audio-artifacts-debug

Audio Artifacts Debug

Audio artifacts have diagnostic signatures — match the symptom to the root cause before touching code.

Step 1 — Characterize the artifact

Ask these questions before reading any code.

| Artifact type | Questions to ask | |---------------|-----------------| | Clicks / pops | Regular or random? On buffer boundaries? At note on/off? After channel strip toggle? | | Crackling / distortion | Constant or load-dependent? Does it correlate with signal level? Worse on silent decay? | | Silence / dropout | Immediate or gradual? Only under load? After a specific number of voices? Recovers? | | DC offset | Constant or drift? Present from first sample? Appears only after long silence? | | Aliasing | Audible as high-frequency mirror tones? Pitch-dependent? Present at all sample rates? | | Phase issues | Stereo image collapse in mono? Comb filtering? Only on parallel paths or mid-side? | | Latency | DAW reports wrong delay compensation? Wet/dry misaligned? Only at certain buffer sizes? |

Step 2 — Narrow to root cause

| Symptom | Likely cause | Skill / check to apply | |---------|-------------|----------------------| | Click at fixed buffer-length intervals | Buffer boundary discontinuity — uninitialized tail, missing sample-accurate fade | audio-dsp-review: check process entry/exit | | Click correlates with xrun log | CPU overload — audio thread missed deadline | audio-dsp-review: scan for allocations, locks, I/O | | Crackling scales with signal amplitude | Clipping or fixed-point overflow | audio-numerics-review: overflow, Q-format multiply | | Crackling on silent decay | Denormal floats — FTZ absent | audio-numerics-review: denormal section | | Dropout / silence under load | xrun, NaN propagation, or buffer too small for latency | audio-dsp-review + audio-numerics-review: NaN guards | | Silence after large value | NaN propagated from unclamped sqrt / division | audio-numerics-review: NaN / Inf section | | DC offset from first sample | Uninitialized filter state or delay line | audio-numerics-review: precision loss / state init | | DC offset after long silence | FTZ leaving near-zero state; missing high-pass | audio-numerics-review: denormal / FTZ section | | Aliasing pitch-tracks with note | Oscillator not bandlimited; no anti-alias before downsampling | audio-numerics-review: check sample-rate handling | | Stereo collapses to mono | Unmatched processing on L/R; phase inversion | audio-dsp-review: check parallel path symmetry | | Comb filtering on mono | Latency mismatch on parallel paths | Plugin reports incorrect getLatencySamples() | | Latency wrong at buffer-size change | Plugin caches latency at init only; not updated on reconfigure | audio-dsp-review: check prepareToPlay reset |

Step 3 — Structured diagnosis report

## Audio Artifact Diagnosis: `[file / symptom]`

### Artifact characterization
Type: [clicks | crackling | silence | DC | aliasing | phase | latency]
Observed: [when / under what conditions]
Reproducible: [always | intermittent | load-dependent]

### Root cause hypothesis
Likely cause: [one sentence]
Evidence: [what in the code supports this]
Skill to apply: [audio-dsp-review | audio-numerics-review | both]

### Specific checks to run
1. [file:line] — [what to inspect]
2. ...

### Recommended fix
[Concrete action — no placeholder text]

For artifact-specific diagnostic questions and check-by-check references see references/artifact-patterns.md.