There is no facility to auto generate subtitles in either Movie Edit Pro, now called Movie Studio, or its "big brother", Video Pro X, sorry. I very much doubt whether any video editing package can do this. Which online service are you considering?
@Mark-Creathorne Hi, yes Vegas 365 subscription will create subtitles but that does require a purchase & I know 0 about that, Vegas will import .srt files as will a lot of software now (Not Magix), but again Vegas needs to be purchased,
I would consider uploading your video to Youtube, from there you can download an .srt file
Free DaVinci resolve will import that srt file from there you can edit if needs be & export as a video file, I had to add a black solid as a video clip, don't know if DR will export just the subtitles as a video clip.. (Edit -I exported as MP4, MMS didn't like the Quicktime option)
Added to MMS with Chroma key,
It's a bit of fannying around but it's a free option.
. . . . I have two feature documentaries which need subtitles. . . .
What is the final delivery format you are creating the documentaries for, eg Disc, Youtube etc, and do you require them to be selectable ie they can be turned on/off?
Thanks for the help, very much appreciated. I used to use Vegas but went onto Movie Studio for ages then purchased the Magix suite. The films are for Amazon Prime. I have found a service to do it now. The you tube option is a good idea too.