In previous versions offset modulation was signed for modulators and unsigned for non-modulators, because the latter case was implemented via delaying, which doesn't support negative values. This was confusing to say the least.
Offset modulation is now (as of version 1.0.20) a true offset in all cases, regardless of the target track's type. Delaying now has its own independent modulation type. Offset modulation is now consistently signed, and delay modulation is always unsigned.
In addition, offset modulation now supports integer scaling via the modulator track's duration value. This works around the step value's very limited range. Large offsets suitable for resynchronizing song sections can now be specified, and in convenient units such as beats or measures.
Delay is still superior to offset for implementing groove, because with delay, all events are played, whereas offsetting can cause events to be skipped. Delay modulation also has more precise timing than offset modulation.
For non-modulator tracks, offset modulation is only accurate to the nearest callback time, even though the offset is specified in ticks. This isn't ideal, but it's good enough for most applications, as a callback is only a few ticks at common timebase and tempo settings.
AddTrackEvents now sums the track's offset modulations once per callback, in the preamble before the main event loop, and applies the resulting offset to the initial event time calculation. The performance impact is around one microsecond for typical documents. It seems to work.
Offset modulation may affect swing, whereas position modulation never does. To avoid corrupting the swing, always offset by a multiple of two steps.
- To vary a pattern by rotating it, use position modulation, because it's in steps and doesn't affect swing.
- To synchronize sections, use offset modulation, because it's in ticks and has extended range.
- To add groove or feel, use delay modulation, because it never skips events.
