Re: [stella] Announcing "webTune2600"

Subject: Re: [stella] Announcing "webTune2600"
From: Doug Dingus <opengeek@xxxxxxxxx>
Date: Fri, 12 Aug 2005 21:54:34 -0400
I did this long ago on the 8bitters. It's true @ 60Hz you will hear it. You 
hear it up to fairly high frequencies. What happens is the ear translates 
these into extra notes or it's heard as a pitch shift happening rapidly if 
the frequency is low enough. 

Because our ears work in frequency / time domain, all of these things are 
well outside our tolerances and we hear them.

One thing that does work fairly well is to alternate the pitches every 
cycle. --with some pattern, 112112112, 121212121, etc... Let each tone run 
for exactly one cycle, then start the other one. I'm not sure the 2600 has 
the muscle to actually get this done however. 

On 8/12/05, Manuel Rotschkar <cybergoth@xxxxxxxx> wrote:
> Hi there!
> >> The idea is to take two adjacent TIA notes that use the same
> >> distortion, and rapidly toggle between them on alternate frames.
> >> Call it "audio flicker"... I *think* the human ear will perceive
> >> this as a frequency halfway between the two, but I'm not sure...
> >
> > Don't underestimate the human ear. AFAIK it's harder to fool than the
> > human eye.
> Yup. At 60Hz you'll hear it vibrating.
> Techniques like that are normally rather used with the volume than with
> the frequency, so for example you can fake 5-Bit quality samples with the
> TIAs 4-Bit volume register by dividing each 5-Bit sample in two 4-Bit
> samples and feeding them to the TIA twice as fast as the 5-Bit
> sample-speed.
> For example
> 5-Bit value = 23 ( /2 = 11.5)
> Will result in
> 4-Bit val 1 = 11
> 4-Bit val 1 = 12
> (Hm... Isn't that called "oversampling"? :-))
> Greetings,
> Manuel
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