Frame rate selection has a major impact on bandwidth consumption for surveillance cameras. While most cameras have a maximum frame rate of 25 to 30 frames per second, users typically choose significantly lower frame rates, driven by a desire to minimize storage consumption. The most direct way to reduce storage is to use a lower bit rate stream for each camera with lower frame rates.

A key practical question is how much bandwidth is saved as the frame rate is dropped? Lower frames rates should result in lower bit rates but how significant are those changes and does this change depending on the scene?

Our Test

In this report, we share our result of a series of experiments we did with 3 IP cameras (Avigilon, Axis and Sony) in 3 different scenes: (1) indoor daytime, (2) indoor dark (< 1 lux), and (3) daytime outdoor (intersection). We did tests at 1, 5, 10, 15 and 30 fps to see how bandwidth consumption varied across a variety of frame rates.

We then produced a series of charts comparing bitrate vs frame rate and average frame size vs frame rate to provide two views on the relationship between these parameters. 

With these test results, we answer the following questions:

• How does bandwidth efficiency vary with changes in the frame rate?
• Are low frame rate streams inefficient?
• How can you project bandwidth consumption for various frame rates?
• Does different scene types impact bandwidth vs frame rate efficiency?
• How does the choice of VBR vs CBR impact the relationship between bandwidth and frame rate?

For background on frame rates, Pro members should review our frame rate fundamentals training and our discussion on what frame rate to choose. Also, for those interested in understanding the impact of bandwidth, review our sister report that examines the relationship between bandwidth and image quality.