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hyperframes/packages
Vance IngallsandClaude Opus 5 0103c2459c fix(core,engine): make a group's preview match what the render bakes
Findings 8-11 and 16 — the render/preview parity set. All group audio,
all invisible to preview or to export alone, which is why each had a
passing test beside it.

9 — The preview bus wired only the automation lane, and
readElementAutomation reads data-automation, so a group's own
`data-volume` never reached the graph at all: the bus stayed at unity
while the render applied it. The export was ~8 dB quieter than what had
been auditioned. The test named for this asserted only
`resolves.not.toBeNull()`.

10 — The volume lane was scheduled on the FX chain's SOURCE, ahead of
the effects, breaking the contract scheduleVolumeLane's own docstring
states: "the volume lane rides the fader, after the effects — where a
DAW puts it, and the order the render bakes it in". The element path
honoured it; the group path did not, so any nonlinear group effect
previewed differently than it rendered. Both now land on a dedicated
post-FX fader node: input → chain → fader → mute → output.

11 — The bus deliberately outlives stopAll(), and groupInput early
-returned on an existing entry, so after a replay or a seek no new ramps
were booked and the gain held the previous pass's last value — 0 after a
fade-out, i.e. silent for the rest of the session. It re-anchors once
per play generation now (ElementFxHandle gains `reanchor`), and the
record keeps its `fx` handle so setRate can re-aim a group's automation,
which its docblock already claimed it did.

8 — The sub-mix summed members at unity (normalize=0) into a pcm_s16le
intermediate, so an over-unity sum hard-clipped at ±1 BEFORE the group's
FX and fader ran: pulling the fader down, or the Giant preset's
compressor, then operated on distortion. The intermediate is float now.
Both downstream readers already took float; applyVolumeEnvelopeToWav did
not, and does now, so a group's envelope is still baked sample-accurately
rather than silently degrading to the expression path.

The new level test is the one that matters here: EVERY tone in that file
is built on ffmpeg's `sine` source, which peaks at ~0.125 full scale, so
nothing in the suite could reach a clip whatever gain it asked for.
`writePeakTone` states the amplitude outright, and the test fails against
the 16-bit intermediate.

16 — mixGroupMembers forked mixAudioTracks' filter build and dropped its
automation-degradation retry, so a member envelope past this ffmpeg
build's expression limits failed the whole composition's audio where an
ungrouped one degrades to base volume with a warning. The retry is back,
reported on a successful result the same way. The group track is also
pushed with its volumeKeyframes when the envelope could not be baked,
instead of losing the group's automation silently.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-20 02:15:37 -07:00
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