Repairing Clipping, Clicks, and Crackle

Clipping, clicks, and crackle are all short-time defects, but their evidence is different. Clipping creates runs at or near a ceiling, a click is an isolated discontinuity, and crackle is a dense set of sample-scale deviations. Detect each defect before choosing its reconstruction method.

Select a detector

Defect	Detector	Repair stage	What to inspect
A flat-topped or over-threshold peak	masteringRepairDetectClipping	masteringRepairDeclip	sampleCount, runCount, and longestRunSamples; long runs use an interpolation fallback.
An isolated impulse-like discontinuity	masteringRepairDetectClicks	masteringRepairDeclick	count, rejected, longestRunSamples, and perSecond.
Dense sample-scale surface damage	masteringRepairDetectCrackle	masteringRepairDecrackle	sampleCount, sampleFraction, and perSecond.

Detection is source-dependent. A square wave, pulse train, or fully limited signal can look like a flat top, while downmixing, resampling, or lossy coding can erase a real flat top. Inspect each original channel before any downmix.

Detect in repair order

The following mono workflow detects again after each selected stage, so later measurements see the waveform that the previous repair produced.

import {
  init,
  masteringRepairDeclick,
  masteringRepairDeclip,
  masteringRepairDecrackle,
  masteringRepairDetectClicks,
  masteringRepairDetectClipping,
  masteringRepairDetectCrackle,
} from '@libraz/libsonare';

await init();

let repaired = samples;
const clipping = masteringRepairDetectClipping(repaired, sampleRate);
if (clipping.sampleCount > 0) {
  repaired = masteringRepairDeclip(repaired, sampleRate);
}

const clicks = masteringRepairDetectClicks(repaired, sampleRate);
if (clicks.count > 0) {
  repaired = masteringRepairDeclick(repaired, sampleRate);
}

const crackle = masteringRepairDetectCrackle(repaired, sampleRate);
if (crackle.sampleCount > 0) {
  repaired = masteringRepairDecrackle(repaired, sampleRate);
}

The positive-count checks are only a starting point. Review the waveform and audition each change; a detector cannot know whether a clipped-looking waveform was intentional.

Listen to a transient-repair A/B

A/B PROCESS · DECLICKIDLE

Click repair — compare before and after

Scroll to load

The declicker detects short impulsive defects and reconstructs their samples from the surrounding signal. This clip also contains hum, hiss and crackle; this demo runs only declick, so those defects can remain. Compare the original and processed signal without extra loudness matching. Musical attacks can also be affected: inspect the result rather than assuming every detected impulse is damage.

Compare

This A/B uses the real WASM declicker on a damaged vinyl-style clip. It does not inject noise, match loudness, or run declip/decrackle/dehum. The source still contains hum, hiss, crackle, and musical attacks, so use it to hear the local click repair rather than as a promise that every defect is removed.

Preserve a stereo image

For stereo, pass both channels to the paired functions. Calling the mono function on each side independently can repair one channel while leaving a matching event in the other channel untouched.

import {
  masteringRepairDeclickStereo,
  masteringRepairDeclipStereo,
  masteringRepairDecrackleStereo,
} from '@libraz/libsonare';

const declipped = masteringRepairDeclipStereo({
  left,
  right,
  sampleRate,
});
const declicked = masteringRepairDeclickStereo({
  left: declipped.left,
  right: declipped.right,
  sampleRate,
});
const decrackled = masteringRepairDecrackleStereo({
  left: declicked.left,
  right: declicked.right,
  sampleRate,
});
console.log(decrackled.leftReport, decrackled.rightReport);

declipStereo takes the union of both channels' clipped runs. A channel with no clipped sample in a union run is left untouched there; each channel still gets its own reconstruction and report. declickStereo repairs a run selected by either channel in both channels, while each fill uses that channel's own samples and LPC model. decrackleStereo processes each channel independently because surface scratches do not form a shared event.

Read the reports

Stage	Useful report fields	Interpretation
Declip	lpcReconstructedRuns, interpolatedRuns, repairedSamples	A run longer than 512 samples uses cubic or linear interpolation; LPC options do not change that fallback.
Declick	detected.rejected, repairedRuns, linkedRuns, lpcModelUsed	A large rejected count usually means maxClickSamples or neighborRatio is too tight, not that the recording is clean.
Decrackle	replacedSamples or shrunkCoefficients	The detector always uses the median criterion. Wavelet mode removes detail coefficients without declaring each removed sample to be crackle.

The detector and repair use signal-level thresholds, not a promise that every damaged sample can be restored. Clipping discards information; reconstruction estimates the missing shape from nearby samples. Keep the original and compare the result at a controlled playback gain.

Limits and the shared order

The complete repair order is declip → declick → decrackle → dehum → denoise → dereverb. Clipping is first because a flat region can hide a click; the remaining impulsive stages run before spectral noise and reverb estimation. The functions here are offline whole-buffer operations and do not perform LUFS matching. For the broader decision flow, see Audio Repair Workflow, and for exact option types see the JavaScript mastering API.