Abstract: A method of dynamically showing a water mark is applied in an audio/video transmitter. The audio/video transmitter includes a plurality of display contents such as a playback area name, a playback date, a playback time and an identification mark. The audio/video transmitter continues obtaining a plurality of frames from an audio/video source such as an audio/video server or an audio/video database and temporarily stores the frames in a buffer. The audio/video transmitter also produces a water mark from at least one display content according to a plurality of display conditions such as display coordinates, appearance, time and frequency, and composes the water mark with at least one frame stored in the buffer to form at least one display screen, and shows the display screen on an output unit, such that the water mark on the display screen cannot be changed or overwritten, and viewers can identify the water mark easily.

Abstract: In a dynamic multilayer video processing method applied to a signal receiving apparatus, the signal receiving apparatus is connected to a display device.

Abstract: A method for distributing encrypted digital content is disclosed in the invention. Firstly, a digital content of a source is encrypted via a symmetric key encryption mechanism by using a first public key, so as to generate an encrypted digital content; the first public key is also encrypted to generate an encryption key at the source by using a second public key via an asymmetric key encryption mechanism provided from a destination, so that the encryption key may only be decrypted by using a private key compatible with the second public key at the destination. Therefore, no matter the encrypted digital content is distributed via secure or insecure routes, the ones who are not at the destination cannot access the digital content.

Abstract: The present invention is to provide a method for centrally distributing screensaver video to protect display devices, which is implemented to a central VOD system comprising a remote video server, a plurality of signal transmission devices, and display devices each connected to a signal transmission device. The remote video server has a plurality of ordinary video data and at least a screensaver video data therein; each signal transmission device may receive a screensaver video data and at least one ordinary video data, and then transmit the screensaver video data and the ordinary video data to the display device connected thereto. The signal transmission device outputs the screensaver data on the display device when not receiving any control signal within a predetermined period of time, and does not resume the original ordinary video data on the display device unless the signal transmission device receives the control signal again.