Abstract
In this paper, a packet loss concealment (PLC) algorithm for CELP-type speech coders is proposed in order to improve the quality of decoded speech under burst packet loss conditions in a wireless sensor network. Conventional receiver-based PLC algorithms in the G.729 speech codec are usually based on speech correlation to reconstruct the decoded speech of lost frames by using parameter information obtained from the previous correctly received frames. However, this approach has difficulty in reconstructing voice onset signals since the parameters such as pitch, linear predictive coding coefficient, and adaptive/fixed codebooks of the previous frames are mostly related to silence frames. Thus, in order to reconstruct speech signals in the voice onset intervals, we propose a multiple codebook-based approach that includes a traditional adaptive codebook and a new random codebook composed of comfort noise. The proposed PLC algorithm is designed as a PLC algorithm for G.729 and its performance is then compared with that of the PLC algorithm currently employed in G.729 via a perceptual evaluation of speech quality, a waveform comparison, and a preference test under different random and burst packet loss conditions. It is shown from the experiments that the proposed PLC algorithm provides significantly better speech quality than the PLC algorithm employed in G.729 under all the test conditions.
Highlights
IntroductionThere have been rapid developments in the wireless sensor networks (WSNs) field due to recent advances in related devices, such as new ultra low-power microcontrollers and short-rage transceivers
wireless sensor networks (WSNs) where each router node is connected by wireless local area network (WLAN) links and real-time transport protocol/user datagram protocols (RTP/UDPs) [3]
A receiver-based packet loss concealment (PLC) algorithm for Code-excited linear prediction (CELP)-type speech coders is proposed as a means of improving the quality of decoded speech under burst packet losses, especially when the packet loss occurs during voice onset intervals
Summary
There have been rapid developments in the wireless sensor networks (WSNs) field due to recent advances in related devices, such as new ultra low-power microcontrollers and short-rage transceivers. A receiver-based PLC algorithm for CELP-type speech coders is proposed as a means of improving the quality of decoded speech under burst packet losses, especially when the packet loss occurs during voice onset intervals. Voice excitation is obtained from the adaptive codebook excitation scaled by a voicing probability, whereas random excitation is generated by permuting the previous decoded excitation in order to compensate for an undesirable amplitude mismatch under burst packet loss conditions This approach has difficulty in accurately reconstructing voice onset signals since parameters such as pitch period, linear predictive coding (LPC) coefficients, and adaptive/fixed codebooks of the previous frames are mostly related to silence frames [9].
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