[Triage] Pinchflat always forces m4a/AAC and ignores yt-dlp format selectors (Opus impossible)

[RudiVL]

Description

Pinchflat currently forces audio extraction to m4a/AAC, even when yt-dlp is explicitly configured to prefer Opus via custom yt-dlp config files.

This makes it impossible to download native Opus audio, despite:

Opus being available from YouTube

yt-dlp correctly selecting Opus when run standalone

Pinchflat loading the custom yt-dlp config file

This behavior appears to be hard-coded and cannot be disabled via UI or config.

Environment

Pinchflat: latest (ghcr.io/kieraneglin/pinchflat:latest)

yt-dlp: 2025.12.08

Docker on Proxmox LXC

Custom yt-dlp config mounted at:

/config/extras/yt-dlp-configs/base-config.txt

Steps to Reproduce

Configure a custom yt-dlp selector in Pinchflat config:

-f ba[acodec=opus]/ba

Download a YouTube video that clearly offers Opus audio:

yt-dlp -F https://www.youtube.com/watch?v=u-HEopHeHb8

Output includes:

251 webm audio only opus 130k 48k

Verify yt-dlp inside the Pinchflat container correctly selects Opus:

yt-dlp -f "ba[acodec=opus]/ba" URL

Result:

test.webm (codec=opus)

Start the same download via Pinchflat UI.

Observed Behavior

Pinchflat always runs yt-dlp with the following hard-coded flags (from logs):

--extract-audio
--format-sort +acodec:m4a
--audio-format best
--format bestaudio/best

Full example from logs:

/usr/local/bin/yt-dlp called with:
--extract-audio
--format-sort +acodec:m4a
--audio-format best
--format bestaudio/best
--config-locations /config/extras/yt-dlp-configs/base-config.txt

Result:

Output is always .m4a

Opus is never selected

Custom yt-dlp format selectors are ignored due to CLI precedence

Expected Behavior

One of the following should be possible:

Allow disabling audio extraction

Allow preserving original audio container/codecs

Allow custom yt-dlp configs to override forced flags

Or expose an option to not force m4a/AAC

At minimum, this limitation should be clearly documented.

Why This Matters

yt-dlp explicitly supports Opus and selects it correctly

YouTube Opus streams are often higher quality than AAC

Power users expect Pinchflat’s “custom yt-dlp config” feature to actually apply

Current behavior makes Pinchflat unsuitable for high-quality audio archiving

Conclusion

This appears to be a design limitation or bug, not a configuration error.

Pinchflat always enforces:

--extract-audio

m4a/AAC preference

overriding any user-defined yt-dlp format selection

Please consider making this behavior configurable or documenting it clearly.