If you’re unlucky enough to find yourself needing to view CCTV in an .AJP file format, (as far as I can tell these are created by older Hangzhou Hikvision DVRs) then the following will hopefully be helpful.
Some Googling suggested an application called JPEG2000 AJP Video Player. Downloading it and installing it (always use a VM! Do not install random applications on a production machine! Eat your greens!), will lead to disappointment. Not just because it’s a hideous old application, but because it doesn’t work on modern Windows – I’ve tested on 32 and 64 bit versions of Windows 7 and no amount of futzing with Compatibility Mode settings will get it to run properly, and often not even install at all.
What you’ll need to do is set up a Windows XP virtual machine (SP3 worked fine for me) and install the JPEG2000 application there. Once installed (it atually calls itself JM Integrated Remote Station) you can view your AJP file with the “Player” section of the application.
The application is pretty user-unfriendly and some features still won’t work reliably (I couldn’t rewind the video without closing the application to start it again!), but there is a silver lining in that you can output the video to a standard AVI file that will play nicely elsewhere. You can only do it one camera at a time, in real time, but having seen other horrible vintage CCTV programs, any standard-ish export option is a good one.