DVR recorder is the central element of the video surveillance system. It records and archive video footage, as well as retrieves it when necessary.

DVRs can be analog, hybrid and IP recorders. They all comply with the basic audio and video requirements, such as the conversion of signal from analogue to digital, compression, reproduction and network monitoring. All recorders use hard drive as storage.

Analog recorder has inputs for analogue CTV cameras, hybrid DVR can be connected to both analogue and IP cameras, while IP DVR accepts only IP video cameras.

DVRs differ according to:

• Number of cameras they accept
• Type of compression they support
• Video quality
• Network transmission
• Local display capabilities
• Type of streaming
• Storage capacity
• Number of functions they execute simultaneously
• Availability of video-analytic features
• Additional connectivity options (sensors, speakers, etc..)

H.265 is the newest industry standard of video compression used by digital video recorders. Current generations of recorders can work with MJPEG, H.264 and H.265 types of video compressions. Latter uses the highest level of compression without compromising the quality of video footage. Four times better than previous compression types, H.265 extends the life of footage because it creates much smaller files. In streaming mode, small files also prevent the computer network from being congested. This is extremely important, especially when video surveillance runs on more than one camera, which could easily suffocate the network without good video compression. 

Having mentioned standard video compression technology, Tiandy has produced it's own, propriatery video compression S+265 which additionally improves H.265 performance by 40%. Not only it saves even more bandwidth and local storage space, but it also provides point-to-point encryption. That means that video stream travelling from camera to DVR can not be decrypted by any man-in-the-middle attack methods. This can be very important, because it prevents sensitive and personal video recording data to be accessible by unauthorized personell.

Video surveillance system can also be accessed from a remote location through the network access (LAN, WAN network or Internet). Important feature of any DVR system is the ability to remotely monitor area under protection and to retrieve the recorded footage.

Today's CCTV systems have in-built advanced functions of video analysis, such as:

• Abnormal audio detection (screaming, gunshots..)
• Heat Map
• Parking detection
• Panic button
• Counting cars and people
• License plates recognition
• Speed detection
• Face recognition
• Wrong direction detection (driving)
• Lost object detection
• Intrusion detection
• Centralized video surveillance with different options for alarm triggering
• Sound warning
• Crowds detection