OpenMPT manual — Samples

The sample tab of openmpt: formats, the edit toolbar, tuning per format, loops and sustain loops, auto-vibrato, time-stretching, the drawing and resizing tools that make chip samples, and the OPL (AdLib) FM instrument editor for S3M and MPTM.

Key claims#

• Loads Amiga IFF (8SVX / 16SVX / MAUD), AIFF, AU, SNES BRR, CAF, FLAC, ITS, MP3, Opus, Ogg, GUS PAT, RAW, S3I (Scream Tracker samples and OPL instruments), SBI, W64, WAV, XI and anything Windows Media Foundation decodes; saves WAV, FLAC, IFF, S3I, RAW. Toolbar: Normalize ("samples should be normalized before being converted to 8-Bit"), Amplify, Remove DC Offset, stereo separation, Resample, Reverse, Silence, Invert Phase, Sign/Unsign (also "nifty-sounding distorted samples"), Crossfade for seamless loops, Tune.
• Tuning: S3M/IT/MPTM set the C-5 frequency directly (with a Transpose helper); MOD/XM use finetune — "1/8 semitone in MOD format, and … 1/128 semitone in XM format" — and a transpose note (locked to C-5 in MOD).
• Loops: off / on / bidi (ping-pong); sustain loops play until Note Off, then the normal loop; the spin buttons hunt for click-free loop points. ProTracker one-shot quirk: with "ProTracker one-shot loops" on, a loop starting at 0 plays the whole sample first — "always trim samples … or not start the sample loop at 0" for other MOD players.
• Auto vibrato per sample (IT/MPTM) or per instrument (XM): waveform, depth in 1/64 semitones, sweep (IT: full depth after depth × 256 ÷ sweep ticks, 255 = fastest; XM: after sweep ticks, inverse), rate (one cycle = 256 ÷ rate ticks); it adds to pattern vibrato and cannot be changed from the pattern.
• Pitch shift / time stretch with a lo-fi granular mode "similar to that found in old hardware samplers"; a Time Stretch Calculator for tempo-matching loops.
• Sample display: draw mode "to fix small mistakes in the sample waveform or to create chip samples", Resize to create a sample from nothing, a sample grid, cue points (MPTM o0x), slice at cues or grid, 8/16-bit conversion, mono conversion, Trim and Trim around Loop Points, Quick Fade, Mix Paste, undo.
• OPL instruments (S3M and MPTM): a built-in Yamaha YMF262 (OPL3) emulator — two operators per voice in additive or FM mode, 8 waveforms per operator (OPL2/S3M only the first four: sine, half sine, absolute sine, pulse sine), 18 voices, panning left/centre/right only. Each operator: ADSR (attack, decay, sustain level, release, "Sustain Sound" hold), volume, tremolo (1 dB), key scaling of envelope and level, frequency multiplier 0.5–15, vibrato (7 cents); the Modulator "can be understood as an equivalent to the filter in an analog synthesizer — the louder the Modulator, the more open the filter is"; feedback gives "rich sounds ranging from metallic to noise". Volume commands scale the carrier in FM mode; cutoff commands scale the modulator; OPL volume is logarithmic — "reducing the volume by 8 units halves it".

Practical takeaways#

Draw or resize to make chip samples, crossfade to loop them, trim after the loop for MOD players; on S3M/MPTM a two-operator FM patch with feedback is a second chip inside the tracker (opl-fm-instruments).

Notable quotes#

"Toggle Draw Mode: Enables or disables sample drawing which can be used to fix small mistakes in the sample waveform or to create chip samples."

Pages touched#

openmpt · chip-samples · sample-looping · vibrato · detune · opl-fm-instruments · s3m-format · multisampling · levels-and-headroom