Impact of video transcoding artifacts on the subjective quality

Video transcoding is an important step to enable interoperability between different networks, terminals, applications, and services for video communication. This paper studies the influence of typical video transcoding artifacts due to frame rate reduction and drift error on the subjective quality. Given a realistic dataset for a DVB-T to DVB-H transcoding scenario, the subjective quality before and after the transcoding is compared against each other. In order to quantify the influence of both artifacts, a pixel domain and an open loop transcoding solution have been considered. Since the strength of both artifacts depends largely on the initial encoding parameters, additional experiments have been conducted to quantify the influence of the distance between I frames and the number of consecutive B frames on the subjective quality.