Abstract: An apparatus for recording a file having a related media data container and a metadata container, the apparatus a receiver for receiving first data packets having packetized first media data samples based on a first clock, and for receiving second data packets having second media data samples based on a second clock different from the first clock, wherein the second media data samples are associated to the first media data samples, and for receiving first control packets including information for indicating a relationship of the first clock to a reference clock and for receiving second control packets including information for indicating a relationship of the second clock to the reference clock, and a recorder for storing the received first and second data packets and at least a portion of the received first and second control packets in the media data container, and for storing associated metadata in the metadata container, the associated metadata having timing information of the received first and second da

Abstract: A method of encrypting a digital television signal carried out in any operative order involves duplicating packets in the digital television signal so as to create first and second duplicate packets; encrypting the first duplicate packets according to a first encryption method to create first encrypted packets; encrypting the second duplicate packets according to a second encryption method to create second encrypted packets; identifying packets in the digital television signal that are of a packet type, while other packets are not of the packet type; replacing the identified packets in the digital television signal with corresponding first and second encrypted packets to produce a multiple partially encrypted digital television signal comprising the other packets that are unencrypted and the first and second encrypted packets; and distributing the multiple partially encrypted digital television signal.

Abstract: A method of processing digital content consistent with certain embodiments involves receiving a signal containing the digital content, wherein the digital content has a first encrypted sample of the digital content, the sample being encrypted under a first encryption method, a second encrypted sample of the digital content, the sample being encrypted under a second encryption method, and an unencrypted portion; and decrypting the first encrypted sample to produce a decrypted sample. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.

Abstract: A multiple partial encryption device consistent with certain embodiments has an input for receiving a unencrypted video signal. An encryption arrangement produces a partially multiple encrypted video signal from the unencrypted video signal. An output provides the partially multiple encrypted video signal. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.

Abstract: In certain embodiments, a method of partially dual encrypting a digital video signal involves examining unencrypted packets of data in the digital video signal to identify a specified packet type. The specified packet type includes packets occurring in a star pattern approximately situated at approximately a center of an image; encrypting packets identified as being of the specified packet type using a first encryption method to produce first encrypted packets; encrypting the packets identified as being of the specified packet type using a second encryption method to produce second encrypted packets; and replacing the unencrypted packets of the specified packet type with the first encrypted packets and the second encrypted packets in the digital video signal to produce a partially dual encrypted video signal. This abstract should not be considered limiting since embodiments consistent with the present invention may involve more, different or fewer elements.

Abstract: According to one embodiment, a digital stream, inclusive of an Internet Protocol (IP) datagram, is transmitted to a digital device. IP datagram comprises an IP header and a body segmented including a plurality of packets in an MPEG format such as MPEG-2 or MPEG-4 for example. The plurality of packets comprises (i) a first packet including a payload having content and a header that comprises a first packet identifier to indicate a type of the content contained in the payload of the first packet, and (ii) a second packet including a payload and a secondary packet identifier to indicate that its payload includes content duplicative of the content contained in the first packet. The second packet precedes the first packet in the digital stream. Upon detecting the presence of duplicative content, the duplicative content is recovered, but the content contained in the payload of the first packet is disregarded.

Abstract: A process for distributing video sequences according to a nominal flux format including a succession of images, where each image includes a succession of blocks, and in which at least one of blocks in one of the images is calculated by motion prediction relative to at least one reference image, where the motion prediction is encoded in the flux with at least one motion vector, the flux being processed, before transmission to client equipment, with an analysis for generating a first modified flux having the format of a nominal flux and having images modified by substitution of selected data with selected data of the same nature, but random, and a second flux of any format including the substituted data and digital information likely to allow reconstruction of the modified flux, then transmitting separately, in real or deferred time, the two fluxes generated from a server toward the client equipment, and for which is calculated on the client equipment a synthesis of a nominal format flux as a function of the pr

Abstract: A method for securing a portable security module for use with a decoding element, the portable security module and the decoding element allowing to descramble scrambled audiovisual information. The method comprises analyzing at the portable security module a sequence of command messages, the command messages of the sequence being received at the portable security module at distinct times.

Abstract: An image control apparatus in an image display system applies scrambling only to image data which requires content protection and notifies to a display apparatus which pixel or pixels are scrambled. Alternatively, when a plurality of windows are displayed at the same time, the image control apparatus scrambles each window individually using a different key, and notifies to the display apparatus which scramble is applied to each pixel.

