How to convert .m1v videos to .mp4 format.
Converting MPEG-1 Videos directly to MPEG-4 Videos (.m1v to .mp4 conversion) is certainly possible and quite straightforward.
Use one of several video editing programs or (online) conversion tools, such as the Freemake Video Converter or Adobe Media Encoder, which allow users to import M1V videos and export them in MP4 format.
Multimedia encoding application from Adobe
A timeline-based video editing software from Adobe
One of the most popular and successful free video conversion softwares
A multimedia converting tool for Windows