It is vital that end-users, system designers and integrators have a clear understanding of the compression technologies available and when each should be used for best results. It’s important to remember that one technology is not objectively “better” than another, but each has its advantages and disadvantages to when trying to meet a project’s requirements.
Comparing Intra-Frame and Inter-Frame Compression
Two of the most popular groups of compression technologies are intra-frame and inter-frame compression.
Intra-frame compression technology works by applying a compression algorithm to each frame captured individually, not built up from multiple frames, so they can be compressed and transmitted out of a camera quickly to reduce latency. Popular intra-frame codecs include MJPEG, JPEG 2000, DNxHD, Cinema DNG and Prores.
Inter-frame compression technology relies on a dual process of compressing data within a single frame and analyzing the data between frames, resulting in a stream of video compressed over multiple frames. By contrast, inter-frame compression attempts to store only incremental changes between frames and stores whole frames only on periodic intervals. This compression technique can result in increased bandwidth efficiencies and lower data rates. H.264, MPEG-4, MPEG-2, and AVCHD are all popular inter-frame codecs.
Introduced in the year 2000, JPEG 2000 has become a widely used standard in various industries including digital cinema, diagnostic medical imaging, document archiving and others. When it was first introduced, JPEG2000 was a major improvement over conventional JPEG compression, generating images that were 30 percent smaller in file size and bandwidth than a JPEG image of the same quality. Additional benefits of JPEG 2000 compression include the ability to capture a wide dynamic range and scale to higher resolutions.
As a variant of the MPEG-4 standard, H.264 is one of the newest compression technologies available. It differs from JPEG and JPEG2000 because it is a temporally compressed format, meaning that the video is comprised of a single I-Frame (key frame), which encodes one entire image, followed by multiple P-frames (delta frames), which encode only the changes since the previous frame. This can have an impact on the level of activity perceived in the video, however, it can also result in substantial savings in bandwidth.
Choosing the Right Compression Technology
When choosing a compression technology for your installation, the first thing to consider is bandwidth; more specifically, how much bandwidth is available on your IP network? Another key consideration is latency; what latency is required for your application? Be sure to keep these considerations in mind before making a decision regarding compression technology.
Opticomm-EMCORE has both types of compression products to fit your particular application for IP video transport. For JPEG2000 applications, the NV series of encoder/decoder products offers the best possible image quality with the lowest latency of transmission.
The new HD4 series as well as the HDE/HDD products provide lower bandwidth solutions utilizing H.264 compression. They produce a professional image quality while operating at lower-per-channel bandwidth.
The EVE/EVD series utilizes a JPEG2000 variant called MJPEG, which is the predecessor of JPEG2000. It currently delivers a quality of video described as “visually lossless” but at a fixed data rate of 150 mb/second, and is the lowest price-point solution where image quality is not of primary concern compared with cost.
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