Abstract: A method and a carrier medium instructing a processor to execute a method. The method includes accepting a compressed video stream compressed by a compression method that uses macroblocks of possibly different macroblock types for each frame predictive encoding frames. The method further includes identifying a sequence of frames that are substantially visually indistinguishable and that include a predictively encoded frame and the at least one reference frame of the predictively encoded frame. The method further includes creating an ordered set of macroblocks, with the macroblock types of different macroblocks in the ordered set used to encode digital watermark information. The method further includes replacing the predictively encoded frame of the identified sequence with a newly-encoded predictively encoded replacement frame that contains the created ordered set of macroblocks, including the encoded watermarking information.

Abstract: A configuration is provided which improves scrambling processing of content and eliminates unauthorized use of content. Scramble rules which differ for each content are used for content scrambling processing. For example, in the event of using shuffling processing, various shuffle states are specified as scramble rules. In the event of using Exclusive-OR processing, a value applicable to EXOR is specified as the scramble rule. Also, in the event of using rotation processing, a shift amount is specified as the scramble rule. In the event of using 32 shuffle elements in shuffling processing, 32! different shuffle states, that is to say, 32! different scramble rules can be specified. Also, the values for EXOR or the rotation shift amount can be set as various values, and many scramble rules can be set.

Abstract: A method of decoding symbols in which a first codeword has been spread by a second codeword to recover first information and second information is provided. The decoding occurs jointly, with an overall output determining both the first and second information. A first parallel code multiplying operation for each codeword of the second code is followed by a second parallel code multiplying operation for the first code. An overall maximum output of the second parallel code multiplying operations determines the output information.

Abstract: A PC-based personal video recorder (PVR) system enables recordation of video content on a general-purpose computer in a way that the computer is unable to perceptively display the recorded content, but is able to playback and distribute the content to a decoder box (e.g., set-top box) for display on a television. In one implementation, the general-purpose computer is equipped with a personal video recorder (PVR) card having a video tuner, a network connection, and scrambling capabilities. The PVR card is configured to receive video content and produce compressed digital video. The card scrambles the video content and stores it in the computer's memory. The scrambled video content is in a form that cannot be perceptibly displayed by the computer. During playback, the PVR card retrieves the scrambled video content from the memory, descrambles it, and outputs the video content to the decoder box for playback on the television.

Abstract: Techniques for securely and adaptively delivering multimedia content are disclosed in which a set of alternate access units for each time slot is obtained. Then, the encryption stream index of each access unit from the set of alternate access units of the previous time slot are obtained. An encryption stream index is then assigned to each access unit in the set of alternate access units in the current time slot, such that the encryption index increases over time. Thus, the invention overcomes the problem of encrypting a multimedia stream that may have multiple access units for each time slot by selecting the encryption index for each access unit such that the encryption index increases, regardless of which access unit the delivery system (e.g., server) selects for transmission.

Abstract: Information is incorporated into motion picture film prints in the form of images or patterns that appear as unobtrusive defects or artifacts. The unique codes are used in association with the print number of the film and are reproduced in video copies of the film made by counterfeiters. This code can be read from the counterfeit copy and can be used to trace the source of the counterfeit. The digits of the print number are recorded in separate frames to increase the difficulty to counterfeiters in detecting and deleting them.

Abstract: Techniques for securely and adaptively delivering multimedia content. It is assumed that a set of alternate access units for each time slot is obtained. Then, the encryption stream index of each access unit from the set of alternate access units of the previous time slot are obtained. An encryption stream index is then assigned to each access unit in the set of alternate access units in the current time slot, such that the encryption index increases over time. Thus, the invention overcomes the problem of encrypting a multimedia stream that may have multiple access units for each time slot by selecting the encryption index for each access unit such that the encryption index increases, regardless of which access unit the delivery system (e.g., server) selects for transmission.

Abstract: A digital media cartridge contains both a controller and memory where the memory stores a digital representation of video and sound in compressed, encrypted form. The controller reads the digital representation, decompresses and decrypts it, converts it into analog video and audio and outputs the analog video and audio to a host device into which the cartridge is inserted. The analog video and audio output are displayed on the screen of the host device and reproduced by speakers or headphones of the host device, respectively, without further processing of the video and audio signals being necessary by the host device. Besides video and audio, the digital media cartridge can also store and execute games that use the user input and display screen of the host device.

