| With the rapid development of multimedia technology, speech compression becomes more and more crucial in the modern society. In the recent decades, various methods have been proposed and used in business. High quality and low rate speech compression arithmetic is the focus in the speech coder research. Digital signal processor (DSP) is especially designed for real-time signal processing, which is designed particular hardware architecture and program environment. DSP provides an excellent planform for speech compression technology development. Telecommunication Standardization Sector of International Telecommunication Union proposed G.729A as a kind of high quality and low rate speech coding solution in 1996. TMS320C6711 is an advanced floating-point DSP, which is released by Texas Instrument. The author implements real-time speech coding and decoding on DSP successfully according to the theory of G.729A and the characters of TMS320C6711 in hardware architecture and software program. Firstly, G.729A is optimized based on the requirements of the project; then it is simulated by ANSI C on PC and the paper lists the result of simulation; in the end, the speech coder is optimized according to TMS320C6711 EVM and realized based on DSP/BIOS RTOS (Real Time Operating System). The author evaluates the speech compression system based on DSP. The test result indicates two items: (1) the arithmetic has passed ITU-T test vector (2) speed coding consumes 1.1ms on every speech frame, and speech decoding consumes 0.29ms on every speech frame, which can real-time implemente multichannel speech coder on TMS320C6711 DSP. This DSP speech compression module can be widely applied in many fields, such as digital speech recorder, VoIP, conference call and digital broadcasting. |
