If IBM has its way, digital CCTV could help the police improve their arrest and conviction rates by putting cameras on almost any police car or motorbike.

At present, apart from the speed-measuring video cameras carried by pursuit cars, very few police vehicles carry cameras and those that do use ordinary videotape, says IBM consultant John Lymer. This wears out and the cassettes are labour-intensive to manage, and laborious to review.

IBM worked with RCT Engineering to design a rugged box, about eight inches (200mm) square, which connects to a screen and camera in the vehicle. Simple to operate, it records video, audio, GPS location and speed data, and car status information such as whether the siren and lights are on.

Digital recording provides higher quality video that is more cost effective and makes better evidence, Lymer says. Data would be pulled off the car at the end of a shift, stored on disk for a few days while it is automatically screened for specific events, then migrated to LTO tape with each cartridge holding the equivalent of 30 VHS tapes.

In-car storage is provided by a 73GB toughened 2.5in Hitachi hard disk. This is enough for 9.5 hours of video at 30 frames per second and better resolution than DVD, so could be left running for an officer's entire shift, says RCT director Toby Nightingale.

The device has been fitted into a Nissan Micra done up in police livery, and this will now be loaned to interested forces for them to try out, with Hampshire and Wiltshire in the lead.

Automatic number plate recognition (ANPR) and facial recognition are not included yet, but could be added. Lymer says that the ANPR software can aggregate several frames for improved recognition. He envisages downloading a daily "hot list" of the 200 most-wanted registrations; the software could then hunt for these at 15 plates per second.

The aim is to persuade police forces that increased use of mobile videorecording could make officers more effective, allowing them to spend more time on patrol and less in the station. RCT is also working on wireless digital camcorders for scene-of-crime video.