See the AUR.
See ebuilds here.
Install them as follows:
x86_64: tar -xvf ddb_waveform_seekbar_x86_64.tar.gz -C ~/.local/lib/deadbeef
i686: tar -xvf ddb_waveform_seekbar_i686.tar.gz -C ~/.local/lib/deadbeef
You need DeaDBeeF (>=0.6) and sqlite3 and their development files
make
./userinstall.sh
Add it to your Layout with Design Mode (Edit -> Design Mode -> right click in player UI).
There are two settings dialogs:
Right click on waveform and select Configure
and
Edit -> Preferences -> Plugins -> Waveform Seekbar -> Configure