In the past years, several works have proposed custom hardware and software-based techniques for the acceleration of Convolutional Neural Networks (CNNs). Most of these works focus on saving computations by changing the used precision or modifying frame processing. To reach a more aggressive energy reduction, in this paper we propose software-only modifications to the CNNs inference process. Our approach exploits the inherent locality in videos by replacing entire frame computations with a movement prediction algorithm. Furthermore, when a frame must be processed, we avoid energy-demanding floating-point operations, and at the same time reduce memory accesses by employing look-up tables in place of the original convolutions. Using the proposed approach, one can reach significant energy gains of more than 25× for security cameras, and 12× for moving vehicles applications, with only small software modifications.

Approximate computing has recently reemerged as a design solution for additional performance and energy improvements at the cost of output quality. In this paper, we propose using a tree-based classification algorithm as an approximation tool for general-purpose applications. We show that, without any hardware support, completely implemented in software, our approach can improve performance by up to 4x (1.95x on average) and reduce EDP by up to 19x (4.04 on average) when compared to precise executions. Besides that, in some cases, our software-based mechanism can even outperform traditional hardware-based Neural Network's state-of-the-art designs.