hello all,

I have been trying to build a chorus effect, but am hearing from discontinuities/pops.  They seem to occur when the lfo starts a new cycle.  It also seems more prevalent at certain delay values (ideloff + idepth), such as 0.03 - 0.35.  

I borrowed quite a bit of code from here (thanks mikelson!):

http://www.csounds.com/mikelson/multifx.orc

I've have adjusted the table size, even going up to 16777216; this reduces the discontinuity/pop, but sometimes it can still be heard.  (that table size seems pretty large to me).  

I have also compared deltapi and deltap3 for writing to the delay buffer...  Maybe this caused by an interpolation issue...  

Any advice/insight would be greatly appreciated, hope everyone is safe and healthy, cheers.



CODE:

;irate      - hz, positive number
;idepth   - range 0 - 1, gets multiplied to 0.2 as chorus delay range is from 20 ms to 40 ms

opcode chorus, aa, aaii
     ainL, ainR, irate, idepth xin

     idepth   *=      0.02           
     imixch   =       0.5             ; Mix of chorused signal
     imix     =       1 - imixch       ; Mix of direct signal
     ideloff  =       .02            ; Delay offset converted to msec.

     kamp     linseg  0, .002, 1, p3-.004, 1, .002, 0

     aosc1    oscil   idepth, irate, 12   ; LFO for chorus
     aosc2    =       aosc1 + ideloff                 ; Add delay offset
     atempL   delayr  idepth + ideloff
     adelL    deltap3 aosc2                         ; Variable delay tap
          delayw  ainL

     aosc3    oscil   idepth, irate, 12, .25   ; LFOs for chorus
     aosc4    =       aosc3 + ideloff                 ; Add delay offset
     atempR   delayr  idepth + ideloff
     adelR    deltap3 aosc4                         ; Variable delay tap
          delayw  ainR

     aoutL     =       (adelL * imixch + ainL * imix) * kamp; Mix direct and chorused signals
     aoutR     =       (adelR * imixch + ainR * imix) * kamp

     xout    aoutL, aoutR
endop

f1 0 16777216 10 1 

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Hello, when writing a chorus/flanger I've found that it doesen't glitch with the vdelay3 opcode, if i use whatever opcode in a delayr/delayw delay line i have discontinuities. Don't know why but vdelay3 with a-rate modulator works (maybe better managing of slow rate tempo changes???).

Ciao

Stefano

Il 27 aprile 2020 alle 18.49 walker davis <walkerdavismusic@GMAIL.COM> ha scritto:

Oeyvind,

You are correct, that is definitely an error.  That being said, this left over error was one of the many things I tried while looking for the fix. I have updated the code below, but I do not think that this resolves the discontinuity/popping/maybe interpolation error I described in my original inquiry...

Thank you for the response though!

opcode chorus, aa, aaii
     ainL, ainR, irate, idepth xin

     idepth   *=      0.02           
     imixch   =       0.5             ; Mix of chorused signal
     imix     =       1 - imixch       ; Mix of direct signal
     ideloff  =       .02            ; Delay offset converted to msec.

     kamp     linseg  0, .002, 1, p3-.004, 1, .002, 0

     aosc1    oscil   idepth, irate, 1   ; LFO for chorus
     aosc2    =       aosc1 + ideloff                 ; Add delay offset
   

     aosc3    oscil   idepth, irate, 1, .25   ; LFOs for chorus
     aosc4    =       aosc3 + ideloff                 ; Add delay offset
     atempR   delayr  idepth + ideloff
     adelR    deltap3 aosc4                         ; Variable delay tap
          delayw  ainR

     aoutL     =       (adelL * imixch + ainL * imix) * kamp; Mix direct and chorused signals
     aoutR     =       (adelR * imixch + ainR * imix) * kamp

     xout    aoutL, aoutR
endop

f1 0 16777216 10 1 

--------------------------------

Walker Davis

On Mon, Apr 27, 2020 at 12:28 AM Oeyvind Brandtsegg < obrandts@gmail.com> wrote:

Hi,

Maybe I'm mistaken, but it looks like you are using table 12 for the oscil, but f1 to define the table. Could there be an issue with the actual table being used for the oscil?

lør. 25. apr. 2020 kl. 22:32 skrev walker < walkerdavismusic@gmail.com>:

hello all,

I have been trying to build a chorus effect, but am hearing from discontinuities/pops.  They seem to occur when the lfo starts a new cycle.  It also seems more prevalent at certain delay values (ideloff + idepth), such as 0.03 - 0.35. 

