Thanks Allen. I'd never counted the steps before! ;-) Have you tested
this and seen results on screen? I'll have to try it sometime...
<L>
Lou Judson =95 Intuitive Audio
415-883-2689
On Oct 19, 2005, at 9:41 PM, Allen Cobb wrote:
> Regarding +-32700 --
>
> With a 16-bit sample size (as used by music CD's, etc.) you can
> count up to 65,536 (including the starting zero). If you take
> one bit to indicate whether the number is positive or negative,
> that cuts the total counting range to 32,768 (or 32700 for
> short).
>
> So "plus" 32700 is the highest point on a waveform and "minus"
> 32700 is the lowest. In other words, in a graphic picture of an
> audio wave, zero is the center line, and Full Scale is plus or
> minus 32700.
>
> If you drew a wave form (one cycle is all you need) that is just
> a square shape with, say, 22 samples at plus 32700 and 22
> samples at minus 32700, you'd have a harmonic-rich full-scale
> signal at 1 kilohertz.
>
> You get the +-32700 wave height by making sure the waveform
> display is not zoomed in vertically, and then zooming in
> *horizontally* until the individual sample "dots" are showing.
> Then just drag the pencil tool at the top and bottom of the wave
> display. Once you have one cycle, you can copy/paste it a few
> times, then reselect them all and copy/paste again, and end up
> with as much time duration of the 1kHz squarewave signal as you
> like.
>
> There are other issues involved in dealing with such a violent
> signal in digital equipment, but this how you could make one
> without special software.
>
> To validate that a recorder is just cloning the input byte
> stream, it probably doesn't matter much what the wave *shape*
> is, so long as it goes full scale. I'm not sure about that, but
> it seems reasonable that just about anything full scale would
> get significantly messed with if it goes through another DA/AD
> conversion. I would think that just 1 cycle, comprising a single
> sample at plus full scale and the next sample at minus full
> scale, would validate that an input is pure digital -- but I
> haven't tested that.
>
> ac
>
>
> Allen Cobb
>
> http://acobb.com
> http://shakespeare.acobb.com
> http://timbreproductions.com
>
>
> -----Original Message-----
> From:
> Behalf Of Lou Judson
> Sent: Wednesday, October 19, 2005 6:25 PM
> To:
> Subject: Re: [Nature Recordists] MT2496 digital input
>
>
> Ah, very clear. That would indeed be a severe test for any
> convertor!
> I'll have to suggest it sometime on an audio elist I'm on.
>
> Thanks for the details. But what does the +or-32700 mean? So
> many
> questions...
>
> <L>
>
> Lou Judson =95 Intuitive Audio
> 415-883-2689
>
> On Oct 19, 2005, at 10:01 AM, Allen Cobb wrote:
>
>> In most waveform editing programs (such as Sony SoundForge)
> you
>> can "draw" waveforms or drag individual samples to whatever
>> level you want. In SoundForge, you can use the "insert
> silence"
>> command to create a short wave comprising only zero samples.
>> Then with the "pencil tool" you can drag individual samples to
> +
>> or - 0db FS (that is, all the way up or all the way down).
> Just
>> don't play the result through your sound system unless the
> level
>> is set very low!
>>
>> ac
>>
>>
>> Allen Cobb
>>
>> http://acobb.com
>> http://shakespeare.acobb.com
>> http://timbreproductions.com
>>
>>
>> -----Original Message-----
>> From:
>> Behalf Of Lou
> Judson
>> Sent: Wednesday, October 19, 2005 11:01 AM
>> To:
>> Subject: Re: [Nature Recordists] MT2496 digital input
>>
>>
>> Can you describe what you mean by this file? How do you make
> it?
>> Sorry
>> if it is a dumb question...
>>
>> <L>
>>
>> Lou Judson =95 Intuitive Audio
>> 415-883-2689
>>
>> On Oct 19, 2005, at 12:37 AM, Gianni Pavan wrote:
>>
>>> Create an "impossible" file with samples alternating
>> among -max and
>>> +max (-32700,+32700,-32700,+32700,....)
>>> Play the file through a digital output
>>
>>
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