论文部分内容阅读
本文主要讨论几种可用来降低LPC声码器语言传输速率的算法,这些算法使传输速率降到300～400b/s,而且其语言质量与固定速率的2400b/sLPC声码器相比仅微有下降。我们的讨论限于传输单比(相对于全部语言段)信息的声码器。我们首先以矢量量化着手,矢量量化使比特率降到大约800b/s,其语言质量与典型的固定速率2400b/s声码器相比虽然有所损失但是可以接受的。然后我们利用以下两种技术中的一种降低帧率,这两种技术是可变内插固定速率传输和最佳可变帧率传输。我们同时还利用其频谱和某些感觉因素的统计相关性,将信源参数(基音、有无声、增益)所必须的数据率从400b/s降到大约为100b/s。最后得出结果在比特率为300b/s时声码器话音质量与固定速率800b/s矢量量化声码器不相上下。在比特率为400b/s时,其话音质量在许多方面都优于800b/s声码器,并可与2400b/S的LPC声码器相媲美。
This article focuses on several algorithms that can be used to reduce the LPC vocoder language transfer rates, which reduce the transfer rate to 300-400b / s and provide a linguistic quality that is minimal compared to a fixed-rate 2400b / s LPC vocoder decline. Our discussion is limited to vocoders that convey single-ratio (relative to all speech segments) information. We first started with vector quantization, which reduced the bitrate to about 800b / s, which is acceptable compared to the typical fixed-rate 2400b / s vocoder. Then we reduce the frame rate using one of two techniques, variable interpolation fixed rate transmission and best variable frame rate transmission. At the same time, we also use the statistical correlation of its spectrum with some of the sensory factors to reduce the data rate necessary for source parameters (pitch, sounder, gain) from 400b / s to around 100b / s. Finally, the result shows that when the bit rate is 300b / s, the vocoder voice quality is comparable with the fixed rate 800b / s vector quantization vocoder. At a bitrate of 400b / s, its voice quality is in many ways better than 800b / s vocoder and comparable with 2400b / s LPC vocoder.