Compression Question
Why does wireless video networking – even with UWB – require compression? It’s a good question. The 1080i displays of today require a huge data stream of 1.87 Gbps. Without compression, you wouldn’t be able to distribute video wirelessly. So what video compression is best? That’s a more difficult question to answer. Perhaps there is no one right answer. All compression technologies strive for the lowest possible data rate while preserving the highest quality, error free picture. JPEG2000 is one choice. It has advantages because of its intra-frame compression scheme. MPEG-4 and MPEG-2 are also widely used because of their coding efficiencies.
Tzero and Analog Devices chose to use JPEG2000 in the companies' wireless HDMI reference design. There are a number of advantages for JPEG2000 today, and those are covered in a new whitepaper and DesignLine article. Other advantages will emerge as display technology advances to 1080p and beyond. For instance, compression schemes like MPEG-2 become less and less efficient as resolutions increase. An independent study conducted as part of the PULSERS EC Integrated Project investigated compression alternatives for wireless systems for high-speed short-range video transmissions. This study concluded that for equivalent video quality (defined as visually lossless), H.264 requires 39.6% more data, MPEG-4 requires 53.5% more data and MPEG-2 requires 150% more data. Visit the PULSERS website for more information.
This isn’t an argument for one compression technology or another. Manufacturers and service providers need to make their own decisions. And UWB has no restriction on what can be used over its high-speed links. Which compression do you think will win out for wireless video?
