| 摘要 |
System for reducing power consumption in MPEG-2 compliant video encoder circuitry employs logic for controlling first clock signals input to functional I, HSU and RSU blocks and functional sub-units performing specific tasks therein. Second clock signals are continuously input to a processing detection circuits requiring continuous clock inputs throughout video encode operations for a functional sub-unit. A trigger signal is asserted by the sub-unit itself or, an external processor, to indicate idle or active processing for that particular sub-unit. The combination of the second clock signals and receipt of the trigger signal enable the sub-unit to generate a sleep signal for that sub-unit which is input to a clock control circuit to either enable input of first clock signals to the functional sub-unit during active processing or, disable input of the first clock signal during idle, in-active processing periods, for as long as the trigger signal is asserted. There are a variety of video input conditions that may be detected which will enable generation of a trigger signal indicating idle processing for one or more functional sub-units, including, for example, detection of still input pictures, fade sequences and specification of high bitstream output rates.
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