I borrowed quite a bit of code from here (thanks mikelson!):

http://www.csounds.com/mikelson/multifx.orc

I've have adjusted the table size, even going up to 16777216; this reduces the discontinuity/pop, but sometimes it can still be heard.  (that table size seems pretty large to me). 

I have also compared deltapi and deltap3 for writing to the delay buffer...  Maybe this caused by an interpolation issue... 

Any advice/insight would be greatly appreciated, hope everyone is safe and healthy, cheers.



CODE:

;irate      - hz, positive number
;idepth   - range 0 - 1, gets multiplied to 0.2 as chorus delay range is from 20 ms to 40 ms

opcode chorus, aa, aaii
     ainL, ainR, irate, idepth xin

     idepth   *=      0.02           
     imixch   =       0.5             ; Mix of chorused signal
     imix     =       1 - imixch       ; Mix of direct signal
     ideloff  =       .02            ; Delay offset converted to msec.

     kamp     linseg  0, .002, 1, p3-.004, 1, .002, 0

     aosc1    oscil   idepth, irate, 12   ; LFO for chorus
     aosc2    =       aosc1 + ideloff                 ; Add delay offset
     atempL   delayr  idepth + ideloff
     adelL    deltap3 aosc2                         ; Variable delay tap
          delayw  ainL

     aosc3    oscil   idepth, irate, 12, .25   ; LFOs for chorus
     aosc4    =       aosc3 + ideloff                 ; Add delay offset
     atempR   delayr  idepth + ideloff
     adelR    deltap3 aosc4                         ; Variable delay tap
          delayw  ainR

     aoutL     =       (adelL * imixch + ainL * imix) * kamp; Mix direct and chorused signals
     aoutR     =       (adelR * imixch + ainR * imix) * kamp

     xout    aoutL, aoutR
endop

f1 0 16777216 10 1

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Any chance of a runnable orchestra?  And score?  Makes it easier to try to 
hear the problem.



On Mon, 27 Apr 2020, walker davis wrote:

