Research On Videophone Quality Assessment Based On The 3G.324M Protocol

The 3G.324M protocol is a point-to-point real-time protocol for videophone over 3G network. In this thesis, the factors which impact the quality of videophone using 3G.324M are analyzed, based on which the related quality assessment is addressed. According to the characteristics of videophone based on G.324M, this thesis is focused on quality assessment using the bit-rate and delay.The coding bit-rate is crucial to the audio and video quality. This thesis first analyses the relationship between the coding bit-rate and the quality of the audio and video, building a model accordingly. Then the quality of videophone is obtained by integrating the audio and video quality.Delay is another key factor to impact the videophone quality. In communications of videophone, excessive transmission delay would cause anxiety, annoying users at both ends and significantly impairing the perpetual multimedia quality. Most existing methods for quality assessment using delay are based on the audio quality. To accurately evaluate the impact of delay on videophone, the actual videophone is used for simulations, giving accurate subjective scores by providing the subjects with real feeling of transmission delay. Moreover, experimental results show that the perception of delay is different for different content of videophone. Accordingly, a quality assessment method based on the temporal characteristic of the conversation content is proposed using delay and the average talkspurts. Performance gain observed from experimental results substantiates the effectiveness of the proposed method.