A DSP-based decompressor unit for high-fidelity MPEG-Audio over TCP/IP networks

Master's thesis for the M.Sc. Eng. Phys. degree

By Bjrn Wesn

At Lund Institute of Technology in cooperation with Axis Communications AB in Lund, Sweden

Supervisors: Stefan Sandstrm (Axis), Mats Cedervall (IT/LTH)

Abstract

Recently, algorithms that can compress audio-signals like music without perceptible loss up to ratios around 1:12 have emerged. This makes it possible and very feasible to store large amounts of music on comparatively small amounts of storage media. It also makes it possible to implement realtime playback of music over low-bandwidth computer networks. The goal of the thesis was to demonstrate this using dedicated, embedded hardware that performs the network accesses and audio decompression without the aid of an external computer. The chosen algorithm is MPEG-1/Layer-3, and it has been implemented using C and assembler on a Texas TMS320C31 DSP. The network access is done using an Axis NPS570 printerserver, using Axis embedded ethernet processor ETRAX. The unit accepts MPEG compressed audio over a network using the TCP/IP protocol suite, and feeds it into the DSP for decompression and playback.

The thesis

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Copyright Notice

Copyright 1997, Bjrn Wesn. All rights reserved.

Permission to use, copy, or modify this documentation for educational research purposes only and without fee is hereby granted provided that this copyright notice and the original author's name appears on all copies and supporting documentation. For any other uses of this documentation in original or modified form, including but not limited to distribution in whole or in part, specific prior permission must be obtained from the author.