Inventors:
Paul Harquail Meehan - Plainsboro NJ
Paul Joseph Panaro - Helmetta NJ
Assignee:
David Sarnoff Research Center, Inc. - Princeton NJ
International Classification:
H03M 1300
H04N 764
Abstract:
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.