Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[robert bristow-johnson]

�
James, your point is right on, but quantitatively you gotta factor of two off.
the 1/f for pink noise applies to power spectrum, not voltage ratios, which is 
why the magnitude response for a pinking filter is 1/sqrt(f) or -3 dB per 
octave.
�


 Original Message 

Subject: Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally 
more than 32 octaves)

From: "James McCartney" 

Date: Mon, April 11, 2016 7:46 pm

To: music-dsp@music.columbia.edu

--



>>The amplitude at 20 Hz of the noise will be 20*log10(2^(20/0.447)) =

> -113 dB

>

> should be:

>

> The amplitude at 20 Hz of the noise will be 20*log10(20/0.447) = -113

> dB

>

> answer is correct, expression was wrong.

>
so i think it should be 10*log10(20/0.447) = -56 dB
after another 12 octaves, somewhere around Nyquist if oversampled by a factor 
of 4, it might be -92 dB .
still the point would be the flicker noise for the lowest subaudible 
frequencies would be a pretty nasty 50+ dB
greater than the audible frequencies. (i would have to integrate 1/f, w.r.t. 
linear f, from -32 octaves to -12 octaves to get the total power. �maybe it 
would come out to be 10 dB. �i think it has to be at least 6 dB more energy in 
the bottom 20 octaves than in the top 12.) �we
usually like to get rid of large, slowly varying DC which is why we need good 
DC-blocking filters. �still cannot see why the OP needs or would even want more 
than at most 12 octaves adherence to the theoretical 1/f power function.
thanks for pointing out the frequency that is 30 octaves
below our highest audible frequency. �that was an obvious point that i missed.�
bestest,
r b-j

> On Mon, Apr 11, 2016 at 4:42 PM, James McCartney  wrote:

>

>> Yes, you don't really want 32 octaves.

>> Wide bandwidth becomes a problem with 1/f noise because the lower

>> frequencies are so much higher amplitude than the upper frequencies.

>> With 32 bit floats and a 24 bit mantissa you can only represent 24 octaves

>> of 1/f noise because 1/f = 1/(2^24) drops below the quantization limit.

>> This means the top 8 octaves of your 32 cannot be represented.

>>

>> Let's assume you want a high sampling rate, say 384 kHz (the problem only

>> gets worse if you lower the sample rate). Nyquist is 192 kHz. 32 octaves

>> below that is 0.447 Hz, or 1 cycle every 3.86 days.. The amplitude at

>> 20 Hz of the noise will be 20*log10(2^(20/0.447)) = -113 dB below the

>> amplitude of the lowest octave. Your signal will be dominated by subsonic

>> audio and the audio range will be below the threshold of hearing.

>>

>> On Mon, Apr 11, 2016 at 10:46 AM, robert bristow-johnson <

>> r...@audioimagination.com> wrote:

>>

>>> being that this is a discussion group about music, which is a subset of

>>> audio. and being that our hearing is at best 10 or 11 octaves, why do you

>>> need 32 octaves?

>>>

>>> and then how closely, in dB, does your pink noise need to conform to the

>>> 1/f power spectrum? +/- 0.1 dB? 0.01 dB?

>>>

>>> all this can be done with a good white noise source and a filter

>>> alternating real poles and real zeros placed at just the right values. for

>>> 32 octaves, i would hate to guess how many pole/zero pairs you would need.

>>> maybe 10.

>>>

>>>

>>>

>>> r b-j

>>>

>>>

>>>  Original Message 

>>> Subject: [music-dsp] High quality really broad bandwidth pinknoise

>>> (ideally more than 32 octaves)

>>>

From: "Seth Nickell" 

>>> Date: Mon, April 11, 2016 12:57 pm

>>> To: music-dsp@music.columbia.edu

>>> --

>>>

>>>

>>> > I'm applying an iterative function to an input signal, in this instance

>>> > pinknoise. Because of the iteration, spectral characteristics in input

>>> > signals tend to "blow up" really quickly, so I'm looking for a really

>>> high

>>> > bandwidth and high quality source of pink noise.

>>> >

>>> > My understanding is that most of the approaches like the supercollider

>>> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As

>>> the

>>> > number of octaves grows, the accurcary drops. Is my understanding

>>> correct?

>>> >

>>> > I'm hoping to find a way to generate pink noise that is:

>>> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves

>>> > 2) Tractable to generate an arbitrarily large number of samples

>>> (billions,

>>> > so can't fft the whole thing in one pass)

>>> >

>>> > Any suggestions? I've read through

>>> > http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems

>>> > focused on fast-generation of pink noise of moderate quality and a

>>> > relatively narrow bandwidth. I'm sort of looking for the other side of

>>> > things... 

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[Evan Balster]

I haven't yet come across an automated process for designing high-quality
pinking filters, so if someone can offer one up I'd also love to hear about
it!

