Positive offsets still delay the whole mix via the delay line (lip-sync fix);
negative offsets now ARM once at StartLive and drop |N| ms off the pipe's write
head so audio events land earlier when audio runs BEHIND video. Slider relabeled
AUDIO SYNC, Min −500, locked while live/recording (IsEditMode). LayoutStore and
VM clamp to −500..500.
OBS reference for eat-the-head negative sync: https://obsproject.com/kb/obs-studio/buffering-time (negative sync values pull audio earlier by discarding buffered player audio).
Test: StartLive_NegativeOffset_AdvancesAudio_ByDroppingTheStreamHead (6x0.9 head
must be eaten before 0.2 bed reaches the wire).
AudioMixer.Start() begins mic/loopback capture at app startup to feed the
level meters, so both 2s ring buffers fill with pre-live audio. StartLive()
drained from the oldest tail sample, putting every recorded event ~2.2s late
in the audio track (confirmed by clap analysis + cross-correlation on two
takes: +2.11 to +2.22s).
Fix: AudioMixer.StartLive() now runs _micBuffer.Clear() + _loopbackBuffer.Clear()
immediately after the pipe starts, before the drain task runs. Recording now
begins at go-live; the <=10ms in-flight chunk evicted by Clear() is imperceptible.
Regression test: StartLive_DiscardsPreLiveBacklog_SoFirstAudioIsCurrent
saturates the loopback ring with stale 0.8 pre-live audio, then asserts the
wire carries fresh post-live 0.2 (max < 0.3).
Reference (external, per derivative-work rule): OBS 'Audio mixer' keeps its
buffers fed continuously and syncs the stream start timestamp at record time
rather than replaying pre-live capture; a go-live flush of the capture buffer
is the accepted pattern for live tools restarting a stream.
Docs: HANDOFF.md (fix shipped), MyMistakes.md (A/V sync measurement recipe).
The recorded audio is full-length silent AAC (−91dB, 1124 frames/23.95s) —
the named pipe carried ~9.1MB of zeros the entire take. The mixer's loop
ran, the pipe connected, ffmpeg read it, and the file is full-length
silence. Sources started fine ('Audio: using system default mic...' logged),
no failure callbacks fired, and the existing integration test
(Mix_WithFiltersDuckAndGain_Lands_On_AudioPipe) proves the loop→pipe path
carries real audio when fed — the fault is capture-side.
Added permanent per-5s live-loop telemetry to startup.log so the next take
names the exact stage without new code:
Audio live: pipe connected= dropped writes= micLevel= loopLevel= drained
N/N samples peakMix N (per 5s)
- AudioMixer.FillAndMix now returns (MicRms, MicDrained, LoopDrained) for
the accumulation; StartLive/StopLive log start/stop lines.
- NamedPipeAudioWriter.DroppedWrites: nonzero = audio dropped before ffmpeg
connected (names 'pipe never connected' stage).
Likely root cause: WASAPI loopback captures the default render endpoint —
if audio plays on a non-default device the recording is silently silent.
The fix requires device enumeration + selection (slice 13 candidate).
Suite 290/291 — same sole pre-existing compositor pixel failure.
The creator-declared known failure (Mix_HonorsProviderGains) and AudioPipelineTests'
standalone hang shared ONE root cause, born in TASK 22: AudioMixer.FillAndMix
dereferenced _delayedMix (declared float[]? , never assigned) as delayed.Length —
every live-mix tick NRE'd before the pipe write, so NO audio ever reached the wire
(tests starved -> hung/fail; app -> swallowed catch logged only ex.Message, 10ms
flood). Now: ctor-allocated + null-check, catch logs WITH stack via AppLog and is
throttled 5s, and a cancelled token breaks out before logging.
Bonus contract fix: AudioGainProvider.LoopbackGain returned unity on a disproven
premise ('loopback scales with endpoint volume'). The creator's tonight observation —
volume at 20%, meter pegged — proves the WASAPI tap is pre-endpoint-volume, so the
mixer must multiply by GameAudioVolume for stream honesty (this is what ai.md always
specified; the 'failing' test encoded the same and was RIGHT).
AudioPipelineTests: 25/25 in 26ms, standalone, no hang. Known-failure count: ZERO.
ai.md tests paragraph rewritten (no more suite-total claims, both ex-'knowns'
explained); TASK 22 regression recorded; MyMistakes: the known-failure-label rules.
Creator ruling 2026-09-01 (stuck REC pill after the failed first recording):
- StopStream clears RecordPillOn + OnAirPillOn — intent resets with reality.
- OnFramePumpFailed: dispatcher-marshalled FULL rollback via StopStream (was:
toast + Error-status only when live — record-only sessions zombied with
IsRecording=true over a dead encoder; the 20:34 attempt proved it). Toast copy
says 'Recording stopped' vs 'stream pipeline stopped'.
- Same zombie class in the three go-live prep failure branches: StreamStatus.Error
limbo replaced by StopStream() (audio loop + recording + pills unwind; a created
broadcast still gets the close-out).
- AudioMixer.StopLive made explicitly idempotent (Stop() twice, rollback paths that
never reached StartLive).
- Seams: OnFramePumpFailed + IsRecording setter internal (InternalsVisibleTo; test
pattern mirrors LayoutPathOverride).
ONE integration test: SessionTeardownTests (real window + temp DB: pump death with
lit pill -> no zombie, no End button, Offline). AudioPipelineTests confirmed to hang
STANDALONE (pre-existing, the declared-known audio class) — ai.md test-count
paragraph corrected to stop claiming a suite total that cannot currently be measured.
- Elements scrollbar no longer deselects element on click (check ScrollViewer, not StackPanel)
- Web source: URI + check/revert buttons merged into single DockPanel row, consistent order (✓ rightmost)
- Countdown timer moved from Elements panel to inline in source list row, range clamped to 1-30 min
- Volume slider click-to-position restored: e.Handled prevents IncreaseLarge from overriding position, Thumb drag still works
- Desktop audio meter: asymmetric smoothing (attack 0.2, decay 0.08) for faster response to silence
- 207 tests passing, 0 warnings
gramps