Digital video decoder for decoding digital high definition and/or digital standard definition television signals
AssigneeHitachi America, Ltd.
InventorsJill M. Boyce, Larry Pearlstein
Life of this patent
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Abstract
Methods and apparatus for reducing the complexity of decoder circuitry and video decoder memory requirements are disclosed. The described video decoders are capable of decoding HDTV pictures at approximately the resolution of standard definition television pictures and can be used to decode HDTV and/or SDTV pictures. The described video decoder may be used as part of a picture-in-picture decoder circuit for providing picture-in-picture capability without providing multiple full resolution video decoders. The reduction in decoder circuit complexity is achieved through the use of a plurality of data reduction techniques including the use of a preparser, downsampling, and truncating pixel values.
Claims23
A decoder circuit for decoding digital video data including pictures at a resolution less than the full resolution of the pictures, each picture including a plurality of macroblocks, each macroblock including a plurality of DCT coefficients, the decoder circuit comprising:
- preparser means for receiving the digital video data and for removing from each macroblock DCT coefficients that exceed a preselected maximum number of DCT coefficients per macroblock;
- and
- a channel buffer coupled to the preparser means for temporarily storing the video data output by the preparser means.
A method of decoding variable length encoded digital video data including pictures, to a resolution less than the full resolution of the pictures, each picture including a plurality of macroblocks, each macroblock including a plurality of DCT coefficients, the method comprising the steps of:
- receiving digital video data;
- parsing the digital video data to identify macroblocks included in the digital video data and the DCT coefficients included in the identified macroblocks;
- discarding from the digital video data the DCT coefficients included in each macroblock that exceed a preselected number of DCT coefficients;
- and
- storing the digital video data in a coded data buffer.
A method of decoding digital data representing a video frame, the digital data representing each video frame including video data representing a plurality of pixels, the video data representing each pixel including a set of bits, the method comprising the step of:
- truncating the least significant bit from each set of bits representing one of the individual pixels;
- and
- storing the truncated set of bits representing each one of the individual pixels in a frame buffer.
A method of decoding variable length encoded digital video data including slice stuffing data, start code zero stuffing data, and macroblocks, the macroblocks representing pictures, to a resolution less than the full resolution of the pictures, the method comprising the steps of:
- receiving the digital video data;
- parsing the digital video data to identify bit slice stuffing and start code zero stuffing data;
- discarding the bit slice stuffing data and start code zero stuffing data;
- and
- storing the remaining video data in a channel buffer.
A method of decoding digital video data including an interlaced picture, to a resolution less than the full resolution of the interlaced picture, the interlaced picture including a plurality of macroblocks encoded in accordance with one of a field DCT basis or a frame DCT basis, the method comprising the steps of:
- downsampling the macroblocks encoded on a field DCT basis on a field basis;
- downsampling the macroblocks encoded on a frame DCT basis on a frame basis;
- storing the downsampled macroblocks in a frame buffer.
The method of claim 27, wherein the video data further comprises a non-interlaced picture, the method comprising the steps of:
- downsampling the non-interlaced picture on a frame basis.
Dependencies are inferred from the claim text.