$ sudo apt-get update
$ sudo apt-get install gmerlin-plugins-avdecoder 

gmerlin-plugins-avdecoder is installed in your system.

Make ensure the gmerlin-plugins-avdecoder package were installed using the commands given below,

$ sudo dpkg-query -l | grep gmerlin-plugins-avdecoder *

You will get with gmerlin-plugins-avdecoder package name, version, architecture and description in a table

gmerlin-plugins-avdecoder package basic information: