Master's thesis report on a DSP-implementation of MPEG-1 Layer-3 audio available

Master's thesis report on a DSP-implementation of MPEG-1 Layer-3 audio available

Post by Bjor » Fri, 14 Nov 1997 04:00:00

(Please use bjorn at for email and dont use the reply-to adress
since I've scrambled it to avoid junk mails)

Now and then there pop up questions about DSP-implementation of MPEG-1
Layer-3 audio, (aka MP3). In my Master's Thesis for a M.Sc. Eng. Phys.
degree, I developed a networkable standalone DSP-based decompressor for MP3
music, including both hardware and software. The work was carried out at
Axis Communications AB in Lund, Sweden, in cooperation with the Lund
Institute of Technology. The report is now available on the web, at:

There is a link inside for downloading the complete document base for local

This is the title and abstract:

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


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."

Hope you might enjoy reading it. If there are any comments, please direct
them to me at the (unscrambled) mail adress at the top of this post.


Bjorn Wesen
R&D Engineer, New Projects
Axis Communications AB
Lund, Sweden


1. MPEG audio Layer-3 shareware available!

Our MPEG audio Layer-3 shareware (stereo encoder and stereo decoder), version
0.99, is now available:

via anonymous ftp from (
via modem download from +49 911 9933662 (Name: FHG),

The programs are written for IBM-PCs or Compatibles with MS-Dos.
On a 486DX2/66, the performance of the software decoder is about 33 % of the
performance necessary for real-time audio processing. The encoder needs about
30 minutes to encode a 1 minute audio data file. These figures assume
encoding/decoding of stereo audio material at 44.1 kHz /sec.

Happy Coding!

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