Convert MP4 to MMF

As far as we know, converting MPEG-4 Videos directly to Synthetic Music Mobile Application Files (.mp4 to .mmf conversion) is, per se, not possible. At least not without a middle step.

It appears that you will first need to convert .mp4 to .mp3. You can then use one of many available media editing programs or (online) conversion tools, which allow users to convert .mp3 to .mmf.