Abstract: A method and system provide for secure sharing of arbitrary data between users with limited mutual trust. A user can encode its information by using a Slepian-Wolf code at a rate which enables a second user to correctly decode only if the side-information it has satisfies a conditional entropy constraint. The key advantages are as follows. Firstly, it is very flexible, in that it enables secure sharing for general data including multimedia data. Secondly, by appropriate Slepian-Wolf code selection, it enables compression in conjunction with security. Thirdly, it can be used for the case where the data model is imperfectly known and trust is to be built up incrementally.

Abstract: A method and system are disclosed for coding and filtering video data. The method comprises the steps of using a predictive coding technique to compress a stream of video data, integrating a noise filtering process into said predictive coding technique, and using said noise filtering process to noise filter said stream of video data while compressing said stream of video data. In the preferred embodiment of the invention, the stream of video data is comprised of a series of macroblocks, including a current macroblock and at least one reference macroblock. Also, in this preferred embodiment, the step of using a predictive coding technique includes the step of calculating the difference between the current macroblock and the at least one reference macroblock, and the step of integrating the noise filtering process includes the step of integrating the noise filtering process into said step of calculating. The invention may be used with a forward predictive code mode and with a bi-directional predictive mode.

Abstract: A method and system are disclosed for selecting a mode to encode video data. The method comprises the steps of (a) transforming a source video frame into a set of coefficients, (b) partitioning said set of coefficients into a plurality of subsets of the coefficients on the basis of probability statistics corresponding to a plurality of encoding modes, wherein each of said subsets is identified for encoding by one of the plurality of encoding modes. The method comprises the further steps of (c) for each of the plurality of subsets of coefficients, computing defined parameters of an associated probability distribution for said subset, and (d) repeating steps (b) and (c) until a predetermined termination condition is satisfied. When this predetermined termination condition is satisfied, the subsets of coefficients, as they exist at that time, are output to a video encoder, which preferably is a Wyner-Ziv encoder.

Abstract: Disclosed are a method and system for video compression, wherein the video encoder has low computational complexity and high compression efficiency. The disclosed system comprises a video encoder and a video decoder, wherein the method for encoding includes the steps of converting a source frame into a space-frequency representation; estimating conditional statistics of at least one vector of space-frequency coefficients; estimating encoding rates based on the said conditional statistics; and applying Slepian-Wolf codes with the said computed encoding rates. The preferred method for decoding includes the steps of; generating a side-information vector of frequency coefficients based on previously decoded source data, encoder statistics, and previous reconstructions of the source frequency vector; and performing Slepian-Wolf decoding of at least one source frequency vector based on the generated side-information, the Slepian-Wolf code bits and the encoder statistics.

Abstract: Disclosed are a method and system for optimized, dynamic data-dependent program execution. The disclosed system comprises a statistics computer which computes statistics of the incoming data at the current time instant, where the said statistics include the probability distribution of the incoming data, the probability distribution over program modules induced by the incoming data, the probability distribution induced over program outputs by the incoming data, and the time-complexity of each program module for the incoming data, wherein the said statistics are computed on as a function of current and past data, and previously computed statistics; a plurality of alternative execution path orders designed prior to run-time by the use of an appropriate source code; a source code selector which selects one of the execution path orders as a function of the statistics computed by the statistics computer; a complexity measurement which measures the time-complexity of the currently selected execution path-order.

Abstract: A real-time MPEG video coding system with information look-ahead for constant bit rate (CBR) applications, such as, for example, Video-on-Demand (VoD) over ADSL. This scheme employs two MPEG encoders. The second encoder has a buffer to delay the input by an amount of time relative to the first encoder to create a look-ahead window. In encoding, the first encoder collects the information of statistics and rate-quality characteristics. An on-line information processor then uses the collected information to derive the best coding strategy for the second encoder to encode the incoming frames in the look-ahead window. The second encoder uses the encoding parameters from the processor as the coding guide to execute the coding strategy and generate the final bitstream.

Abstract: A real-time MPEG video coding system with information look-ahead for constant bit rate (CBR) applications, such as, for example, Video-on-Demand (VoD) over ADSL. This scheme employs two MPEG encoders. The second encoder has a buffer to delay the input by an amount of time relative to the first encoder to create a look-ahead window. In encoding, the first encoder collects the information of statistics and rate-quality characteristics. An on-line information processor then uses the collected information to derive the best coding strategy for the second encoder to encode the incoming frames in the look-ahead window. The second encoder uses the encoding parameters from the processor as the coding guide to execute the coding strategy and generate the final bitstream.

Abstract: A method and apparatus for decompressing data in a data-compression system with decoder-only side information is provided. In one aspect, the method comprises generating side information using a source reconstruction and decoding using the generated side information to generate a new source reconstruction. The method further includes iterating the steps of generating and decoding, the generating step using at least the new source reconstruction output by the previous decoding step, and the decoding step using the side information output by the previous generating step. The method may stop the iteration when one or more predetermined criteria are met.

Abstract: A method (and system) for coding a signal includes comparing a first prediction which is based upon a previously reconstructed signal to an actual signal to determine a first prediction error, comparing a second prediction which is based upon temporal filtering to the actual signal to determine a second prediction error, and selecting one of the first prediction error and the second prediction error.

Abstract: A video transcoding method is provided for transcoding a first signal stream compressed by a first coding scheme to a second signal stream compressed by a second coding scheme. The method employs an adaptive frame rate and a joint temporal-spatial rate control technique, such that the overall quality of compressed MPEG video can be significantly enhanced when the transcoding is controlled in the joint temporal (picture or frame rate) and spatial (quantization) domains. One embodiment considers transcoding from high bit rate video with larger image size (e.g. 4CIF/4SIF, CIF) coded by one coding technique, e.g., MPEG-2 to a lower bit rate video with smaller image size (e.g. CIF, QCIF) coded by the same or another coding technique, e.g., MPEG-4.

