Checklist

• ✅ I have searched the issues page for any duplicate issues open or closed and confirmed that this bug has not been reported before.
• ✅ I have tested the issue with the current build.
• ✅ I have attached log files, uploaded sample data, and commands used so that the issue can be easily reproduced by the developers.

Bug Description

When I hifi-decode a PAL SVHS tape with --pal as one of the parameters, the output flac sounds distorted. When this parameter is omitted, the output sounds better.

Steps to Reproduce

1. Download sample file https://drive.google.com/file/d/1y9hlM5Nr0HmiW-waeQl1eOLJeiwJy3DT/view?usp=drive_link
2. Try hifi-decode --normalize --noise_reduction on --auto_fine_tune on --audio_mode s --threads 3 --pal --frequency 40 --audio_rate 48000 SVHS-157-hifi.s16 SVHS-157-hifi.flac. Output flac sounds heavily distorted.
3. Try the same command without --pal. Output flac sounds better.

Expected Behaviour

Including --pal should give high-quality hifi flac, as this is a PAL tape.

Actual Behaviour

Including --pal makes output worse. Without including --pal, hifi-decode assumes this is an NTSC tape. However, the output sounds better.

Environment

• Decode version: vhs-decode commit cfb0ceb
• Operating System: MacOS Sequoia 15.5
• Hardware Used: Mac Mini M4 ARM

Additional Information

• I also tried with --noise_reduction off, --auto_fine_tune off and adding --bg, but none of these improved the output.
• Stdout shows additional message No module named 'PyQt5' multiple times, even though PyQt5 should be installed. I assume this is unrelated.

Is it related to tbc-video-export?

No