start slice followed by last slice, followed by the second slice, followed by the second to last slice, and so on following a divergent order from the Start slice.
Random
Plays slices in random order.
Random Swap
Randomly selects “sibling” slices based on a half-note spacing. For example, the “2 and” of a bar, and the “4 and” of a bar are siblings. Unlike Random, which can sound very “outside,” Random Swap preserves much of the original feel of a loop, while simultaneously adding random variations with each repeat of the loop.
Step (Step 2–5)
Plays slices by stepping over some number of adjacent slices (2–5). For example, selecting Step 2 with a loop containing eight slices will play back slices 1, 3, 5, 7, 2, 4, 6, 8, and repeat.
Span (Span 2–5)
Plays slices by stepping forward some number of slices (2–5) then skipping back to play the stepped over slices in order. For example, selecting Span 3 with a loop containing eight slices would play slices 1, 4, 3, 2, 5, 4, 3, 6, 5, 4, 7, 6, 5, 8, 7, 6, and so on.
Straddle (Straddle 2–5)
Plays slices by stepping forward then making a small step backward. For example, selecting Straddle 4 with a loop containing eight slices would play slices 1, 5, 2, 6, 3, 7, 4, 8, and so on.
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Depending on where you start playback in the Pro Tools timeline, the start position will affect the exact sequence of slices when using Step, Span, or Straddle. Typically, you will want to be sure to start playback on the downbeat of a bar, and that the aligns with the number of bars in the loop.