Embedding Perceptual Metrics in Rate Control Algorithms

In this paper, we describe a perceptually-motivated rate control algorithm for variable bit rate (VBR) speech coding. Unlike the existing rate selection strategies that are based on statistical metrics, the proposed method employs a perceptual loudness (PL) measure. The VBR speech standard TIA IS-127 enhanced variable rate codec (EVRC) has been chosen as the test-bed for evaluating the performance of the PL-based rate selection strategy relative to three other existing methods. In particular, the comparative study includes the following rate determination algorithms: voice activity detection, speech frame energy-thresholding, and phonetic segmentation. Experimental results demonstrate that the proposed PL-based RDA compares well against other rate selection techniques in terms of average bitrate and speech quality