Seth -- as you say, "the error from 1/f can't be corrected by increasing
the number of iterations".  Adding octaves to the Voss-McCartney algorithm
only lowers its bottom frequency.  But do consider my suggestion above...
The ripple in VM noise has a logarithmic periodicity of 1 octave in the
frequency domain...  You could eliminate it by way of destructive
interference if you generate the pink noise at equally-spaced sampling
rates between N (inclusive) and 2N (exclusive).  With this approach you
could get an arbitrarily flat slope -- if you're willing to pay the cost!

Your project sounds totally bonkers, but I'll give you the benefit of the
doubt on that.  :)

– Evan Balster
creator of imitone 

On Mon, Apr 11, 2016 at 6:59 PM, Seth Nickell  wrote:

> Hi Robert,
>
> I know very little about filter design (hazy undergrad memories, you know
> the type), is this something I could sanely rig for myself, or is that
> total madness as a filter novice? Could you point me toward the right terms
> I need to read up about to learn more about this?
>
> -Seth
>
> On Mon, Apr 11, 2016 at 10:47 AM robert bristow-johnson <
> r...@audioimagination.com> wrote:
>
>> being that this is a discussion group about music, which is a subset of
>> audio.  and being that our hearing is at best 10 or 11 octaves, why do you
>> need 32 octaves?
>>
>> and then how closely, in dB, does your pink noise need to conform to the
>> 1/f power spectrum?  +/- 0.1 dB?  0.01 dB?
>>
>> all this can be done with a good white noise source and a filter
>> alternating real poles and real zeros placed at just the right values.  for
>> 32 octaves, i would hate to guess how many pole/zero pairs you would need.
>>  maybe 10.
>>
>>
>>
>> r b-j
>>
>>
>>  Original Message 
>> Subject: [music-dsp] High quality really broad bandwidth pinknoise
>> (ideally more than 32 octaves)
>> From: "Seth Nickell" 
>> Date: Mon, April 11, 2016 12:57 pm
>> To: music-dsp@music.columbia.edu
>> --
>>
>>
>>
>> > I'm applying an iterative function to an input signal, in this instance
>> > pinknoise. Because of the iteration, spectral characteristics in input
>> > signals tend to "blow up" really quickly, so I'm looking for a really
>> high
>> > bandwidth and high quality source of pink noise.
>> >
>> > My understanding is that most of the approaches like the supercollider
>> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As
>> the
>> > number of octaves grows, the accurcary drops. Is my understanding
>> correct?
>> >
>> > I'm hoping to find a way to generate pink noise that is:
>> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
>> > 2) Tractable to generate an arbitrarily large number of samples
>> (billions,
>> > so can't fft the whole thing in one pass)
>> >
>> > Any suggestions? I've read through
>> > http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems
>> > focused on fast-generation of pink noise of moderate quality and a
>> > relatively narrow bandwidth. I'm sort of looking for the other side of
>> > things... what's the most ideal pink noise I can generate en masse?
>> >
>> > Thanks,
>> > -Seth
>>
>>
>> --
>>
>> r b-j  r...@audioimagination.com
>>
>> "Imagination is more important than knowledge."
>>
>>
>> ___
>> dupswapdrop: music-dsp mailing list
>> music-dsp@music.columbia.edu
>> https://lists.columbia.edu/mailman/listinfo/music-dsp
>
>
> ___
> dupswapdrop: music-dsp mailing list
> music-dsp@music.columbia.edu
> https://lists.columbia.edu/mailman/listinfo/music-dsp
>
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[Seth Nickell]

Hi Robert,

I know very little about filter design (hazy undergrad memories, you know
the type), is this something I could sanely rig for myself, or is that
total madness as a filter novice? Could you point me toward the right terms
I need to read up about to learn more about this?

-Seth

On Mon, Apr 11, 2016 at 10:47 AM robert bristow-johnson <
r...@audioimagination.com> wrote:

