fix(audio): stop trusting a peak measured by the superseded analysis - #603
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Closes #586. Clipping prevention caps the gain at -20*log10(peak) so the loudest sample lands exactly at full scale. It is only as good as that peak. Rows written before #545 took their peak over a mono downmix. An out-of-phase mix sums to near silence while its samples sit at full scale, so such a row under-reports its peak, the cap computed from it is too generous, and the boost it allows clips for real. The note in library.md said the residual mismatch was bounded by clipping prevention anyway — that is not true for the value clipping prevention is computed from, and the failure is audible distortion rather than a few dB of level. Those rows could not even be found. track_analysis carried no marker, so the only way to tell an old row from a new one was to compare analyzed_at against the date #545 shipped, which breaks on a restored backup, a profile carried between machines, a late upgrade or a wrong clock, and gets less reliable the longer it is left. So: an additive analysis_version column, written by both persist paths from a constant that lives next to analyze_file, where whoever changes the algorithm will see it. Existing rows read NULL, which is exactly the "produced by something older" signal that was missing. TrackGain gains peak_unverified, set when the peak came from a versionless row. The limiter then reads that peak as a lower bound rather than a measurement: the headroom is capped at 0 dB so no boost survives, while any attenuation it asks for is still applied in full — a downmix already reading above full scale describes a master that clips harder still. The doubt travels with the peak it belongs to, so a file carrying its own REPLAYGAIN_TRACK_PEAK clears it. The library sweep now also picks up versionless rows, so they heal by being re-measured. It still never deletes one, which was the decision taken when #545 shipped and is not reopened here. Auto-analyze is opt-in and off by default, so no existing install starts re-decoding on its own. Verified: the migration applied to a database built from every migration in order with foreign_keys ON, both changed queries run against real rows, and the seventeen replay_gain tests pass, four of them new. Claude-Session: https://claude.ai/code/session_01Mvi54fX8T3MyxNX1asWsxd
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Included review availability: 4 reviews are currently available. Your included PR review attempts over the past 7 days set your current allowance at 8 reviews per hour. 📝 WalkthroughWalkthroughLe changement ajoute ChangesVersionnement et réanalyse audio
Mise à jour documentaire du scanner
Priority: ➖ Normal Estimated code review effort: 3 (Moderate) | ~20 minutes Severity of issue fixed: Medium Merge Risk: ⚪ Minimal · up to Audio analyses now carry a generation marker, and legacy or unknown peak measurements cannot authorize ReplayGain boosts until re-analysis. Existing results are retained and stale rows can be refreshed safely. Sequence Diagram(s)sequenceDiagram
participant Bibliothèque
participant analyze_library
participant BaseDeDonnees
participant fetch_replay_gain
participant TrackGain
participant ReplayGain
Bibliothèque->>analyze_library: lance le balayage
analyze_library->>BaseDeDonnees: sélectionne les analyses absentes ou obsolètes
analyze_library->>BaseDeDonnees: enregistre ANALYSIS_VERSION
fetch_replay_gain->>BaseDeDonnees: lit analysis_version et peak
fetch_replay_gain->>TrackGain: marque peak_unverified si la version est inconnue
TrackGain->>ReplayGain: fournit le pic et son statut
ReplayGain->>ReplayGain: bloque l’amplification du pic non vérifié
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✅ Passed checks (4 passed)
Full details: Out of Scope Changes checkExplanation Le changement dans
✨ Finishing Touches📝 Generate docstrings
🧪 Generate unit tests (beta)
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In `@src-tauri/crates/app/src/commands/analysis.rs`:
- Around line 291-292: Mettre à jour
src-tauri/crates/app/src/commands/analysis.rs lignes 291-292 pour sélectionner
les lignes dont analysis_version est NULL ou différente de ANALYSIS_VERSION, en
liant cette constante à la requête. Dans
src-tauri/crates/app/src/commands/player.rs ligne 83, définir peak_unverified
lorsque analysis_version != Some(ANALYSIS_VERSION).
