Video data compression using MPEG-2 and frame decimation

Video systems have seen a resurgence in military applications since the recent proliferation of unmanned aerial vehicles (UAVs). Video systems offer light weight, low cost, and proven COTS technology. Video has not proven to be a panacea, however, as generally available storage and transmission systems are limited in bandwidth. Digital video systems collect data at rates of up to 270 Mbs; typical transmission bandwidths range from 9600 baud to 10 Mbs. Either extended transmission times or data compression are needed to handle video bit streams. Video compression algorithms have been developed and evaluated in the commercial broadcast and entertainment industry. The Motion Pictures Expert Group (MPEG) developed MPEG-I to compress videos to CD ROM bandwidths (1.5 Mbs) and MPEG-2 to cover the range of 5-10 Mbs and higher. Commercial technology has not extended to lower bandwidths, nor has the impact of MPEG compression for military applications been demonstrated. Using digitized video collected by UAV systems, the effects of data compression on image interpretability and task satisfaction were investigated. Using both MPEG-2 and frame decimation, video clips were compressed to rates of 6Mbs, 1.5 Mbs, and 0.256 Mbs. Experienced image analysts provided task satisfaction estimates and National Image Interpretability Rating Scale (NIIRS) ratings on the compressed and uncompressed video clips. Results were analyzed to define the effects of compression rate and method on interpretability and task satisfaction. Lossless compression was estimated to occur at similar to 10 Mbs and frame decimation was superior to MPEG-2 at low bit rates.