You can change the subtitle delay for Teletext and DVB Subtitles. We can't control the delay with Closed Captions, since this type of subtitles are taken care of by Windows directly, and the api doesn't give us any control over the delay.
For Teletext and DVB subtitles you can press Ctrl-D, and select the delay from the popup. For Closed Captions I'm not aware of any way to change the delay.
I'm playing an MKV video with a SRT subtitle track. The video leads the subtitles by about 5 secs. In KODI I can advance the subtitle track and get them both synced up.
Yeah I know, I led you on a goose chase
I'm not sure where I left off with the VSFilter thing, but if I open the subtitle menu and select the SRT file I actually get 2 subtitles, one over the top of the other.
Does that help?
The subtitle that appears when you open the subtitle menu and select SRT is the one generated directly by NextPVR, and I could add some ability to tweak the delay for this. The other subtitle, which is probably being added by VSFilter, I'd have no ability to control it's delay.