Abstract: A video transcoding method is provided for transcoding a first signal stream compressed by a first coding scheme to a second signal stream compressed by a second coding scheme. The method employs an adaptive frame rate and a joint temporal-spatial rate control technique, such that the overall quality of compressed MPEG video can be significantly enhanced when the transcoding is controlled in the joint temporal (picture or frame rate) and spatial (quantization) domains. One embodiment considers transcoding from high bit rate video with larger image size (e.g. 4CIF/4SIF, CIF) coded by one coding technique, e.g., MPEG-2 to a lower bit rate video with smaller image size (e.g. CIF, QCIF) coded by the same or another coding technique, e.g., MPEG-4.

Abstract: A method and system for extrapolating and interpolating a visual signal including determining a first motion vector between a first pixel position in a first image to a second pixel position in a second image, determining a second motion vector between the second pixel position in the second image and a third pixel position in a third image, determining a third motion vector between one of the first pixel position in the first image and the second pixel position in the second image, and the second pixel position in the second image and the third pixel position in the third image using a non-linear model, determining a position of the fourth pixel in a fourth image based upon the third motion vector.

Abstract: The present invention relates to computer-based systems and methods for visual signal extrapolation or interpolation based on statistic similarity estimation. Specifically, a first and a second reference pictures are provided, and motion estimation is conducted on the first and second reference pictures to generate motion vectors indicative of movement of at least one of the first and second reference pictures in relation to the other. Subsequently, an estimate picture is generated by extrapolation or interpolation from the first and/or the second reference picture using the motion vectors, followed by optional refinement of the estimate picture. Statistic similarity estimation is used either in motion estimation or in refining the estimate picture, or a combination of both, so as to provide improved visual signals.

Abstract: A method to predict visual quality of a DCT (discrete cosine transform) based compressed image or video stream without referring to its source. When applied to an MPEG video stream, the method is based on (1) an estimation of quantization errors using MPEG quantization scales and statistics of the inverse quantized DCT coefficients, (2) a blind estimation of the 8×8 and 16×16 blocking effect, and (3) an adaptive combination of the quantization error estimation and the blocking effect estimation using the MPEG motion vector information. The method may be used in many applications, such as network video servers, switches and multiplexers for automatic quality monitoring and control of video services, video encoders, decoders, transcoders, and statistical multiplexers for picture quality optimization.

Abstract: A system for transcoding compressed video signal, including a plurality of pictures, comprising an estimator to gather information and estimate the signal characteristics about the video signal; a decoder to completely or partially decode the compressed video signal; and an encoder to compress the reconstructed video signal according to a coding scheme devised on the estimated signal characteristics from the estimator.

Abstract: A real-time MPEG video coding system with information look-ahead for constant bit rate (CBR) applications, such as, for example, Video-on-Demand (VoD) over ADSL. This scheme employs two MPEG encoders. The second encoder has a buffer to delay the input by an amount of time relative to the first encoder to create a look-ahead window. In encoding, the first encoder collects the information of statistics and rate-quality characteristics. An on-line information processor then uses the collected information to derive the best coding strategy for the second encoder to encode the incoming frames in the look-ahead window. The second encoder uses the encoding parameters from the processor as the coding guide to execute the coding strategy and generate the final bitstream.

Abstract: A video transcoding method is provided for transcoding a first signal stream compressed by a first coding scheme to a second signal stream compressed by a second coding scheme. The method employs an adaptive frame rate and a joint temporal-spatial rate control technique, such that the overall quality of compressed MPEG video can be significantly enhanced when the transcoding is controlled in the joint temporal (picture or frame rate) and spatial (quantization) domains. One embodiment considers transcoding from high bit rate video with larger image size (e.g. 4CIF/4SIF, CIF) coded by one coding technique, e.g., MPEG-2 to a lower bit rate video with smaller image size (e.g. CIF, QCIF) coded by the same or another coding technique, e.g., MPEG-4.

Abstract: A decoding power aware encoding method for generating a predictively encoded data stream, in which predictions, that result in a reduction in the amount of data transferred from the secondary memory to primary memory during the decoding process, are favored, said method for favoring certain predictions comprising: a model for transfer of data from secondary memory to primary memory in the decoding process; a scheme for weighting the relative merits of favoring a certain prediction and the associated loss in compression gain; and based on said weighting scheme, choosing a particular prediction from the candidates allowed by the compression scheme.

Abstract: A method to predict visual quality of a DCT (discrete cosine transform) based compressed image or video stream without referring to its source. When applied to an MPEG video stream, the method is based on (1) an estimation of quantization errors using MPEG quantization scales and statistics of the inverse quantized DCT coefficients, (2) a blind estimation of the 8×8 and 16×16 blocking effect, and (3) an adaptive combination of the quantization error estimation and the blocking effect estimation using the MPEG motion vector information. The method may be used in many applications, such as network video servers, switches and multiplexers for automatic quality monitoring and control of video services, video encoders, decoders, transcoders, and statistical multiplexers for picture quality optimization.

Abstract: A system and method for generating an MPEG compliant video stream with satisfactory visual quality. The method employs re-encoding at a higher (or lower) bit rate, only the segments with unsatisfactory visual picture quality while retaining other parts of the original video stream and then merging the re-encoded segments with the remaining original portions. If the original video stream is coded at a reasonable bit rate, the number and length of those segments with unsatisfactory visual picture quality will be few and short. Re-encoding only those segments can save very significant amount of cost and only requires minimal additional storage space. Furthermore, the portions with satisfactory picture quality will be retained. The system and method is applicable to MPEG and non-MPEG compliant data streams.