Analog vs IP Video

In the good old days, you had to have a guy walk in front of an automobile, ringing a bell to warn pedestrians that a car was coming (at walking pace), it was unreliable, difficult to operate, and one false move and it became an instant death trap. Horses, on the other hand, were easy to replace, they all fit in the old barn, and they all ate pretty much the same food.

The car analogy is not to say that IP is the car of today compared to a horse; the analogy is that when cars first came about, it took a long time before they became as homogeneous as they are today. Back then it was very difficult to see cars as a viable alternative to the horse. The point I was trying to make is that we are busy designing a better car, while others are convinced that Horse 2.0 is the way to go.

So is IP really better than Analog?

A DVR is analog – right?

Well… Let’s define the terms a little, to avoid the semantic confusion. In this discussion, “analog” refers to the transmission mechanism from the camera to the recording device. “analog” means that the camera sends an analog, uncompressed NTSC/PAL signal directly to the recording device. Whereas the an IP camera captures the image, compresses it and sends it via an IP network to the recording device.

The recording device may be labelled “DVR” or “NVR”, but in most cases the internal components are roughly the same. A DVR usually comes with a framegrabber card preinstalled that allows the recorder to capture the analog video and store it in digital form on a storage medium (is this starting to sound like lawyer-speak?). Likewise, an NVR may be retrofitted with a framegrabber card too, and thus the DVR and NVR becomes almost indistinguishable. Therefore, the discussion is not about DVR vs NVR, but rather analog vs. digital transmission of video.

Cabling
If you already have cabling in place, or if the placement of the cameras is such that you can’t cluster the cameras, then the cabling part of it is equal. But if you can do clustering, it is extremely cheap to do with IP cameras. Also, as Mark Schweitzer pointed out in the LinkedIn forum, IP comes with a built-in upstream channel, so if you ever need to replace a fixed camera with a PTZ, you do not need any additional cabling. Wireless transmission can also be achieved and you can monitor a camera (or a cluster of cameras) via the internet. As far as I can tell, HDcctv cannot piggyback off cat5, but need new HD-SDI cabling (I’m sure Todd Rockoff can clearify on the cabling requirements). I don’t know if SDTI is commonly used in HDcctv installations either.

Image Quality
Analog comes in a few flavors; the most common is NTSC/PAL(and their variations). NTSC has a resolution of 486 lines which in many cases is too low to identify faces unless they are very close to the camera. IP allows you to pick cameras that fit the purpose; cheap, low res cameras for overview, more expensive HD cameras for details and so on. If you so desire, you can easily replace one camera with another of higher or lower resolution. HDcctv seems to allow 1080P (2MP) as the maximum resolution. I think the increased flexibility of IP makes a winner overall.

Live viewing
For those who look at video, live, and respond to it, low latency and fluidity (high framerate) is important. High resolution less so. The reason is that you do not need crisp video to see that someone is fighting on the street, it is only when you go back to investigate and later go to court that the high resolution is real important (identification of license plates etc). Some IP cameras allow you to run 2 streams at the same time. One that gets recorded and one which is called up on demand when you want to view live video. Naturally, you are constrained by the bandwidth available to you as well as the ping-time. If you are cabling like you would an analog installation, you would have no problems with latency or quality at all.

On the other hand, if your IP camera does not provide dual streaming capabilities, then what you record is is what you get to see live. This means that if you run a low framerate and high compression then your live view will reflect that. On the other hand, you can always replace the camera with a better one that supports dual streams.

Playback
Even if the transmission of analog video is lossless the recorder will compress the video using the same compression technology as the IP camera. Any compression artifact introduced by the IP camera will also be introduced by the recorder as it compresses the video. However, while the IP solution may provide playback video in substantially higher resolution than the live video feed (which has an emphasis on framerate and latency), the analog solution can never provide higher quality than the live feed. What you see live is the highest “quality” that you will ever see.

Again, apples to apples, if IP is deployed using analog cabling conventions, you can certainly get the same live/playback quality as an analog system (e.g. VGA/30fps). Furthermore, your recorded video may be of much better fidelity than your live video (e.g. 1080p/10fps). This makes it possible to identify faces and license plates on the recorded video as you are conducting an investigation. It must be stressed that this is not always possible to achieve, bandwidth constraints are always a factor that must be taken into consideration. You should never expect to get 5MP, high quality, 30 fps recordings over a dial-up internet connection.

Scalability
IP cameras is like a BYOB party. Everyone brings their own beer, so you just need to consider how many people will physically fit in your pad. IP cameras already do the compression for you, so the recorder simply needs to pipe the data to the hard-drives. In an analog system, the recording device is handing out the beer as people arrive. The host might have enough beer for a 16 people, but once you are out of beer the party stops. Furthermore, some IP cameras will allow you to do motion detection, or even video analytics directly on the camera (this technology is still in its infancy though). Obviously, a system based on analog transmission can also scale, by adding more/stronger/faster recorders. In terms of scalability I think IP eeks out the advantage, but not by much.

Conclusion
I think the prudent investment is not in more barns for horses or investing heavily in horse 2.0 (which requires special pavement to achieve the speed of a car).

With that said – Happy Holidays folks

Advertisements
Tagged , ,

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: