1 CCTV SYSTEMS DIGITAL VIDEO RECORDERS (DVRs) 2 CCTV SYSTEMS The DVR (digital video recorder) has replaced the VCR as the device used to record CCTV video for detection and documentation purposes. The DVR can be networked for viewing images over the internet, however a distinction has been established in the industry between a DVR and an NVR (networkable video recorder). 3 CCTV SYSTEMS DVRs accept analog signals via coax cable connected with BNC terminations. Some DVRs can be networked and can be accessed remotely over the internet, not all DVRs have this capability. RJ-45 PORT FOR CONNECTIVITY TO THE INTERNET 4 CCTV SYSTEMS An NVR is strictly a digital device that only accepts digital signals via RJ-45 connections and is specifically designed for remote viewing over the internet. Cameras are managed through a PoE switch and then networked into the NVR which is considerably different than a DVR. 5 CCTV SYSTEMS NVR: 4/8/16 CHANNEL NOTICE THAT THERE ARE NO CAMERA PORTS ON THIS DEVICE, CAMERAS ARE CONNECTED TO A NETWORK SWITCH DVR: 8 CHANNEL WITH NETWORK CONNECTION 6 CCTV SYSTEMS Whether it’s a DVR, hybrid DVR or NVR they all have the same basic features and functions and they all have the option to record audio. These devices are menu driven and a considerable amount of time can be spent in configuring a DVR 7 CCTV SYSTEMS A DVR CCTV system provides a multitude of advanced functions over VCR technology including video searches by event, time, date and camera. There is also much more control over quality and frame rate allowing disk space usage to be optimized and the DVR can also be set to overwrite the oldest security footage should the disk become full. 8 CCTV SYSTEMS One of the main considerations in choosing a DVR is it’s storage capacity. DVR’S come in 250GB, 500GB, 1TB and 2TB storage capacities just to name a few. The numbers are associated with the hard drives in a DVR, many DVRs are customizable upon request. 9 CCTV SYSTEMS Hard drives can also be swapped out, if a hard drive crashes it can be easily replaced with a new SATA (serial advanced technology attachment) drive. A smaller hard drive can be replaced with a larger drive as needed. 10 CCTV SYSTEMS This diagram shows the inside of a DVR. 11 CCTV SYSTEMS There is another type of hard drive to mention though SATA is the most popular. PATA (parallel ATA) drives are an older standard and were prevalent up to 2007. 12 CCTV SYSTEMS Other factors that will have implications on the storage capacity of the DVR: Frames per second 30fps or less Resolutions- high res. vs low res. Continual recording vs motion only recording Audio recording Compression standards 13 CCTV SYSTEMS In the DVR menu for recording set up it will ask you to pick a value for frames per second, you will be able to choose 1 to 30fps. 1 to 20fps is a fairly choppy video image while 30fps is a smooth video image, the lower the fps the choppier the video. Using the 30fps selection uses more disk space. 14 CCTV SYSTEMS The DVR menu under video setup will ask you to pick a resolution. Under VGA (video graphics array) you will be able to choose 1024 x 768 or 1280 x 1024, some DVRs may give you more choices. The higher the resolution is the more disk space that will be used. 15 CCTV SYSTEMS In the DVR menu for camera setup you will be given an option to motion record which means that when the camera senses motion it will start recording. The other option would be continuous recording which again will use more disk space. It should be noted that motion sensing by a camera is done at a fairly close range, so continuous recording can pick up an event by several cameras for better angles. 16 CCTV SYSTEMS The compression standard is built into the DVR and is not configurable by the operator. There are many video compression standards in use today, the most popular for DVRs are: MPEG-2 or MPEG-4 JPEG-2000 H.263 and H.264 a UTI-T standard 17 CCTV SYSTEMS The latest compression standard is the H.264 The H.264 video format has a very broad range that covers all forms of digital video from low bit-rate Internet streaming applications to HDTV broadcast and digital applications with nearly lossless coding. 