When you say Analog DVR I am going to assume it only has Analog inputs. If so, your only real chance is if the camera happens to have a utility NTSC output. Many IP cameras do, many don't. For instance, Axis cameras as a rule don't, but Samsung cameras often have them.
Also, where the analog connection is may not be obvious, on the Samsung SNB-5004 it comes out of an unusual connector, so it could be missed.
Short of that you could use a IP decoder, but that is likely to cost as much as a camera, so...