David Sarnoff Research Center, Inc.

Thomson Licensing S.a.

Paul Harquail Meehan

Scott D Casavant

Charles Benjamin Dieterich

Michael Anthony Isnardi

Robert Norman Hurst

Paul Joseph Panaro

Noise reduction circuitry, in a video signal compression apparatus of the predictive DPCM compression type includes a simple nonlinear processing element within the DPCM loop to eliminate residues between predicted and real image signals, which are smaller than a predetermined value. Elimination of such residues dramatically reduces the amount of compressed data generated for signals including even modest amounts of noise.

Video signal compression apparatus using noise reduction

A method and apparatus for creating and using an encoded bitstream to evaluate a video decoder. The bitstream contains a sequence of pictures or frames such that when a video decoder decodes the bitstream correctly, a desired visible pattern is produced on a video display. Specifically, various display parameters or flags are varied in the bitstream to test the video decoder's ability to implement display features such as '3:2 pulldown'. For example, the bitstream is capable of demonstrating incorrect decoding of the top.sub.-- field.sub.-- first and repeat.sub.-- first.sub.-- field flags by a MPEG compliant video decoder.

Method and apparatus for evaluating field display functionality of a

A method and apparatus for creating and using a test bitstream to evaluate a video decoder. The test bitstream contains a plurality of variable length code and/or escape sequences (combination of escape code, run length code and/or level code) for testing the video decoder's ability to decode syntax elements for discrete cosine transform (DCT) coefficients. The method of fabricating the test bitstream requires the selection of the proper DCT coefficients, run and quantizer product to produce a valid test bitstream for exercising all possible test levels without causing an overflow condition. The method selects a test level and a desired DCT coefficient and then computes for an appropriate quantizer product. In turn, the quantizer product is used to compute a quantizer scale and a run. This method is repeated for all desired test levels and the resulting level/run pairs and quantizer scales are encoded into the test bitstream.

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Plainsboro, NJ, United States of America

Paul Harquail Meehan