Lip reading using external viseme decoding

Lip-reading is the operation of recognizing speech from lip movements. This is a difficult task because the movements of the lips when pronouncing the words are similar for some of them. Viseme is used to describe lip movements during a conversation. This paper aims to show how to use external text data (for viseme-to-character mapping) by dividing video-to-character into two stages, namely converting video to viseme and then converting viseme to character by using separate models. Our proposed method improves word error rate by an absolute rate of 4% compared to the typical sequence to sequence lipreading model on the BBC-Oxford Lip Reading dataset (LRS2).