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alpass problem??

Date2003-10-21 01:47
Fromgerald wenzel
Subjectalpass problem??
Hello all.  I'm working on a track that can be rendered solely from a  
csound sco and orc files.  I want to add a dub feel to track so I  
decided to send all of the audio through a reverberator that uses the  
alpass opcode.  I'm using a zak mixer to channel the audio.  Sending 
all  the audio through the alpass did indeed create a dubby feel.  
However,  the output seemed heavy on the low end.  So, after the alpass  
reverberator I sent the audio through a highpass filter.  When I do 
this  I get a bunch of samples out of range and the highpass doesn't 
even seem  to be working right.  If I lower the output on the alpass 
filter to keep  samples from going out of range, things sound really 
bassy and it  actually sounds like the highs are being filtered.  I also 
noticed a high pitch....like feedback???  If I use these  intruments by 
themselves the track sounds okay and the instruments seem  to work, but 
if i route the audio to my highpass filter after using the  alpass 
reverb it doesn't work.  Any ideas why?  



here are the orc files and the lines from the sco that call them:
;allpass Reverberator
;--------------------------------------------------------------------------
;instr    str       dur          amp   rise    decay     rvb_time 
loop_time inchl inchr outchl outchr
i1101   0.000   162.000  .01     0.000 0.000    .5              [.125] 
       99    100     101    102  
;--------------------------------------------------------------------------
;HIGH PASS BUTTERWORTH FILTER
;--------------------------------------------------------------------------
;             strt    dur    amp    rise    decay    filtstr        
filtend        inchl    inchr    outchl    outchr    balon
i1103     0        162   .1         0           0         50           
50              101      102       103        104         0



#define        alpass_reverb(i)    #

;--------------------------------------------------------------------------- 
      
; allpass Reverb
;--------------------------------------------------------------------------- 
      
    instr     $i.
idur        =        p3    
iamp        =         p4    
irise          =         p5    
idec          =         p6    
irvt          =         p7   
iloop_time    =        p8
iinchl      =         p9    
iinchr      =         p10    
ioutchl      =         p11    
ioutchr      =         p12    
      
;convert linen envelope parameters to percentages of the total duration 
of note       
irise         =         irise * idur   
idec         =         idec * idur   
kvol         linen         iamp, irise, idur, idec
      
asigl         zar         iinchl     
asigr         zar         iinchr     
      
;scale the signal       
aleft         alpass        asigl, irvt, iloop_time   
aright         alpass        asigr, irvt, iloop_time   

;aleft         alpass        asigl, 4, .025  
;aright         alpass        asigr, 4, .025   
      
        zawm        (aleft * kvol), ioutchl 
        zawm         (aright * kvol), ioutchr 
    endin                   #

#define        high_pass_filter(i)    #

; HIGH PASS FILTER with balanced output       

   instr    $i.                   
idur        =        p3                       
iamp        =        p4                       
irise        =        p5                       
idec        =        p6                       
ifiltstr    =        p7                       
ifiltend    =        p8                       
iinchl        =        p9                       
iinchr        =        p10                       
ioutchl        =        p11                       
ioutchr        =        p12                       
ibalon        =        p13                       
                              
;convert linen envelope parameters to percentages of the total duration 
of sound object                               
irise        =        irise * idur               
idec        =        idec * idur               
                              
;volume envelope                               
kvol        linen        iamp, irise, idur, idec
asigl        zar        iinchl                       
asigr        zar        iinchr                       
                              
;high pass butterworth line                               
kfilt        line        ifiltstr, idur, ifiltend       
afiltl        butterhp    asigl, kfilt               
afiltr        butterhp    asigr, kfilt               
                              
if ibalon = 0    kgoto        nobalancing           
                              
aball        balance        asigl, afiltl               
abalr        balance        asigr, afiltr               
afiltl        =        aball                       
afiltr        =        abalr                       
                              
nobalancing:                               
       zawm        (afiltl    * kvol), ioutchl       
       zawm        (afiltr    * kvol), ioutchr       
   endin            #               


-- 
gerald wenzel
@pplication specific - music is necessary
http://apspec.com

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