A Low-Power Video Recording System With Multiple Operation Modes for H.264 and Light-Weight Compression

摘要

An increasing demand for mobile video recording systems makes it important to reduce power consumption and to increase battery lifetime. The H.264/AVC compression is widely used for many video recording systems because of its high compression efficiency; however, the complex coding structure of H.264/AVC compression requires large power consumption. A light-weight video compression (LWC), based on discrete wavelet transform and set partitioning in hierarchical trees, consumes less power than H.264/AVC compression thanks to its relatively simple coding structure, although its compression efficiency is lower than that of H.264/AVC compression. This paper proposes a low-power video recording system that combines both the H.264/AVC encoder with high compression efficiency and LWC with low power consumption. The LWC is used to compress video data for temporal storage while the H.264/AVC encoder is used for permanent storage of data when some events are detected. For further power reduction, a down-sampling operation is utilized for permanent data storage. For an effective use of the two compressions with the down-sampling operation, an appropriate scheme is selected according to the proportion of long-term to short-term storage and the target bitrate. The proposed system reduces power consumption by up to 72.5% compared to that in a conventional video recording system.