School of Information and Communications, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
Sensors (Basel). 2011;11(5):5323-36. doi: 10.3390/s110505323. Epub 2011 May 17.
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.
本文提出了一种用于 CELP 型语音编码器的分组丢失隐藏（PLC）算法，以提高无线传感器网络中突发分组丢失情况下解码语音的质量。G.729 语音编解码器中的传统基于接收机的 PLC 算法通常基于语音相关性，通过使用从前一个正确接收的帧中获得的参数信息来重建丢失帧的解码语音。然而，这种方法在重建语音起始信号时存在困难，因为前一帧的参数，如基音、线性预测编码系数和自适应/固定码本，主要与静音帧有关。因此，为了在语音起始间隔中重建语音信号，我们提出了一种基于多个码本的方法，该方法包括传统的自适应码本和由舒适噪声组成的新的随机码本。所提出的 PLC 算法被设计为 G.729 的 PLC 算法，然后通过语音质量感知评估、波形比较和在不同随机和突发分组丢失条件下的偏好测试，将其性能与 G.729 中当前使用的 PLC 算法进行比较。实验结果表明，在所测试的所有条件下，所提出的 PLC 算法比 G.729 中使用的 PLC 算法提供了显著更好的语音质量。
