Q1 : What is a video server?
The term "video server" refers to a network-attached server for video that is connected to a computer network like a LAN. A video server can deliver live video, automatically or on request, to a browser or other professional security applications. Security systems have traditionally been based on analog CCTV (closed-circuit television) technology. Video servers digitize analog video sources and distribute digital video over an IP network turning analog cameras into IP cameras. A video server can also be connected via a modem for access over a phone or ISDN line.

Q3 : What's the advantage using MPEG-4?
MPEG-4 provides DVD quality video, but uses lower bit rate so that it’s feasible to transmit digitized video streams in LAN, and also in WAN, where bandwidth is more critical, and hard to guarantee. MJPEG's bandwidth requirement is a little bit more than MPEG-4, while its resolution and frame rate are much worse. MPEG-2 can provide DVD-like video, just like MPEG-4. However, MPEG-2's bandwidth requirement is so high that it’s not possible to use in a LAN or WAN environment.

Here is a video quality comparison between Shany's video server and a competitor's MPEG-4 video server. It’s obvious that although both video servers use MPEG-4 compression technology, Shany's video server has better video quality since Shany is MPEG-4 ASP compliant, while the competitor is MPEG-4 Short Header compliant. The right-hand picture is Shany's video, while the left-hand one is from the competitor.

Q5 : What's the advantage to use MPEG-4 ASIC over DSP?
Current most popular DSP cannot provide enough processing power to process MPEG-4 full D1/30 fps encoding algorithm. The video quality processed via DSP cannot compete with that processed by ASIC. Current DSP usually supports up to CIF (360x240) right now, while ASIC can support not only CIF, but also full D1 (720x480).

Q6 : Why is it so important to have DDNS support?
If an IP camera can support DDNS (Dynamic Domain Name Server), users can set the IP camera at a virtual domain name (such as cam1.kitchen.Taipei.xxx.xxx) at dynamic IP, and be able to view this IP camera anywhere that has access to the internet. It saves money when setting up the broadband with service provider, whether it’s ADSL or cable modem, since fixed IP is not a must.

Some IP camera manufacturers claim to provide DDNS. However, they are software solution that needs to be installed at client site’s PC. Therefore, it requires users to see those IP cameras at the PCs that have installed the specific AP from manufacturers. This is not as user-friendly. Shany has DDNS function built-in the IP camera so that users can view the IP camera from anywhere.

Q7 : What does "Digital Time Code Embedded" means? Why is it important?
The "Digital Time Code Embedded" function is embedded in MPEG data stream. Therefore, the exact time each frame is recorded will be stored. It is very useful when users want to find the video at an exact time or a certain time interval. If an IP camera doesn’t support this function, users have to search for the whole video stream by looking through the video, which takes a lot of time. Some cameras provide software solution to simulate this function. However, this is not as accurate. Video streams with Digital Time Code Embedded are so-called "Smart Video", and can enable a lot of useful applications at client site.

The other advantage of Digital Time Code Embedded is that it provides watermark on the video streams. Since the time code is written in the video stream, if the video is modified by others, the time code will disappear from the video stream, and therefore, the time code can act like a watermark for the video stream and users will find if the video is modified by unauthorized people.

Q8 : Why is it important to have WAN and LAN on the video server?
Shany's video servers provide two RJ-45 connectors. One is WAN and one is LAN. Both of them are 10/100. The difference between a WAN and a LAN is that WAN is to be connected to the internet, while LAN is to be connected to a local network. Since the internet's bandwidth is very critical, Shany provides hardware QoS (Quality of Service) on the WAN port to ensure the bandwidth when uploading video streams through the internet. Also, the WAN port is equipped with PPPoE (Point-to-Point Protocol over Ethernet) which enables the video servers to be connected to an ADSL or cable modem without the need to go through a router first. If the video servers are to be deployed at a large area, it will be very costly to provide routers to each video server. Using video servers with PPPoE built-in, installers will be able to save a lot of cost over routers.

Written by MIS Doctor Wang

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