Converting OKT to IT, terrible quality loss of samples.

Started by rodentMinn, September 13, 2022, 04:17:02

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I have an Oktalizer file which I modified to correct a small mistake in the song, and it sounds perfectly fine; but when I try saving it as IT (or even MPTM or S3M), the samples all sound very distorted. I even tried compatibility export, and that didn't work. I tried saving all of the samples as Wave, FLAC, and Raw; none of them worked. The samples were saved in bad quality there too. Even appending the OKT to a blank IT file messed up the quality.

I saw one person on this forum get a loss of quality when he tried converting IT to MOD, but I'm trying to convert OKT to IT, and even saving the samples individually or at once trashed the sound quality. Is there something I'm missing here, like something obvious I'm not doing to make the samples save in the purest possible quality I can? I did manage to save a bad sounding sample from an STK file, use the fixed sample in the same song and save the new song as a MOD file, and it sounds perfect - no quality loss. So, what's going on here? How I fix?

Saga Musix

What you are most likely observing is that playing a MOD file in OpenMPT by default uses an emulation of the Amiga's Paula sound chip, which will play samples exactly the way they would sound on a real Amiga, while playing an IT file uses more modern resampling methods by default using a Sinc filter. The question why this filter sounds "terrible" (when applying it to old samples) is answered in the FAQ.

There are two options:

  • Change the default resampling filter to "No Interpolation", but that applies all samples, even those which would benefit from higher-quality resampling, and it applies to all modules.
  • Upsample the samples from your OKT files twice, using the "No Interpolation" filter. They will always sound crisp then, no matter which resampling filter is chosen.
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I did the second option you suggested, and it worked great! Thank you so much!

I didn't know the Paula chip was emulated - Honestly, I thought you pulled the samples straight from an Amiga. That is really interesting with how MOD or OKT behave in comparison to IT. Now I know.

There was one thought I had, to simply have the song rewritten using my own timbre, but it just wouldn't be the same, you know?

By the way, I really like OpenMPT. It's a great program, and y'all have done an excellent job with it.