> being that this is a discussion group about music, which is a subset of
> audio.  and being that our hearing is at best 10 or 11 octaves, why do you
> need 32 octaves?
>
> and then how closely, in dB, does your pink noise need to conform to the
> 1/f power spectrum?  +/- 0.1 dB?  0.01 dB?
>
> all this can be done with a good white noise source and a filter
> alternating real poles and real zeros placed at just the right values.  for
> 32 octaves, i would hate to guess how many pole/zero pairs you would need.
>  maybe 10.
>
>
>
> r b-j
>
>
>  Original Message 
> Subject: [music-dsp] High quality really broad bandwidth pinknoise
> (ideally more than 32 octaves)
> From: "Seth Nickell" 
> Date: Mon, April 11, 2016 12:57 pm
> To: music-dsp@music.columbia.edu
> --
>
>
>
> > I'm applying an iterative function to an input signal, in this instance
> > pinknoise. Because of the iteration, spectral characteristics in input
> > signals tend to "blow up" really quickly, so I'm looking for a really
> high
> > bandwidth and high quality source of pink noise.
> >
> > My understanding is that most of the approaches like the supercollider
> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As
> the
> > number of octaves grows, the accurcary drops. Is my understanding
> correct?
> >
> > I'm hoping to find a way to generate pink noise that is:
> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
> > 2) Tractable to generate an arbitrarily large number of samples
> (billions,
> > so can't fft the whole thing in one pass)
> >
> > Any suggestions? I've read through
> > http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems
> > focused on fast-generation of pink noise of moderate quality and a
> > relatively narrow bandwidth. I'm sort of looking for the other side of
> > things... what's the most ideal pink noise I can generate en masse?
> >
> > Thanks,
> > -Seth
>
>
> --
>
> r b-j  r...@audioimagination.com
>
> "Imagination is more important than knowledge."
>
>
> ___
> dupswapdrop: music-dsp mailing list
> music-dsp@music.columbia.edu
> https://lists.columbia.edu/mailman/listinfo/music-dsp
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[Seth Nickell]

My justification: the result sounds awesome. If I play a show with it in
the next few months I'll post the result of this madness here. Sorry to be
a little vague about it, I've got a couple years of composition work going
into this.

-seth

On Mon, Apr 11, 2016 at 5:26 PM Evan Balster  wrote:

> I haven't yet come across an automated process for designing high-quality
> pinking filters, so if someone can offer one up I'd also love to hear about
> it!
>
> Seth -- as you say, "the error from 1/f can't be corrected by increasing
> the number of iterations".  Adding octaves to the Voss-McCartney algorithm
> only lowers its bottom frequency.  But do consider my suggestion above...
> The ripple in VM noise has a logarithmic periodicity of 1 octave in the
> frequency domain...  You could eliminate it by way of destructive
> interference if you generate the pink noise at equally-spaced sampling
> rates between N (inclusive) and 2N (exclusive).  With this approach you
> could get an arbitrarily flat slope -- if you're willing to pay the cost!
>
> Your project sounds totally bonkers, but I'll give you the benefit of the
> doubt on that.  :)
>
> – Evan Balster
> creator of imitone 
>
> On Mon, Apr 11, 2016 at 6:59 PM, Seth Nickell  wrote:
>
>> Hi Robert,
>>
>> I know very little about filter design (hazy undergrad memories, you know
>> the type), is this something I could sanely rig for myself, or is that
>> total madness as a filter novice? Could you point me toward the right terms
>> I need to read up about to learn more about this?
>>
>> -Seth
>>
>> On Mon, Apr 11, 2016 at 10:47 AM robert bristow-johnson <
>> r...@audioimagination.com> wrote:
>>
>>> being that this is a discussion group about music, which is a subset of
>>> audio.  and being that our hearing is at best 10 or 11 octaves, why do you
>>> need 32 octaves?
>>>
>>> and then how closely, in dB, does your pink noise need to conform to the
>>> 1/f power spectrum?  +/- 0.1 dB?  0.01 dB?
>>>
>>> all this can be done with a good white noise source and a filter
>>> alternating real poles and real zeros placed at just the right values.  for
>>> 32 octaves, i would hate to guess how many pole/zero pairs you would need.
>>>  maybe 10.
>>>
>>>
>>>
>>> r b-j
>>>
>>>
>>>  Original Message
>>> 
>>> Subject: [music-dsp] High quality really broad bandwidth pinknoise
>>> (ideally more than 32 octaves)
>>> From: "Seth Nickell" 
>>> Date: Mon, April 11, 2016 12:57 pm
>>> To: music-dsp@music.columbia.edu
>>>
>>> --
>>>
>>>
>>>
>>> > I'm applying an iterative function to an input signal, in this instance
>>> > pinknoise. Because of the iteration, spectral characteristics in input
>>> > signals tend to "blow up" really quickly, so I'm looking for a really
>>> high
>>> > bandwidth and high quality source of pink noise.
>>> >
>>> > My understanding is that most of the approaches like the supercollider
>>> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth.
>>> As the
>>> > number of octaves grows, the accurcary drops. Is my understanding
>>> correct?
>>> >
>>> > I'm hoping to find a way to generate pink noise that is:
>>> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
>>> > 2) Tractable to generate an arbitrarily large number of samples
>>> (billions,
>>> > so can't fft the whole thing in one pass)
>>> >
>>> > Any suggestions? I've read through
>>> > http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems
>>> > focused on fast-generation of pink noise of moderate quality and a
>>> > relatively narrow bandwidth. I'm sort of looking for the other side of
>>> > things... what's the most ideal pink noise I can generate en masse?
>>> >
>>> > Thanks,
>>> > -Seth
>>>
>>>
>>> --
>>>
>>> r b-j  r...@audioimagination.com
>>>
>>> "Imagination is more important than knowledge."
>>>
>>>
>>> ___
>>> dupswapdrop: music-dsp mailing list
>>> music-dsp@music.columbia.edu
>>> https://lists.columbia.edu/mailman/listinfo/music-dsp
>>
>>
>> ___
>> dupswapdrop: music-dsp mailing list
>> music-dsp@music.columbia.edu
>> https://lists.columbia.edu/mailman/listinfo/music-dsp
>>
>
> ___
> dupswapdrop: music-dsp mailing list
> music-dsp@music.columbia.edu
> https://lists.columbia.edu/mailman/listinfo/music-dsp
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[Seth Nickell]

