Two bugs in the export pipeline:
1. Container duration from WebM metadata can be unreliable (Chromium bug
on Linux — reports Infinity, 0, or inflated values). The pipeline
trusted this value, causing inflated exports, frozen video, and
"decode ended early" errors.
Fix: scan actual packet timestamps in loadMetadata() and compare
against container duration. Use packet-based ground truth when they
diverge.
2. The speed-aware audio path (renderPitchPreservedTimelineAudio)
recorded in real-time via MediaRecorder but never paused recording
during trim-region seeks. Seek dead time was captured as audio,
inflating the audio track beyond the video duration.
Fix: pause MediaRecorder during trim seeks, skip past initial trim
before recording starts, wait for seek completion before resuming.
Fixes#276, #433. Partially addresses #428.
Enriquefft
5e62ad3215