摘要:
Methods for exchanging signals via a network with nodes (11-15) improve the performance of the network by letting a destination node (12) s receive the signals originating from a source node (11) via different first and second signal routes, and by processing and correlating these signals in the destination node (12). In dependence of a correlation result, a process for processing a signal in a node (11-15) is adjusted. This process may be situated in the destination node (12), or in the source node (11) or an io intermediate node (13-15), in which case a control signal is to be exchanged. A learning algorithm for the adjusting of the process can be run in the nodes (11-15). Label switched routing can be introduced, whereby the label signal is sent from the source node (11) to the destination node via a third signal route different from the first and second signal route, to improve the efficiency of the nodes (11-15).
摘要:
A method for driving a lamp (2) comprises the steps of: generating a lamp current (ICONST) having a constant magnitude; defining a commutation period having a duration TCOMM; defining a time base of original commutation moments, having fixed mutual intervals of 0.5*TCOMM; receiving data to be embedded in the light output; commutating the lamp current at commutation moments; wherein individual commutations are time-modulated in order to encode said received data. Preferably, a commutation moment is: either equal to an original commutation moment if there are no data to embed; or advanced over a modulation distance (Δ) with respect to the corresponding original commutation moment in order to encode data having a first value (“0”); or delayed over said modulation distance (Δ) with respect to the corresponding original commutation moment in order to encode data having a second value (“1”).
摘要:
The invention relates to a method of copy-protection of information stored on an information carrying medium. The method allows a reading device (e.g. a DVD drive) and an application device (e.g. an MPEG decoder) to exchange copy-protection information regarding the information carrying medium (e.g. an optical record carrier like a CD or DVD) and the content on that medium. The method is cryptographically secure, taking into account the situation where reading device and application device are connected to an open bus in a personal computer. In view of the high-volume nature of the drive, the method can be implemented cheaply. The inventive method is robust against a so-called man-in-the-middle attack.The invention relates also to a method of exchanging copy-protection information, to a copy-protection system and to devices for carrying out these methods, in particular a reading device, an application device and a device for playback and/or recording of information.
摘要:
Recent copy-protection schemes for digital video copy-protection rely on a pixel-watermark together with the presence of a ‘ticket’ to implement the ‘copy-once’ state of content. This ticket is designed to entitle the owner of a disk/tape to making one copy of digital content. We disclose a method to pass along this ticket with the video signal after content has been converted to the analog domain. This form of the ticket is called the analog ticket. The analog signal may be recorded on a legacy device that does not comply with the copy-protection scheme (e.g. ordinary VCRs). The analog ticket is designed such that it is automatically removed in these legacy devices. Next generation copies by compliant devices are made impossible. Three possible ways of embedding the ticket signal into the analog video signal are proposed.
摘要:
A watermark detector is disclosed to judge whether multimedia content can be copied or not. The watermark detector examines the multimedia content and outputs a signal indicating whether a watermark is present or not. A decision variable indicating to which extent the watermark is present is determined, for example, the amount of correlation between the input signal and a reference copy of the watermark to be detected. The watermark is detected if the decision variable exceeds a predetermined threshold (y2). The detector also generates a random output signal for a predetermined range of decision values between the threshold (y2) and a further threshold (y1).
摘要:
A system for copy protecting content information has an arrangement for receiving and controlling the playback of encoded video. The video content, e.g. MPEG compressed digital video, is watermarked and includes a control signal indicating the status (e.g. playback only, one generation of copy allowed, etc). In the receiver device a check is performed to allow playback in dependence of the watermark. The watermark is extracted in a separate decoder device, such as an external MPEG decoder. The receiver device starts the playback via the external decoder, and the separate decoder communicates retrieved watermark information via a link to the playback device. The playback device checks the watermark information against further supplemental information, such as a physical mark on the record carrier or the control signal. Said communication may be protected by cryptographic methods, such as a digital signature.
摘要:
A record carrier has substantially parallel tracks having first variations of a first physical parameter and second variations of a second physical parameter of the track. The first variations represent information recorded on the record carrier, this information being recoverable by a controllable type of data processing. A modulation pattern of the second variations represents a code for controlling the type of data processing. In respect of a code track that includes the modulation pattern, the modulation pattern in the left neighboring track is aligned to the modulation pattern in the right neighboring track. Thereby crosstalk due to the second variations is decreased, and at least two tracks have the same modulation pattern. The playback device has a demodulator (50) and a control unit (56) for retrieving the code from at least two tracks.
摘要:
An MPEG-encoded video signal includes groups of pictures (GOPs), each GOP having an intraframe coded (I) picture and a series of predictively encoded (P) pictures and bidirectionally predictively encoded (B) pictures. Usually, the GOP structure IBBPBBP . . . is used. However, in order to embed a watermark in the MPEG-encoded video signal, the MPEG encoder is forced to produce a GOP structure which does not normally occur, e.g., a GOP including a BPP sequence. Different symbol values can be assigned to different positions of the BPP sequence in the GOP.
摘要:
A record carrier has substantially parallel tracks, which exhibit first variations of a first physical parameter and second variations of a second physical parameter of the track. The first variations represent information recorded on the record carrier, which information is recoverable by means of a controllable type of data processing. A modulation pattern of the second variations represents a code for controlling the type of data processing. With respect to a code track that includes the modulation pattern, the modulation pattern in the left neighboring track is aligned to the modulation pattern in the right neighboring track. Thereby crosstalk due to the second variations in decreased, and at least two tracks have the same modulation pattern. The playback device has a demodulator and a control unit for retrieving the code from at least two tracks.
摘要:
An electronic watermarking scheme is proposed that can significantly increase the security of copy protection mechanisms. The watermarking methods works at high level in the hierarchy of the (MPEG) source signal. This ensures that the watermark is easily detectable, but difficult to erase without significant transcoding effort. Such transcoding is considered a difficult and expensive task that may furthermore lead to loss of quality or increase in bit rate.