youtube-transcript-to-pdf

Known Issues

Active limitations

Non-Latin text becomes ? in the downloaded PDF

Severity: medium · Workaround: use Print

src/lib/pdf.js uses the standard Helvetica fonts, which are WinAnsi (Latin-1). Typographic characters are transliterated — — becomes --, curly quotes become straight — but CJK, Cyrillic, Arabic, Greek, and Hebrew become ?. The Print button exists precisely for this: Chrome’s renderer handles every script correctly.

Fixing it properly means embedding a Unicode TrueType font with a subsetted CID-keyed font program, which is a large amount of code and roughly a megabyte of font data, for something the print path already solves.

The transcript panel is not a public API

Severity: high, latent · Workaround: see the runbook

src/content/scrape-transcript.js reads YouTube’s rendered transcript panel. YouTube has already migrated once, from ytd-transcript-segment-renderer to transcript-segment-view-model, and the current markup’s class names are obfuscated. The reader handles both generations and falls back to structural matching, but a future redesign will eventually break it.

When it does, the extension reports “YouTube would not release the captions” rather than producing wrong output. See runbooks/transcript-panel-broke.md.

Strategy 2 briefly opens a tab

Severity: low · Workaround: open the video first

When no tab is open on the requested video, the extension opens one in the background and closes it when done. It is visible in the tab strip for a few seconds. This is a direct consequence of YouTube’s token requirement — there is no way to render the panel without a page.

If a tab is already open on that video, it is reused and nothing new appears.

Direct caption download rarely succeeds

Severity: low, by design

Strategy 1 usually returns an empty body and the extension falls through to strategy 2. The code is kept because it is fast when it works and costs one request when it does not.

No coverage of the chrome.* layer

Severity: medium

The service worker, popup, content script, and viewer have no automated tests. Mocking the extension API would test the mock. The manual test plan covers this instead.

Videos that will never work

• No captions. There is no speech-to-text fallback.
• Age-restricted. YouTube requires a signed-in session, which the extension deliberately does not use.
• Private, unlisted-without-link, members-only, or removed. Reported as “YouTube will not serve that video”.
• Live streams still in progress. No complete transcript exists yet.

Not bugs

• A consent screen instead of a video page. Reported as “YouTube did not return a usable video page”. Open the video in a tab and retry — the tab will be reused.
• Auto-generated transcripts have no punctuation. That is what YouTube produced. Paragraph grouping falls back to speech gaps and length.
• Timestamps drift from the audio by a second or two. Cue boundaries come from YouTube.

Reporting

Open an issue with the video URL, whether its captions are auto-generated, and anything red in the service worker console.

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