www.makemkv.com

Also, I found the RotK first disc should be cut to 7655, instead of 7656.

Of course, your mileage may vary.

Also, I found the cut off time for the TT to be 6394 on my disc, 6396 left two seconds of black screen.

Here are the steps that I used: 1. Create both mkvs using whatever programs you prefer. 2. Open FOTR part 1 in mkvmerge. 3. Set the output filename to what you want. 4. Note the number of chapters (27). 5. On the global tab, check Enable splitting... ...after this duration. Place 6338s in the box. ...