METHOD AND DEVICE FOR DETERIORATING PICTURE QUALITY IN THE CASE OF COPYING DIGITAL MOVING PICTURE WITHOUT PERMISSION

摘要

PURPOSE:To automatically deteriorate a digital moving picture when the digital moving picture is copied for a livelihood by decoding the digital moving picture and applying irreversible coding to the decoded picture again after that. CONSTITUTION:An original signal inputted from a camera or the like has picture quality of Q(0) and the picture quality is deteriorated onto picture quality Q(1) through compression of a digital signal and the result is recorded. When the digital signal whose picture quality is Q(1) is dubbed or copied, the picture quality Q(1) is deteriorated into Q(2) by copying and recording the signal via a picture quality deterioration device C. Concretely the signal is reproduced as moving picture information visible to a person by, e.g. a decoder and picture information is stored in a reproduction picture buffer. The irreversible coder receives sequentially picture information from the reproduction picture buffer and applies re-coding by the digital moving picture coding synchronizing signal newly and the result is outputted externally. The picture quality is gradually deteriorated by repeating copying through the use of the irreversible coder and it is also devised that the picture quality must not deteriorated any more in excess of a number of times (n).