Storyteller silent-audio failure: wrong source file
Diagnosing an audiobook reader where one volume showed no audio playback at all and another threw a 404 on a navigation resource
When a synced-audiobook reader produces an aligned EPUB with media:duration=00:00:00.00 and zero MediaOverlays/Audio items in the manifest while the storyteller:media-overlays-modified meta IS set, the pipeline ran to completion but the speech-to-text transcript could not align against the book text — the most common cause is that the uploaded narration is the wrong book entirely (whisper transcribed it fine, alignment matched zero sentences, finalize wrote the empty overlay set without erroring). md5sum the raw audio against neighboring books to detect duplicates instantly. Separately, a 404 on ~readium/guided-navigation.json?ref=partXXXX is NOT a regression when the ref points to back-matter (TOC, copyright, end credits) — those pages legitimately have no narration; Readium returns the explicit error "referenced resource has no associated guided navigation document" only for unmapped spine items.
Compare md5 of audio sources across books first, and read the first whisper transcript chunk to confirm it matches the expected text — both checks take seconds and would have skipped a long investigation.