> Oeyvind,
> 
> You are correct, that is definitely an error.  That being said, this left over
> error was one of the many things I tried while looking for the fix. I have
> updated the code below, but I do not think that this resolves the
> discontinuity/popping/maybe interpolation error I described in my original
> inquiry...
> 
> Thank you for the response though!
> 
> 
> 
> opcode chorus, aa, aaii
>      ainL, ainR, irate, idepth xin
> 
>      idepth   *=      0.02           
>      imixch   =       0.5             ; Mix of chorused signal
>      imix     =       1 - imixch       ; Mix of direct signal
>      ideloff  =       .02            ; Delay offset converted to msec.
> 
>      kamp     linseg  0, .002, 1, p3-.004, 1, .002, 0
> 
>      aosc1    oscil   idepth, irate, 1   ; LFO for chorus
>      aosc2    =       aosc1 + ideloff                 ; Add delay offset
>      atempL   delayr  idepth + ideloff
>      adelL    deltap3 aosc2                         ; Variable delay tap
>           delayw  ainL
> 
>      aosc3    oscil   idepth, irate, 1, .25   ; LFOs for chorus
>      aosc4    =       aosc3 + ideloff                 ; Add delay offset
>      atempR   delayr  idepth + ideloff
>      adelR    deltap3 aosc4                         ; Variable delay tap
>           delayw  ainR
> 
>      aoutL     =       (adelL * imixch + ainL * imix) * kamp; Mix direct and
> chorused signals
>      aoutR     =       (adelR * imixch + ainR * imix) * kamp
> 
>      xout    aoutL, aoutR
> endop
> 
> f1 0 16777216 10 1 
> 
> 
> --------------------------------
> Walker Davis
> 
> 
> On Mon, Apr 27, 2020 at 12:28 AM Oeyvind Brandtsegg 
> wrote:
>       Hi,
> Maybe I'm mistaken, but it looks like you are using table 12 for the
> oscil, but f1 to define the table. Could there be an issue with the
> actual table being used for the oscil?
> 
> lør. 25. apr. 2020 kl. 22:32 skrev walker :
>       hello all,
>
>       I have been trying to build a chorus effect, but am hearing
>       from discontinuities/pops.  They seem to occur when the lfo
>       starts a new cycle.  It also seems more prevalent at certain
>       delay values (ideloff + idepth), such as 0.03 - 0.35. 
>
>       I borrowed quite a bit of code from here (thanks mikelson!):
>
>       http://www.csounds.com/mikelson/multifx.orc
>
>       I've have adjusted the table size, even going up to
>       16777216; this reduces the discontinuity/pop, but sometimes
>       it can still be heard.  (that table size seems pretty large
>       to me). 
>
>       I have also compared deltapi and deltap3 for writing to the
>       delay buffer...  Maybe this caused by an interpolation
>       issue... 
>
>       Any advice/insight would be greatly appreciated, hope
>       everyone is safe and healthy, cheers.
> 
> 
>
>       CODE:
>
>       ;irate      - hz, positive number
>       ;idepth   - range 0 - 1, gets multiplied to 0.2 as chorus
>       delay range is from 20 ms to 40 ms
>
>       opcode chorus, aa, aaii
>            ainL, ainR, irate, idepth xin
>
>            idepth   *=      0.02           
>            imixch   =       0.5             ; Mix of chorused
>       signal
>            imix     =       1 - imixch       ; Mix of direct
>       signal
>            ideloff  =       .02            ; Delay offset
>       converted to msec.
>
>            kamp     linseg  0, .002, 1, p3-.004, 1, .002, 0
>
>            aosc1    oscil   idepth, irate, 12   ; LFO for chorus
>            aosc2    =       aosc1 + ideloff                 ; Add
>       delay offset
>            atempL   delayr  idepth + ideloff
>            adelL    deltap3 aosc2                         ;
>       Variable delay tap
>                 delayw  ainL
>
>            aosc3    oscil   idepth, irate, 12, .25   ; LFOs for
>       chorus
>            aosc4    =       aosc3 + ideloff                 ; Add
>       delay offset
>            atempR   delayr  idepth + ideloff
>            adelR    deltap3 aosc4                         ;
>       Variable delay tap
>                 delayw  ainR
>
>            aoutL     =       (adelL * imixch + ainL * imix) *
>       kamp; Mix direct and chorused signals
>            aoutR     =       (adelR * imixch + ainR * imix) * kamp
>
>            xout    aoutL, aoutR
>       endop
>
>       f1 0 16777216 10 1
>
>       Csound mailing list
>       Csound@listserv.heanet.ie
>       https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
>       Send bugs reports to
>               https://github.com/csound/csound/issues
>       Discussions of bugs and features can be posted here
> 
> Csound mailing list Csound@listserv.heanet.ie
> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND Send bugs reports to
> https://github.com/csound/csound/issues Discussions of bugs and features
> can be posted here
> 
> Csound mailing list Csound@listserv.heanet.ie
> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND Send bugs reports to
> https://github.com/csound/csound/issues Discussions of bugs and features can
> be posted here
>

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Hi,

Anything with feedback shouldn't be done with vdelay3. So, chorus should
be OK, but for a flanger you should use deltap3.

Cheers.


