[CUD] Odd Output: DC offset of once channel

[Fred Floberg]

Since Dave asked about panning separate channels in an orc,
I went looking through and old orc/sco pair which does panning,
to give an example. It was then that I remembered that this
orc/sco outputs audio with one of the channels offset above
zero. Looking at a WAV file generated by the orc/sco with
an audio file editor you can see one of the channels "floating"
above the zero crossing line. The orc/sco is a complete piece
of music and is pretty complex (for me, anyway), and it has
annoying clicks in the output which I've never been able
to isolate and get rid of. It occured to me just now that
these clicks might be the result of clipping due to the DC offset
of that channel, although I can't prove that.

I thought I'd ask here for help in finding the reason for the
offset, and hence possibly the source of the clicks. However,
the orc/sco is pretty large (over 60k total). Does anyone mind
if I post such a large file to this list?

In the mean time, what I can do is to post the global fader,
global reverb, and global echo section of the orc for your
inspection, because these are the only instruments which would
effect an entire channel. Let me know if you see anything that
I'm doing wrong.

Thanks,

Fred

                instr 4 ; Master Fader
; This instrument runs throughout the performance. It provides fade-in and
; fade-out by means of an envelope created with linseg. The fade-in moves
; from a factor of 0 to 1 over a period determined by ifit in seconds.
; The factor is held at 1 for iht seconds (which equates to the perf time
; minus the fade-in and the fade-out times.
; The fade-out factor moves from 1 to 0 over a period of ifot seconds

ifit    =       4; fade-in in seconds
ifot    =       8; fade-out in seconds
iht     =       p3 - (ifit+ifot); performance - fade-in and fade-out times

gavol   linseg 0, ifit, 1, iht, 1, ifot, 0
endin

                instr 99 ; Global Reverb
; Reverb timers (play with these values to get different effects)

irtl1   =       0.75/4
irtr1   =       0.75/4

irtl2   =       0.75
irtr2   =       0.75

; Loop timers for comb reverb (play with these too)

ilptl   =       0.05
ilptr   =       0.15

; Initialize global buffers on startup

garl init 0
garr init 0

asigl        reverb    garl,  irtl1  ; First reverb for Left channel
asigr        reverb    garr,  irtr1  ; Ditto for Right channel
asigl        comb    asigl+garl,  irtl2, ilptl  ; Second reverb mixed from
                                                ; first reverb and dry
                                                ; signal. Left
asigr        comb    asigr+garr,  irtr2, ilptr  ; and Right channels

outs  asigl*gavol, asigr*gavol ; Output mixed signals, faded in and out
                               ; using Master Fader from above 


garl  = 0 ; Clear out global reverb buffers 
garr  = 0
endin     

                instr 98 ; Global Echo
ideltimer    =         .00085
ideltimel    =         .000053
gadl init 0
gadr init 0

asigl   delay    gadl,  ideltimel
asigr   delay    gadr,  ideltimer
asigl   delay    gadl+asigl, ideltimel*2
asigr   delay    gadr+asigr, ideltimer*2

outs  asigl*gavol, asigr*gavol

gadl = 0
gadr = 0
endin