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Visamp Docs
Visript 5.2 Open Visamp (new tab)

Migrating audio scripts to 4.0

Engine 4.0 removes the three audio globals. They now produce a compile error with a source location and replacement suggestion. There are no legacy aliases. The language remains Visript and the extension remains .viscript.

RemovedReplacementRange / meaning change
$FREQUENCY_DATAaudio::detect::get_spectrum()0–255 browser-scaled dB bins → 0–1 linear amplitudes
$TIME_DOMAIN_DATAaudio::detect::get_waveform()0–255 unsigned PCM → −1…+1 signed PCM
$BEATaudio::detect::get_beat()Old frame-timed energy detector → latched rhythmic bass attacks

Converting calculations

A name replacement alone is insufficient. Review every use, including array aliases, loop variables, history buffers and user-function arguments.

  • Spectrum values already fit colour channels. Replace an old bin / 255.0 with the normalized bin. For old bin / 256.0, use bin * (255.0 / 256.0) to retain its slightly smaller output range.
  • Calculations tuned to byte magnitudes can use bin * 255.0 at the point of consumption. This retains their numerical scale, not the old analyser’s transfer function. Keep the array itself normalized and shared.
  • Waveform silence is now zero, rather than 128. Use a signed sample directly for displacement, or (sample + 1.0) / 2.0 for a 0–1 signal centred at 0.5. An approximate former byte magnitude is (sample + 1.0) * 128.0 (clamp to 255 if that exact bound matters).
  • The current waveform has 1,024 samples, rather than 2,048. A visual grouping sixteen old samples into each of 128 bars should group eight current samples. Spectrum length remains 1,024 in this implementation. Do not make either length a permanent assumption in new designs.
  • Audio arrays now contain floats. If a sample controls an integer index, range, bitwise operation or count, convert deliberately with value \ 1 (or math::floor(value: value) \ 1).
  • Silence produces zero-filled arrays, so loops still execute. Scripts that used an empty array as a “source connected” test need a different condition.

The new spectrum uses a different window, normalization and smoothing policy. Multiplying by 255 cannot reproduce the old browser dB bins. Visual sensitivity, colour response and motion may need artistic tuning with music after migration. The new beat detector also fires differently; use get_onset() when the desired trigger is any sharp attack rather than a recurring rhythmic bass event.

For new level-driven visuals, prefer get_level() (smoothed waveform RMS) or get_bass() / get_mid() / get_treble(). A spectral average from an old script is not equivalent to waveform RMS, so switching that measurement is a design change rather than a mechanical migration.

See Audio detection for the complete contract.

Restoring the original frequency response (4.1)

Use audio::detect::get_frequency() when porting the former $FREQUENCY_DATA. It returns the browser’s 1,024 integer bins in 0–255 with the original analyser settings. Keep the old divisions, nonlinear calculations and history-buffer units. get_spectrum() remains available for linear amplitude data.

If a script was already converted to the linear spectrum, start from the original backup; replacing the getter without undoing the numeric changes would scale it incorrectly. The prepared 4.1 restoration follows this approach, retaining only the necessary signed-waveform and beat syntax changes. Its rollback restores the current sources captured before restoration, including recent experiments.