How to convert .mp3 audio to .264 format.
Converting MP3 Audio Files directly to Ripped Video Data Files (.mp3 to .264 conversion) should be possible and relatively straightforward, even though your options might be limited. It relates to users attempting to encode MP3 audio to 264 video.
It appears that your best option is using the Freemake Video Converter, which should be capable of converting MP3 to 264.
A free video converter for Mac & PC
One of the most popular and successful free video conversion softwares