I know this is an unusual situation, but I really do want 32 octaves[1].
Also, I'm working with 64-bit floats already (many iterations, small
numbers, don't want to think about rounding).

I'm sampling at 3MHz right now, but I'd like to go higher. The differences
in sound quality for my algorithm are pretty blatant every time I run with
a wider bandwidth.

BTW, I used SC for my prototypes until I realized I wanted to go higher
than 384khz and had to rewrite everything in C. Missing SC pretty badly,
thanks James for spoiling me ;-)

My understanding of the Voss-McCartney algo is that while it can be
extended to an arbitrary number of octaves, the error from 1/f can't be
corrected by increasing the number of iterations, is that true or did I
misunderstand?

Again, because this is a (highly highly) iterative procedure, small
deviations from a smooth spectrum tend to blow up and dominate the signal.
I want the small deviations to come from the nature of sampled noise, not
to be dominated by the nature of the algo that produced the
almost-but-not-quite-pink-noise.

-Seth

[1] My iterative procedure results in spectral shifts over time, so while
yes, my final output is a 48KHz signal, I need to run at 3MHz or higher to
run the process.

On Mon, Apr 11, 2016 at 4:43 PM James McCartney  wrote:

> Yes, you don't really want 32 octaves.
> Wide bandwidth becomes a problem with 1/f noise because the lower
> frequencies are so much higher amplitude than the upper frequencies.
> With 32 bit floats and a 24 bit mantissa you can only represent 24 octaves
> of 1/f noise because 1/f = 1/(2^24) drops below the quantization limit.
> This means the top 8 octaves of your 32 cannot be represented.
>
> Let's assume you want a high sampling rate, say 384 kHz (the problem only
> gets worse if you lower the sample rate). Nyquist is 192 kHz. 32 octaves
> below that is 0.447 Hz, or 1 cycle every 3.86 days..  The amplitude at
> 20 Hz of the noise will be 20*log10(2^(20/0.447))  = -113 dB below the
> amplitude of the lowest octave. Your signal will be dominated by subsonic
> audio and the audio range will be below the threshold of hearing.
>
> On Mon, Apr 11, 2016 at 10:46 AM, robert bristow-johnson <
> r...@audioimagination.com> wrote:
>
>> being that this is a discussion group about music, which is a subset of
>> audio.  and being that our hearing is at best 10 or 11 octaves, why do you
>> need 32 octaves?
>>
>> and then how closely, in dB, does your pink noise need to conform to the
>> 1/f power spectrum?  +/- 0.1 dB?  0.01 dB?
>>
>> all this can be done with a good white noise source and a filter
>> alternating real poles and real zeros placed at just the right values.  for
>> 32 octaves, i would hate to guess how many pole/zero pairs you would need.
>>  maybe 10.
>>
>>
>>
>> r b-j
>>
>>
>>  Original Message 
>> Subject: [music-dsp] High quality really broad bandwidth pinknoise
>> (ideally more than 32 octaves)
>> From: "Seth Nickell" 
>> Date: Mon, April 11, 2016 12:57 pm
>> To: music-dsp@music.columbia.edu
>> --
>>
>>
>> > I'm applying an iterative function to an input signal, in this instance
>> > pinknoise. Because of the iteration, spectral characteristics in input
>> > signals tend to "blow up" really quickly, so I'm looking for a really
>> high
>> > bandwidth and high quality source of pink noise.
>> >
>> > My understanding is that most of the approaches like the supercollider
>> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As
>> the
>> > number of octaves grows, the accurcary drops. Is my understanding
>> correct?
>> >
>> > I'm hoping to find a way to generate pink noise that is:
>> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
>> > 2) Tractable to generate an arbitrarily large number of samples
>> (billions,
>> > so can't fft the whole thing in one pass)
>> >
>> > Any suggestions? I've read through
>> > http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems
>> > focused on fast-generation of pink noise of moderate quality and a
>> > relatively narrow bandwidth. I'm sort of looking for the other side of
>> > things... what's the most ideal pink noise I can generate en masse?
>> >
>> > Thanks,
>> > -Seth
>>
>>
>> --
>>
>> r b-j  r...@audioimagination.com
>>
>> "Imagination is more important than knowledge."
>>
>>
>>
>> ___
>> dupswapdrop: music-dsp mailing list
>> music-dsp@music.columbia.edu
>> https://lists.columbia.edu/mailman/listinfo/music-dsp
>>
>
>
>
> --
> --- james mccartney
> ___
> dupswapdrop: music-dsp mailing list
> music-dsp@music.columbia.edu
> https://lists.columbia.edu/mailman/listinfo/music-dsp
___
dupswapdrop: music-dsp mailing 

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[James McCartney]

ah, yes.. oops.
thanks.

