I'm moving forward with ways to preserve the soon-to-be retro Csound tuning
csound, starting with cpspch.  I'm currently using an UDO to do this.  Here
is the first "retro" cpspch prototype:


opcode rcpspch_i, i, ii
	ipch, ires xin

	ifrac = frac( ipch ) * ( 25.0 / 3.0 )
	iloct = ( floor( ipch ) + ifrac ) * ires
	ival  = floor( iloct ) - ( floor( iloct / ires ) * ires );
	itab  = ( 2^( ival / ires ) ) * 1.02197486
	icps  = ( 2^( floor( iloct / ( ires ) ) ) ) * itab
	
	xout icps
endop



Right now, it only works at i-rate.  And it takes a second argument, giving
it new functionality.  Here's how it would be used.

	ipch rcpspch_i 8.09, 8192


8192 is the resolution of the current cpspch table.  However, for an even
more grungy tuning system, set it much lower.  Doesn't have to be a
power-of-two either.

I did some tests comparing the output of cpspch and rcpspch_i @ 8192 for
every 12 note octave between 0 through 11.  There are some minute
differences.   Half the frequencies were unaffected.  Out of the other half,
the greatest difference in Hz is 0.000977, while the greatest difference in
cents is 0.001599.  Not sample accurate.  However, perceived pitch, phasing
and beating should hold up much better for pieces composed under the
"detuned" micro-temperament.  

I'll check back in as I move forward with this.  I'm going to be extremely
busy in the next two weeks, so it may be awhile.

I do have two questions.  Since this UDO is sort of a derivative of the
csound code, does this mean it requires the LGPL license?  If yes, does that
mean anyone distributing csd/orc files using this UDO would have to
distribute their work with an LGPL or compatible license?


Best, 
Jake 

---- 
The Csound Blog 
http://www.thumbuki.com/csound/blog 



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Jake,

I hope you will be adding this to the UDO database.

-dB

On Aug 26, 2007, at 7:10 PM, Jacob Joaquin wrote:

>
> I'm moving forward with ways to preserve the soon-to-be retro  
> Csound tuning
> csound, starting with cpspch.  I'm currently using an UDO to do  
> this.  Here
> is the first "retro" cpspch prototype:
>
>
> opcode rcpspch_i, i, ii
> 	ipch, ires xin
>
> 	ifrac = frac( ipch ) * ( 25.0 / 3.0 )
> 	iloct = ( floor( ipch ) + ifrac ) * ires
> 	ival  = floor( iloct ) - ( floor( iloct / ires ) * ires );
> 	itab  = ( 2^( ival / ires ) ) * 1.02197486
> 	icps  = ( 2^( floor( iloct / ( ires ) ) ) ) * itab
> 	
> 	xout icps
> endop
>
>
>
> Right now, it only works at i-rate.  And it takes a second  
> argument, giving
> it new functionality.  Here's how it would be used.
>
> 	ipch rcpspch_i 8.09, 8192
>
>
> 8192 is the resolution of the current cpspch table.  However, for  
> an even
> more grungy tuning system, set it much lower.  Doesn't have to be a
> power-of-two either.
>
> I did some tests comparing the output of cpspch and rcpspch_i @  
> 8192 for
> every 12 note octave between 0 through 11.  There are some minute
> differences.   Half the frequencies were unaffected.  Out of the  
> other half,
> the greatest difference in Hz is 0.000977, while the greatest  
> difference in
> cents is 0.001599.  Not sample accurate.  However, perceived pitch,  
> phasing
> and beating should hold up much better for pieces composed under the
> "detuned" micro-temperament.
>
> I'll check back in as I move forward with this.  I'm going to be  
> extremely
> busy in the next two weeks, so it may be awhile.
>
> I do have two questions.  Since this UDO is sort of a derivative of  
> the
> csound code, does this mean it requires the LGPL license?  If yes,  
> does that
> mean anyone distributing csd/orc files using this UDO would have to
> distribute their work with an LGPL or compatible license?
>
>
> Best,
> Jake
>
> ----
> The Csound Blog
> http://www.thumbuki.com/csound/blog
>
>
>
> -- 
> View this message in context: http://www.nabble.com/Preserving-that- 
> retro-cpspch-sound-tf4332625.html#a12339471
> Sent from the Csound - General mailing list archive at Nabble.com.
>
> -- 
> Send bugs reports to this list.
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