[sdiy] Some theoretical discussion...

[Tom May]

This is reminding me of audio compression algorithms which use a model
that outputs what they expect the sound to be like in the near future,
presumably based on what it was like in the (near?) past, then send a
sequence of correction values to adjust the model to what really
happened.

Tom.

Studio 271 Productions <studio271 at mail.ev1.net> writes:

> At first I thought this could be considered OT, and it probably still
> will be by some, but I hope it inspires people to think about such a
> thing or at the very least tell me about something like this that may
> already exist.
> 
> I was waiting for the bus today when a thought struck my
> content-stricken mind. We have delay effect for sound, but why not a
> reverse delay effect; a way of hearing a sound before it actually
> occurs? That's when I decided to google up some information, and found
> a document on natural piano playing envelopes that described something
> called "yaled" ("delay" backwards), so I decided to call this
> theoretical effect this as a way of assigning it a name while I thoght
> about it.
> 
> Delay, in terms of writing styles, would be a nonfiction book about
> the past; yaled, OTOH, could either be a nonfiction futuristic book
> which derives it's information from premonitions into the future, such
> as Nostradamus' writings (this does not necessarily mean it has to
> come true, though, because it is still just a premonition. Unless
> someone here believes in predestination...) The other would be a
> fiction futuristic book (sci-fi?) which derives it's information from
> past events, such as George Orwell's "1984". This first option would
> most likely be impossible with our current technology and views about
> physics (although I remember seeing a physics program which showed a
> guy who sent analog audio through a wire and through a empty space or
> something and somehow the music got through the space before the
> wire. At least that's what I think happened; it was a few years ago
> after all. Maybe it was just a misunderstood metaphor? ;/ ), but the
> second option, the fiction futuristic based on past events seems
> plausible.
> 
> It would be a lot like a delay to a listener, maybe even almost
> identical, but it WOULD be very interesting to hear a frequency begin
> to slow down before you have it actually happen. In our state of
> technology it would basically be a type of "randomizer" which
> attempted to guess a change in the voltage level before one actually
> occurs.
> 
> It took me a while to come up with a way that one could do this, but I
> came up with a logic structure to base it on:
> 
> x = streamed instantanious sound
> a = x
> wait a designated amount of time
> b = x
> if a = b,  then c = b
> if a > b, then c = b(minus an arbitrary unit)
> if a < b, then c = b(plus an arbitrary unit)
> output c
> 
> That seems to represent what I am talking about. However, I would like
> some feedback so people can "debug my logic". An analog equivelent
> would probably involve a BB... er... sorry... tape delay and some
> comparators.
> 
> I hope I didn't leave anything out that I thought of earlier, because
> I tend to do that. I have written this purely at a theoretical
> viewpoint to inspire further thinking about "yaled". Just remember
> that I am NOT talking about traveling into the future, taking a
> voltage level and outputing it in the present. If that were possible,
> I would suspect it to sound very interesting, OTOH.
> 
> - Drew