Running two related commands in Subprocess Python - python-2.7

Question

I am trying to start mjpg-streamer from a python script on the raspberry pi. The instructions for how to start it from the command line are here and consist of running
export LD_LIBRARY_PATH=. ./mjpg_streamer -o "output_http.so -w ./www"
-i "input_raspicam.so"
from /var/www/mjpg-streamer/mjpg-streamer-experimental. When I do it in the terminal, it works fine.
However, I am trying to run it using subprocess.call like this:
subprocess.call('export LD_LIBRARY_PATH=.', shell=True, cwd='/var/www/mjpg-streamer/mjpg-streamer-experimental')
subprocess.call('./mjpg_streamer -o "output_http.so -w ./www" -i "input_raspicam.so -x 640 -y 480 -fps 15 -vf -hf"', shell=True, cwd='/var/www/mjpg-streamer/mjpg-streamer-experimental')
And that is giving me the error:
MJPG Streamer Version: svn rev: ERROR: could not find input plugin
Perhaps you want to adjust the search path with:
# export LD_LIBRARY_PATH=/path/to/plugin/folder
dlopen: input_raspicam.so: cannot open shared object file: No such file or directory
I'm guessing it is because the first command doesn't provide the relevant link to the plugin? I'm not entirely sure of how these commands work anyway, so any insight into that would also be helpful!
I have also tried using os.system to run these commands and have received the same error.
I'm sure I'm doing something silly, so thanks in advance for your patience!