Abstract: In a Viterbi decoder, 2n-way add-compare-select (ACS) operations are performed by sequential and/or parallel two-way ACS operations. In one embodiment, first two-way ACS operations generate an interim path metric for each of a plurality of interim states. Second two-way ACS operations generate a path metric for each of a plurality of next states. This process may be repeating for subsequent groups of bits to generate branch transitions through a trellis. A path having a lowest path metric may be selected and a decoded bit sequence determined based on the selected path. In generating the decoded bit sequence, the interim states of the selected path do not have to be used for code rates k/n when k is two or greater. The interim states may be used for code rates k/n when k=1.

Abstract: A method an apparatus for rendering DVD subpicture data on a computer system having graphics data without a loss of subpicture resolution includes inserting a key into the subpicture data during or right after decoding and storing the subpicture data in the primary graphics surface. This key indicates whether the data is graphics (GUI) information or subpicture information. The key is then examined by hardware logic in the graphics chip, allowing other hardware logic to blend DVD subpicture data with DVD video data without losing subpicture color resolution. The key may be implemented differently for different color modes of the primary surface, and may be unnecessary in certain modes.

Abstract: A method and apparatus for block-oriented pixel filtering reduces the number of hardware multipliers required for an image processing operation by increasing the speed of the pixel filter and rearranging the math operations. A sorter is employed in the line buffers so that defined groups of input pixel components are provided to the multipliers of the pixel filter. An accumulator is employed to receive products from the multipliers and assemble output pixels. The savings in gate count from reducing the number of multipliers is greater than additional costs, if any, of the sorter and other logic. The method and apparatus of the invention also simplify the addressing logic for the provision of scaling coefficients during an image processing operation.

Abstract: In a Viterbi decoder, 2n-way add-compare-select (ACS) operations are performed by sequential and/or parallel two-way ACS operations. In one embodiment, first two-way ACS operations generate an interim path metric for each of a plurality of interim states. Second two-way ACS operations generate a path metric for each of a plurality of next states. This process may be repeating for subsequent groups of bits to generate branch transitions through a trellis. A path having a lowest path metric may be selected and a decoded bit sequence determined based on the selected path. In generating the decoded bit sequence, the interim states of the selected path do not have to be used for code rates k/n when k is two or greater. The interim states may be used for code rates k/n when k=1.

Abstract: A Viterbi decoder and method rescale branch metrics by a minimum value of a prior state's path metric. A branch metric unit generates branch metrics from groups of bits of a received bit stream, and an ACS operation unit rescales the branch metrics and performs ACS operations to generate path metrics for the next state of the decoder. The rescaled branch metrics may be stored in branch metric registers of the ACS operation unit for use in a subsequent ACS operation. Rather than resealing path metrics within individual ACS elements, branch metric rescaling is performed outside the individual ACS elements.

Abstract: An apparatus and method for converting computer graphics images into a format suitable for display on a TV. A flicker filter is combined with a vertical scaling filter and/or vertical overscan compensation filter to produce an interlaced image formatted for display on a TV, more efficiently than if the processes occurred sequentially. The apparatus and method are not limited to any particular filter sizes or set of filter coefficient values. The apparatus and method may be used as part of a multimedia computer system.

Abstract: A method and apparatus for deinterlacing video frames selects a location for deinterlacing, and measures motion at that location. A deinterlacing method is selected based on the measured motion. A pixel value is created for the location.