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A question of bandwidth

When you’re designing a new CCTV system or upgrading your existing technology, it’s important to make sure your system has enough bandwidth to function properly. Calculating your typical bandwidth requirements will help you make the right decision.

IP video transmits through your network as a data stream. Network bandwidth refers to the maximum amount of data a network can transmit over a specified period of time. Typically, that time period is one second.

Bits per second (bps or b/s) is the most common unit for measuring bandwidth. Some prefer to use bytes per second (Bps or B/s), which is a much larger unit – one byte is equal to eight bits.

Although bandwidth is often referred to as connection speed, the two are different concepts. Bandwidth refers to the amount of information your system transmits, while speed is the amount of time it takes to download the data.

Sufficient bandwidth is necessary for providing the desired speed. For example, having more bandwidth available allows you to send live video feeds to your servers faster than you’d be able to with a lower bandwidth connection.

Why is bandwidth important for CCTV systems?

Determining your bandwidth requirements is a crucial step in planning an IP camera system. When you underestimate your average consumption, you could experience severe bandwidth bottlenecks, resulting in:

• Stream delays.

• Video packet loss.

• Footage jitter.

• Poor video quality.

• Corrupted video.

These problems can prevent your system from catching critical incidents on video and prevent your recording device from performing as intended. That’s why your recorder’s upload speed is the most important factor in calculating bandwidth.

What factors affect bandwidth consumption?

Every CCTV system is different, so it makes sense that every system has varying bandwidth requirements. For example, a surveillance system in harsh environments needs to use more bandwidth than one in a milder setting due to the increased physical demand on the hardware.

These factors have the most impact on your bandwidth consumption:

• Video resolution: Typically, a higher resolution requires greater bandwidth consumption. The same goes for frame rate.

• Number of cameras: The more cameras you add to your system, the higher your bandwidth consumption will be.

• Lighting: Due to camera noise, recording in areas with poor lighting often requires significantly more bandwidth than recording in brightly lit spaces.

• Camera model: Bandwidth requirements can vary between camera models depending on their processing capacity. In most use cases, IP cameras use more network bandwidth than analogue or non-IP cameras.

• Scene complexity: When a camera picks up more activity, it uses more bandwidth. Cameras in less active areas use less bandwidth.

• Video compression: Raw, uncompressed video streams are much larger files than compressed video streams, so they use more bandwidth. Different compression standards also consume different amounts of bandwidth.

• Recorder placement: The farther your cameras are from the recording device, the more bandwidth you’ll consume. For example, a system covering multiple buildings would use less bandwidth if there was a recorder in every building.

• Smart Codec: If you have Smart Codec enabled on your camera, it can intelligently adjust frame rate and compression to simultaneously reduce bandwidth consumption and optimise streaming performance.

• Video analytics: Processing and evaluating footage with artificial intelligence-powered video analytics consumes high amounts of bandwidth.

• Type of video storage: Unlike conventional CCTV storage, cloud-based systems stream video directly to your cloud environment. Areas without proper bandwidth, however, are likely to experience streaming issues – this is why it’s important to ensure consistency in your bandwidth coverage.

How to determine your bandwidth needs

Here’s a simple calculation you can use to get a rough estimate of your current bandwidth requirements:

1. Multiply the number of cameras in your main stream by its bit rate.

2. Multiply the number of cameras in your sub-stream by its bit rate.

3. Add the two numbers together to get the required bandwidth in megabits per second.

This formula provides you with a basic estimate of your bandwidth requirements. For a more accurate result, you’ll need to factor in influences such as lighting, camera location, typical scene complexity and audio.

While figuring out your bandwidth usage by hand can help account for unique circumstances, such as mobile surveillance applications, it’s much quicker to use a camera bandwidth calculator. While you can find many such calculators online, it’s important to use one that you know will provide reliable results.

All you have to do is plug in basic information about your system, such as:

• How many cameras you have.

• Your camera resolution.

• Video compression type.

• Average retention period.

• Frame rate.

• Recording frequency.

The calculator will use those inputs to determine your system’s bandwidth requirements. Some calculators can also perform other useful functions to help you improve your surveillance system’s design, such as your required archive storage.

How can you reduce bandwidth consumption?

If you discover your bandwidth needs are higher than expected, there are steps you can take to reduce the amount of bandwidth your system uses during day-to-day operation. These features and techniques can help you keep network bandwidth low without affecting your surveillance quality:

• Multiplexing: If you have many operators viewing the same streams simultaneously, this technique can reduce local bandwidth consumption by sending video through the cloud.

• Motion detection: Although continuous recording is necessary for some applications, it uses enormous bandwidth. Cameras with motion detection capabilities record in lower resolutions until something begins moving in frame, minimising bandwidth consumption.

• Alternate stream recording: This technique uses two streams – one at a high resolution and one at a low resolution. Using the low-resolution stream for live viewing and the high-resolution stream for video recording helps keep bandwidth usage low while ensuring your video archive files are high-quality.

Using equipment with built-in video management system (VMS) software, such as Milestone’s Video Accelerator, can also help you cut your bandwidth usage by automatically balancing server resources. This specific system works by reducing the CPU load when the camera detects motion and utilizes NVIDIA GPU resources when they become available.

BCD’s bandwidth calculator

BCD’s storage calculator uses your inputs to make a precise estimate of your network bandwidth requirements and your video archive’s hard-disk drive storage needs. Whether your deployment is large or small, BCD can optimise your system design to meet your specific needs.

Article sourced from www.bcdvideo.com/blog/how-much-bandwidth-your-security-system-need/. To find BCD’s Bandwidth Calculator, got to www.bcdvideo.com/bandwidth-storage-calculator/

For more information, go to www.bcdvideo.com, or www.firstdistribution.com/bcd/

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