EDIT: Guitar has been fixed and updated in the current version 0.15

All the issues for Ogg files  listed in version 0.13 have been fixed!
There may be an unkown bug in there somewhere - time will tell

This took a long while to figure out and I gave up several times but it kept gnawing at me because I was damn close. The big issue as mentioned before was Seeking to a spot on the track. I finally resolved this by stopping all the files, seeking each player to the right frame in the PCM buffer. I then I took the last played frame from my root player, and used that as a marker to begin playback on all the other players and it worked!

All features were also upated to be on par with the native files. Fading in/out, instrument muting, crowd sing alongs, rewind, etc, are all working great. I had to write my own fading function. 

What took me the longest to resolve was actually the loud POP when going from the native player to the FFmpeg player in the song menu. I tried so many combinations and settings. I muted all my players and the POP was still there. it was infuriating and I had written it off as an apple bug. Then I looked through the FFmpeg engine and it was setting up an empty AVAudioPlayerNode with the volume of 1 at the start! OMG, that was so stupid. change that to 0 and everything is great again!

I also added more details to Discord Rich Presence like Phrase, Charter, etc. If a song is missing detail information like Album, Phrase, etc, it now displays alternate information. More updates to this feature will be added.