IT note variation and S3M AdLib compatibility reference
====================================================

The per-note swing arithmetic and associated compatibility decisions were
studied against the OpenMPT soundlib implementation and public player tests.
Reference authors: Olivier Lapicque; OpenMPT Project Developers and Contributors.

https://github.com/OpenMPT/openmpt/blob/master/soundlib/Snd_fx.cpp
https://github.com/OpenMPT/openmpt/blob/master/soundlib/Sndmix.cpp
https://wiki.openmpt.org/Development:_Test_Cases/IT
https://wiki.openmpt.org/Development:_Test_Cases/S3M

The upstream BSD license and copyright notices are retained in OpenMPT-BSD.txt.
The legacy ModPlug mixing/pitch rules and DMO WavesReverb compatibility network
were studied against the pinned libopenmpt-0.8.9 sources:
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/Load_it.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/Snd_fx.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/plugins/dmo/WavesReverb.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/plugins/dmo/WavesReverb.h
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/plugins/PlugInterface.cpp
The bounded impulse-response implementation retains the same BSD attribution.
Native MOD period/finetune and legacy vibrato tables, S3M C2SPD/mixer rules,
XM envelope/voice compatibility and HMN cycle-swap semantics also reference
OpenMPT at libopenmpt-0.8.9 (5d605f5bd6944931fad9266947dad953017ed9b0):
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/Tables.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/Load_mod.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/Load_s3m.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/InstrumentSynth.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/ModInstrument.cpp
Existing OpenMPT-BSD.txt retains the full copyright and redistribution notice.
The expanded complete-song campaign also studies old IT instrument-header
layout/NNA, integer-Hz pitch and slide arithmetic, vibrato/arpeggio rounding,
per-voice surround and compatible XM instrument-portamento phase retention:
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/ITTools.h
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/ITTools.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/ModChannel.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/Sndmix.cpp
https://github.com/OpenMPT/openmpt/blob/libopenmpt-0.8.9/soundlib/Snd_fx.cpp
Pinned source revision: 5d605f5bd6944931fad9266947dad953017ed9b0.
MLT does not bundle libopenmpt as its playback engine. The separately pinned
libopenmpt WASM build is used only by the independent test harness.
Native note-clock controls also reference Mozilla's integer source clock and
inverse-rate conversion, experimentally confirmed in installed Firefox:
https://searchfox.org/firefox-main/source/dom/media/webaudio/AudioBufferSourceNode.cpp
No Mozilla or Speex implementation is bundled or modified by this correction.
MLT's bounded integer-clock planner and cache are original application code.