General Instrument Corporation of Delaware

Chris Hoogenboom

Paul Moroney

Bao K Vuong

Ray M Nuber

A random access memory of a digital video decompression processor is mapped to enable the reconstruction of successive video frames of pixel data represented by a compressed video bitstream. A FIFO buffer is provided in the RAM for the compressed video bitstream. A first luminance anchor frame buffer and a first chrominance anchor frame buffer are provided for storing a full frame of luminance data and a full frame of chrominance data for a first anchor frame used to predict B-frames. A second luminance anchor frame buffer and second chrominance anchor frame buffer are provided for storing a full frame of luminance data and a full frame of chrominance data for a second anchor frame used to predict the B-frames. A first B-frame luminance buffer is provided in the RAM and sized to store less than 100% of the amount of luminance data in a first B-frame field. A second B-frame luminance buffer is provided in the RAM and sized to store at least 100% of the amount of luminance data in a second B-frame field. A B-frame chrominance buffer is provided in the RAM to store at least 100% of the amount of chrominance data in a B-frame. The anchor frames and B-frames are read from the RAM to enable the reconstruction of successive video frames. The memory mapping is particularly well suited for the decompression of formatted video in an MPEG-2 decoder.

Dram mapping for a digital video decompression processor

A method and apparatus are provided for communicating VBI user information for digital television. A syntax is provided which allows the transport of closed captions, non-realtime video, sampled video and AMOL. Non-realtime video can be used to transport various types of data, such as a vertical interval test signal (VITS) through the system at full resolution. The provision in the syntax of a count for each type of VBI user information enables the adjustment of a digital television data stream to accommodate variable amounts and types of such information without space being reserved in advance. The provision of a priority number in the syntax enables decoders to discard VBI user information priorities which are not supported by the particular decoder.

Bandwidth efficient communication of user data in digital television

Pixel data is stored and subsequently read from a random access memory of a video decompression processor in a manner that reduces the number of times different rows of the RAM must be addressed in order to retrieve portions of the pixel data therefrom. Pixel data from a video frame is stored in the RAM as a plurality of pages. Each page substantially fills a different row of the RAM and corresponds to a different section of the video frame. A motion vector is decoded to determine the location of a prediction area within the video frame. In the event that the prediction area encompasses more than one of the pages of the video frame, the pixel data is retrieved one page at a time, minimizing the number of row changes required when addressing the RAM to retrieve the data.

Method and apparatus for efficient addressing of DRAM in a video

A method and apparatus are disclosed for interpolating pixels to obtain subpels for use by a video decompression processor. A prediction area is defined from which subpels are necessary to decompress a portion of a video image. Instead of reading all of the pixels from the prediction area and then processing them together to perform the necessary interpolation, portions of the pixel data are read and simultaneously averaged using in-place computation in order to reduce hardware requirements. Rounding of subpixel results is achieved using the carry input of conventional adders to add a binary '1' to the averaged pixels, which are subsequently truncated to provide the interpolated subpels.

Pixel interpolation filters for video decompression processor

A video syntax parser is provided for a video decompression processor. A compressed bitstream is examined until a start code is located. The start code is decoded to enable a particular parser state corresponding thereto to be initiated. The parser state is communicated to a plurality of subsystems of the video decompression processor. Each subsystem monitors the parser state to determine which parsed data following the start code, if any, is intended for that subsystem. The subsystem then retrieves the parsed data it requires via a data bus which receives the parsed data from the parser.

Syntax parser for a video decompression processor

A video decompression processor acquires video data for a desired service from a packetized data stream. The data stream includes transport packets carrying different components of the desired service. Each component is identified by a unique packet identifier (PID). One of the components includes a program clock reference (PCR) providing timing information for the desired service. The PIDs of the transport packets are monitored to recover video packets. Header information from the recovered packets is processed to recover packetized elementary stream (PES) packets having a PES header and picture information. Time stamp information obtained from the PES header is appended to the picture information for storage in a video memory. Picture information can subsequently be read from the memory and decoded using the appended time stamp information without having to reaccess the PES header. Various schemes for detecting, masking and recovering from transmission errors are disclosed.

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Calabasas, CA, United States of America

Chris Hoogenboom