The Outputs Tab: HTTP Output
Checking the "Use HTTP (Web) output" check box enables the controls in the "HTTP (Web)" group box. The HTTP output provides a continuous stream to a specified port on the local host, which can be viewed in a Web browser by using the address "http://localhost:8080" (replace "8080" with the port chosen in the group box). Depending on your host's settings, you can view the stream directly over the Internet (not recommended), or use it as an input to something like ZoneMinder.
You can as many outputs at once as are available; MJPG-streamer supports up to ten, but only three exist at the time of writing, and one of those is of very limited utility. The remaining two are presented on the "Outputs" tab.
The "WWW directory" line edit is required, and is pre-filled with a default value that should be correct in normal cases. If you haven't explicitly set up an alternate WWW directory, it's best to leave this as is. Should you ever need to revert to the default setting, clicking on the button to the right of the line edit will bring up a file dialog that starts you off in the mjpg-streamer directory, which contains the default WWW directory (aptly named "www"). Choose that "www" directory, click OK, and all will be well.
The "TCP Port" spin box is the only other required element for HTTP output. It allows you to specify which HTTP port will carry the stream. The arbitrary default is 8080, but this can be anything that isn't used for something else already.
You can require users to enter a name and password to access the HTTP stream by checking the "Require user name/password" check box. If you check the box, you must supply a valid user name and password (white space and special characters are not allowed).
MJPG-streamer has the ability to send camera movement and image adjustment commands to webcams that support it, and the default Web page provided by MJPG-streamer includes controls to send those commands. To prevent those controls from being available, check the "Disable camera controls" check box.