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Vance IngallsandClaude Opus 5
2fc689bd91
Three defects in the offline FX path, none of which any test could see. **Float output silently disabled sample-accurate volume automation.** The writer emitted 32-bit IEEE float; the very next mixer step bakes the volume envelope into the samples and accepts only 16-bit PCM, returning null otherwise. So enabling any effect downgraded that track to the ffmpeg expression path — capped at 32 straight segments, quantising a curved envelope, and on a dense one falling back to base volume. It now writes 16-bit PCM, clamped rather than wrapped so a limiter at 0 dB or a resonant filter cannot turn overshoot into a click. A test asserts the baker accepts the writer's own output and actually fades it. **Everything was folded to mono.** `prepareAudioTrack` goes out of its way to emit stereo — its pan filter exists to dodge ffmpeg's 3 dB mono-to-stereo rematrix — and this folded it, then wrote one channel. So adding a single peaking EQ collapsed a bed's width and cost ~3 dB in the render, while preview stayed stereo. Channels now travel as one plane each, through an OfflineAudioContext of the same width, and come back interleaved. **Small results decoded the wrong length.** `new Float32Array(buf.buffer)` discards byteOffset and byteLength, and Node pools small allocations: a 400-byte payload sits at offset 8 inside an 8 KiB pool, so a clip under ~1024 samples decoded as 2048 samples of unrelated memory — and the empty-result guard could not see it. The reader has the mirror-image fix: a float data chunk on an odd boundary (ffmpeg's pcm_f32le writes fmt(18) + fact, landing `data` at 58) now copies instead of throwing RangeError on an unaligned view. The tail limitation is now stated rather than mis-stated: the context is exactly as long as the input, so a reverb or delay still ringing is cut there. The old comment claimed the opposite. How far a tail may run past a clip's end changes the clip's length in the mix, so it is a product decision, not one to make here. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>