Fine Tuning 3GP files

I am unable to Fine Tune when I use 3GP audio files. (OS X)

I believe it is a 3GP playback issue. Is there a known way to enable 3GP playback in Chome, etc.

I wondering if you could create your timing files with the .mp3 files, and do your fine tuning there; and then later swap the .mp3 files for the .3gp files and hope it all works. (worth a try on one book?)

I have done that before. Just wondering if I can simplify.

Currently, the correct thing to do is use .mp3 to do the fine tuning and then swap out .3gp later.