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docs/features/library.mddocs/features/playback.mdsrc-tauri/crates/app/src/audio/engine.rssrc-tauri/crates/app/src/audio/replay_gain.rssrc-tauri/crates/app/src/commands/analysis.rssrc-tauri/crates/app/src/commands/player.rssrc-tauri/crates/core/src/analysis.rssrc-tauri/crates/core/src/scanner/extract.rssrc-tauri/migrations/profile/20260909210000_track_analysis_version.sql
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…NULL Review catch. Both sites tested `analysis_version IS NULL`, which today behaves identically because NULL is the only other value that exists — and would keep behaving identically forever, which is the bug. The constant's own doc says to bump it whenever a change would move a stored number, but a bump to 2 would have left every version-1 row neither re-swept nor distrusted. The mechanism disarmed itself at its first use. The two sites want different comparisons, though: The gain lookup distrusts anything that is not the generation it knows, older or newer alike. A row from a build ahead of this one is just as unaccounted for as one from before the column existed, and refusing a boost costs nothing when we are wrong. The sweep re-measures only what is strictly older. A profile carried back from a newer build holds measurements this build has no better replacement for, and re-running an older analyzer over them would downgrade the data. Playback is still safe there, because the lookup above already declines to boost them. NULL keeps its own arm since `NULL < ?` is NULL rather than true. Verified against the same database: the sweep picks up the versionless row and the never-analysed one while leaving a version-2 row alone, the lookup flags NULL and version 2 but not version 1, and raising the constant to 2 correctly pulls the version-1 row back in. Claude-Session: https://claude.ai/code/session_01Mvi54fX8T3MyxNX1asWsxd
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Closes #586.
Clipping prevention caps the gain at
-20·log10(peak)so the loudest sample lands exactly at full scale. It is only ever as good as that peak — and on some rows, the peak is wrong in the direction that hurts.The bug
Rows written before #545 took their peak over a mono downmix. An out-of-phase mix sums to near silence while its samples sit at full scale, so such a row under-reports its peak. The cap computed from it is too generous, and the boost it allows clips for real.
docs/features/library.mdsaid the residual mismatch from those rows was bounded by clipping prevention anyway. That is not true for the value clipping prevention is computed from. And the two stale values are not equally harmless: the loudness discrepancy is a few dB of level, this one is audible distortion — on exactly the material that is hardest to notice in advance.Worse, the rows could not be found.
track_analysiscarried no marker, so the only way to tell an old row from a new one was to compareanalyzed_atagainst the date #545 shipped — which breaks on a restored backup, a profile carried between machines, a late upgrade or a wrong clock, and degrades the longer it is left.The fix
A marker. An additive
analysis_versioncolumn, written by both persist paths from a constant that lives next toanalyze_file, where whoever changes the algorithm will actually see it. Existing rows readNULL— precisely the "produced by something older" signal that was missing. Additive by necessity:track_analysisis a child oftrack, andforeign_keys = ONturns dropping a parent into a cascading delete.A limiter that knows what it is reading.
TrackGaingainspeak_unverified, set when the peak came from a versionless row. The limiter then treats that peak as a lower bound rather than a measurement:The doubt travels with the peak it belongs to, so a file carrying its own
REPLAYGAIN_TRACK_PEAKclears it: that number came from a tagger, not from our superseded pass, and it wins anyway.A way back to health. The library sweep now picks up versionless rows alongside the never-analysed ones, so they heal by being re-measured. It still never deletes one — that decision was taken when #545 shipped and is not reopened here. Auto-analyze is opt-in and off by default, so no existing install starts re-decoding on its own.
What I deliberately left out
get_track_analysisdoes not expose the version. Surfacing "measured by an older build" in the Properties dialog would be reasonable, but it needs a frontend consumer and 17 locales, and none of it is required for the bug. Adding a serialised field with nothing reading it is dead weight.Verification
foreign_keys = ON, and the resultingtrack_analysisschema checked.replay_gaintests pass, four of them new: an unverified peak never licenses a boost, still asks for its own attenuation, is moot when clipping prevention is off, and is cleared by a tag peak.cargo fmt --check,cargo clippy --workspace --all-targetsandcargo check --workspace --all-targetsall clean.Not verified on real audio — the failure mode is by nature material-dependent, and this box has no sound device.
Adjacent, not included: #587 (ReplayGain album mode) meets the same question from the other side, since album mode has to cap with the album peak, and that peak has the same freshness problem for anything measured rather than tagged.
peak_unverifiedis the seam it will extend.Summary by CodeRabbit