Video Conferencing Bandwidth & Quality of Service (QoS)

This web page complements the Nefsis data sheet providing additional details and illustrations on the topics of IP-based video conferencing bandwidth consumption and quality of service.

Fixed-site boardrooms and telepresence installations generally use some form of dedicated (not shared) network routes and Internet access. Dedicated routes are required to achieve full-screen, full-motion video.

These dedicated routes are very expensive, and most importantly, sit idle while not being used. Moreover, if you or your company are not familiar with detailed grades of service and leased-line installation, they can be quite complex too.

Today, more options are available. Nefsis is the next generation of of IP-based video conferencing software and online services, and it's capable of running over existing networks anddelivering high-quality video.

Nefsis can run over dedicated routes too, which is useful for "apples to apples" comparison between boardroom hardware such as Polycom and IP conferencing software such as Nefsis. But the value proposition and most popular Nefsis configuration is running over existing networks. This often leads to questions regarding bandwidth consumption and quality of service.

Nefsis Bandwidth Consumption & Video Codecs

Video applications consume bandwidth similar to web browsing, web conferencing, desktop sharing and VoIP. Video differs in one important respect, video is continuous. When sharing a desktop, bandwidth is usually only consumed while you are moving the mouse around or changing the display; with VoIP, only while you are talking; and with Nefsis PowerPoint and document sharing, only when the document is initially shared, thereafter only page change commands go "over the wire".

The quality of a video over IP depends on the network connection and Internet access, including bandwidth or data carrying capacity, and latency, or the speed of the connection. Note it is possible to have a high-bandwidth connection, but long latency (slow). For example, a high-end satellite link may provide good bandwidth, but still have one or two seconds of latency.

Other considerations include the video codec, the compression quality setting (low, medium, high), size (1/8th screen, 1/4 screen, full screen), and frame rate (1 to 30 frames per second, 6 default). Some industry veterans say they can tell the difference between the video coder/decoder too. Nefsis uses MPEG4 as a default, with optional H263 and H263+.

Nefsis users do not need to worry about these details, as the meeting host can go to the Conference menu and select Set-All-Video to low, medium or high, and then Play-All. Or just say Play-All, and Nefsis will use defaults. Conference hosts can also make individual video settings if desired. Say for example, making the primary speaker's video the largest, or "floating" their video (see screen shots above). Nefsis will not allow settings that are not possible under current network conditions, on a connection-by-connection basis. Once set, Nefsis also dynamically optimizes, raising or lowering the frame rate in response to changing real-time conditions, all without interrupting the host or meeting participants.

In the screen shot shown at left, the small videos are running at low quality, 177x144, also known as 1/16th screen or "postage stamp". These use ~28 kbps each, and multiparty video conferences are possible over virtually any broadband connection.

In this example, the videos are running at medium during a desktop sharing session (CAD). The conference room window was "floated" by the conference host and stretched, but the native resolution is 320x240, also known as 1/4th screen. At default 6 frames/second, this will use ~128 kbps for each person talking or moving around.

The last example shows the conference host at high quality, full screen (640x480). At 6 fps this will be ~256 kbps, at full motion, or 30 fps, it will run ~512 kbps. Bandwidth consumption is not linear due to compression involved.

Please click the button at right for Word document materials and spreadsheet-driven, bandwidth estimation tools for site-specific analysis. These materials are available to Nefsis customers and evaluators.

Bandwidth Guide

An Nefsis user will generate an uplink load averaging 28 kbps or less for VoIP; with video ranging from ~28 kbps (low), ~128 kbps (medium, 6 fps, default), ~256 kbps (high), all the way up to ~512 kbps for full-screen video conferencing (high, 30 fps). The latter is not recommended except for internal conferences, dedicated routes, or other specific circumstances where exceptional (DS3 and above) bandwidth is available (same as traditional boardroom hardware). These averages vary by customer, quality of video capture and so on. For example, better video cameras may use, on average, more bandwidth as they have better sensitivity.

User uplink bandwidth is cumulative at the server, so the server requires a symmetric Internet connection.

Any broadband connection. DSL and other “asymmetric” connections with limited uplinks will support low and medium video at best.

This can be complex, as various scenarios may include all internal conferencing, conferencing with a mix of internal and external participants, or one employee conferencing with hundreds of external participants.

However, the following chart, albeit oversimplified, is a useful guide. Please contact us for assistance. We help our customers every day with this topic, and the easiest solution of all is most often starting out with Nefsis as an online service.


