I have been asked to put some IP cameras to record traffic on few roads entering a town.
The police is concerned about the quality as they need to record the plates (also some part of the vehicle).
The pole is ~3-4m heigh and maybe ~6-7m to the center of the road.
Can anybody suggest any device? It must be IP (ethernet, not wireless) and ability to record the streams on any IP DVR..
"... record the plates" at 40ish feet...
Biggest factor in that will likely be the lens used - typical surveillance cams tend to have wider-angle lenses, you'll want a much narrower angle (higher magnification) for this I suggest. (you'll also be looking at potential motion blur, probably best overcome by good lighting at the target) Without a narrower lens angle you'll unquestionably need 1080p or higher, and you'll be pushing some serious bandwidth streaming a wide-angle hires image with moving vehicles and what-not. Better IMHO would be a 720p camera with an appropriate lens to give you a clear shot of JUST the license plate and a few feet each way around it.
BTW I said '40ish feet' because you're talking about a camera mountpoint ~15ft high and 20-30ft from the center of the road, but you won't be looking at the center of the road, you'll be looking 'upstream' or 'downstream' at the passing traffic. Likely your best angle to clearly see license plates will end up aiming at a point about 40 feet down the road from the mountpoint.
"...ability to record the streams on an IP DVR"
This is a tricky bit - this depends on the NVR/DVR as much as the camera. I'd guesstimate that 80-90% of the NVR devices out there are capable of recording video from 80-90% of the IP cams available - you'll really want to contact support on the NVR to be used to ensure that any planned camera will be compatible. (and if the camera has on-board motion detection, some setups allow that to be a trigger for the NVR, meaning it doesn't need to stream video 100% of the time while the NVR ignores unchanged frames)
For us, we frequently use VideoInsight as the NVR with Vitek cameras, but most of our installations are housing authorities and business that are explicitly targeting a wider field of view.