Did the camera come with any documentation? Model #, etc. As a lot of info should be within the documentation, and once you know how to access each piece of functionality, programming it, won't be terribly difficult.
it has SDK doc , and maybe i can execute the command by calling dll , but i have no idea how ,if you want i can send you SDK doc.
i have read it , but i did not understand it
Here below the dll usage investigation I did to get the data from the DVR:
1- QTSocketStartUp to initialize the dll global and static data.
2- QTOpen to setup the connection with the DVR; passing the parameters of the cameras as specified by the documentation sent. One importance tip here is that there should be a window handle to be passed. The window handle should be created and the WndProc should be overridden to receive the user defined messages from the dll. A workaround for this for the web implementation is using a silent window to process the messages and send the results for the web form/page.
From my quick overview of the SDK and the Network Protocol, you need a much strong language than PHP to handle this. All of the SDK and Network Protocol refer to things that would be used in C, C++, Java, or something along those lines.
Not without a low level application running in the background that your web application can talk to. You may want to look to see if someone else has created a commercial product that does this already, as it will require a significant amount of work.