Converting .mp4 videos to .dash format.
Converting MPEG-4 Videos directly to MPEG-DASH Video Files (.mp4 to .dash conversion) should be possible and straightforward, even though your options are somewhat limited.
Your best bet appears to be using DASHEncoder or FFmpeg, which allow users to import MP4 videos and export them in DASH format.
A free utility used to create DASH content
Program for multimedia streaming and conversion