This paper evaluates subjective quality and response time of real-time distance interactive environments in multipoint IP communications. Buffering control at receiver terminals is effective in improving intra-stream and inter-stream media synchronization quality, while it may degrade the inter-destination synchronization quality. By experiment, we quantitatively clarify factors which affect the subjective quality and response time when the buffering control is exerted. We then see that the overall subjective quality and response time are affected by the inter-destination synchronization quality. Furthermore, we show that the improvement of subjective quality and response time enhances the inter-destination synchronization quality.
