$ sudo apt-get update
$ sudo apt-get install qmmp-plugin-projectm 

qmmp-plugin-projectm is installed in your system.

Make ensure the qmmp-plugin-projectm package were installed using the commands given below,

$ sudo dpkg-query -l | grep qmmp-plugin-projectm *

You will get with qmmp-plugin-projectm package name, version, architecture and description in a table

qmmp-plugin-projectm package basic information: