Adaptive MPEG-4 video transmission over PSTN using buffer constraints and RTP feedback

Video transmission over PSTN often suffers from some difficulties such as the bandwidth fluctuation, packet loss and transmission delay. Combining the send buffer and network feedback information, this paper brings forward an adaptive video transmission control algorithm JCBAF to timely notify the encoder to get a better match between the output bit-rate and fluctuated bandwidth. Furthermore, a smooth control strategy is proposed to inform the encoder to achieve a better trade off between a lower delay and a good perceptual video quality. Experimental results show that the method can effectively control delay in very low bit-rate video transmission over PSTN or other error prone channels while maintain the video quality.