Greetings everyone.

I'm an fellow archivist from Brazil, and I'd like to share a free tool I made, wich goes by the name EternalDub. It takes a dub that only survives on a bad source (Like a TV recording, VHS, old DVD) and puts it on a better copy of the same film, like a Blu-ray remux. Without ever re-encoding the video or the original audio.

Why this matters to me?
Many classic dubs only exist on poor-quality copies. When a film gets a nice Blu-ray release, the dub usually isn't on it.

I made EternalDub thinking on my brother, who has dyslexia. Following subtitles is very hard for him. I want him to have the best picture and still hear it in his own language.

Being clear: I don't really know how to code (yet)
So I built it with Claude (Anthropic's AI). I didn't just ask for an app and post it: I defined what it had to do, tested every version on my own files, reported what went wrong and asked for fixes until it worked. It took me a while. I do understand the logic behind it: find the delay between the two audios, map where the dub source has cuts or drift, and fix each section without cutting any dialogue.

Saying more the features, it:
- Detects the delay automatically by comparing the dub with the film's audio
- Handles sources with cuts or drift, fixing section by section (not just one global delay)
- Shows both waveforms so you can check and drag the seams by hand
- Preview plays exactly what the final file will have
- Never re-encodes video or original audio (FFmpeg stream copy); only the dub can become lossless FLAC when it needs editing
- Organizes the final MKV: track order, languages, default and forced flags, external subtitles
- Windows .exe, interface in English, Portuguese, Spanish, French, Italian and German

One title example that i managed to "fix", was Mad Monster Party (1967)
The Brazilian dub only was just avaible at a bad source, with missing pieces and moments where the audio went out of sync.

You can find it on GitHub: Moguel0818/EternalDub

This is something that i've really made thinking on personal use. I've never got to see an actual tool that sucessfuly Works.

It's a free and open source project. So Feedback and bug reports are very welcome, from people who wants to improve this work.

I trully believe that it can help on the future of preserving media.

Sorry for any English errors, and thanks for the attention