Method and apparatus for descrambling digital video data and digital audio data using control data

Abstract

A copy prevention method and apparatus of a digital magnetic recording/reproducing system performs the copy prevention function by encoding to insert a marker involving copy prevention function information and executing the function and allows a program supplier to realize a desired copy prevention function of various patterns, in which the marker formed by a control word for scrambling audio and video bit straps and copy prevention information for preventing an illegal copy is encrypted by an encoded key to be multiplexed with the audio and video bit strips scrambled by the control word. The marker transmitted is detected from the bit strips to be decrypted and analyzed by the encoded key to determine whether the copy is permitted or not, so that the detected marker is updated to be recorded on a video tape and the control word is produced from the marker to perform the descrambling to supply the result to a monitor to be displayed. Thus, the program supplier selects the copy prevention function, and a separate format converting apparatus is not required since a field defined within a GA format is utilized while an existing DVCR is not need to be changed for performing the copy prevention function as the data amount to be recorded is not increased.A method and apparatus for descrambling digital data are discussed. According to an embodiment, the method includes reproducing, by a digital data processing apparatus, a digital data stream from a portable recording medium, the reproduced digital data stream including a first sub data unit and at least one second sub data unit succeeding the first sub data unit, the first sub data unit including a control data portion and a scrambled data portion, the control data portion including control data, each of the second sub data unit including a scrambled data portion, each of the scrambled data portions of the first and second sub data units including scrambled digital video or audio data; initializing a descrambler of the apparatus based on the control data; and descrambling by the descrambler the scrambled data portions of the first and second sub data units based on the same control data.