Appeal No. 2002-1961
Application No. 09/133,430 Page 9
supplies the difference values to terminal (b) of switching
circuit 105 and the discrimination circuit 106 as a difference
signal. The discrimination circuit 106 compares efficiencies for
encoding the signals of the present frame and the predictive
signal, and outputs a discriminating result which indicates which
signal is better for encoding. In short, the discrimination
circuit 106 selects the encoding system between the intra-frame
encoding and the inter-frame encoding systems. The
discrimination result controls the switching circuit 105 and
switching circuit 118 through OR circuit 108 such that (col. 4,
lines 11-21):
terminal (a) connects to a common terminal when
the efficiency for encoding the signal of the present
frame is better than for encoding the predictive
signal, and the terminal (b) connects to the common
terminal when the efficiency for encoding the
predictive signal is better than that for encoding
the signal of the present frame. On the other hand,
a control signal for forcibly setting the intra-frame
encoding system to periodically execute the refresh
operation is produced by the control circuit 107
and is supplied to another input of the OR circuit 108.
When switching circuits 105 and 118 are at terminal (a) intra-
frame encoding is being executed, and the output of adding
circuit 117 is similar to the output of block dividing circuit
103 (col. 5, lines 16-26). When switching circuit 118 is
connected to terminal (b) switching circuit 105 is outputting a
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Last modified: November 3, 2007