Video Compression & the Art of Surveillance

Video compression makes it possible to reduce the size of digital video files while maintaining a useful level of image quality, thus allowing for efficient management of file sizes and bandwidth requirements. But not all compression standards are created equal. The new H.264 standard is rewriting the rules of what's possible in today's world of video compression and streaming network transmission.

Compression is a tool to manage video data and minimize bandwidth/storage needs. Some of the more historically popular standards for video compression include:

Motion JPEG (MJPEG) compression requires each individual video frame encoded as a separate image. However, the video takes up too much bandwidth to be practical for most streaming video applications.

Motion JPEG2000 compression is an update to MJPEG that uses wavelet-based image compression while adding features such as scalability and the ability to handle a large range of effective bit rates. JPEG2000 offers about a 20 percent gain over standard JPEG compression, but requires more computing power and memory.
MPEG-4 compression does not encode each frame separately. Some frames (I-frames) contain complete data, but between the I-frames are “predictive” frames that include only what has changed. Some cameras and systems use a combination of compression standards.

H.264 can save bandwidth and storage by compressing even the highest megapixel images to manageable sizes. However, more advanced processing is required to compress the video. In the beginning this need for additional computing power complicated the adoption of H.264. Many companies have developed dedicated H.264 compression chipsets that handle the “heavy lifting” for the device that uses them. This has positioned H.264 as the standard to deliver the perfect balance of low bandwidth, high quality images and high frame rates. In fact, H.264 compression technology works so well that many big companies outside the security industry are quickly implementing the compression technology, including Apple, Intel, Blu-ray, Sony and some satellite providers.

Because H.264 provides superb compression, in most security applications it more than doubles the record times compared to previously popular compression methods. Here is a comparison of H.264 to other compression technologies, using a 160GB hard drive, recording video at 30 frames per second, at a resolution setting of 720 x 480:

• H.264 records 77 hours

• MPEG-4 records 44 hours

• JPEG2000 records 13 hours

The ability to record longer on the same-sized hard drive can save your customers money and greatly increase the amount of video they can archive.
Although other compression methods may provide quality pictures, they require more hard drive space or bandwidth.

In addition, H.264 can bring together high quality and low memory sizes to allow more seamless presentations of video. Your customers will find watching real-time H.264 to be a smoother experience where they don't even realize that the video they're watching has been compressed. This explains why so many broadcast companies around the globe have adopted it. However, it is also important to note that while H.264 compression is a step forward in video technology for all industries, it does typically require either a dedicated chip for handling the compression (such as in Apple's iPhone), or the allocation of more computing resources to deal with the real-time video streams when using a conventional processor.

Jake Lahmann is the vice president of Technology, Supercircuits, Austin, Texas .