I recently installed the youtube-dl and while running it I got the error as follows.
avconv: error while loading shared libraries: libx265.so.43: cannot open shared object file: No such file or directory
Find the one that is currently in use
$ ldd $(which ffmpeg) | grep -i "libx265"
It will display something like
libx265.so.79 => /usr/lib/x86_64-linux-gnu/libx265.so.79 (0x00007fdff37b7000)
Now, we have to create symlink to this file. In my case, I symlink libx265.so.43 to libx265.so.79. We should use the full path for both files. Use the command given below.
$ sudo ln -s "full_path_to_actual_file" "full_path_to_missing_file"
Here, actual_file is libx265.so.79 and missing_file is libx265.so.43 that was reported earlier.
$ sudo ln -s /usr/lib/x86_64-linux-gnu/libx265.s0.79 /usr/lib/x86_64-linux-gnu/libx265.so.43
After this command was executed. My avconv started working. I can now use it with youtube-dl, ffmpeg.