Apply dynamic range compression and peak limiting to audio files.
Feed this tool an audio file and it narrows the gap between its loudest and quietest moments, then caps whatever peaks remain so the output never exceeds a set ceiling. Compression pulls down levels that cross a threshold by a chosen ratio; limiting is a much steeper version of the same idea, clamping transients that would otherwise clip. Processing happens on the file you provide, so results depend entirely on the settings you pick. The part people get wrong most often: pushing the ratio and threshold too hard flattens transients, so speech or drums end up sounding squashed and pumped rather than simply 'more even.'
A concrete input and expected output from the current implementation.
Input
Audio peaking at -6 dBFS, threshold set to -20 dB, ratio 4:1
Expected output
Compressed level around -16.5 dBFS before makeup gain (the 14 dB the signal sits above threshold is reduced to 3.5 dB of overshoot)
Standard downward compression math: output = threshold + (input - threshold) / ratio, so -20 + (-6 - (-20)) / 4 = -16.5 dBFS; the limiter stage then guarantees the final peak stays under whatever ceiling is set, regardless of this intermediate value.
Any part of the signal above the threshold has its gain reduced by the ratio you set - a 4:1 ratio turns a 12 dB overshoot into a 3 dB overshoot. A soft knee blends the transition around the threshold so the effect eases in rather than kicking in abruptly; a hard knee applies the full ratio the instant the signal crosses the line.
Attack controls how fast gain reduction engages once a signal crosses threshold; release controls how fast it lets go afterward. After compression and any makeup gain, the limiter acts as a final, far steeper stage that stops peaks from crossing a fixed ceiling - a safety net that catches sudden transients slower compression alone would let through.
The compressor reduces gain gradually above a threshold at whatever ratio you set, so louder passages come down but stay dynamic. The limiter is effectively a much steeper ratio applied as a final stage - it exists specifically to stop any remaining peak from crossing the ceiling, which a moderate compression ratio alone won't always guarantee.
No. This tool works on peak levels and threshold-based gain reduction, not integrated loudness measurement. Getting to an exact LUFS target requires a loudness meter and iterative adjustment - treat this tool as dynamic range and peak control, not a loudness-normalization tool.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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