On the Importance of a VoIP Packet

If highly compressed multimedia streams are transported over packet networks, losses of individual packets can impair the perceptual quality of the received stream in different degrees, depending on the content and context of the lost packet. In this paper, we investigate the impact of individual packet loss on the perceptual speech quality in Voice-over-IP systems using three popular coding types and receiver-side loss concealment algorithms. We set up a testing environment to measure the impairment of individual packet losses and define an appropriate quality metric. We evaluate published algorithms on packet loss quality prediction (DTX, Source-Driven Packet Marking and SPB-DiffMark) and identify their strengths and weaknesses. The quality of a VoIP telephone call can be enhanced significant, if a precise packet-loss quality model decides for each VoIP packet, how it should be forwarded throughout the network.