A Rate-scalable Perceptual Wavelet-based Vibrotactile Codec

For a fully immersive virtual reality experience, humans have to be presented with high quality haptic stimuli in addition to audio and video. However, delivering haptic stimuli with high level of realism is still challenging. An important component of haptic stimulation is based on vibrotactile signals. They are emitted when sliding a tooltip or a finger over a textured surface and carry a large amount of information about the surface material properties. Vibrotactile signals have received considerable attention so far, though as the number of interaction points to be displayed will start to increase soon, it is vital that data rates are kept low. This calls for an efficient codec that is able to compress these signals while maintaining perceptual transparency. The IEEE P1918.1.1 standardization group has issued a call for contributions for such a codec. In this work, we present our contribution to this standardization effort. We have developed a highly efficient codec which employs a discrete wavelet transform, human tactile perceptual modeling, quantization, and lossless coding to achieve high compression, while maintaining perceptual signal quality. The proposed vibrotactile codec compresses the signals at least by a factor of 10 with practically no perceptual impairment for most signals. Thus, our approach significantly outperforms the current state-of-the-art.