On Mon, Apr 11, 2016 at 5:15 PM, robert bristow-johnson <
r...@audioimagination.com> wrote:

>
>
> James, your point is right on, but quantitatively you gotta factor of two
> off.
>
> the 1/f for pink noise applies to power spectrum, not voltage ratios,
> which is why the magnitude response for a pinking filter is 1/sqrt(f) or -3
> dB per octave.
>
>
>
>
>  Original Message 
> Subject: Re: [music-dsp] High quality really broad bandwidth pinknoise
> (ideally more than 32 octaves)
> From: "James McCartney" 
> Date: Mon, April 11, 2016 7:46 pm
> To: music-dsp@music.columbia.edu
> --
>
> >>The amplitude at 20 Hz of the noise will be 20*log10(2^(20/0.447)) =
> > -113 dB
> >
> > should be:
> >
> > The amplitude at 20 Hz of the noise will be 20*log10(20/0.447) = -113
> > dB
> >
> > answer is correct, expression was wrong.
> >
>
> so i think it should be 10*log10(20/0.447) = -56 dB
>
> after another 12 octaves, somewhere around Nyquist if oversampled by a
> factor of 4, it might be -92 dB .
>
> still the point would be the flicker noise for the lowest subaudible
> frequencies would be a pretty nasty 50+ dB greater than the audible
> frequencies. (i would have to integrate 1/f, w.r.t. linear f, from -32
> octaves to -12 octaves to get the total power.  maybe it would come out to
> be 10 dB.  i think it has to be at least 6 dB more energy in the bottom 20
> octaves than in the top 12.)  we usually like to get rid of large, slowly
> varying DC which is why we need good DC-blocking filters.  still cannot see
> why the OP needs or would even want more than at most 12 octaves adherence
> to the theoretical 1/f power function.
>
> thanks for pointing out the frequency that is 30 octaves below our highest
> audible frequency.  that was an obvious point that i missed.
>
> bestest,
>
> r b-j
>
>
> > On Mon, Apr 11, 2016 at 4:42 PM, James McCartney 
> wrote:
> >
> >> Yes, you don't really want 32 octaves.
> >> Wide bandwidth becomes a problem with 1/f noise because the lower
> >> frequencies are so much higher amplitude than the upper frequencies.
> >> With 32 bit floats and a 24 bit mantissa you can only represent 24
> octaves
> >> of 1/f noise because 1/f = 1/(2^24) drops below the quantization limit.
> >> This means the top 8 octaves of your 32 cannot be represented.
> >>
> >> Let's assume you want a high sampling rate, say 384 kHz (the problem
> only
> >> gets worse if you lower the sample rate). Nyquist is 192 kHz. 32 octaves
> >> below that is 0.447 Hz, or 1 cycle every 3.86 days.. The amplitude
> at
> >> 20 Hz of the noise will be 20*log10(2^(20/0.447)) = -113 dB below
> the
> >> amplitude of the lowest octave. Your signal will be dominated by
> subsonic
> >> audio and the audio range will be below the threshold of hearing.
> >>
> >> On Mon, Apr 11, 2016 at 10:46 AM, robert bristow-johnson <
> >> r...@audioimagination.com> wrote:
> >>
> >>> being that this is a discussion group about music, which is a subset of
> >>> audio. and being that our hearing is at best 10 or 11 octaves, why do
> you
> >>> need 32 octaves?
> >>>
> >>> and then how closely, in dB, does your pink noise need to conform to
> the
> >>> 1/f power spectrum? +/- 0.1 dB? 0.01 dB?
> >>>
> >>> all this can be done with a good white noise source and a filter
> >>> alternating real poles and real zeros placed at just the right values.
> for
> >>> 32 octaves, i would hate to guess how many pole/zero pairs you would
> need.
> >>> maybe 10.
> >>>
> >>>
> >>>
> >>> r b-j
> >>>
> >>>
> >>>  Original Message
> 
> >>> Subject: [music-dsp] High quality really broad bandwidth pinknoise
> >>> (ideally more than 32 octaves)
> >>>
> From: "Seth Nickell" 
> >>> Date: Mon, April 11, 2016 12:57 pm
> >>> To: music-dsp@music.columbia.edu
> >>>
> --
> >>>
> >>>
> >>> > I'm applying an iterative function to an input signal, in this
> instance
> >>> > pinknoise. Because of the iteration, spectral characteristics in
> input
> >>> > signals tend to "blow up" really quickly, so I'm looking for a really
> >>> high
> >>> > bandwidth and high quality source of pink noise.
> >>> >
> >>> > My understanding is that most of the approaches like the
> supercollider
> >>> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth.
> As
> >>> the
> >>> > number of octaves grows, the accurcary drops. Is my understanding
> >>> correct?
> >>> >
> >>> > I'm hoping to find a way to generate pink noise that is:
> >>> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
> >>> > 2) Tractable to generate an arbitrarily large number of samples
> >>> (billions,
> >>> > so can't fft the whole thing in one pass)
> >>> >
> 

