[Csnd] question regarding hsboscil

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[Csnd] question regarding hsboscil

orebronerd
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I'm reading the latest Csound book by Lazzarini et al. I am studying the
Haiku examples, and got interested in the hsboscil opcode. It´s hard for me
though to understand what the ioctfn parameter actually do. In the manual it
only says: "function table used for weighting the octaves, usually something
like: f1 0  1024  -19  1  0.5  270  0.5"
I understand it as the function describes a wave with the first partial, the
amplitude, the phase and a scaling factor. But I cannot really see how this
relates to the changing of octaves in the sound. Can anyone describe in other words,
so I hopefully understand more? Does it affect the relative strength of all
the octaves, like som kind of filter, or what?

Best regards Martin Flodin



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Re: [Csnd] question regarding hsboscil

Iain McCurdy

Hi Martin,


ioctfn acts like a spectral envelope which is applied to the stack of octave-separated oscillators created by hsboscil. The function table you quote uses part of a sine function which forms a shape like a bell curve meaning that the oscillators at the bottom and the top of the window will be faded out smoothly. The envelope can be shifted up or down using the kbrite control which thereby acts like the cutoff frequency of a bandpass filter. Other GEN routines can be considered for creating this spectral envelope. For example, if you use GEN20 type=6 (gaussian) you can vary the openness of the envelope and thereby implement a kind of bandwidth control.


I hope this helps,

Iain




From: A discussion list for users of Csound <[hidden email]> on behalf of orebronerd <[hidden email]>
Sent: 23 April 2018 12:12
To: [hidden email]
Subject: [Csnd] question regarding hsboscil
 
I'm reading the latest Csound book by Lazzarini et al. I am studying the
Haiku examples, and got interested in the hsboscil opcode. It´s hard for me
though to understand what the ioctfn parameter actually do. In the manual it
only says: "function table used for weighting the octaves, usually something
like: f1 0  1024  -19  1  0.5  270  0.5"
I understand it as the function describes a wave with the first partial, the
amplitude, the phase and a scaling factor. But I cannot really see how this
relates to the overtones in the sound. Can anyone describe in other words,
so I hopefully understand more? Does it affect the relative strength of all
the partials, like som kind of filter, or what?

Best regards Martin Flodin



--
Sent from: http://csound.1045644.n5.nabble.com/Csound-General-f1093014.html



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Re: [Csnd] question regarding hsboscil

orebronerd
Thank you for the reply, and thank you for an interesting chapter in the
book. The opcode makes more sense now.
Best regards Martin Flodin



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