libavcodec56 software package provides Libav codec library, you can install in your Debian 8 (Jessie) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install libavcodec56
libavcodec56 is installed in your system.
Make ensure the libavcodec56 package were installed using the commands given below,
$ sudo dpkg-query -l | grep libavcodec56 *
You will get with libavcodec56 package name, version, architecture and description in a table
| Distro | Debian 8 jessie |
| Section | Libraries |
| Package | libavcodec56 |
| Version | 6:11.8-1~deb8u1 |
| Description | Libav codec library |
| Sub Section | libs |