| Bugs item #3292594, was opened at 2011-04-25 11:37
Message generated for change (Comment added) made by veplaini
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Category: Opcodes
Group: csound5
>Status: Closed
>Resolution: Wont Fix
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
>Assigned to: Victor Lazzarini (veplaini)
Summary: VCO opcode buggy (very instable amplitude)
Initial Comment:
Platform: Windows XP
CSound Version: 5.13 (double samples)
The vco opcode seems to be buggy and far away from
being stable in amplitude. I've provided
two csd file examples, containg just a simple vco with
a pulse waveform (pulse width 0.5).
I've also provided two screenshots of the resulting waveforms
for two arbitrary frequencies.
The main problem is, that the amplitude is very instable and
the oscillator seems to be AM modulated.
I've used an FGEN with a reasonable size (2048 samples).
It turns out that the amplitude issue decreases as the
size of the FGEN table increases, but it never really disappears.
The vco2 opcode does not seem to have these problems.
To understand, what I mean, take example "VcoTestFLTK.csd"
and move the "fine2" frequency shift slider to the left.
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>Comment By: Victor Lazzarini (veplaini)
Date: 2011-04-25 17:55
Message:
This is not really a bug, but a behaviour inherent to the algorithm. I have
tried the test CSD with a function table of 131072 points and it seems to
resolve the issue. There are no bugs to be seen in the code; one could
argue the code may be improved, but it's been there for almost thirteen
years and it is not really a priority of the current developers.
----------------------------------------------------------------------
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https://sourceforge.net/tracker/?func=detail&atid=564599&aid=3292594&group_id=81968
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