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[James McCartney]

>The amplitude at 20 Hz of the noise will be 20*log10(2^(20/0.447))  =
-113 dB

should be:

The amplitude at 20 Hz of the noise will be 20*log10(20/0.447)  = -113
dB

answer is correct, expression was wrong.

On Mon, Apr 11, 2016 at 4:42 PM, James McCartney  wrote:

> Yes, you don't really want 32 octaves.
> Wide bandwidth becomes a problem with 1/f noise because the lower
> frequencies are so much higher amplitude than the upper frequencies.
> With 32 bit floats and a 24 bit mantissa you can only represent 24 octaves
> of 1/f noise because 1/f = 1/(2^24) drops below the quantization limit.
> This means the top 8 octaves of your 32 cannot be represented.
>
> Let's assume you want a high sampling rate, say 384 kHz (the problem only
> gets worse if you lower the sample rate). Nyquist is 192 kHz. 32 octaves
> below that is 0.447 Hz, or 1 cycle every 3.86 days..  The amplitude at
> 20 Hz of the noise will be 20*log10(2^(20/0.447))  = -113 dB below the
> amplitude of the lowest octave. Your signal will be dominated by subsonic
> audio and the audio range will be below the threshold of hearing.
>
> On Mon, Apr 11, 2016 at 10:46 AM, robert bristow-johnson <
> r...@audioimagination.com> wrote:
>
>> being that this is a discussion group about music, which is a subset of
>> audio.  and being that our hearing is at best 10 or 11 octaves, why do you
>> need 32 octaves?
>>
>> and then how closely, in dB, does your pink noise need to conform to the
>> 1/f power spectrum?  +/- 0.1 dB?  0.01 dB?
>>
>> all this can be done with a good white noise source and a filter
>> alternating real poles and real zeros placed at just the right values.  for
>> 32 octaves, i would hate to guess how many pole/zero pairs you would need.
>>  maybe 10.
>>
>>
>>
>> r b-j
>>
>>
>>  Original Message 
>> Subject: [music-dsp] High quality really broad bandwidth pinknoise
>> (ideally more than 32 octaves)
>> From: "Seth Nickell" 
>> Date: Mon, April 11, 2016 12:57 pm
>> To: music-dsp@music.columbia.edu
>> --
>>
>>
>> > I'm applying an iterative function to an input signal, in this instance
>> > pinknoise. Because of the iteration, spectral characteristics in input
>> > signals tend to "blow up" really quickly, so I'm looking for a really
>> high
>> > bandwidth and high quality source of pink noise.
>> >
>> > My understanding is that most of the approaches like the supercollider
>> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As
>> the
>> > number of octaves grows, the accurcary drops. Is my understanding
>> correct?
>> >
>> > I'm hoping to find a way to generate pink noise that is:
>> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
>> > 2) Tractable to generate an arbitrarily large number of samples
>> (billions,
>> > so can't fft the whole thing in one pass)
>> >
>> > Any suggestions? I've read through
>> > http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems
>> > focused on fast-generation of pink noise of moderate quality and a
>> > relatively narrow bandwidth. I'm sort of looking for the other side of
>> > things... what's the most ideal pink noise I can generate en masse?
>> >
>> > Thanks,
>> > -Seth
>>
>>
>> --
>>
>> r b-j  r...@audioimagination.com
>>
>> "Imagination is more important than knowledge."
>>
>>
>>
>> ___
>> dupswapdrop: music-dsp mailing list
>> music-dsp@music.columbia.edu
>> https://lists.columbia.edu/mailman/listinfo/music-dsp
>>
>
>
>
> --
> --- james mccartney
>



-- 
--- james mccartney
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[James McCartney]

Yes, you don't really want 32 octaves.
Wide bandwidth becomes a problem with 1/f noise because the lower
frequencies are so much higher amplitude than the upper frequencies.
With 32 bit floats and a 24 bit mantissa you can only represent 24 octaves
of 1/f noise because 1/f = 1/(2^24) drops below the quantization limit.
This means the top 8 octaves of your 32 cannot be represented.

