| 摘要 |
A synchronization control apparatus and method enables synchronization control which can flexibly accommodate various frequencies using a simple circuit construction. A storage device that has a predetermined capacity, such as a FIFO, stores externally input data. A CPU controls an output frequency at which data stored in the storage device are output, based on an average frequency which is an average of the output frequency and on a coefficient for setting the average frequency at a fixed value, the first frequency controlling device calculating the average of the output frequency whenever a timing signal is input in accordance with a predetermined cycle and determining the coefficient depending on a free capacity of the storage device at a time of inputting of the timing signal. The CPU operates if the calculated average frequency continuously exhibits a fixed value for a predetermined time period, to decrease the output frequency when the free capacity of the storage device is larger than a predetermined upper threshold value, while increasing the output frequency when the free capacity of the storage device is smaller than a predetermined lower threshold value. The upper threshold value and the lower threshold value each comprise two different values.
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