Converting .dash videos to .mp3 format.
Converting MPEG-DASH Video Files directly to MP3 Audio Files (.dash to .mp3 conversion) is, per se, not possible; at least not without a workaround.
You will first need to convert DASH to MP4, then you can easily convert MP4 to MP3.
As far as we know, there are no currently available audio editing programs or converters capable of converting DASH to MP3.
A free utility used to create DASH content
Program for multimedia streaming and conversion
One of the most popular multi-platfom multimeda player