High quality video at a low bit rate: the promise of H.264
With the growing number of video surveillance equipment manufacturers using H.264 compression technology in their digital cameras, encoders and recorders, end users hope that the technology can reduce the effects of multiple video transmissions on the network while improving vast recording capacity
Also known as MPEG-4 Part 10, the H.264 format is a codec standard for digital video, completed in 2003, which promises to compress video data at a very low bit rate while preserving video. High Quality. Today, many CCTV systems are forced to sacrifice bandwidth and expensive network storage space. However, if H.264 keeps its promise, the resources used today can stream and store more video streams with higher frame rates and better resolution.
Anixter’s Infrastructure Solutions Lab recently ran several tests to compare the differences in bandwidth usage between H.264 and MJPEG video streams to a camera that supports both compression technologies.
Result:
In tests with little or no motion, the video stream used only 10% of the bandwidth of an equivalent MJPEG video stream. During high-motion tests, the difference in network bandwidth consumption was smaller but still significant.
Results
The laboratory discovered significant differences in the use of network resources between the two compression methods. When the camera saw little or no movement, the H.264 compressed video transmission used about 10% of the network bandwidth required for an equivalent MJPEG compressed video transmission. In tests with a high degree of movement, the H.264 transmission used more bandwidth, so the difference in network resource consumption was smaller but still significant. There is the biggest potential difference in terms of network usage at high frame rates. The differences are not so great for low frame rates.
Video quality observations
Videos taken with each of the two compression methods were examined using the same cameras, lenses and displays. The qualitative evaluation of the laboratory engineers revealed a slight difference in quality between them. The laboratory estimates that the H.264 video has a quality equivalent to about 95% of that produced with MJPEG compression technology.
It has also been observed that the strobe effect of certain shaded or raster patterns could significantly increase the bit rate of the compressed H.264 video stream compared to scenes without such patterns. When these patterns took up much of the camera’s field of view, they appeared to represent a large motion area for the camera’s encoding engine, resulting in an increase in the amount of data required for image transfer. However, these extraordinary peaks did not reach the level of the resources required to transmit and store an equivalent sequence in MJPEG.
Conclusions
Video streams encoded with the H.264 compression method have significantly reduced network storage requirements compared to streams compressed in MJPEG. Even if these tests do not measure the storage space required to record these images, there is a direct link between the use of network bandwidth for compressed data transfer and the storage space required for capturing this data. For IT and security administrators, the lab recommends using H.264 compression technology to reduce the bandwidth load of network video transmissions while increasing storage space for the same amount of Live Video.
