TMS320C54X实现ITUG 728语音编码标准

Implementation of ITU G 728 Speech Codec on TMS320C54X

ＩＴＵ Ｇ７２８ 标准是国际电信联盟于１９９２ 年推出的一种比特率为１６ Ｋｂ／ｓ低延时ＣＥＬＰ类型语音编解码器。本文首先对Ｇ７２８ 编解码算法和定点数字信号处理芯片ＴＭＳ３２０Ｃ５４Ｘ作了简单介绍。由于Ｇ７２８ 标准是一种低延时语音编码标准，因此计算复杂度高，在实时实现中需要作特别处理。本文着重介绍了这种低延时ＣＥＬＰ（ＬＤＣＥＬＰ）算法在ＴＭＳ３２０Ｃ５４Ｘ上实现的软、硬件设计和在定点ＤＳＰ芯片上实现此算法的一些关键技术，并给出了实际试验结果。实际结果表明，一路全双工实现所需计算量为３３ ＭＩＰＳ（兆整点指令每秒），１．７ Ｋ字程序空间和２．３ Ｋ 字数据空间。

ITU G 728 recommendation is a scheme for coding speech at 16 Kbit/s using low delay code excited linear prediction (LD CELP). In this paper, the algorithms of LD CELP and TMS320C54X fix point DSP chip are presented briefly. As the G 728 recommendation is a low delay speech codec, its complexity is very high. So how to reduce the complexity is a key issue during real time implementation. This paper introduces some key techniques for the real time implementation of LD CELP based on TMS320C54l chip in detail. As a result, one full duplex implementation needs 33 MIPS, 1.7 K words of program memory, and 2.3 K words of data memory.