Let's assume you want a high sampling rate, say 384 kHz (the problem only
gets worse if you lower the sample rate). Nyquist is 192 kHz. 32 octaves
below that is 0.447 Hz, or 1 cycle every 3.86 days..  The amplitude at
20 Hz of the noise will be 20*log10(2^(20/0.447))  = -113 dB below the
amplitude of the lowest octave. Your signal will be dominated by subsonic
audio and the audio range will be below the threshold of hearing.

On Mon, Apr 11, 2016 at 10:46 AM, robert bristow-johnson <
r...@audioimagination.com> wrote:

> being that this is a discussion group about music, which is a subset of
> audio.  and being that our hearing is at best 10 or 11 octaves, why do you
> need 32 octaves?
>
> and then how closely, in dB, does your pink noise need to conform to the
> 1/f power spectrum?  +/- 0.1 dB?  0.01 dB?
>
> all this can be done with a good white noise source and a filter
> alternating real poles and real zeros placed at just the right values.  for
> 32 octaves, i would hate to guess how many pole/zero pairs you would need.
>  maybe 10.
>
>
>
> r b-j
>
>
>  Original Message 
> Subject: [music-dsp] High quality really broad bandwidth pinknoise
> (ideally more than 32 octaves)
> From: "Seth Nickell" 
> Date: Mon, April 11, 2016 12:57 pm
> To: music-dsp@music.columbia.edu
> --
>
>
> > I'm applying an iterative function to an input signal, in this instance
> > pinknoise. Because of the iteration, spectral characteristics in input
> > signals tend to "blow up" really quickly, so I'm looking for a really
> high
> > bandwidth and high quality source of pink noise.
> >
> > My understanding is that most of the approaches like the supercollider
> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As
> the
> > number of octaves grows, the accurcary drops. Is my understanding
> correct?
> >
> > I'm hoping to find a way to generate pink noise that is:
> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
> > 2) Tractable to generate an arbitrarily large number of samples
> (billions,
> > so can't fft the whole thing in one pass)
> >
> > Any suggestions? I've read through
> > http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems
> > focused on fast-generation of pink noise of moderate quality and a
> > relatively narrow bandwidth. I'm sort of looking for the other side of
> > things... what's the most ideal pink noise I can generate en masse?
> >
> > Thanks,
> > -Seth
>
>
> --
>
> r b-j  r...@audioimagination.com
>
> "Imagination is more important than knowledge."
>
>
>
> ___
> dupswapdrop: music-dsp mailing list
> music-dsp@music.columbia.edu
> https://lists.columbia.edu/mailman/listinfo/music-dsp
>



-- 
--- james mccartney
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[Seth Nickell]

not an EE undergrad :-P CS with enough music interest to take a few classes
and learn enough to shoot my foot off.

-seth

On Mon, Apr 11, 2016 at 5:30 PM robert bristow-johnson <
r...@audioimagination.com> wrote:

