7 Questions to Ask in Bandwidth Calculation

Your guide to bandwidth and video quality


 

Question 5: How does the VMS handle multiple streams?

Using event-based streaming is a way for the system designer to minimize bandwidth and storage. This is done by configuring the camera to only send a stream when detecting motion, audio, when a relay is triggered, etc.

When using event-based streaming, understand that video management software (VMS) providers handle multi-streaming differently. Certain VMS programs work with in-camera analytics to pull a single stream when an event is triggered. However, if the VMS is using server-based analytics, a separate stream is often pulled constantly so the video can be analyzed. A second recorded stream is then requested on the event. This is how the benefits of in-camera, or “edge,” analytics improves bandwidth efficiency.

A similar consideration must be taken into account when granting video access to different viewers. Higher end VMS providers can multi-cast video from the recording device to multiple different viewer clients (PC, laptop, iPad, etc.). One stream, multiple viewers. Lower end VMS programs, however, will call up a separate stream from the camera each time a viewer accesses the video.

 

Question 6: What happens at night?

Surveillance is a 24-hour a day need so it’s unfortunate how many people forget to test their installation at night. When light goes down, gain goes up. If not controlled, this can cause bandwidth spikes.

If the user requires nighttime surveillance in areas of limited lighting, the first step is to select a camera with advanced noise reduction algorithms (i.e. Lightfinder). After that, there are three considerations:

1.) Plan accordingly on the hardware side—most networks today are at least 1 GigE, which should be adequate. Bandwidth also equates to storage. Fortunately, storage today is much more inexpensive compared to five years ago.

2.) Adjust motion detection settings—what appears as video noise to us can be misinterpreted as motion by the camera. If the camera senses movement, it will encode the video and send to the recording device. This can cause 50 to 80 percent bandwidth spikes at night when there’s no real motion. Today’s best IP cameras employ advanced video motion detection to reduce these false alarms and motion detection settings can be adjusted.

3.) Set ‘bookmarks’ for gain and shutter speed—tuning the gain and shutter speed settings can reduce noise. Set the camera’s min. and max. range to ensure that the bandwidth will not spike as the camera performs automatic gain control. Test the camera at night to find the right balance between motion blur and bandwidth.

 

Question 7: Will there be advanced uses?

How will the customer use the system? Will they use advanced analytics that require high resolution, such as license plate recognition? Can they employ cloud topology with supplemental edge storage to lower upstream bandwidth requirements? Are most of the users mobile (if so, see Table 1 for how setting resolution to mobile devices affects bitrate)?

A useful part of a more advanced video surveillance system design process is to identify bandwidth usage at various locations on the network. Command center, workstations and telecom workspaces might all have different video bandwidth consumption and varying network requirements. For such installations, an important design step is to plan for and verify all users have the video data they need, with room for expansion. A way to communicate this to the network infrastructure management team so quality of service (QoS) is maintained is shown below in a “Bandwidth Estimation Table” (Table 2).

 

Adding all the variables

Each security device will be asked to perform its own task. Each camera and VMS manufacturer handles bandwidth-related configuration settings differently. Each environment seen by each camera presents unique activity and lighting scenarios. Consider every variable by covering this checklist of questions and testing at each turn to accurately calculate bandwidth requirements.