[sdiy] Vector-based ADC/DAC?

[ChristianH]

Well, if you're comparing vector graphics vs. raster graphics, then some
kind of an equivalent would be synthesized sound vs. sampled sound.

In graphics, vector data usually (today, that is) is converted into
raster, which could be compared to digitaly recording a synthesized
sound.
Interesting idea to skip the quantizing step. There has been something
equivalent in graphics world, pen plotters and vector CRT displays, both
pretty much extinct nowadays. 
Considering sound, this would be some kind of resynthesizing - with the,
um, simplest, form being an analog synth, which has quite limited
capabilities in terms of wave form variation. But in general, all
parameters of a patch (be it digitally stored or manually tweaked)
constitutes a set of vector elements (in the EPS sense) to create an
output sound "image".

Another place where something distantly similar takes place is the JPEG
compression. A target image is not just sampled but kind of described by
DCT (discrete cosine transform) coefficients, and reconstructed from
that on decoding.
I'm not sure about MP3, but I'd expect it to be similar. But this as
well first generates a sampled sound to be run through a normal DAC.

Another faintly related topic is vocoding. Language is converted into a
set of CVs (one for each band), and then those vector values are used to
generate something that at least has some similarity to the original
speech, without actually transmitting the original signal.

Gee, it's philosophical in here. Better open the window for a moment...

Christian



On Thu, 11 Nov 2004 19:33:47 -0500 Jay wrote:

> I guess this is sort of off-topic, but have any of you ever heard of this
> being attempted? I've had the idea in my head for a few years.
> 
> It would be basically consist of using a high speed ADC to convert audio
> vector curves, sort of an EPS file for sound recordings. Then using what I
> can best describe as a "digitally voltage-controlled high speed variable
> slope analog envelope generator" as a sort of DAC. Excuse me if my idiocy in
> this field is showing, but wouldn't that then eliminate all quantization
> that is inherent in digital recordings?
> 
> Is this even possible in real time? Is it possible as a DIY project?
> 
> Just thinking out loud...