Abstract: Watermark detectors have a buffer in which a number of image tiles are folded and accumulated prior to computing the correlation between buffer contents and the watermark pattern being looked for. The intention of the folding and accumulation process is to average out the video content while accumulating the embedded watermark energy. This no longer appears to hold for strongly compressed video, such as DIVX, which exhibits a lot of artificial noise and undesired similarity (block patterns). As a result thereof, correlation peaks are often below the threshold. In a similar manner, the compression affects scale detection. According to this invention, only frames (or parts thereof) that are not so heavily compressed and therefore have a high probability of carrying enough watermark energy are folded and accumulated. To this end, a quality metric is calculated, the quality metric being indicative of the degree of compression of the data.

Abstract: A conditional access scrambling or encryption technique for a packetized digital data stream, e.g., a MPEG-2 bitstream, (1) by scrambling or encrypting the data payload of selective transport payload packets (e.g., every nth packet); (2) by scrambling or encrypting only a portion (e.g., a central portion) of the data payload of every transport payload packets; or (3) by both scrambling or encrypting the data payload of every nth packet and scrambling or encrypting only a portion of the data payload of every transport payload packet. With advance knowledge by the subscriber's descrambler of which payload packets are being scrambled, and/or of which portion of which payload packets, descrambling can be performed with minimal processing and without the need to first recreate the underlying image and/or audio.

Abstract: A method generates a marked data flow from an encoded data flow; at least one first data flow section of the encoded data flow is marked as a marked data flow section; and the marking of the marked data flow section indicates that the marked data flow section is suitable to be mixed with a watermark. A method inserts watermarks into the marked data flow, and devices generate the marked data flow and insert watermarks into the marked data flow.

Abstract: An image processing apparatus that is capable of presenting a general overview of the contents of an original image from its corresponding scrambled image is disclosed. The image processing apparatus applies a discrete wavelet transform to a pixel value of each of at least one rectangular region into which image data are divided and hierarchically compresses the image data into a compressed code stream. Then the image processing apparatus performs a scrambling process on compressed code within the compressed code stream that is of a level corresponding to a high resolution image component and refrains from performing the scrambling process on compressed code other than that of the level corresponding to the high resolution image component.

Abstract: A transmitting apparatus transmits, to a receiving apparatus, a content that contains at least, in the stated order, a first portion that is encrypted with a shared key shared between the transmitting apparatus and the receiving apparatus, a second portion that is not encrypted, and a third portion that is encrypted with the shared key. In this situation, in the case where the encrypted third portion has become a transmission target after the second portion has been transmitted, and also, there is a possibility that the shared key stored in the receiving apparatus may be invalidated when the encrypted third portion is received, the transmitting apparatus sequentially transmits a fourth portion and the encrypted third portion to the receiving apparatus, the fourth portion containing at least element data that belongs to the last group in the second portion.

Abstract: An interface block (11) converts the format of input downstream data (STRM). A CPU (12) receives the format-converted data (DIF) and realizes the MAC function. A TEK process block (13) receives TEK process data (DTEK) obtained from the data (DIF), analyzes the data structure of the TEK process data, and performs decryption processing based on a result of the analysis.

Abstract: Methods and systems enable content authors to achieve frame-accurate editing and, in at least some embodiments, reduce the amount of content that needs to be decompressed in order to operate on the frames. Some embodiments ensure that bit rate integrity is preserved so that bit rate conditions associated with streaming environments are preserved. Various embodiments intelligently determine which content portions should be decompressed, processed, and recompressed and which content portions should not be decompressed.

Abstract: An encrypted program received in an MPEG transport stream is decrypted by receiving an address in the MPEG transport stream, reading a key from a memory in accordance with the received address, and decrypting the encrypted program based on the key.

Abstract: A method comprises receiving a bit sequence associated with at least one file, the bit sequence comprising payload data in a compressed format and characterization data that maps the compressed format of the payload data. The method continues by encrypting the characterization data that maps the compressed format of the payload data. The method concludes by transmitting the bit sequence such that the characterization data is encrypted and at least a portion of the payload data is unencrypted.

Abstract: Processing an MPEG elementary stream contained in multiple PID streams in a conditional access overlay environment. A multi-program transport stream contains numerous video and audio elementary streams. Critical packets in the elementary streams are encrypted with two different encryption schemes creating a stream having multiple PID values. The streams are then sent from the headend to individual set-top boxes. One encryption scheme can be decoded by the incumbent set-top box and the second encryption scheme can be decoded by the overlay set-top box. The overlay set-top box uses a dual filter system to filter and decode the PIDs for each video and audio stream of the desired program.

