An Efficient H.264/AVC to HEVC Transcoder for Real-Time Video Communication in Internet of Vehicles

Because of the co-existing of H.264/AVC and high efficiency video coding standard (HEVC) in the coming long period, video transcoding technology has become an essential part of multimedia communication in the field of the Internet of Vehicles (IoV). However, due to the huge computational complexity of re-encoding processes, traditionally cascaded transcoders greatly increase the computing burden of the embedded devices and impact the real-time capability of transportation communication systems. In order to address this problem, a fast transcoding solution is proposed in this paper. First, we exploit the mapping relationship among H.264/AVC decoding information and HEVC coding unit (CU) depth decision and prediction unit (PU) mode decision. Then, a three-output classification model is built for CU depth decision processes, and a two-output classification model is built for PU mode selection processes by using support vector machine method. Finally, the models are applied into the cascaded transcoder to accelerate the re-encoding process. The experimental results show that our proposal averagely achieves up to 53.7% and 52.3% complexity reductions under Lowdelay_P_main and Randomaccess_main configurations, respectively, with the negligible rate-distortion degradation, which show a great potential in improving the transcoding efficiency in the real-time video communication system of IoV.