WAV playback to fast in preview

[sparhawk]

I downloaded sample pack from here: https://archive.org/details/AmigaSoundtrackerSamplePacksst-xx. I created a MOD project in OpenMPT and when I load the samples as instruments and play them, they sound as I would expect them to.
however, when I try to browse through the files to find out what sample I want to use, I use the "preview" view and play them from there. And strangely the playback is way to fast. However, this doesn't appear to be the sole problem of the OpenMPT, because in any other Windows player, the same happens. All the samples are playing fast and highpitched (because of the speed). Only as instruments they sound normal.

So I wonder if there is some way how I can preview the files to browse through them easily, playing them with a different speed, similar to when they are used as an instrument.

[Saga Musix]

When you click on a file to preview it, it is previewed at its middle-C frequency (i.e. C-5 in OpenMPT). The middle-C frequency for those sample files is wrong, it's a poor conversion. For most of these samples the original middle-C frequency was around 8 kHz but but it's set to 44 kHz in the WAV conversions, that's simply wrong. If you want to preview them correctly, you need to manually set the correct middle-C frequency and re-save the files.

[sparhawk]

But in my pattern, I use i.E. C-5 or C#5 and there it sounds as I expect it to.

Touching all the files is a lot of work, because there are hundreds of them. Is there some tool that can do batch processing? I wouldn't mind, creating a duplicate of the directories, one for browsing and one for playing, because I want to use the MOD on an Amiga game, so I guess I should keep these files as they are. I have to check how they sound when I play the MOD on an Amiga machine.

[Saga Musix]

But in my pattern, I use i.E. C-5 or C#5 and there it sounds as I expect it to.

That sounds like you are using the samples in the MOD format. The middle-C frequency cannot be set in the MOD format, so it always falls back to 8272 Hz (+/- a few Hz if finetune is used).

I cannot recommend you any specific batch processing tools but there are a few out there. Just be sure that you only change the sample rate and not resample the samples.
Another way would be to get the original raw files and re-save them in OpenMPT; when importing a raw file it will normally fall back to an 8 kHz sample rate instead of 44 kHz.