Here's a little tool which inserts blank rows every other row. Perfect for times when you start composing your song, but then realize you needed double the row resolution.
Issues: Don't use on songs with more than 128 frames per row. D effects besides D00 aren't adjusted correctly.
Yes, I reverse engineered most of the FTM format, even though Famitracker is open source
I thought it was easier to do it that way than to try to read existing code.
I mainly reverse-engineered the pattern and sequence data format. But not the instrument data, I referred to the original source for that part. The Instrument Data/Sequences stuff is a mess, because there were so many different versions, including a buggy version that needs to be specially handled.