Comparative Analysis of Audio Coders and Packet-Loss Recovery

T.-K. Chua and D.C. Pheanis (USA)


: audio coder, packet loss, VoIP, iLBC, G.729A, Quality of service (QoS), Mean Opinion Score (MOS).


Voice over Internet Protocol (VoIP) is a technology that transports voice data packets across a packet switched network using the Internet Protocol (IP). The routers in the network can drop voice packets, especially when the network is congested, and losing packets degrades the quality of the audio. To miti gate the undesired effects of packet loss, some devel opers use audio-coder algorithms with packet-loss ro bustness, and other designers use delivery techniques that are resilient in the face of packet loss. We analyze and compare the packet-loss robustness of two audio-coder algorithms and one packet-loss re covery technique. We study the effectiveness of each approach under various loss conditions. To produce a fair, thorough comparison, we consider related factors that affect audio quality. We find that a good packet loss recovery technique can provide better packet-loss resilience than we can achieve with comparable band width using an audio-coder algorithm that includes packet-loss robustness.

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