M65727FP Datasheet, PDF (13/55 Pages) Mitsubishi Electric Semiconductor – MPEG2 MOTION ESTIMATION LSI

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3.2.3 Motion detection Unit
The function of this block is to select the vest motion vector of the integer-pel precision by comparing
the 16-bit mean absolute error coming from the Integer-pel Unit. In addition, this block stores
distortion of vector (0,0). In case when the distortions for multiple motion vectors are same, the most
suitable motion vector is determined according to the order of priority.
The output data depends on the modes. When the integer-pel precision search mode is specified during
the Field/Frame mode, the following items are output to the Output Unit. They are three sets of best
integer-pel precision motion vectors, the distortion for each, and the distortion for each vector (0,0). If
the half-pel precision search mode is specified when the Field/Frame mode, the three sets of best
integer-pel precision motion vectors and the distortion for each vector (0,0) are output to the Output Unit.
And, the distortions for each integer-pel precision vector are output to Half-pel Unit.
3.2.4 Half-Pel / Dual-Prime Unit
This Unit calculates, during the Field/Frame mode, the mean absolute errors for half-pel precision
vectors and detects the minimum distortions using the partial search window image data around best
integer-pel precision vectors.
The search window image consists of 18x18 pixels and two sets of 18x10 pixels around the three sets of
integer-pel precision motion vectors detected at the Motion detection Unit. Eight kinds of interpolated
images are generated by the half-pel interpolation filter. This image is matched against the template
MB data given from the integer-pel Unit and the minimum distortions are detected from the above
results.
During the Field/Frame Dual-Prime mode, it detects the best dmv from the template MB data, the first
search window image data and the second search window image data.
The first and second search window image consist of 18x18 pixel (10) each. The interpolated
image from the first search window is generated according to the central position information
(Displacement based on 0.5 pixel from 16x16 (8) pixels contained in 18x18 (10) pixels). Similarly,
nine sets of interpolated images are generated through the interpolated filter from the second search
window. Then, the nine sets of averaging images of the first and the second images are obtained.
Next, the block matching between the template MB data is conducted and the best dmv is obtained. In
case of the Frame Dual-Prime mode, not only the minimum evaluation value, but all the evaluated
values for all the displacement are output.
3.2.5 Output Unit
This is the interface circuit related to the Output Port, DOUT. Necessary data comes from the
Motion detection Unit and Half-pel / Dual-Prime Unit and is output to through DOUT in sync with the
output request signal, OREQC.
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