A perception-aware low-power software audio decoder for portable devices

We propose a new software audio decoder for processors supporting multiple discrete voltage-frequency operating points. The proposed decoding scheme allows the user to switch between multiple output quality levels, where each level is associated with a different rate at which the processor consumes energy. This is an attractive feature in battery-powered portable audio players and mobile phones, where battery-life is often more crucial than the output quality, especially in noisy environments. Towards this, the frequency range of the decoder is partitioned into multiple groups, in accordance with their perceptual relevance. When a longer battery life is desired, only the most relevant frequency components are decoded, which allows the processor to be run at a lower voltage and frequency. We have implemented this scheme using the MP3 decoder and obtained up to 95% savings in the energy consumed by the processor for AM quality output (in contrast to CD quality output, which is associated with the maximum energy consumption). This scheme is easy to implement, has no runtime overhead and does not involve any runtime voltage or frequency scaling.