On 27/4/20 15:08, 00000008a49663bc-dmarc-request@LISTSERV.HEANET.IE wrote:
> Hello, when writing a chorus/flanger I've found that it doesen't glitch with the vdelay3 opcode, if i use whatever opcode in a delayr/delayw delay line i have discontinuities. Don't know why but vdelay3 with a-rate modulator works (maybe better managing of slow rate tempo changes???).
>
> Ciao
>
> Stefano
>
>
>> Il 27 aprile 2020 alle 18.49 walker davis  ha scritto:
>>
>>     Oeyvind,
>>
>>     You are correct, that is definitely an error.  That being said, this left over error was one of the many things I tried while looking for the fix. I have updated the code below, but I do not think that this resolves the discontinuity/popping/maybe interpolation error I described in my original inquiry...
>>
>>     Thank you for the response though!
>>
>>
>>
>>     opcode chorus, aa, aaii
>>          ainL, ainR, irate, idepth xin
>>
>>          idepth   *=      0.02           
>>          imixch   =       0.5             ; Mix of chorused signal
>>          imix     =       1 - imixch       ; Mix of direct signal
>>          ideloff  =       .02            ; Delay offset converted to msec.
>>
>>          kamp     linseg  0, .002, 1, p3-.004, 1, .002, 0
>>
>>          aosc1    oscil   idepth, irate, 1   ; LFO for chorus
>>          aosc2    =       aosc1 + ideloff                 ; Add delay offset
>>        
>>
>>          aosc3    oscil   idepth, irate, 1, .25   ; LFOs for chorus
>>          aosc4    =       aosc3 + ideloff                 ; Add delay offset
>>          atempR   delayr  idepth + ideloff
>>          adelR    deltap3 aosc4                         ; Variable delay tap
>>               delayw  ainR
>>
>>          aoutL     =       (adelL * imixch + ainL * imix) * kamp; Mix direct and chorused signals
>>          aoutR     =       (adelR * imixch + ainR * imix) * kamp
>>
>>          xout    aoutL, aoutR
>>     endop
>>
>>     f1 0 16777216 10 1 
>>
>>
>>     --------------------------------
>>     Walker Davis
>>
>>
>>
>>     On Mon, Apr 27, 2020 at 12:28 AM Oeyvind Brandtsegg < obrandts@gmail.com mailto:obrandts@gmail.com > wrote:
>>
>>         > >         Hi,
>>>         Maybe I'm mistaken, but it looks like you are using table 12 for the oscil, but f1 to define the table. Could there be an issue with the actual table being used for the oscil?
>>>
>>>         lør. 25. apr. 2020 kl. 22:32 skrev walker < walkerdavismusic@gmail.com mailto:walkerdavismusic@gmail.com >:
>>>
>>>             > > > hello all,
>>>>             I have been trying to build a chorus effect, but am hearing from discontinuities/pops.  They seem to occur when the lfo starts a new cycle.  It also seems more prevalent at certain delay values (ideloff + idepth), such as 0.03 - 0.35. 
>>>>
>>>>             I borrowed quite a bit of code from here (thanks mikelson!):
>>>>
>>>>             http://www.csounds.com/mikelson/multifx.orc
>>>>
>>>>             I've have adjusted the table size, even going up to 16777216; this reduces the discontinuity/pop, but sometimes it can still be heard.  (that table size seems pretty large to me). 
>>>>
>>>>             I have also compared deltapi and deltap3 for writing to the delay buffer...  Maybe this caused by an interpolation issue... 
>>>>
>>>>             Any advice/insight would be greatly appreciated, hope everyone is safe and healthy, cheers.
>>>>
>>>>
>>>>
>>>>             CODE:
>>>>
>>>>             ;irate      - hz, positive number
>>>>             ;idepth   - range 0 - 1, gets multiplied to 0.2 as chorus delay range is from 20 ms to 40 ms
>>>>
>>>>             opcode chorus, aa, aaii
>>>>                  ainL, ainR, irate, idepth xin
>>>>
>>>>                  idepth   *=      0.02           
>>>>                  imixch   =       0.5             ; Mix of chorused signal
>>>>                  imix     =       1 - imixch       ; Mix of direct signal
>>>>                  ideloff  =       .02            ; Delay offset converted to msec.
>>>>
>>>>                  kamp     linseg  0, .002, 1, p3-.004, 1, .002, 0
>>>>
>>>>                  aosc1    oscil   idepth, irate, 12   ; LFO for chorus
>>>>                  aosc2    =       aosc1 + ideloff                 ; Add delay offset
>>>>                  atempL   delayr  idepth + ideloff
>>>>                  adelL    deltap3 aosc2                         ; Variable delay tap
>>>>                       delayw  ainL
>>>>
>>>>                  aosc3    oscil   idepth, irate, 12, .25   ; LFOs for chorus
>>>>                  aosc4    =       aosc3 + ideloff                 ; Add delay offset
>>>>                  atempR   delayr  idepth + ideloff
>>>>                  adelR    deltap3 aosc4                         ; Variable delay tap
>>>>                       delayw  ainR
>>>>
>>>>                  aoutL     =       (adelL * imixch + ainL * imix) * kamp; Mix direct and chorused signals
>>>>                  aoutR     =       (adelR * imixch + ainR * imix) * kamp
>>>>
>>>>                  xout    aoutL, aoutR
>>>>             endop
>>>>
>>>>             f1 0 16777216 10 1
>>>>
>>>>             Csound mailing list
>>>>             Csound@listserv.heanet.ie mailto:Csound@listserv.heanet.ie
>>>>             https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
>>>>             Send bugs reports to
>>>>                     https://github.com/csound/csound/issues
>>>>             Discussions of bugs and features can be posted here
>>>>
>>>>         > >         Csound mailing list Csound@listserv.heanet.ie mailto:Csound@listserv.heanet.ie https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND Send bugs reports to https://github.com/csound/csound/issues Discussions of bugs and features can be posted here
>>>     >     Csound mailing list Csound@listserv.heanet.ie mailto:Csound@listserv.heanet.ie https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND Send bugs reports to https://github.com/csound/csound/issues Discussions of bugs and features can be posted here
>
>
>
> Csound mailing list
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> Send bugs reports to
>         https://github.com/csound/csound/issues
> Discussions of bugs and features can be posted here
>

