Question 1

Why does yt-dlp Python API SponsorBlock postprocessor report 'No matching segments were found' while the CLI works?

Accepted Answer

The bug is `'categories': 'ModifyChapters'` — `categories` must be a set of SponsorBlock category names, and `ModifyChapters` is a separate postprocessor that must be added to write the chapters into the file. Passing a single string matched zero categories, so nothing was found.

The CLI flag `--sponsorblock-mark all` actually configures TWO postprocessors. Use [devscripts/cli_to_api.py](https://github.com/yt-dlp/yt-dlp/blob/master/devscripts/cli_to_api.py) to convert any CLI command to API options. The correct config:

```python
ydl_opts = {
    'format': 'worstvideo+worstaudio',
    'outtmpl': '%(title)s.%(ext)s',
    'merge_output_format': 'mkv',
    'postprocessors': [{
        'key': 'SponsorBlock',
        'api': 'https://sponsor.ajay.app',
        'categories': {'sponsor', 'selfpromo', 'interaction', 'intro',
                       'outro', 'preview', 'music_offtopic', 'filler',
                       'poi_highlight', 'chapter'},
        'when': 'after_filter',
    }, {
        'key': 'ModifyChapters',
        'force_keyframes': False,
        'remove_chapters_patterns': [],
        'remove_ranges': [],
        'remove_sponsor_segments': set(),
        'sponsorblock_chapter_title': '[SponsorBlock]: %(category_names)l',
    }]
}
```

API options are documented in the `YoutubeDL` docstring in `yt_dlp/YoutubeDL.py`; for anything undocumented, run your working CLI command through `cli_to_api.py` to get the exact Python equivalent.

Question 2

Why does yt-dlp only show storyboard (sb0/sb1) formats and fail with 'challenge solving failed: Some formats may be missing' on YouTube?

Accepted Answer

YouTube requires solving a JavaScript challenge to unlock the real video formats, but no JS runtime was detected (verbose log shows `JS runtimes: none` and all JS Challenge Providers 'unavailable'), so yt-dlp only lists storyboard formats and then fails with 'Requested format is not available'. Fix: install a supported JavaScript runtime so the EJS challenge solver (yt_dlp_ejs) can work — e.g., install Node.js (LTS), Deno, or Bun and make sure it's on your PATH, then re-run yt-dlp. This is required especially when using `--cookies`. See the official guide: https://github.com/yt-dlp/yt-dlp/wiki/EJS#step-1-install-a-supported-javascript-runtime

Question 3

How to fix "Error parsing Opus packet header" when extracting YouTube audio with yt-dlp and FFmpeg 8.0?

Accepted Answer

This is an FFmpeg parsing issue with Google's served WebM/Opus file, not a yt-dlp download corruption. It was fixed upstream in FFmpeg (issue #20954). Upgrade FFmpeg to a patched 8.x/newer build or a distribution package that includes the fix. Verify with `ffmpeg -version`. On distributions where the fix is unavailable, such as a stable Nixpkgs branch, use Nixpkgs unstable or an official static FFmpeg build. As a workaround, use the `.opus` file produced by yt-dlp's `--extract-audio`; the remuxed Opus file normally passes validation even when the original `.webm` triggers the warning. You can also ignore the warning if FFmpeg completes successfully and the output audio plays correctly.

Question 4

Why is the audio pitched lower after downloading a YouTube video with yt-dlp when playing it in mpv?

Accepted Answer

This is an mpv playback/configuration issue, not a corrupted yt-dlp download. Verify by playing the file in VLC or running `mpv --no-config video.mkv`. If the pitch is normal there, remove or comment out the custom `video-sync-max-video-change` line in your mpv config (`~/.config/mpv/mpv.conf` on Linux/macOS, `%APPDATA%\mpv\mpv.conf` on Windows), then restart mpv. This setting can trigger audio resampling/speed adjustment on videos with unusual timing, making the pitch sound lower.

Question 5

How to fix 'nsig extraction failed' and 'Sign in to confirm you’re not a bot' errors in yt-dlp?

Accepted Answer

1. Update yt-dlp to the latest nightly version: `yt-dlp -U` or `pip install -U yt-dlp`.
2. If you still get the 'Sign in to confirm you’re not a bot' error, pass browser cookies to bypass YouTube’s bot detection. Use `--cookies-from-browser BROWSER` (e.g., `--cookies-from-browser chrome`) or export cookies file with `--cookies COOKIES_FILE`. For detailed steps, see: https://github.com/yt-dlp/yt-dlp/wiki/Extractors#exporting-youtube-cookies
3. The 'nsig extraction failed' warning often disappears after updating; if not, it’s a known temporary issue – follow the linked GitHub issues for updates.

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