Ripley, 16 juni 2006.

I once looked at the feasibility of this, and calculated that it is
theoretically possible to write a real-time MP3 decoder (i.e. one that can
handle a stream) on a dsPIC running at the highest frequency, with a large
amount of memory (possibly even requiring 32 KB of external RAM). It is
highly unlikely that this could be accomplished in C, however. Especially
the critical path will need finely tuned assembly code, and even then it
would be impossible to get higher than stereo 128 kb/s of decoding speed.
You could cut corners by reducing the number of bits in the calculations,
but this would increase the noise level to above that required by the
standard.

I believe a frenchman (Gerard Samblancat) succeeded writing such a decoder
for a dsPIC demoboard in one of the Microchip competitions, but I have not
seen the actual implementation, nor do I know what the maximum speed of the
MP3 file was. Also, that demoboard had certain audio facilities available,
which he might have used.

Of course, decoding a MP3 from an external card to an external card, without
the real time requirement, is easily possible, but this wouldn't be
considered a "stream".

Greetings,
Maarten Hofman.
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist