| ITU-T G.723.1 is a dual rate speech codec standard from International Telecommunication Union-Telecommunication standardization sector (ITU-T). This codec has two kinds of bit rates, i.e., 5.3 Kbps and 6.3 Kbps, which corresponds to two different algorithms. For 5.3 Kbps codec, Algebraic Code Excited Linear Prediction (ACELP) principles are used, while for the 6.3 Kbps codec, Multi Pulse-MaximumLikelihood Quantization (MP-MLQ) techniques are used. Silence compression techniques are also used in the annex A of the standard, which can further reduce the bit rate and provide more flexibility for the system design and applications. The codec standard is widely used in multi-media communication, cellular mobile communication and VoIP.The MCF5249 was designed as a system controller/decoder for MP3 music players. The 32-bit ColdFire core with Enhanced Multiply Accumulate (EMAC) unit provides optimum performance and code density for the combination of control code and signal processing. The integrated peripherals and EMAC allow the MCF5249 to replace both the microcontroller and the DSP in certain applications. It is an excellent general purpose system controller at a very competitive price.The main task of this thesis is to develop and optimize G.723.1 codec on the Freescale's MCF5249. The time consumed by the codec, which run onμClinux OS, should not be more then 18ms/frame and the test vector should be all passed. For the complexity and computational requirement for the G.723.1, there are a lot of works to do. By careful exploiting the algorithm and rewrite most of the functions in assemble language, we can meet the challenges. |
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