[Stk] Pops and Crackling on Windows

[Tom Gideon]

Hi Ted,
    My approach to finding the problem was the former. (I am an amateur
programmer, my background is in mathematics.) I am currently developing a
generalization of the STK FM instruments, a modest attempt at building a
TX81Z emulator. In this process I observed the same pops and crackling.
When looking at the waveforms in Audacity I saw, immediately, that the
problem was with a note envelope's onset and release. I then debugged the
code using 'oStream_ << "print something here";' placed at key points. That
brought me to the Voicer class. I then noticed that an instantiation of a
Voicer object required an initial value for decay, it seemed a reasonable
guess to augment that value to a value noted elsewhere when I had used grep
to find "Voicer(".
    I would like to share my work on the TX81Z emulator as soon as I get it
working in the best way for all to use.
Cheers
Tom




On Tue, Sep 10, 2013 at 9:33 PM, Ted Stockwell <emorning at yahoo.com> wrote:

> Thanks very much!
>
> I haven't spent much time looking at the STK code since I'm currently
> reading Real Sound Synthesis (and this is a side project for me).
> I'm curious though how you diagnosed this issue.
> Was it just a matter of becoming more familiar with the code and making an
> intelligent guess as to what might make a difference?
> Or was there a specific tool you used?
> I'm guessing that a debugger is not going to be much help :-).
>
>   ------------------------------
>  *From:* Tom Gideon <tegideon at gmail.com>
> *To:* Ted Stockwell <emorning at yahoo.com>
> *Cc:* Perry Cook <prc at cs.princeton.edu>; "stk at ccrma.stanford.edu" <
> stk at ccrma.stanford.edu>
> *Sent:* Tuesday, September 10, 2013 6:52 PM
>
> *Subject:* Re: [Stk] Pops and Crackling on Windows
>
> Hi
>     I'm new to this mailing list and STK. I think I have found the problem
> with regard to "Pops and Crackling ..." In the file "demo.cpp" there is a
> line that reads
>
>   data.voicer = (Voicer *) new Voicer( 0.0 );
>
> I changed the 0.0 to 0.2 and the pops and crackling disappered. The pops
> and crackling seemed to be the result of the release time not being
> activated and the waveform had a "discontinuity" at the end of each note,
> and this seemed, sometimes, to carry over to the beginning of the next note.
> I hope this helps.
> Tom Gideon
>
> ...
>
>
> On Fri, Aug 30, 2013 at 10:18 PM, Ted Stockwell <emorning at yahoo.com>wrote:
>
> Thanks very much for the hints, I will try all of them.
> Actually, I did see a couple of messages about exceeding +/- 1.0....
>
>   ------------------------------
>  *From:* Perry Cook <prc at CS.Princeton.EDU>
> *To:* Ted Stockwell <emorning at yahoo.com>
> *Cc:* "stk at ccrma.stanford.edu" <stk at ccrma.Stanford.EDU>
> *Sent:* Friday, August 30, 2013 5:41 PM
> *Subject:* Re: [Stk] Pops and Crackling on Windows
>
> Hey Ted,
>
> I'm doing some STK on RPi already!  It works quite well if you
> pay attention to how much computation you're asking for at
> any given time.
>
> Since it happens the same way at the same instant, it could
> be clipping for some reason.  The CPU spiking might be
> something inside STK checking for exceeding of +/- 1.0.
>
> I'd try changing the gain (downward) just a bit.  This could
> be done in a variety of places, including right in the main
> program.  Find a nice place where the Instrument.tick() method
> is being called, and multiply that times your test gain hack.
>
> Something like:  dac.tick(myRev.tick(0.5*myInstrument.tick())));
> where you add in that 0.5.
>
> Another thing to try would be to run the demo with the GUI
> and see if things click any.  Wish I could help more.
>
> PRC
>
> On Aug 30, 2013, at 2:59 PM, Ted Stockwell wrote:
>
> > Hi All,
> >
> > I'm a programmer that is totally new to sound synthesis and STK.
> > I've built the demo project on Windows XP, I'm playing with it, and I
> have some questions...
> >
> > When I play a SKINI file in realtime I hear a lot of pops and
> crackling/buzzes at specific times in the sequence (demo Clarinet -or -if
> scores/bookert.ski).
> > The pops and crackling always happens at the same points in the sequence.
> > I've noticed that my CPU usage tops out when the crackling starts (BTW,
> I have 3.4 Ghz Pentium 4 CPU).
> > If I generate a .wav file instead and play the .wav file then I don't
> hear any crackling (demo Clarinet -if scores/bookert.ski -ow clarinet.wav) .
> > I figure the issue must be related to the realtime synthesis of the
> sound (but I suppose it could be the actual playing of the sound).
> >
> > I've tried increasing RT_BUFFER_SIZE from 512 to 4096 but that made no
> difference.
> > Can anybody suggest a remedy?
> > My ultimate goal is too use STK on a Raspberry Pi so I'll need to
> understand/solve this issue in order to be comfortable moving forward.
> >
> > Thanks in advance,
> >
> > -ted stockwell
> >
> >
> > PS: I've ordered a copy of Real Sound Synthesis for Interactive
> Applications but I haven't received it yet, so I don't understand how any
> of this stuff works :-).
> >
> > _______________________________________________
> > Stk mailing list
> > Stk at ccrma.stanford.edu
> > http://ccrma-mail.stanford.edu/mailman/listinfo/stk
>
>
>
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