Video telephony - quality of experience: a simple QoE model to assess video calls using subjective approach

One problem about using video calls or video telephony applications is a quality issue. Therefore, this paper contributes the simple QoE model, a mathematical model, to assess quality of video calls provided by video telephony applications or services. This mathematical model has been created based on the results from 200 subjects who joined the subjective test using short conversation scenario via two applications, Skype and LINE, two popular applications/services in Thailand. Based on the subjective results, the weighted coefficients for audio quality and video quality have been found, while the coefficient for audio quality is weighted higher than the one for video quality. Nevertheless, after using ANOVA and t-test, statistical analysis tools, based on the first set of the subjective data, it has been found that there are significant differences (p-values<0.05) when compared to most previous QoE models from other research works. However, after performance evaluating using Mean Absolute Percent Error (MAPE), it has been found that its performances are better than previous models with average MAPE values of 10.4 and 5.65% in the first and the second round evaluation with the other 48 subjects and 32 subjects respectively. Therefore, these are evident that this model can be applied to evaluation quality of video calls with confidence.