Abstract: A metadata extraction unit has a feature point selection and motion estimation unit 62 for extracting at least one feature point representing characteristics of the video/audio signals in a compressed domain of the video/audio signals. Thus, reduction of time or cost for processing can be realized and it makes it possible to process effectively.

Abstract: An improved clear air turbulence (CAT) detector sensing infrared radiation in the 27-33 micrometer range of the water vapor rotational wavelength band. The improved clear air turbulence detector for use on an aircraft includes a forward looking and upwardly oriented between 8.degree. to 12.degree. optical assembly having a thallium bromoiodide infrared lens, a 27-33 micrometer wavelength interference filter and an infrared detector; a radiometer amplifier for amplifying the output of the optical assembly and for generating an analog voltage signal related to the received infrared intensity, a processing unit for analyzing the analog signal, and a display unit for generating a first signal when no clear air turbulence is detected, a second signal when a moderate turbulence is detected, and a third signal when extreme turbulence is detected. A method for determining the advance time for entering the clear air turbulence after detection is based upon the altitude of the aircraft.