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Hi Gulliermo, 
for feedback do you think that something along these lines should work?

afeed init 0
achor vdelay3 ain + afeed, amodulator, 100
afeed = achor * kfeedback



> Il 27 aprile 2020 alle 21.15 Guillermo Senna  ha scritto:
> 
> 
> Hi,
> 
> Anything with feedback shouldn't be done with vdelay3. So, chorus should
> be OK, but for a flanger you should use deltap3.
> 
> Cheers.

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The problem with vdelay (and also with delay) is that the feedback part
is always from the previous cycle. So, in the impulse response each echo
gets delayed by an additional kr period. And this has a cumulative effect.

I also recently learned that if your delay time is constant you can just
subtract ksmps/sr from it and that fixes the problem. But what happens
when you want to modulate the delay time? Then it becomes much harder to
know how much time to subtract. That's why I think that anything with
feedback shouldn't be done with vdelay. deltapi and deltap3 should work
fine.

Of course, it could also be that my guess is wrong!


On 27/4/20 16:46, 00000008a49663bc-dmarc-request@LISTSERV.HEANET.IE wrote:
> Hi Gulliermo, 
> for feedback do you think that something along these lines should work?
>
> afeed init 0
> achor vdelay3 ain + afeed, amodulator, 100
> afeed = achor * kfeedback
>
>
>
>> Il 27 aprile 2020 alle 21.15 Guillermo Senna  ha scritto:
>>
>>
>> Hi,
>>
>> Anything with feedback shouldn't be done with vdelay3. So, chorus should
>> be OK, but for a flanger you should use deltap3.
>>
>> Cheers.
> Csound mailing list
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i am having trouble hearing anything but lookinfg at the spectrograph and 
wave form  see a series f notches 32 samples apart (which is ksmps).  If I 
change ksmps t 10 te notches occur every 10 samples -- only in bursts from 
time to time.

nOt sure if this is what you are hearing.

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could those notches be related to the k rate envelopes in the
instrument and opcode?

On Mon, Apr 27, 2020 at 1:49 PM john  wrote:
>
> i am having trouble hearing anything but lookinfg at the spectrograph and
> wave form  see a series f notches 32 samples apart (which is ksmps).  If I
> change ksmps t 10 te notches occur every 10 samples -- only in bursts from
> time to time.
>
> nOt sure if this is what you are hearing.
>
> Csound mailing list
> Csound@listserv.heanet.ie
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> Send bugs reports to
>         https://github.com/csound/csound/issues
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Hi Oeyvind,

I don't know if we are addressing the same thing. I've already posted
this code to the dev list, so I apologize for the double post. But here
is what I mean. This code produces -inf dBFS.



sr = 48000
ksmps = 10
0dbfs =  1
nchnls = 1

instr 1
    iTime_delay     =           0.005 - ksmps/sr
    iTime_delayr    =           0.005
    iGain                =           0.5

    aRnd               rand         1,                   
2,                  1

    aDelL          init           0
    aOutL           =            aRnd + aDelL * iGain
    aDelL         delay        aOutL,   iTime_delay
   
    aDelR         delayr      iTime_delayr
    aOutR           =           aRnd + aDelR * iGain
                     delayw      aOutR
   