Standard DSL
At any video setting – not recommended for dedicated server, use Nefsis online service

Symmetric DSL
Note: figures below depend on actual grade of service delivered. This type of service often varies with distance from customer physical location to telephone company network access point (NAP) and can be as little as 128 kpbs uplink in rare cases.

Low quality video – 5 to 10 total
Medium quality video – up to 5 total
High quality video – not recommended for dedicated server, use Nefsis online service

Low quality video – 5 to 10 total
Medium quality video – up to 5 total
High quality video – up to 2 total - For larger meetings, use Nefsis online service

DS-3 or Better

Low quality video – up to practical limits, 10-20 per meeting
Medium quality video – up to practical limits, 10-20 per meeting
High quality video – up to practical desktop limits, 2-3 per meeting

Note that without a conference room build-out, you can only display two full screens at a time with a standard dual monitor set-up.

With DS-3 or better, multiple meetings in these ranges are possible. Please contact us for details and assistance. For large applications, consider Nefsis online services below, which have ample bandwidth and scalability for any application.

Video Camera & Bandwidth Consumption Chart
This PDF chart lists Nefsis compatible video conferencing cameras and their bandwidth consumption at various settings: HD & USB video cameras & bandwidth.


Low quality video – up to practical limits (screen display area)
Medium quality video – up to practical limits (screen display area)
High quality video – up to practical desktop limits (screen display area)

Multiple online meetings routine; in addition to video participants, there can be dozens or hundreds of conference participants.

Nefsis online services can be activated with a free trial or a single phone call. Contact us for bulk, group or company-wide activations or deployments. With Nefsis, you can can complement our scalable online services with dedicated, on-premise servers at any time. If any of the material on this page is unfamiliar, conference hours or traffic is hard to predict, or there are other unknown variables involved, then starting with online services if often the best alternative. Please contact us for a scheduled live demo, impromptu Q&A, or a site-specific recommendation.

Quality of Service (QoS) Defined

Quality of service, abbreviated QoS, as broadly defined refers to control mechanisms that allow IT staff to set different priority levels for network traffic specific to certain applications and users on their network. QoS discussions can be a challenge because of differences between computer networking and telephony terms, and growing informal notions of "responsiveness" associated with this topic. QoS is important though, because VoIP and video are typical application areas, and the user experience may benefit from a good QoS implementation, especially for internal conferences.

Nefsis QoS

With respect to Nefsis audio and video over IP, the following are some important points regarding this topic:

  • QoS settings are made on network equipment, not Nefsis. Nefsis operates within industry standards and tags its packets, operates on known ports, IP addresses and host/domain names. Beyond that, the priority, latency and load controls are set at the router(s).

  • Older QoS facilities used packet inspection and required applications to tag their packets, but modern routers allow controls by additional means including application, network service (IP address or host/domain name), users, and more. Nefsis tags its packets, so its traffic can be managed by older equipment.

  • QoS is relevant on your network, settings generally do not work over the public Internet, where many of the tags are ignored and you do not control the routing infrastructure. For IP conferencing over public networks, the user application experience may not benefit; but internal users and other prioritized applications might. This may change in the future as real-time connections become more prevalent, more specific grades of Internet service come online with end-to-end control, and more organizations become fortunate enough enjoy Internet2 connections.


In summary, Nefsis observes industry standards for tagging, allowing customers to control the priority and quality of service for Nefsis voice (VoIP) and video communications. QoS settings apply to company controlled LANs and network infrastructure, they generally do not extend to routers on the public Internet or the network infrastructure of external online meeting attendees.

Nefsis is extremely bandwidth efficient, and employs state-of-the-art technology for mixing data, VoIP and video packets, and dynamically adjusts to real-time conditions on each conference connection. Nefsis generates an uplink load of roughly 28 kbps or less for VoIP; with video ranging from ~28 kbps to ~128 kbps at the most popular low and medium settings. High quality video is easily possible with desktop peripherals, but requires more bandwidth (see above).

Nefsis users do not need to be video experts,they can simply select Play-All on the video or host control menu. For those that choose to make specific settings, Nefsis will not allow settings that exceed current network conditions, plus it adjusts automatically to real-time changes in throughput.

Most importantly, Nefsis allows IT staff and Nefsis online customers to put limits on users, VoIP and video features for peace-of-mind in limited bandwidth scenarios.

Start With a Quick Test

You can start a free trial right now, or contact us for more information. Dedicated server options are available to Nefsis customers, please inquire.

For a real quick test, schedule a live demo and see Nefsis right from your own desktop without re-engineering your network. Your conference host can show you Nefsis built-in monitors and you can easily see your video conferencing bandwidth consumption in real-time.