Abstract: A method and apparatus for encrypting and decrypting digital data employing multiple Huffman tables and at least one encryption key to enhance security of the digital data. At least one image parameter for characterizing the digital data, such as a motion vector table or DC-luminance, is selected as an image parameter. All possible Huffman tables according to the image parameter are then generated by Huffman tree mutation. A predetermined number of active Huffman tables from all possible Huffman tables are selected using a first encryption key and a hash function. Afterward, a coding sequence for the active Huffman tables is generated using a second encryption key and the hash function. Finally, the digital data is encrypted into an encrypted bit stream by the active Huffman tables with the coding sequence. Encrypted symbols of the image parameter can be reduced by symbol statistic analysis, thus reducing computation effort.

Abstract: Methods and systems for allowing multiple devices to share the same serial lines (e.g., SDIO, SEN and SCLK) are provided. Such devices can be located, e.g., on an optical pick-up unit. Each device includes a serial interface, a device enable number (DEN) that differs from the DEN of each other device, and a plurality of registers, with at least one register being designated a device select register (DSR). The DSRs of the plurality of devices share a common address. The plurality of serial interfaces are collectively enabled and collectively disabled (e.g., via the SEN line). However, only one of the plurality of serial interfaces can be selected at one time, with the remaining of the plurality of serial interfaces being deselected. The serial interface of a device is selected when the DEN of the device is the same as the content of the DSR of the device, and deselected when the DEN of the device is not the same as the content of the DSR of the device.

Abstract: An apparatus and a method for overlaying parts of a displayed presentation of a video by using graphic content rendered by a receiving device such as a set top box or television to complete a displayed presentation of the video. The apparatus receiving frame synchronizing information from a content provider and then conveying the frame synchronizing information as a graphic overlay to the video. The frame synchronizing information comprises frame starting identifier data, frame ending identifier and positional information for describing frame locations and frame timing for overlaying the graphic content and positional information to indicate where to place the graphic content to be overlaid. The frame synchronizing information provides the information necessary to place graphic content, such as a graphic image or graphic animation, at specified positions that are synchronized to the displayed presentation. The same method also enables audio information to be synchronized.

Abstract: Disclosed herein is a data transmission system permitting secure and more reliable transmission of data from a data transmitter to a data receiver or receivers. The system comprises: a data transmitter for encrypting data and transmitting the encrypted data; data receivers for receiving the encrypted data from the data transmitter; satellite links used for data transmission from the data transmitter to the data receivers; and bidirectional communication channels which are also used for transmitting data from the data receivers to the data transmitter and which have a smaller capacity of data transmission than the satellite links. The satellite links are used to transmit encrypted data from the data transmitter to the data receivers. At least the bidirectional communication channels are used to communicate restrictive data transmission control information between the data transmitter and the data receivers.

Abstract: A media object authentication system uses layers of security features based on digital watermarks embedded in media objects. The system generates a first digital watermark with a message payload carrying data about the object, such as a hash of text data printed on the object. The first digital watermark is combined with a content signature derived from features of the media object, such as frequency domain attributes, edge attributes, or other filtered version of the media signal (e.g., image photo on a secure document) on the media object. This combination forms a new digital watermark signal that is embedded in the host media object. To verify the object, the digital watermark payload is extracted and compared with the data about the object. The combined digital watermark and content signature is also evaluated to authenticate the media signal on the media object.

Abstract: An encryption technique and a decryption technique that are applied to video data that is encrypted on a predetermined domain of compressed video data are disclosed. For example, JPEG2000 compressed video data can be compressed using a wavelet conversion. Compressed video data is input. The input video data is decompressed to a predetermined domain of the compression process, and the decompressed video data is then encrypted. The encrypted video data is then compressed in accordance with the decompression process, and information representing the encrypted compression domain is stored in a predetermined area of the compressed video data.

Abstract: On an encrypted object code obtained by encrypting an object code, there is discriminated whether an inhibited code defined in data format is present in a code concerning such encrypted object code, and, in case such inhibited code is judged absent, the encrypted object code is determined as an encryption result of the object code.

Abstract: Disclosed are methods and systems for providing transcodability to media in a network, comprising separating an amount of media data into a segment, and combining the segment and a transcoder readable payload header into a data packet payload, wherein the segment comprises data coded in a frame.

