If you’ve ever looked at the specifications of a CCTV camera or video recorder, you might have seen a category called “compression” followed by a series of letters and numbers (H.264, MJPEG, etc.). If you’re new to CCTV, you might be wondering what these stand for. These are known as CCTV codecs.
What are CCTV Codecs?
CCTV codecs involve two steps, compression (CO) and decompression (DEC). The device that generates the video will compress it before sending it to another device which will decompress it. With compression, the file size of the generated video is reduced by taking out any unnecessary information. Video compression is needed in order to save on bandwidth and storage space. After compression, the device that receives the video will decompress it and display it onto a viewing device. This process for codecs will look differently, depending on the type of CCTV system.
In an analog CCTV system, the camera records the images in the form of video signals. These signals are then transported to a DVR which will convert the signals into digital video. Since the DVR is the device that produces the video, it is also the device responsible for compression. The DVR will then send the compressed digital video to a connected monitor that will decompress and display the video.
In an IP CCTV system, the camera already records images in the form of digital video. Since the camera generates the video, it must also compress it. The NVR that receives the video will decompress it and display it on a monitor or a remote device.
Types of CCTV Codecs
The purpose of using CCTV codecs is to remove any unneeded information to shrink the video’s file size as much as possible but without sacrificing too much of the video’s quality. There are various types of CCTV codecs that aim to do this, but using different methods. We will cover 4 of the most common codecs.
You might be familiar with the file format JPG or JPEG since this is the form that images are in. MJPEG is short for motion JPEG. This codec works by evaluating and compressing each frame of the video and sending the receiver device all of these individual images. The JPEG images would then be put together in a rapid succession to give off the appearance of motion, like a flip book animation.
MPEG-4 works similarly to MJPEG, but this codec breaks down each frame and separates them into complete and partial images whereas MJPEG only deals with complete images. Essentially what MPEG-4 does is keep the parts that don’t move and isolates the parts that do move. Then the device that receives these bits and pieces will combine all of them together. The goal of this method is to reduce the file size by not having so many completed images that need to be put together.
The method behind H.264 is basically the same as MPEG-4, but this CCTV codec uses an advanced algorithm that uses less bandwidth for transmission and storage. H.264 is currently the most commonly used format, but a newer technology is on the rise.
H.265 is the newest CCTV codec as of right now. The way it works is similar to H.264, but more refined and vigorous. This codec performs a higher level of compression while still keeping video quality as compared to H.264. This standard is popular for usage with 4K CCTV cameras since higher resolutions require more bandwidth and storage.