MP3 decoder was developed for two different processors. The first one was based on a popular DSP from DSP Group ( www.dspg.com ) called TeakLite DSP. The second case a multimedia VLSI processor, from a reputed Japanese company, was used for development.

The reference software for MP3 decoding is available from ISO standard ISO/IEC 11172-5 (www.iso.ch) and also from MPEG sites (www.mpeg.org). This reference code is in double precision floating point format and hence unsuitable for fixed point processing. Furthermore the code is very inefficient from porting point of view and a great number of optimizations need to be performed on them.

Quality testing was performed using both subjective and objective criteria. MP3 compliance is found in the ISO standard ISO/IEC 11172-4. It defines syntax & semantic checks as well as accuracy criteria. MPEG committee defined two objective measurement standards for MP3. One is called full compliance and the other, less stringent but suitable for mobile systems, called limited compliance. Since we had to develop based on 16bit fixed point processor, we attempted and achieved for limited compliance.

Subjective testing was carried out as per ISO document "Report on the MPEG 2 AAC Stereo Verification Tests" (ISO/IEC JTC1/SC29/WG11) guidelines. The average MOS score was more than 4.5, out of 5.0

The performance parameters for TeakLite processor for standard stereo (Joint) music mp3 files at 44.1 MHz and 128 kbps and extreme cases mp3 files are as given below:-

	Standard	Worst Case
Processor Load	< 16 MIPs	< 24 MIPs
Program Memory ( Including Tables )	23 K Words	23 K Words
Data Memory	25 K Words	25 K Words