Appeal No. 2002-0723
Application 08/965,637
signal samples (figure 1, item 130). The coder also produces
quantization error signal samples for the base layer by inverse
quantizing (figure 1, item 140) the output of the quantizer
(130) and subtracting this inverse signal from the original input
to the quantizer (130). The second layer of the coder compares
the quantization error signal samples to a threshold reference
value (180). If the error signals samples are larger than the
threshold, then the second layer subtracts the threshold
reference value from these error signal samples (145). The
result is quantized and output by the second layer (190)
(Appellant’s spec. at page 9, lines 11-23). The threshold
reference value (180) is continuously updated as a function of
the inverse quantized (125) output of the second layer (190).
The multi-layer decoder works in an inverse manner to the coder.
Claim 1 is representative of the claimed invention and is
reproduced as follows:
1. A method of producing quantization error signal
samples for a layer of a multi-layer coder applied to
successive video frames, said method comprising:
processing in a transform domain quantization
error signal samples produced by an immediately
preceding layer, the processing including using
reference quantization error signal samples if a
measured quantization error for the quantization error
signal samples exceeds a predetermined criterion.
2
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