Abstract: A video communication system, for example, video surveillance and video conferencing, is disclosed in which regions of interest of video scenes are scrambled to protect privacy and/or allow anonymous participation. The regions of interest may be arbitrary and selectable by the participant or user, such as the face of the participant. Initially, the video content is analyzed to locate an arbitrary shape of interest, such as a human face or part of a human body. Once the region of interest is located, it is scrambled, for example, in conjunction with two well known video coding schemes; MPEG-4 and Motion JPEG-2000. The arbitrary regions can be scrambled in the transform-domain during coding and reversibly encrypted to allow authorized users to decrypt and decode the regions of interest.

Abstract: A scrambling architecture protects data streams in the operating system and hardware components of a computer by scrambling the otherwise raw data prior to the data being handled by the operating system. Scrambled content is passed to a filter graph (or other processing system) where the content is processed while scrambled. A scrambler also generates a random signal based on a first key and a second key. After processing, the scrambled data is passed to a driver for output. A driver may implement a descrambler to detect tone patterns in the content and recovers the first key from varying amplitudes of the tone patterns. The descrambler may also receive the second key via a separate channel and generates the same random signal using the recovered first key and the second key. The descrambler subtracts the tone patterns and the random signal from the scrambled content to restore the content.

Abstract: In a class of embodiments, the invention is an open computing system (e.g., a PC) in which a protected, closed subsystem is embedded. The closed subsystem typically includes multiple parts that ensure that content protection keys and protected content are never revealed outside the closed subsystem. Content (e.g., high-definition digital video) that enters the closed subsystem (and is typically decrypted and re-encrypted within the closed subsystem) is afforded a similar level of protection within the open system as can be obtained in standalone closed systems. Other aspects of the invention are methods for protecting content within an open computing system, a closed system (or disk drive thereof) configured to be embedded in an open computing system, and circuitry configured to be embedded in an open computing system for combining the output of a closed subsystem with other output (e.g., graphics and/or audio output) of the open computing system.

Abstract: An aspect of the current invention involves an apparatus and method for protecting media content from being read and copied by an unauthorized party. In one embodiment of the invention, this is accomplished by storing keys for decrypting encrypted media content on a secure memory device located in proximity to a computer processor. A secure memory device located in proximity to a computer processor allows for decryption keys to be sent to a user of the computer processor in advance of the user receiving an encrypted media content that will be decrypted with the decryption keys. With the secure memory device, the decryption keys can be stored indefinitely without an unauthorized party gaining access to them. Another embodiment of the invention allows for multiple media content providers to store their own decryption keys for their own encrypted media content simultaneously on a secure memory device located with a user's personal computer.

Abstract: The invention concerns a method of inserting a suppementary information item in a set of data reprenting physical quantities, the data having been processed by the steps of, a) partitioning (E2) the set into subsets, b) entropic coding (E4) of each of the subsets, c) selecting (E8), for each of the subsets, a compression rate and distortion pair according to a global compression rate or a global distortion, d) writing, for each of the subsets, an index (Tij) representing the selected compression rate and distortion pair, in a file containing the coded subsets, characterised in that it also includes a step (E11) of modifying the selected compression rate and distortion pairs, according to the supplementary information (wm).

Abstract: An image container file has at least first and second multimedia streams (MSs). The first MS includes first image data representing an image. The second MS includes arbitrary data, which can for example, correspond to: a different representation of the same image; annotations to the first image data; second image data that together with the first image data form a new image with greater dynamic range, resolution, field of view or other attributes that can be derived from processing two or more independent images; or an executable file related to the first MS. The image container file can also include an extensible metadata to hold information describing one or more multimedia streams of the image container file. Further, the image container file may include DRM information to provide information related to obtaining a license to access encrypted data or verifying the authenticity of encrypted or unencrypted data.

Abstract: A system for encoding and decoding data words including an anti-analysis encoder unit for receiving an original plaintext and producing a recoded data, a data compression unit for receiving the recoded data and producing a compressed recoded data, and an encryption unit for receiving the compressed recoded data and producing an encrypted data. The recoded data has an increased non-correlatable data redundancy compared with the original plaintext in order to mask the statistical distribution of characters in the plaintext data. The system of the present invention further includes a decryption unit for receiving the encrypted data and producing a decrypted data, a data decompression unit for receiving the decrypted data and producing an uncompressed recoded data, and an anti-analysis decoder unit for receiving the uncompressed recoded data and producing a recovered plaintext that corresponds with the original plaintext.

