Embedded Linux Mp3 Player And Implementation

After digitization of audio signal, one important problem emerge it' s that how to storage and transport so enormous datas . so the application of audio compress technology in the filed of broadcast, network transport and multimedia is been pay more attention to , it has became the pivotal thechnology in process of audio signal.MPEG is short for ( Moving Picture Experts Group). In the end of 1992 MPEG institute the first audio encoding standards for Hi-Fi (High-Fidelity) audio inner the whole world range, it's MPEG-1. MPEG-1 dispart to three parts, it's Layer1, Layer2 and Layer3. If the serial number is higher then the complexity is bigger, but it provide better eccoding rate, especially in low bit rate.MP3 is short for MPEG-1 Layer3 and MP3 is a algorithms base on apperception encoding.It is a usuallu method of audio compress in CD timbre Currently. We can obtain higher compression ratio of music data using MP3 technology, and at the same time we could receive good playback quality. The decoder of MP3 is so complex and involve lots of mathematic algotithms, further more the demand of CPU and memory is high. Currently ARM more and more popularly to the developer of embedded technologh, Because of high proportion between capability and price and abundant peripheral equipment.Because of the above background ,we have proposed the software decode scheme based on ARM9 (Advanced RISC Machines 9) microprocessor that guarantees the high tone quality while reducing the hardware cost.The thesis firstly introduces the current situation of the development of audio compress and audio code basic technology . Secondly, introduces the MPEG series international standard and MP3 audio compress standard including subband filter bank, psychoacoustic model, adaptive window switch over, Huffman coding, etc. Then, we design the hardware platform of embedded system for MP3 including how to choose the MPU etc. fourthly introduces MP3 decode procedure and file format of MP3 paticularly, Afterward thoroughly studies the international standard algorithms of each modules of the MP3 decoding procedure and explains how to realize MP3 decoding procedure. At last we analysis the deficiencies existing at present and how to improve them.