                        out          aOutL - aOutR
endin



i  1      0          1




On 27/4/20 18:31, Oeyvind Brandtsegg wrote:
> It is correct that the feedback will add ksmps number of samples extra
> delay,
> but I think this should happen likewise with any delay opcodes. It is built
> in to the way block based audio processing works. Use ksmps = 1 to avoid
> it. This can also be done locally inside a UDO so that you don't have to
> run your whole orc at that ksmps.
>
> I usually use vdelayx for these kinds of variable delay btw.
>
> Also, you might be hitting the max delay time of delayr exactly, and get an
> artifact, here:
>  atempL   delayr  idepth + ideloff
> Try adding a small extra time to the delay buffer allocation.
>  atempL   delayr  idepth + ideloff +.1
>
> all best
>
> man. 27. apr. 2020 kl. 22:21 skrev Guillermo Senna :
>
>> The problem with vdelay (and also with delay) is that the feedback part
>> is always from the previous cycle. So, in the impulse response each echo
>> gets delayed by an additional kr period. And this has a cumulative effect.
>>
>> I also recently learned that if your delay time is constant you can just
>> subtract ksmps/sr from it and that fixes the problem. But what happens
>> when you want to modulate the delay time? Then it becomes much harder to
>> know how much time to subtract. That's why I think that anything with
>> feedback shouldn't be done with vdelay. deltapi and deltap3 should work
>> fine.
>>
>> Of course, it could also be that my guess is wrong!
>>
>>
>> On 27/4/20 16:46, 00000008a49663bc-dmarc-request@LISTSERV.HEANET.IE wrote:
>>> Hi Gulliermo,
>>> for feedback do you think that something along these lines should work?
>>>
>>> afeed init 0
>>> achor vdelay3 ain + afeed, amodulator, 100
>>> afeed = achor * kfeedback
>>>
>>>
>>>
>>>> Il 27 aprile 2020 alle 21.15 Guillermo Senna  ha
>> scritto:
>>>>
>>>> Hi,
>>>>
>>>> Anything with feedback shouldn't be done with vdelay3. So, chorus should
>>>> be OK, but for a flanger you should use deltap3.
>>>>
>>>> Cheers.
>>> Csound mailing list
>>> Csound@listserv.heanet.ie
>>> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
>>> Send bugs reports to
>>>         https://github.com/csound/csound/issues
>>> Discussions of bugs and features can be posted here
>> Csound mailing list
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>> Send bugs reports to
>>         https://github.com/csound/csound/issues
>> Discussions of bugs and features can be posted here
>>
> Csound mailing list
> Csound@listserv.heanet.ie
> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
> Send bugs reports to
>         https://github.com/csound/csound/issues
> Discussions of bugs and features can be posted here
>


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Indeed, not yet...

But I tried to replicate this same thing with deltap3 and vdelay3 and
couldn't make it work unless I chose a constant time for the delay time
(which kind of defeats the purpose of using vdelay). The problem seems
to be that it is not possible to account for this problem of having to
use the feedback from the previous cycle when you are constantly
changing the delay time. So the impulse response from deltap3 was
correct, but the one from vdelay3 got the echoes shifted in time. If I'm
not mistaken the subtraction needed won't be by a constant but by
something related to the modulation signal. Anyway, I think it's just
easier to use deltap3 for something with feedback than having to worry
about this issue.

