I followed the directions in an old thread to help me split an MKV apart so I could edit its subtitle file and then merge it all back together using mkvmerge. When I did, I got a message saying the program couldn't dertermine the frames-per-second and that I'd need to provide it. I tried a few things. 24 seems right, but ends up with a lag in the video behind the audio by the end of the file. If I could find out the FPS of the original file, I could just use that, I'm sure. I used the mkvinfo GUI that came with MKVtoolnix, but I couldn't read the results (I'm an amateur, if you can't tell). I thought I found a FPS value, but when I tried it, it was at least twice too fast. After that, I got a figure just from Media Player Classic's Properties functions. This is almost perfect, but there's a tiny slowdown I very nearly didn't notice until I compared it with the original file.
And of course, the answer is that simple. Apologies for my ignorance. That worked perfectly. Thank you very much.