Abstract: A data encryption apparatus operable to apply encryption to input data having at least a format identifying portion and a payload portion comprises means for discriminating between the format identifying portion of the input data and the payload portion of the input data; and means for selectively applying encryption to the input data in dependence upon an output of the discriminating means so as to encrypt at least a part of the payload portion of the input data but not to encrypt the format identifying portion. A corresponding decryption apparatus is also provided.

Abstract: The present invention is directed to a streaming system for encrypting compression-encoded image data to distribute it via network of a predetermined transport protocol, and a streaming server used in this system transmits, to a client terminal, on the RTP packet basis, stream data encrypted so that encryption is performed every encryption block size from the leading portion of each GOP without encrypting the last data having less than encryption block size. In this instance, portions of prior and/or posterior stream data are stored into an extended area of RTP header so that size of stream data transmitted every RTP packet is integral multiple of encryption block size. Further, size information of added prior additional data and/or posterior additional data are also stored into the extended area. This streaming server suppresses increase in size by encryption to have ability to support both real time production and down-load reproduction without replacement of encryption.

Abstract: An architecture for content-aware compression and/or encryption of various segments of a application is disclosed. The architecture advantageously allows decompression and decryption units to be placed various levels of a memory hierarchy.

Abstract: Various embodiments are directed towards employing a container and communication protocol proxy component within a client device to receive securely real-time streamed, progressively downloaded, or adaptively streamed container over a network using one container and communication protocol, and to securely decrypt the container and provide it to a media player using a different container and communications protocol. In one embodiment, the container is in Flash Video (FLV) file format. A browser or the media player on the client device may be used to request the container. The requested container is sent over one communication protocol and intercepted by the container and communication protocol proxy component. The container may be received as selectively encrypted container. The container and communication protocol proxy component then may enable decryption of the container and providing of it to the media player using another container and communication protocol combination.

Abstract: Certain embodiments consistent with the present invention involve a method of selectively encrypting digital video content that involves receiving a plurality of packets containing the digital video content; identifying packets containing start of frame (SOF) headers; inserting padding into the packets containing SOF headers to move the content of the packets containing the SOF headers to a previous or subsequent packet and create padded packets containing the SOF headers; selecting certain of the packets for encryption according to a selection criterion, wherein the selected packets exclude the padded packets containing SOF headers; encrypting the selected packets; and retaining the padded packets containing the SOF headers unencrypted to form selectively encrypted digital video content. Corresponding decoding method as well as encoding and decoding apparatus are also taught. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.

Abstract: An apparatus of a flexible and common MPEG-2 IPMP system (Intellectual Property Management and Protection) is invented to provide flexibility and interoperability by introducing a IPMP Control Information which includes IPMP Tool List and an optional Tool Container. The IPMP Control Information is put in PSI in MPEG-2 transport stream, and a special PES packet in MPEG-2 program stream. IPMP Stream is defined to carry IPMP information that is to be sent to each individual IPMP tool instance. The concept of Tool Manager, Message Router from MPEG-4 IPMP extension is mapped into MPEG-2 terminal to form MPEG-2 IPMP framework together with introduced IPMP Control Information and IPMP Stream. As a result of this invention, the same protected MPEG-2 content is able to play back by different types of MPEG-2 IPMP terminals, and the same MPEG-2 content can be protected by using different vendors' IPMP system.

Abstract: The invention provides a system that preserves the synchronization of the audio and video presented at a secure conferencing site without necessitating decryption, decompression, compression, and encryption of signals at the hub. The presently preferred embodiment of the invention provides an apparatus and method for synchronizing audio and video in encrypted videoconferences that comprises a plurality of conference sites; and a hub for receiving a compressed and encrypted, composite audio and video signal from each site, for determining a currently active site, and for transmitting said composite audio and video signal from said currently active site to all other sites; said hub receiving a compressed and encrypted audio only signal from each site; wherein said hub routes all incoming compressed and encrypted audio only signals to each site.

Abstract: An adaptive compression technique which is an improvement to Lempel-Ziv (LZ) compression techniques, both as applied for purposes of reducing required storage space and for reducing the transmission time associated with transferring data from point to point. Pre-filled compression dictionaries are utilized to address the problem with prior Lempel-Ziv techniques in which the compression software starts with an empty compression dictionary, whereby little compression is achieved until the dictionary has been filled with sequences common in the data being compressed. In accordance with the invention, the compression dictionary is pre-filled, prior to the beginning of the data compression, with letter sequences, words and/or phrases frequent in the domain from which the data being compressed is drawn. The letter sequences, words, and/or phrases used in the pre-filled compression dictionary may be determined by statistically sampling text data from the same genre of text.