18 CCTV SYSTEMS With the use of H.264, bit rate savings of 50% or more are reported. For example, H.264 has been reported to give the same Digital Satellite TV quality as current MPEG-2 implementations with less than half the bitrate, with current MPEG-2 implementations working at around 3.5 Mbit/s and H.264 at only 1.5 Mbit/s. 19 CCTV SYSTEMS To date the H.264/MPEG 4 compression standard provides the best image details with the best compression rate to save disk space. Most of the older (2 years ago) DVRs have H.263 or MPEG-2 compression standards, these standards are not that old and are still used today. 20 CCTV SYSTEMS Some DVRs are quoted with a quadplex function which means it can record, playback, backup and perform network transfer all at the same time. DVRs can also provide e-mail notification of an alarm event. 21 CCTV SYSTEMS DVRs are password protected, you can choose not to use a password or if a password code is configured and later forgotten the DVR has to be re-set internally. There is no reset button like those seen on wireless routers, the DVR’s housing has to be removed and an internal electronic jumper has to be shorted. 22 CCTV SYSTEMS The exact jumper to short is determined by the manufacturer, that information can be obtained by the supplier. 23 CCTV SYSTEMS Some of the other recording functions of most DVRs are the recycle function, it overwrites the oldest data and keeps recording and saving the newest video for about a week or so. Triplex function (record, playback and remote access, all can be done at the same time). 24 CCTV SYSTEMS Lets look at some of the connections on the back of a DVR. We will look at each connections more closely. 25 CCTV SYSTEMS The USB port is for an external mouse to navigate menu options rather than using he controls on the front of the DVR. The other USB is for A flash drive. The CH1 through CH8 BNC ports are the camera inputs, some DVRs have two BNC ports per channel which allows for any camera to be viewed on a different monitor. 26 CCTV SYSTEMS The main out VGA is for an LCD monitor, the BNC main out is for a CRT monitor. The RJ-45 port (LAN) is for networking the DVR. VGA MAIN OUT 27 CCTV SYSTEMS The green termination block is for alarm inputs such as PIR (passive infra-red) motion detectors or door switches. 1 thru 4 are for the positive lead and the “G” is a common ground for each alarm device. The alarm out provides 3 connections: N.O. (normally open) COM (common) and a “G” for ground, this can be used for a sounder or other notification device. 28 CCTV SYSTEMS The RS485 connection is for a PTZ controller (A and B) with a ground connection which is usually used for the shield connection. 29 CCTV SYSTEMS The audio connection on this DVR is similar to a VGA connection and requires a special audio cable. 30 CCTV SYSTEMS Here is the a DVR with all of the connections made to the interfaces we just looked at. 31 CCTV SYSTEMS Here are the controls on the front of a DVR, these are pretty common from manufacturer to manufacturer. 32 CCTV SYSTEMS A closer look at the controls, again this is a typical layout for most DVRs. 33 CCTV SYSTEMS A very important aspect of DVR interfaces is being able to retrieve recorded video footage and transfer it to another media device. This is done through the use of a DVD/RW drive which is available in some DVRs. Increasingly though most DVRs provide USB ports to transfer video onto a memory stick. 34 CCTV SYSTEMS This DVR has a USB port on the front for downloading video onto a memory stick (jump drive or USB flash drive). 35 CCTV SYSTEMS To view recorded video that’s been retrieved from a DVR a special MPEG CODEC needs to be downloaded to decode the video images. These can be obtained from the supplier or downloaded for free from the internet. Sometimes the CODEC will be downloaded onto your stick the first time you retrieve video from the DVR. 36 CCTV SYSTEMS This DVR also has a scrolling knob, another common feature found on 16 channel systems which allows the operator to easily fast forward or reverse through video footage quickly. TOGGLE CONTROL 37 CCTV SYSTEMS This diagram shows the interconnections for networking a DVR. 38 CCTV SYSTEMS Here is a micro DVR that is about the size of flash drive for those of you that have everything…. Micro DVR with built In camera supports up-to 2Gb micro SD card to record up to 2 hours of video.