IJSRD - International Journal for Scientific Research & Development| Vol. 1, Issue 6, 2013 | ISSN (online): 2321-0613 All rights reserved by www.ijsrd.com 1295 Abstract— MP3 has become one of the most popular standards for digital audio and video broadcasting. High compression ratios offered by MP3 codecs in various standalone players and hand held devices over the last few years has increased its popularity immensely. Internet users, music lovers who would like to download highly compressed digital audio files at near CD quality are the most benefited. Psychoacoustic model, Modified Discrete Cosine Transform (MDCT) and Huffman coding play a vital role in achieving such magnificent compression ratios. In this work, the performance and result of each different block of Mp3 decoder is shown in VHDL using Modalism as the simulation tool. Testing and simulation were made to ensure full functionality of the design. An MP3 song of 128bitrate, 44 KHz and single channel is selected for the simulation. The simulation results show the effectiveness to implementation of Mp3 decoder in VHDL. Keywords: MP3, Decoder, VHDL I. INTRODUCTION The mobile multimedia service has changed people’s daily lifestyles. It is not difficult to find people who listen to music or watch TV via their mobile devices such as mobile phones, MP3 players, and portable media players. People can have a variety of experiences with their mobile devices. MPEG Layer-3, otherwise known as MP3, has generated a phenomenal interest among Internet users, or at least among those who want to download highly-compressed digital audio files at near-CD quality [1-3]. In this work, the decoding process of MP3 decoder is presented. Incoming MP3 streams are fed into the input module of the decoder and processed. If the synchronization word is found and CRC word is successfully checked, the output main data containing scale factors and Huffman code bits are sent to a predefined buffer. Huffman decoder reads data from buffer and decodes them. The decoded scale factors are delivered to requantizer component. The output 576 frequency lines are written to main memory. Using the input scale factors, requantizer descales the 576 small integer numbers output from Huffman decoder. Reordering process is applied to reorder the frequency lines including short window blocks. The functionality of the last four components--- anti alias, IMDCT, frequency inversion and filter bank is to transform the MP3 from frequency domain to time domain. By merging frequencies using butterfly calculations, anti-alias reduces the alias effects introduced from the non-ideal Bandpass filter used in encoding process. In IMDCT, 576 frequency lines are divided into 32 sub bands with 18 frequency lines in each. Applying multiplications and cosine calculations to each 18 samples depending on four classes of window type, IMDCT generates samples for filter bank component. After the frequencies of the input samples are inverted by frequency inversion, filter bank exploits MCT to translate the aliased signals and filter out the undesired aliasing in translated signals by using windowing. Hence, the signals in frequency domain are converted back to their time domain origins. A. II. DECODER DESIGN FLOW CHART Fig. 1: MPEG 1 Layer III decoder flow chart II. MP3 DECODER OPERATION The quantized samples are derived from the Huffman codes in the Huffman decoding block. The necessary side information needed for Huffman decoding is obtained from Mp3 Decoder Design & Implementation Using VHDL Ravindar Sharma 1 Ghanshyam Kumar Singh 2 Ram Mohan Mehra 3 1,2,3 Department of ECE,School of Engineering & Technology 1,2,3 Sharda University, Greater Noida, UP, India.