hifisampler
Simplified Guide
Disclaimer: This Method worked for me, it may or may not work if there is something else missing on your Computer, since I'm not familiar with coding in python I'll recommend searching or asking for the problem more qualified people than me in these regards to fix the issue.
Original Guide (Korean):https://www.postype.com/@codasvs/post/19024722
In this small Guide I will show You a easy way to insall and run hifisampler.
1: First download and Install python 3.10 (currently the required version to run it). python 3.10 Link
2: Download the hifisampler from github depository (there is currently 0.0.4, but it is possibly a patch comparing the file sizes, untested by myself). Unzip it in your resampler folder, either keep hifisampler-main or rename it, is up to You, keep the file structure as it is (is very recommended).
3: Download from Team.Coda both the "install.bat" and "run.bat" files from their Depository Link. Unzip and insert them in Your hifisampler folder.
4: Run "install.bat" and let install the packages that it needs (may or may not open a popup warning before proceeding, just as a side note), takes a bit (like every python package installs it will be large, 4+GB is stated), after it is finished don't reinstall if it is not really needed, if there are problems with the initial installation, You need to adress the issue looking online.
5: Run "run.bat" and let it create the enviroment, this step is always required to use hifisampler at the startup - without there is no sound.
6: Open OpenUTAU, open the Song, change the resampler into "hifisampler.exe", change Your wavtool according to functionality (untested other options, site suggests wavtool.exe, I used wavtool4vcv.exe and worked), and now it should render depending on Your OU settings.
Small side note: Depending on Your samples quality some sounds can sound quite harsh, especially breaths, and some background noise could be heard as residue artifacts especially in ending sounds where is silence, may or may not be your case, my voicebanks are mess XD.