Hard coding URL parameters for reverse proxy - nginx

Question

I am trying to create a reverse proxy for one of my IP cameras so I can access it without passing basic credentials. The long URL for this is:
http://username:password#172.16.0.38/cgi-bin/mjpg/video.cgi?channel=1&subtype=1
The goal is to be able to hit http://nginx-server:56700.
My nginx.conf file:
user nginx;
worker_processes 1;
error_log /var/log/nginx/error.log warn;
pid /var/run/nginx.pid;
events {
worker_connections 1024;
}
http {
include /etc/nginx/mime.types;
default_type application/octet-stream;
log_format main '$remote_addr - $remote_user [$time_local] "$request" '
'$status $body_bytes_sent "$http_referer" '
'"$http_user_agent" "$http_x_forwarded_for"';
access_log /var/log/nginx/access.log main;
sendfile on;
keepalive_timeout 65;
server {
listen 56700;
location / {
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://172.16.0.38/cgi-bin/mjpg/video.cgi?channel=1&subtype=1;
proxy_set_header Authorization "Basic xxx";
}
}
include /etc/nginx/conf.d/*.conf;
}
When I try to run it without the full parameterized URL, it only forwards to the IP, but I need to hard code the URL parameters. When I try the above config file, it doesn't load the server.
Any help would be appreciated.