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14 lines
525 B
Text
14 lines
525 B
Text
Investigations into how the fine tuning field affects OPL register writes.
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Findings:
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* Fine tuning only affects double voice instruments. It is only applied to
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the second voice and not the first.
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* The fine tuning value adjusts the index into Doom's frequency table. The
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offset is divided by two before being applied, so a fine tuning value of
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10 causes an offset of 5.
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* Due to integer rounding, odd numbered negative offsets are rounded down
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(away from zero), so a tuning of -3 gives an offset of -2.
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