Its hard not to notice the recent revolution in digital video recording technology. It was precipitated by sharp decline in logic chip costs and finally enough hard drive capacity to be considered a serious surveillance tool. Digital recording is certainly the way of the future. But before you throw away your tried & true time-lapse VCR, consider the following:

High Resolution

This is meaningless if you dont maintain resolution continuity between the recorder, processor, monitor and camera(s). It would be a waste of money to add a 700 line digital recorder to an existing system that outputs barely half that resolution. If the video stream starts with 350 line cameras for example, you will only see 350 lines of resolution on playback on your fancy new 700 line recorder. And even if you do replace your cameras with high res models, you still can’t expect to see any improvement if you are processing the signal through the same old 380 line quad or multiplexer or a 330 line monitor. The bottom line is, if you are considering going digital, be sure that your existing equipment won’t cancel out the benefits. You may be faced with upgrading other components that have to be considered into your digital investment.

Higher quality Playback

Unlike standard VCRS, digital video isn’t plagued by horizontal noise bars in fast search modes. Even in normal play speeds, the digital video typically offers less “jump” and ‘jittering” of the picture, necessary when looking for small details such as the object in your employee’s hand; was that a pack of cigarettes or 20 pound from the Till?.

High Speed Playback

Tired of waiting on your VCR to rewind or fast forward to a segment on tape? Digital can eliminate the wait. Most machines offer instant search by time & date, alarm event, even by word search. Because the hard drive read head need only move a fraction of an inch to advance to the segment on the hard disk that you want to see, it is nearly instantaneous. The images can then be Archived to a partition of the disk for permanent storage, transferred another medium such as CD or removable hard drive. CD offers the better solution. The image is encrypted to prevent third party alteration. Some DVR's also load the playback software onto the CD at the same time. This will enable the CD to be used as evidence and played back on any laptop/PC

Future expansion

Although some digital recorders are locked into a fixed format, many are PC based and can accommodate future upgrades in both firmware and software, a benefit with this fast evolving technology. Unlike conventional VCRS, increasing the recording capacity of most digital recorders is be as easy as replacing the hard drive. Some DVR's have remote viewing option allowing images to be monitored over the Internet/LAN/WAN, you can even control Pan/tilt/dome cameras and select individual cameras.

Compatibility

While VHS time-lapse VCRS can often interchange tapes with other brands, that’s about where compatibility ends. And if you’re using a multiplexing system, the coded tape cannot be reviewed without reprocessing it through the multiplexer, often causing problems when supplying your local police department with video evidence. If you wanted to take a snapshot of one frame of video from that tape, you would have to purchase a video printer to accomplish this. Then if you wanted to clean up the frame of video in order to read a license plate on a car, you would need a video capture card in a computer to import the video, then convert it to a compatible format before enhancing it with a popular program such as Photoshop. With many PC based digital recorders, this is achievable within the unit in a matter of minutes! Think of the possibilities.

How much will it cost?

Since standard time-lapse VCRS became popular in the 60s, they continue to decrease in price every year. This is mainly due to time-lapse technology being so popular today, plus manufacturer’s original tooling and R&D costs have long since been paid off. Today you can purchase a quality 24 hour time-lapse VCR for under £150. Expect to pay a lot more for even a basic digital recorder. A 4 camera DVR can cost as little as £400 .(excluding installation)and upto many thousands depending on system size and complexity. You would have to accept the fact that you are paying for opportunity value.

System complexity

Digital recorders typically offer a dizzying array of menu choices that can overwhelm someone who grew up on standard time-lapse machines. With digital, gone are the days of simply inserting a video tape, selecting the recording speed and pressing the record button. The new generation of PC based and Embedded software recorders offer a variety of resolution settings, compression ratios, adjustable frame rates, optional motion detection, multiple screen display sizes, conditional refresh processing, and other parameters that can make it a challenge just to anticipate when your hard drive will fill up. And unlike standard VCRS, saving video is a two step process of first filling the hard drive then downloading evidence to an external storage medium The Hard drive record in a loop so old images would be recorded over. Whether the added complexity is worth it depends entirely on the value you place on the added features. But don’t assume that trading up to digital lets you leave behind all the wear & tear of moving parts in a standard VCR. In fact, the mechanics of digital recording are more similar to standard VCRS than you think. A standard VCR has a high speed spinning tape drum, a tape loading mechanism and a read/write head that scans a magnetic tape passing over it. Digital recorders also use a high speed spinning hard drive, a removable media loading mechanism and a read/write head that scans a magnetic disk that spins under it. In defense of digital recorders, the incidence of PC hardware failures is lower than typical VCR failures.