pmjpg is kinda proxy for a mjpg camera.
This was needed to be able to use a IP camera (DSC-5030L) inside a Diapora (PowerPoint). A plugin is used to show a web page in the Diapora (www.liveslides.com) which embed a Chromium version 43.0.2357.0 which doesn't support the mjpg format.
An other problem needed to be resolved: the URL http://user:pwd@ip is not supported anymore,
but it was mandatory that the camera couldn't be used without some kind of credential.
It's a simple GO HTTP sever, which will exposed a GET /image handler and any other one define
in the template directory.
The template can be any valid HTML page with some variable to be define, and which should call
the Get /image at the desired frequency, see the idx?.html file for some example.
The "X-Idx" optional header is used to reused the same connection to the camera allowing a much faster frequency and avoiding sharing it with different client. It's the server that will generate it, when generating the template.