[sdiy] Weird data patch question

[Tim Ressel]

Yo,

--- jbv <jbv.silences at club-internet.fr> wrote:
> Let's say you have a large amount of data
> about partials (time / freq / amp) somewhere
> on a HD or a flashcard or in SRAM or wherever,
> and you want to use it in some (still to be
> designed)
> DSP-based module that will process these data
> (for additive synthesis or whatever - I told you it
> was weird), how would you implement the patch
> system to transfer this data stream across modules ?
> USB ? Optical ?
> IOW it should be a high speed and wide bwth
> equivalent of MIDI-thru...

Are we talking about a one-time load, or is the data
being accessed in real time? Its its a one-time load,
then USB would be an atractive solution. You can get
those Thumb Drives that are the size of a USB
connector and store 64MB and higher.

As far as inter-module comms, again we need to know
the need. Are we talking super-fast water-cooled
cables 'are-minds-are-one' kinda comms, or occasional
massive data dumps and small packet passing? The first
might be handled by a 10base-t micronet. Its pretty
easy to impliment 10MBS interfaces these days. The
second could be something as simple as a RS-485
network.

The above solutions suggest a uP paired up with each
DSP to handle data stuff. DSPs tend to be not so
[good, easy] to make handle mundane tasks like
networks. And since uPs are so cheap these days... Or
there are uPs with built-in DSP stuff. And DSPs with
built-in uP stuff. Its all so confusing!  ;-)

Patch amangement is another issue. If you want to
load/unload/move/shuffle/save data, then you're gonna
need a display and buttons and a GUI and yuck...
Another reason for an embedded uP. 

> And while we're at it, what about a module that
> would perform realtime generation of data (about
> partials for instance, with internal consistency
> according to a few parameters that would be VC)
> to be used by other modules that would crunch /
> process these numbers, according to some other
> VC parameters ?
> This kind of partials data stream contains the
> typical
> parameters used by a DVCO performing additive
> synthesis, but the idea is to use the raw data for
> other
> purposes (don't ask me which ones)...

So a master thingie generating partial info, and some
slave thingies making sounds with those partials?
Well, anything is possible. Which the engineer's
curse. An infinity of ideas: which one to do?

A DSP can take an extensive partials map
(freq/amp/time/excitation amp/excitation position),
run several digital oscillators based on said
partials, sum the results, and slam the data out to a
DAC.

I should point out that partials may not be enough.
take a guitar string: as the string vibrates over the
nut, the effective length of the string changes. When
the string is up, it is longer. When it is down, its
shorter. So the pitch changes on a per-cycle basis.
This kind of effect can be done ina DSP, but different
info would be needed.
 
> Yes, it sounds more like an analog emulation
> project that would be easier to implement on the
> Nord Modular or similar gear.
> But still I find the idea of hardware implementation
> quite exciting...

One of my dreams is to do analog modelling like this
on a DSP. My little Sharc wuld do nicely...

--tr


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