On 27/4/20 19:15, Oeyvind Brandtsegg wrote:
> I would expect it to produce silence yes, since the delayr/w writes first
> then reads on the next k-cycle and then we get the extra ksmps delay time.
> But the exact same feedback path can be built with both techniques (as long
> as we adapt the delay time). Varying the delay time does not change this
> behaviour, so you can safely use the same method of adapting the delay time
> (n-ksmps) as you use here.
> Just beware that you don't ask for a negative delay time (for example zero
> minus ksmps) as that would be asking Csound to predict the future, which it
> can not do .... yet. :-)
>
> man. 27. apr. 2020 kl. 23:56 skrev Guillermo Senna :
>
>> Hi Oeyvind,
>>
>> I don't know if we are addressing the same thing. I've already posted
>> this code to the dev list, so I apologize for the double post. But here
>> is what I mean. This code produces -inf dBFS.
>>
>> 
>> 
>> sr = 48000
>> ksmps = 10
>> 0dbfs =  1
>> nchnls = 1
>>
>> instr 1
>>     iTime_delay     =           0.005 - ksmps/sr
>>     iTime_delayr    =           0.005
>>     iGain                =           0.5
>>
>>     aRnd               rand         1,
>> 2,                  1
>>
>>     aDelL          init           0
>>     aOutL           =            aRnd + aDelL * iGain
>>     aDelL         delay        aOutL,   iTime_delay
>>
>>     aDelR         delayr      iTime_delayr
>>     aOutR           =           aRnd + aDelR * iGain
>>                      delayw      aOutR
>>
>>                         out          aOutL - aOutR
>> endin
>> 
>>
>> 
>> i  1      0          1
>> 
>>
>> 
>>
>> On 27/4/20 18:31, Oeyvind Brandtsegg wrote:
>>> It is correct that the feedback will add ksmps number of samples extra
>>> delay,
>>> but I think this should happen likewise with any delay opcodes. It is
>> built
>>> in to the way block based audio processing works. Use ksmps = 1 to avoid
>>> it. This can also be done locally inside a UDO so that you don't have to
>>> run your whole orc at that ksmps.
>>>
>>> I usually use vdelayx for these kinds of variable delay btw.
>>>
>>> Also, you might be hitting the max delay time of delayr exactly, and get
>> an
>>> artifact, here:
>>>  atempL   delayr  idepth + ideloff
>>> Try adding a small extra time to the delay buffer allocation.
>>>  atempL   delayr  idepth + ideloff +.1
>>>
>>> all best
>>>
>>> man. 27. apr. 2020 kl. 22:21 skrev Guillermo Senna :
>>>
>>>> The problem with vdelay (and also with delay) is that the feedback part
>>>> is always from the previous cycle. So, in the impulse response each echo
>>>> gets delayed by an additional kr period. And this has a cumulative
>> effect.
>>>> I also recently learned that if your delay time is constant you can just
>>>> subtract ksmps/sr from it and that fixes the problem. But what happens
>>>> when you want to modulate the delay time? Then it becomes much harder to
>>>> know how much time to subtract. That's why I think that anything with
>>>> feedback shouldn't be done with vdelay. deltapi and deltap3 should work
>>>> fine.
>>>>
>>>> Of course, it could also be that my guess is wrong!
>>>>
>>>>
>>>> On 27/4/20 16:46, 00000008a49663bc-dmarc-request@LISTSERV.HEANET.IE
>> wrote:
>>>>> Hi Gulliermo,
>>>>> for feedback do you think that something along these lines should work?
>>>>>
>>>>> afeed init 0
>>>>> achor vdelay3 ain + afeed, amodulator, 100
>>>>> afeed = achor * kfeedback
>>>>>
>>>>>
>>>>>
>>>>>> Il 27 aprile 2020 alle 21.15 Guillermo Senna  ha
>>>> scritto:
>>>>>> Hi,
>>>>>>
>>>>>> Anything with feedback shouldn't be done with vdelay3. So, chorus
>> should
>>>>>> be OK, but for a flanger you should use deltap3.
>>>>>>
>>>>>> Cheers.
>>>>> Csound mailing list
>>>>> Csound@listserv.heanet.ie
>>>>> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
>>>>> Send bugs reports to
>>>>>         https://github.com/csound/csound/issues
>>>>> Discussions of bugs and features can be posted here
>>>> Csound mailing list
>>>> Csound@listserv.heanet.ie
>>>> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
>>>> Send bugs reports to
>>>>         https://github.com/csound/csound/issues
>>>> Discussions of bugs and features can be posted here
>>>>
>>> Csound mailing list
>>> Csound@listserv.heanet.ie
>>> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
>>> Send bugs reports to
>>>         https://github.com/csound/csound/issues
>>> Discussions of bugs and features can be posted here
>>>
>>
>> Csound mailing list
>> Csound@listserv.heanet.ie
>> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
>> Send bugs reports to
>>         https://github.com/csound/csound/issues
>> Discussions of bugs and features can be posted here
>>
> Csound mailing list
> Csound@listserv.heanet.ie
> https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
> Send bugs reports to
>         https://github.com/csound/csound/issues
> Discussions of bugs and features can be posted here
>

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