I've used MIDI, well, since it began almost, but I use it sporadically and really know little about the technical details. I'm composing in MuseNet/GPT-2 artificial intelligence (it's free for anyone to use), and I save my files in MIDI since I insert tempo changes etc. using my own software in post-process, and also I have a nicer sounding piano VST. You can hear several of my MuseNet compositions on my YouTube channel "Timzart7"
All my piano files have come out fine, but today, wouldn't you know, I loaded my MIDI file to probably the best thing I've composed in two weeks, and it sounds muffled and bad, kind of low volume as well, and the piano VST makes it worse. Reading about Sekaiju here, I compared a MIDI file that is piano alone, just like the corrupted file, and they look identical to me in the parameters, but I don't know what I'm looking for. Any help or suggestions would be much appreciated. If anyone would like to look at the MIDI file itself, the text from the Sekaiju file or anything, I'd be happy to send it on. I've never had the problem of a corrupt MIDI before. Thanks in advance.