I had VideoProc 3.5 installed -- I had to delete the C:\Users\ [UserName]\ AppData\ Roaming\ VideoProc folder before v. 3.9 would activate.
Importing a .m2ts file [AVC encoded Blu-ray video] into VideoProc, selected H.264 encoding, then clicked the star on the H.264 icon/thumbnail to get to the encoding settings. Then clicked the Tools tab on the bottom, clicking Trim, and selecting a ~5 minute clip. The CPU = Ryzen 2700, NVMe drive for output file, AMD RX470 GPU. At default settings, 1080p frame size, AMD hardware assist selected, got around 112 fps encoding -- without hardware assist got ~124 fps. Per MediaInfo the encoded files were pretty standard -- a few converters skip some of the post processing options to give a faster encode at the cost of quality.
I did however have a hard time setting the encoder to variable bit rate [VBR], which in VideoProc is called ABR [Average Bit Rate]. With hardware assist on, it reset itself to Constant Bit Rate [CBR]. Trimming the video reset it to CBR -- re-setting ABR disabled the trim, so the entire video would be encoded. VBR/ABR uses a lower bit rate for "quiet" scenes, with a higher bit rate during action where it's needed. VBR has been pretty standard since DVDs came out, giving max quality for minimum file size.
Starting up VideoProc was also annoying, since you have to wait for the ad to pop up for upgrades, and that apparently requires the app to contact the home base servers, which today sometimes took quite a while.
As with most of these ffmpeg-based converters, VideoProc is self contained -- it doesn't install Direct Show filters or anything -- with few registry entries, and files in just 3 folders: the program's folder, and 2 in C:\Users\ [UserName]\ AppData\ Roaming\.
As noted in the past, best way to do subs is to convert them to .srt text files, e.g. use SubtitleEdit to OCR image or graphics-based DVD/Blu-ray subs. Loads of players can use those .srt files in the same folder & with the same name as the video, and they are real subs that you can turn on/off.