Module formats

 Feature

 MOD

 XM

 S3M

 IT

 Channel limit  4 or 8  32  16  64
 Linear Slides  No  Yes  No  Yes
 NNA
 No  No  No  Yes
 Volume/Pan Envelopes  No  Yes  No
 Yes
 Pitch/Filter Envelopes  No  No  No  Yes
Lowpass resonant filter  No  No  No  Yes
 Channel volume/panning  No  No  No  Yes
 Sample Tuning
 No Yes Yes (c5freq)
 Yes (c5freq)
 Nibbles  No  Yes  No  No

Linear Slides

When a tracker uses linear slides, each octave is divided into an equal number of "micro-notes", and as a result, pitch sliding effects like portamentos and vibratos cover the same range of pitch no matter what octave they're played on. Without linear slides (aka "amiga slides"), only the period of the note is used (the reciprocal of the frequency), and pitch sliding effects change the period directly, so that a vibrato at C-5 will be twice as deep as a vibrato at C-4.

NNA

NNA (New Note Action) allows you to specify what happens when a new note occurs in a channel where a note is already playing. Cutting the note is the default behavior, and is what occurs in formats without NNA. Other options are Note Off (which starts the envelope release), Note Fade (to linearly fade out), and Continue (continuing the envelope without release). NNA requires "virtual channels" to support the multiple notes that may be playing in any given channel of the pattern.

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