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SoundEnvelope

SoundEnvelope (Statement)​

Format​

soundenvelope attack, decay, sustain, release
soundenvelope array[]
soundenvelope

Description​

Shapes the volume of generated tones over their duration, instead of playing them at a flat level. It affects tones generated after it is called.

Four-value (ADSR) form — the classic amplitude envelope:

  • attack — time, in milliseconds, to rise from silence to full amplitude.
  • decay — time, in milliseconds, to fall from full amplitude to the sustain level.
  • sustain — the held amplitude, 0.0 to 1.0.
  • release — time, in milliseconds, to fade from the sustain level down to silence at the end.

Array form — a custom envelope given as alternating level, duration breakpoints ending with a level and then a release time: level0, dur0, level1, dur1, ..., levelN, release. Levels are 0.0 to 1.0 and durations are in milliseconds. The array therefore always has an even number of values, at least four. The amplitude moves in straight lines between successive levels.

No arguments — removes the envelope, so tones play at a constant amplitude again.

Example​

soundenvelope 50, 100, 0.6, 200    # attack 50ms, decay 100ms,
                                   # sustain 0.6, release 200ms
sound 440, 1000
soundenvelope                      # back to flat tones

See Also​

Sound, SoundHarmonics, SoundWaveform, Volume

Availability​

BASIC-256 2.0 and later. Documented from the BASIC-256 v2.1 continuation project.