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A Feed-Forward Dynamic Voltage Control Algorithm for Low Power MPEG4 on Multi-Regulated Voltage CPU
Hideo OHIRA Kentaro KAWAKAMI Miwako KANAMORI Yasuhiro MORITA Masayuki MIYAMA Masahiko YOSHIMOTO
IEICE TRANSACTIONS on Electronics
Publication Date: 2004/04/01
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Low-Power System LSI, IP and Related Technologies)
MPEG4 encoder, low power, feed-forward voltage control, multi-regulated voltage CPU,
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In this paper, we describe a feed-forward dynamic voltage/clock-frequency control method enabling low power MPEG4 on multi-regulated voltage CPU with combining the characteristics of the CPU and the video encoding processing. This method theoretically achieves minimum low power consumption which is close to the hardware-level power consumption. Required processing performance for MPEG4 visual encoding totally depends on the activity of the sequence, and high motion sequence requires high performance and low motion sequence requires low performance. If required performance is predictable, lower power consumption can be achieved with controlling the adequate voltage and clock-frequency dynamically at every frame. The proposed method in this paper is predicting the required processing performance of a future frame using our unique feed-forward analysis method and controlling a voltage and frequency dynamically at every frame along with the forward analysis value. The simulation results indicate that the proposed feed-forward analysis method adequately predicts the required processing performance of every future frame, and enables to minimize power consumption on software basis MPEG4 visual encoding processing. In the case that CPU has Frequency-Voltage characteristics of 1.8 V @400 MHz to 1.0 V @189 MHz, the proposed method reduces the power consumption approximately 37% at high motion sequences or 65% at low motion sequences comparing with the conventional software video encoding method.