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江兆祥 《电信工程技术与标准化》2003,(4):89-91
本首先介绍了语音编码技术中对语音质量的评价方法,然后对几种典型的IP电话语音压缩技术标准进行了阐述,最后,对三种常用的IP电话语音压缩技术参数进行了比较。 相似文献
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Results of experimental comparisons of forward- and backward-adaptive prediction in differential pulse code modulation (DPCM) of speech are presented. Two different types of comparisons are conducted. In one comparison, both predictors are used with the same three/five-level pitch compensating quantizer (PCQ). For this comparison, forward prediction clearly outperforms backward prediction, but with the penalty of a 10% increase in data rate due to the need to transmit coefficients. In the second comparison, the forward-prediction DPCM system and the backward-prediction DPCM system are constrained to have the same data rate of 16 kbits/sec. The backward-adaptive predictor outperforms forward prediction for this latter comparison. The speech data base for the simulations is one sentence spoken by a male speaker in four different languages: English, French, German, and Arabic. The performance comparisons are based on signal-to-quantization noise ratio, signal-to-prediction error ratio, sound spectrograms, and formal subjective listening tests. 相似文献
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本文主要介绍了CCITT G.722建议的编译码器的硬件实现,以及利用低速EPROM与高速RAM替代高速PROM的方法.在系统不增加额外的管理控制CPU的情况下,将低速EPROM内的汇编码字分别写到编码器和译码器的高速RAM内.在不引起编译码系统混乱的前提下,将时钟由低切换到高. 相似文献
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