Performance evaluation of video coding schemes working at very low bit rates

Video coding at very low bit rates (VLBR), in the range of a few tens of kbit/s, is becoming very attractive for a number of new applications such as mobile videocommunication, videotelephony on the public switched telephone network (PSTN), multimedia electronic mail, remote sensing, interactive data bases, etc. The paper describes two VLBR predictive transform video coding schemes, compatible with existing standards. A subjective test was carried out to compare their performance. The assessment method was based on the double stimulus impairment scale method, even though important deviations were introduced to obtain more representative data. Results are presented in terms of both mean opinion score (MOS) and signal to noise ratio (SNR). Analysis of variance was also performed to evaluate the contribution of coding parameters to subjective quality variability