Abstract: A pre-processing system and method is used to compensate for global brightness changes in consecutive video frames. The system and method uses a brightness change model to identify the global brightness changes and to discard the brightness in a source frame so that the brightness changes between consecutive reconstructed video frames is kept to a minimum. The Hough Transform is used as one example of the model to accumulate votes for different values of brightness change model parameters. Compensation for any detected brightness changes in the source frame is performed with filtering of the model parameters when necessary, to help avoid any artifacts in the compensated source frame. Different application sequences of the brightness change model allows for multiple levels of processing delays.

Abstract: A method of motion vector prediction for use in differential motion vector coding within a block motion-compensation-based video coder. The video coder employs a generalized multiple reference picture buffer which may contain multiple reference pictures in both the forward and backward temporal direction from the current picture. For the purpose of coding selections of reference pictures within the buffer, the pictures are organized into two, potentially overlapping, lists of reference pictures. The prediction of a motion vector that selects a reference picture using a given reference picture list is not dependent upon any motion vectors that select their reference pictures using the other reference picture list. The values of spatially neighbouring motion vectors that use the same list of reference pictures as the notion vector being predicted are used for prediction, regardless of the relative temporal direction of the current and neighbouring motion vectors.

Abstract: A video coding method progressively refines a predicted motion vector to obtain an estimated motion vector. Subsequent steps are omitted if the estimated motion vector matches a current macroblock. Variable matching thresholds can permit dynamic adjustment of image quality and computational cost to optimize encoding performance for available computational resources. The method permits control of desired encoding speed and bit rate by adjusting encoding parameters. Video coders according to the invention may comprise a motion estimator, transform computer and coder each of which operates according to one or more parameters. A speed rate control and/or a bit rate control may adjust the parameters to maintain a desired encoding speed and output bit rate. A coder according to the invention may be implemented in software running on a general purpose computer. The method may be used in block-based video encoders including MPEG-2 and H.263 encoders.

Abstract: A system and method is provided to avoid or otherwise reduce luminance and/or chrominance trailing artifacts in block-based hybrid video coders using multiple block sizes and shapes. The proposed trailing artifact avoidance approach has at its core three main components. The first component is a method to identify flat blocks in the source frame that are most susceptible to the appearance of trailing artifacts, and where flatness is determined according to several proposed criteria. The second component is a method to identify bad blocks, which refer to predicted blocks in motion estimation that correspond to flat blocks in the source frame and that contain trailing artifacts. The third component is a method to avoid trailing artifacts when they are detected within a bad block, and where the avoidance is achieved by employing one or more tools from among a proposed set of high fidelity coding tools and/or high performance motion estimation tools.

Abstract: A pre-processing system and method is used to compensate for global brightness changes in consecutive video frames. The system and method uses a brightness change model to identify the global brightness changes and to discard the brightness in a source frame so that the brightness changes between consecutive reconstructed video frames is kept to a minimum. The Hough Transform is used as one example of the model to accumulate votes for different values of brightness change model parameters. Compensation for any detected brightness changes in the source frame is performed with filtering of the model parameters when necessary, to help avoid any artifacts in the compensated source frame. Different application sequences of the brightness change model allows for multiple levels of processing delays.

Abstract: A video coding method progressively refines a predicted motion vector to obtain an estimated motion vector. Subsequent steps are omitted if the estimated motion vector matches a current macroblock. Variable matching thresholds can permit dynamic adjustment of image quality and computational cost to optimize encoding performance for available computational resources. The method permits control of desired encoding speed and bit rate by adjusting encoding parameters. Video coders according to the invention may comprise a motion estimator, transform computer and coder each of which operates according to one or more parameters. A speed rate control and/or a bit rate control may adjust the parameters to maintain a desired encoding speed and output bit rate. A coder according to the invention may be implemented in software running on a general purpose computer. The method may be used in block-based video encoders including MPEG-2 and H.263 encoders.

Abstract: A subband coder with jointly optimized multistage residual quantizers and entropy coders for image coding which allows the subband coder to exploit both linear and non-linear dependencies that may exist within and across the subbands. Both inter- and intra-band dependencies are simultaneously exploited via jointly optimizing the subband coders and entropy coders in an entropy constrained optimization framework involving rate, distortion and complexity. The multistage quantization structure and the effectiveness of the statistical modeling algorithm results in an attractive balance among reproduction quality, rate and complexity.

Abstract: A subband coder with jointly optimized multistage residual quantizers and entropy coders for image coding which allows the subband coder to exploit both linear and non-linear dependencies that may exist within and across the subbands. Both inter- and intra-band dependencies are simultaneously exploited via jointly optimizing the subband coders and entropy coders in an entropy constrained optimization framework involving rate, distortion and complexity. The multistage quantization structure and the effectiveness of the statistical modeling algorithm results in an attractive balance among reproduction quality, rate and complexity.