[sdiy] Vocoder dabblings

[Richie Burnett]

Hi all,

Thanks for the feedback, some comments below...

Paul Maddox wrote:
    > This going to be available as a module? or some kind of kit?

Unfortunately not, it is just really for a bit of fun.  It doesn't come 
close to the pristine 24-bit 96kHz audio spec people have come to expect 
these days, so I don't plan on developing it into a product or anything.  I 
do have a bright blue VFD screen from a cash-register here though, so might 
try to pimp it up with that showing the vocoder band levels and just keep it 
as a toy!

Dan Snazelle wrote:
    > Id love to Know what the code looks like!!! Ive been trying real hard 
to find dspic projects i can learn from

It looks like a real mess!  It's written in dsPIC assembly language and some 
of the instruction-level optimisations make it very hard to follow now. 
There are quite a few work-arounds too to make it viable on a 16-bit DSP so 
it's definitely not the best starter project to get you into DSP!

Tom Farrand wrote:
    > F'in ace man!  Wish I had the chops to code that up.  Are there any 
RDKs
    > out there that would help a noob slog through such things?

The best way to get into this stuff is to start programming small things 
like Delay, Chrous and Flanger effects as you did, then move on to filters, 
reverbs, compressors, etc, and combine the blocks together as you get more 
confident.  The vocoder is really just a shed load of filters and controlled 
gain blocks.  The details (and challanges) come in the implementation.  You 
can find a lot of good stuff about audio DSP in the archives of the Music 
DSP mailing list and on Julius O Smith's excellent website.  The effects 
papers by Jon Dattorro are also worth grabbing for a read.

    > About a decade ago I turned a PIC18F part into a low-quality flanger. 
It
    > was crude but the effect was more than just noticeable.  Still, 
absolute
    > crap compared to your demos, as I had little idea what I was doing...

Quality can be improved.  It's just good you got it working.  It's easy to 
see your mistakes and improve once you've got V1.0 working on your desk.

-Richie,

PS. Tom Wiltshire, I composed a reply to your post while away.  Will email 
from laptop tonight :-)