Configuring a security camera includes many settings, but there is one variable that is critical to the overall CCTV system health and optimum performance and that is the resolution. The resolution selected determines the quality and the size of the video, and the number of days of recorded video to keep, and consequently the cost to maintain it. What follows is a brief introduction to the security camera resolution and how the various settings impact the variables just mentioned.
It should be mentioned that some settings that I will describe might not be available with the security camera you are using because the camera is designed to capture video in a specific format.
There may be a drop-down box for compression or format
and most likely the options will be either MPEG or H.264. MPEG and H.264 are the two most popular compression techniques used where MPEG is the older compression and H.264 is the new one.
There are currently 4 MPEG compression: MPEG1, MPEG2, MPEG3, and MPEG4. However, MPEG1 and MPEG3 are used for audio-only where MPEG2 and MPEG4 for audio and Video. The difference between Mpeg2 and MPEG4 is the compression algorithm they use. MPEG4 creates smaller files while maintaining HQ video which makes it suitable for transferring and viewing on multiple devices especially mobile ones. However, MPEG2 produces better quality video but much larger files, which makes it suitable for local storage and use.
If your security camera has an MPEG option most likely you will not ask you to choose between the two, it will just be MPEG meaning it is MPEG2. Some camera software will provide a description of the option, but the easiest way to verify what codec is used is using the VLC
player which is free to download from https://www.videolan.org/vlc/. Once you install the VLC player open the video you like to examine and from the Tools menu select Codec information. If the video captured is saved in a file with an mp4 extension, do NOT assume the file is encoded as MPEG4. MP4 is just a container and it could include other formats as well.
H.264 is the new compression format and it more advanced than MPEG 4. Actually H.264 is also known as MPEG 4 version 10, Advance Video Coding. Reference Wikipedia post (https://en.wikipedia.org/wiki/Advanced_Video_Coding). One of the advantages of H.264 is the varying bit rate feature providing smoother video playback when there is internet traffic congestion or bandwidth limitations. Additionally, H.264 is compatible with more devices and media player and it should be your option of choice if you intent to share your security camera video with others.
An H.264 video file is 1.2 to 2 times smaller than an MPEG4 file Ref.: (https://stackoverflow.com/)
Resolution is measured in Pixels Per Inch (PPI). The higher the PPI the higher the quality of the image. PPI is used mostly when printing an image. When it comes to video though that will be displayed on a monitor or TV the dimensions of the displayed device should be accounted for as well. The height of the frame is used to indicate the video resolution. In a 16:9 format TV when we say the resolution is 1080 we are referring to the 9 of the 16:9 format. Therefore, a 16:9 1080 resolution is actually 1920 x 1080.
Resolution is divided into the following three types:
- Standard Definition (SD – 480)
- High Definition (HD – 720, 1080) and
- Ultra-High Definition (UHD – 4K).
Keep in mind the resolution is per frame. Therefore, the file size can increase substantially very fast causing storage and bandwidth issues.
Interlacing and Progressive scanning
Sometimes when selecting your camera resolution, especially the higher ones you might see an i or a p appended at the end e.g. 720i 0r 1080p. The i refers to the interlacing method of rending a video on a TV or monitor. A frame is divided into even and an odd number of lines and during interlacing only the odd or even number of lines are displayed, and because it happens so fast (1/60 of a sec) our eyes fill in the missing lines. It was the old way of transmitting video since most frames per second could be displayed. However, the technological advances and the increased internet speed allowed to display the entire frame (progressive scanning) though eliminating the interlacing problems such as a lower quality image. Select the p resolution if that is an option.
Frames per Second (FPS)
Frames per second refers to how many frames are displayed per second. A Frame is a still image and when multiple frames are displayed sequentially video is produced. The size and quality of a frame depends on the resolution selected as described above. The recommended PFS is 25 – 30 PFS which provides a crispier and smother motion video. Additionally, it helps when the video in displayed in slow motion. For example, the distance it takes a person to walk 10 feet is about 2 seconds. If the video is recorded in 1 PFS and views the video, then the person will be seen probably at the beginning of the 10 feet distance, in the middle, and then the end. It does not matter how slow the video will be played; you don’t have the required frames to display the video in slow motion.
Bit rate is the speed the IP camera transmits the image to the receiver. The image is converted into bits zeros and ones and then transmitted, therefore the number of bits transmitted per second is called bit rate (bps). An IP set to 96Kbps transmits 96000 bits per second, where 2Mbps setting transmits 2000000 bits per second. Remember what we talked about data transmission we talk about bits per second. If we talk about file size we are using Bytes and the notation is KB or MB
or GB etc. Notice the difference in notation: Mbps is bits per second MB is megabytes.
How to calculate bandwidth Requirements
The following simple formula is used to determine the required bandwidth:
Bandwidth (Mbps) = Bitrate X number of cameras
concurrently streaming video. Therefore, if 10 cameras are transmitting video at 256Kbps the required speed is 2560Kbps or 2.5Gbps
Storing the security cameras video on the cloud it could be expensive if not carefully planned. As already discussed, the resolution, FPS, and compression affect the video size and quality. Therefore, carefully review your needs, establish your requirements, calculate the required bandwidth, consider the cost of cloud storage and ISP subscription, and then decide how to proceed.
I hope this brief overview of security camera resolution and related topics provides you enough information to make an educated good decision to best meet your need. If however, there are unclear points or questions, please leave your comments below and I will address them the soonest possible.