Zhongbo Li

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In voice over IP (VoIP) applications, playout buffering algorithms based on a tradeoff between delay and loss can be used to alleviate the effect of jitter. In the past, the aim of most buffer algorithms was not to improve the perceived speech quality directly, but to reduce the buffer delay and the packet loss rate. Then a quality-driven approach was(More)
Packet loss affects the received speech quality greatly in VoIP (voice over Internet Protocol) applications. PCM (pulse code modulation) coders are often used for VoIP and also face such problems. In this paper, a packet loss recovery algorithm is proposed based on CSI (coding with side information) and rate-distortion optimization. Two virtual(More)
In VoIP (Voice over Internet Protocol) applications, packet loss affects the received speech quality greatly. PCM (Pulse Code Modulation) coders are often used for VoIP and also face such problems. In this paper a side information based packet loss recovery algorithm is proposed, which introduces a small part of corrective information to provide an enhanced(More)
The quality of service (QoS) limitation of Internet is major challenge for Voice over IP (VoIP). Delay jitter and packet loss are two essential problems which impair the communication quality. Conventional quality- driven QoS control methods usually use ITU-T E-Model to maximize the Mean Opinion Score (MOS) in terms of delay and loss. However, all these(More)
Prediction-based speech codecs are known to be sensitive to packet loss because of inter-frame dependencies in their prediction states. If a packet is lost, internal states between the encoder and decoder will become automatically out of synchronization. This causes the state error propagation and will degrade the speech quality even if the decoder receives(More)
Adaptive playout algorithms are used at the receiver to combat jitter problems in voice over IP (VoIP). The playout algorithms rely on short term estimations of the characteristics of network delay that would be experienced by up-coming voice packets. This paper proposes a new adaptive playout algorithm based on wavelet transform and kernel estimation. The(More)
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