MIDI Channel and Polyphonic Aftertouch Tracking

Certain aspects of player output may - depending on implementation - be affected by MIDI Channel Aftertouch and MIDI Polyphonic Aftertouch messages.

The traditional meanings are:

  • Channel Aftertouch is intended to affect player output for all voices triggered on the same MIDI Channel Numer as the Channel Aftertouch message.
  • Polyphonic Aftertouch is intended to affect player output for voices triggered by the same MIDI Note Number on the same MIDI Channel as the Polyphonic Aftertouch message. Depending on implementation, Polyphonic Aftertouch may or may not be fully implemented.

These use chanaft and polyaft suffixes respectively: pitchlfo_freqchanaft. cutoff and cutoff2 have the extra underscore: cutoff_polyaft.

The targets are:

  • _depth and _freq for amplfo, fillfo and pitchlfo -- see below
  • cutoff and cutoff2 -- see the first example for cutoff

See the opcode list and search for chanaft or polyaft to see the syntax in full.

LFO modulation example

The same basic principle applies as in the SFZ1 LFO tutorial, just using chanaft or polyaft in place of ccN:

pitchlfo_freq=2
pitchlfo_freqchanaft=10
pitchlfo_depthpolyaft=33