peter green wrote:

>> Maybe a PIC is not the adequate tool to do the actual detecting. It
>> probably is better suited to process the detection signal of some
>> simple hardware circuitry (similar to what you find in a typical light
>> organ).

> the way i'd do it is to do any filtering (i don't belive you'll actually
> need filtering if its direct from a dvd player) and the envelope
> detection in hardware but leave the pic to decide what level of the
> results represents sound to provide some easy software control over
> sensitivity.

An envelope detector usually contains a low-pass filter, unless you want to
sample in audio real-time, so you'd usually do filtering in the hardware
envelope detector. 

The main characteristics of envelope detection are the relative weight of
frequency bands (in the simple case, all get the same weight), the time
constant of the envelope low-pass (usually set in the hardware, can also be
different for different frequency bands) and the resulting value of the
output (that's what you can measure easily with a PIC).

Gerhard

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