How Nighttime Video May Crash Your Network

Author: Ethan Ace, Published on May 02, 2012

Nighttime video may crash your network. During the day, under ideal conditions, bandwidth remains relatively stable. However, when the lights go down, bandwidth changes can become severe, creating problems like lost video, degraded quality and network instability. In this note, we look at the causes and negative effects of these low-light issues, and give our recommendations for overcoming them.

Bandwidth Planning

Most surveillance networks are designed using average numbers (typically from daytime video) or manufacturer camera calculators. Both of these methods are, if not best case, optimistic, and do not account for nighttime spikes. In other video industries, such as broadcast and A/V, constant bitrate encoding is generally used, to provide more stable, predictable bandwidth consumption. In surveillance, this is not the case, as our poll shows most prefer VBR to CBR, due to the storage savings it provides. However, it creates the potential for spikes and variations which CBR does not.

The Causes of Nighttime Bandwidth Issues

VBR encoding, along with noise created when automatic gain controls turn on, are the typical causes of this issue. Under normal circumstances, video is relatively clear and noise-free. As light levels lower, however, gain controls activate to digitally increase the brightness of the image. This digital correction introduces noise, however, which results in increased video bandwidth.

The following video illustrates surging bandwidth when using an Axis Q1604:

The increase from ~100 kBps (800 kbps) to over 2800 (over 22 Mbps) illustrates just how potentially dangerous surges are.

Network Issues

A nearly 28x increase in bandwidth, as shown above, may easily overload the network. For example, assuming five cameras and a server are connected to a 10/100 switch, bandwidth surges at this level would quickly overwhelm the server's connection to the network, as it totals over 100 Mbps. This could result in a dropped connection, lost video, and other unexpected issues.

The issue is even more critical when using limited-bandwidth connections, such as wireless, 3G/4G, or cable/DSL. Even a moderate surge in bandwidth on a single camera may exceed available bandwidth, dropping the connection.

This is also dangerous when sharing the network with other services. If designers are accounting for 4 Mbps bandwidth on all cameras sharing a LAN with voice and data applications, these spikes may result in interruption to other services, potentially overwhelming switch interconnects and backbone connections.

Storage Issues

Surges may greatly reduce expected storage durations, as well. If storage calculations are based on cameras using average bandwidth, even moderate surges could cut days or even weeks off of retention periods. This is especially dangerous if the organization must meet state or federal regulations, such as the gaming industry, or in critical use systems, such as municipal or government security.

Solutions

There are two ways to account for these nighttime bandwidth spikes: setting bitrate caps on VBR streams, or using constant bitrate streams. We cover both of these in detail in our VBR vs. CBR streaming report:

  • Use VBR with a cap: The preferred way to handle these spikes is to set a maximum bitrate when using VBR streaming. This allows bandwidth to remain low most of the day, but increase to reasonable levels in low-light situations.
  • Use CBR: The second, though less preferred method for dealing with variations in bandwidth is to use constant bit rate streaming. This allows designers to account for variations, as bandwidth should generally not exceed the set rate. However, the CBR bitrate must be set high enough that degradation does not occur during bandwidth surges. This results in higher overall bandwidth and storage usage, where VBR would be lower during other times.

Using gigabit switches may also alleviate minor or moderate network issues, given their higher capacity. However, in larger systems, using 24- or 48-port switches, even gigabit links may not provide enough headroom.

Finally, gain management should be carefully considered. Most often, installers leave cameras set to default gain settings, which typically results in very aggressive levels, and resulting increased noise and bandwidth. Gain should be set to the lowest possible levels which still produce quality images, to avoid this. Users may see our automatic gain control test results for more information on setting gain, as well as comparisons of differing gain levels.

Comments : PRO Members only. Login. or Join.

Related Reports

Mobile Surveillance Trailers Guide on Jan 17, 2019
Putting cameras in a place for temporary surveillance where power and communications are not readily available can be complicated and expensive....
Testing Bandwidth Vs. Low Light on Jan 16, 2019
Nighttime bandwidth spikes are a major concern in video surveillance. Many calculate bandwidth as a single 24/7 number, but bit rates vary...
2019 IP Networking Book Released on Jan 14, 2019
The new IP Networking Book 2019 is a 285 page in-depth guide that teaches you how IT and telecom technologies impact modern security...
WDR Tutorial on Jan 11, 2019
Understanding wide dynamic range (WDR) is critical to capturing high quality images in demanding conditions. However, with no real standards, any...
Winter 2019 IP Networking Course on Jan 10, 2019
Today is the last day to register for the Winter 2019 IP Networking course. This is the only networking course designed specifically for video...
Worst Products Tested In Past Year on Jan 09, 2019
IPVM has done over 100 tests in the past year. But which products performed the worst? Which ones should users be most aware of? In this report,...
Managed Video Services UL 827B Examined on Jan 09, 2019
Historically, UL listings for central stations have been important, with UL 827 having widespread support. However, few central stations have...
H.265 / HEVC Codec Tutorial on Jan 08, 2019
H.265 support improved significantly in 2018, with H.265 camera/VMS compatibility increased compared to only a year ago, and most manufacturers...
2019 Video Surveillance Cameras Overview on Jan 07, 2019
Each year, IPVM summarizes the main advances and changes for video surveillance cameras, based on our industry-leading testing and...
IPVM Best New Products 2019 Opened - 70+ Entrants on Jan 07, 2019
The inaugural IPVM Best New Product Awards has been opened - the industry's first and only program where the awards are not pay-to-play and the...

Most Recent Industry Reports

The IP Camera Lock-In Trend: Meraki and Verkada on Jan 18, 2019
Open systems and interoperability have not only been big buzzwords over the past decade, but they have also become core features of video...
NYPD Refutes False SCMP Hikvision Story on Jan 18, 2019
The NYPD has refuted the SCMP Hikvision story, the Voice of America has reported. On January 11, 2018, the SCMP reported that the NYPD was using...
Mobile Surveillance Trailers Guide on Jan 17, 2019
Putting cameras in a place for temporary surveillance where power and communications are not readily available can be complicated and expensive....
Exacq Favorability Results 2019 on Jan 17, 2019
Exacq favorability amongst integrators has declined sharply, in new IPVM statistics, compared to 2017 IPVM statistics for Exacq. Now, over 5 since...
Testing Bandwidth Vs. Low Light on Jan 16, 2019
Nighttime bandwidth spikes are a major concern in video surveillance. Many calculate bandwidth as a single 24/7 number, but bit rates vary...
Access Control Records Maintenance Guide on Jan 16, 2019
Weeding out old entries, turning off unused credentials, and updating who carries which credentials is as important as to maintaining security as...
UK Fines Security Firms For Illegal Direct Marketing on Jan 16, 2019
Two UK security firms have paid over $200,000 in fines for illegally making hundreds of thousands of calls to people registered on a government...
Access Control Cabling Tutorial on Jan 15, 2019
Access Control is only as reliable as its cables. While this aspect lacks the sexiness of other components, it remains a vital part of every...
Avigilon Favorability Results 2019 on Jan 15, 2019
Since IPVM's 2017 Avigilon favorability results, the company was acquired by Motorola and has shifted from being an aggressive startup to a more...
Gorilla Technology AI Provider, Raises $15 Million, Profiled on Jan 15, 2019
Gorilla Technology is a Taiwanese video analytics manufacturer that recently announced a $15 million investment from SBI Group, saying this...

The world's leading video surveillance information source, IPVM provides the best reporting, testing and training for 10,000+ members globally. Dedicated to independent and objective information, we uniquely refuse any and all advertisements, sponsorship and consulting from manufacturers.

About | FAQ | Contact