Everyone is aware of the increasing overlap of AV with IT by now. We are adding video to our clients network switches through the use of HD over IP, IP surveillance cameras, and video teleconferencing (VTC) and telepresence systems.

As we add video to our clients network traffic, we need to be able to advise them on some strategies to keep things moving and to avoid bottlenecks.

Here are 10 things to consider when adding video to a client’s network.

Segmentation
This advice is given quite often. Keep distributed video on a separate network switch. For example, if you have a distributed digital signage network that uses IP to distribute content, put those signs on one switch, while keeping the computers on another to make sure video traffic doesn’t impede employee productivity. This separate video switch will typically have one port connected to the PC network switch or to the incoming data circuit to grant Internet access as needed for updates to the signage server.

Distribution
Is the video being distributed within the facility, such as a hotel with signage throughout for room scheduling, event announcements, and canned media, or is the video being pushed out to another location? If the video is leaving the facility, segmentation may not be enough to assure your video data is not impeded as it travels to its end point, nor that your PC bandwidth is not eaten up with video traffic.

Bandwidth
Obviously total bandwidth of the Internet service connection greatly affects video on the network when it needs to leave the premises as it does from a signage server serving remote locations, a Network Video Recorder being monitored remotely, or in a video teleconferencing system. Even as far back as four years ago, it was recommended to have 2-4 MB of free bandwidth for a VTC system serving up video and data content in an office. A standard 1.5 MB T1 falls short of that.

Circuit Architecture and Infrastructure
What kind of service does the facility have? Even if you segment switches within the facility, and keep video separate from normal PC network traffic, in most cases you are building a pyramid of switches that eventually culminate in a pyramid crown that is the inbound circuit connected to a modem that feeds the top switch. This is the only entry/exit point for any kind of data from any of the segmented switches. You will be limited by the data transfer rate of that last wire leaving the building. T1s have set limits on bandwidth, but can be bonded to create more broadband service has high potential bandwidth that varies greatly based on how many other users are on the system, and FiOS obviously has the least potential for issues due to the capacity of fiber to carry data.

Each end point on the network is also connected to the switch by a piece of wire. Make sure that wire and the associated connectors are capable of supporting the data rate needed for video transmission. 10G over Cat5/6, Cat 5e, Cat6, fiber, etc.

Video Quality
The size of the file affects the amount of traffic as well. File size commonly hinges on two things which are resolution (pixel data) and frame rate. Production quality video frame rates are typically 60fps while surveillance and VTC frame rates are typically 30fps. A third consideration can arise, but does so rarely, which is color bit depth. Most content we distribute is 8 bit (or 24 bit if you multiply it by the three colors). However DCI content for digital movie theaters is 12 bit, and deep color is 10 bit and technically supported by Blu-ray etc, although I have seen many equate the potential of Deep Color in that compression strategy to the mythical Unicorn.

Packet Size
Here is a hard one to control, as there are several packet standards and redundant packet strategies employed for data, even within a single standard like H.264 video compression used in Blu-ray and in surveillance and VTC video transmission. Large packets take up more bandwidth, but in shorter bursts. However if the packet is not received on the other end, there will be a larger gap in the transmission.

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About the author

Mark Coxon

Mark started his technology career at IBM in 2000 before migrating into AV integration in early 2002. He currently works at Orange ProAV, a division of Mad Systems Inc., where he helped the company transition from the niche Museum marketplace to the corporate, education, government, and retail markets. Mark lives in Orange County with Lesley, his wife of 11 years and his 3 children.

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