>
>
> assuming you were EE undergrad, do you remember "Bode plots" doing
> frequency response in analog electronics?
>
> start out with a wire.  you're frequency response is flat: 0 dB per octave.
>
> then add a pole at a frequency of around  0.447 Hz (that's the bottom
> of your 32 Octaves assuming Nyquist at 192 kHz).  we can't hear the bottom
> 19 octaves.  then we hear from octave 20 up to octave 29.  octaves 30, 31,
> and 32 are above our hearing range.  so starting at that terribly low
> frequency, put in a pole.  that gives you a corner and the slope is
> starting to bend down and if you don't do anything about it, eventually to
> -6 dB/oct (twice as much as you want).  then maybe an octave above that,
> put in a zero.  that will bend it flat again.  then an octave above that
> another pole.  and octave above that another zero. etc.
>
> so your slope will be bending between 0 and -6 dB/octave, but really
> doesn't get to either asymptote.  keep the spacing equally spaced in log
> frequency except for the two ends, then you'll have to tweak the poles or
> zero placement at the ends because of "end effect".  but in the middle the
> poles and zeros are equally-spaced in log frequency.  the tighter the
> spacing, the more pole/zero pairs you will need and the better conformance
> to -3 dB per decade.
>
> r b-j
>
>  Original Message 
>
> Subject: Re: [music-dsp] High quality really broad bandwidth pinknoise
> (ideally more than 32 octaves)
> From: "Seth Nickell" 
>
> Date: Mon, April 11, 2016 7:59 pm
> To: r...@audioimagination.com
> music-dsp@music.columbia.edu
> --
>
>
>
> > Hi Robert,
> >
> > I know very little about filter design (hazy undergrad memories, you know
> > the type), is this something I could sanely rig for myself, or is that
> > total madness as a filter novice? Could you point me toward the right
> terms
> > I need to read up about to learn more about this?
> >
> > -Seth
> >
> > On Mon, Apr 11, 2016 at 10:47 AM robert bristow-johnson <
> > r...@audioimagination.com> wrote:
> >
> >> being that this is a discussion group about music, which is a subset of
> >> audio. and being that our hearing is at best 10 or 11 octaves, why do
> you
> >> need 32 octaves?
> >>
> >> and then how closely, in dB, does your pink noise need to conform to the
> >> 1/f power spectrum? +/- 0.1 dB? 0.01 dB?
> >>
> >> all this can be done with a good white noise source and a filter
> >> alternating real poles and real zeros placed at just the right values.
> for
> >> 32 octaves, i would hate to guess how many pole/zero pairs you would
> need.
> >> maybe 10.
> >>
> >>
> >>
> >> r b-j
> >>
> >>
> >>  Original Message
> 
> >> Subject: [music-dsp] High quality really broad bandwidth pinknoise
> >> (ideally more than 32 octaves)
> >>
> From: "Seth Nickell" 
> >> Date: Mon, April 11, 2016 12:57 pm
> >> To: music-dsp@music.columbia.edu
> >>
> --
> >>
> >>
> >>
> >> > I'm applying an iterative function to an input signal, in this
> instance
> >> > pinknoise. Because of the iteration, spectral characteristics in input
> >> > signals tend to "blow up" really quickly, so I'm looking for a really
> >> high
> >> > bandwidth and high quality source of pink noise.
> >> >
> >> > My understanding is that most of the approaches like the supercollider
> >> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth.
> As
> >> the
> >> > number of octaves grows, the accurcary drops. Is my understanding
> >> correct?
> >> >
> >> > I'm hoping to find a way to generate pink noise that is:
> >> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
> >> > 2) Tractable to generate an arbitrarily large number of samples
> >> (billions,
> >> > so can't fft the whole thing in one pass)
> >> >
> >> > Any suggestions? I've read through
> >> > http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems
> >> > focused on fast-generation of pink noise of moderate quality and a
> >> > relatively narrow bandwidth. I'm sort of looking for the other side of
> >> > things... what's the most ideal pink noise I can generate en masse?
> >> >
> >> > Thanks,
> >> > -Seth
> >>
> >>
> >> --
> >>
> >> r b-j r...@audioimagination.com
> >>
> >> "Imagination is more important than knowledge."
> >>
> >>
> >> ___
> >> dupswapdrop: music-dsp mailing list
> >> music-dsp@music.columbia.edu
> >> https://lists.columbia.edu/mailman/listinfo/music-dsp
> >
>
>
> --
>
> r b-j 

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[robert bristow-johnson]

�
assuming you were EE undergrad, do you remember "Bode plots" doing frequency 
response in analog electronics?
start out with a wire. �you're frequency response is flat: 0 dB per octave.
then add a pole at a frequency of around �0.447 Hz (that's the
bottom of your 32 Octaves assuming Nyquist at 192 kHz). �we can't hear the 
bottom 19 octaves. �then we hear from octave 20 up to octave 29. �octaves 30, 
31, and 32 are above our hearing range. �so starting at that terribly low 
frequency, put in a pole. �that gives you a
corner and the slope is starting to bend down and if you don't do anything 
about it, eventually to -6 dB/oct (twice as much as you want). �then maybe an 
octave above that, put in a zero. �that will bend it flat again. �then an 
octave above that another pole. �and octave above
that another zero. etc.
so your slope will be bending between 0 and -6 dB/octave, but really doesn't 
get to either asymptote. �keep the spacing equally spaced in log frequency 
except for the two ends, then you'll have to tweak the poles or zero placement 
at the ends because of "end
effect". �but in the middle the poles and zeros are equally-spaced in log 
frequency. �the tighter the spacing, the more pole/zero pairs you will need and 
the better conformance to -3 dB per decade.
r b-j


 Original Message 

Subject: Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally 
more than 32 octaves)

From: "Seth Nickell" 

Date: Mon, April 11, 2016 7:59 pm

To: r...@audioimagination.com

music-dsp@music.columbia.edu

--



> Hi Robert,

>

> I know very little about filter design (hazy undergrad memories, you know

> the type), is this something I could sanely rig for myself, or is that

> total madness as a filter novice? Could you point me toward the right terms

> I need to read up about to learn more about this?

>

> -Seth

>

> On Mon, Apr 11, 2016 at 10:47 AM robert bristow-johnson <

> r...@audioimagination.com> wrote:

>

>> being that this is a discussion group about music, which is a subset of

>> audio. and being that our hearing is at best 10 or 11 octaves, why do you

>> need 32 octaves?

>>

>> and then how closely, in dB, does your pink noise need to conform to the

>> 1/f power spectrum? +/- 0.1 dB? 0.01 dB?

>>

>> all this can be done with a good white noise source and a filter

>> alternating real poles and real zeros placed at just the right values. for

>> 32 octaves, i would hate to guess how many pole/zero pairs you would need.

>> maybe 10.

>>

>>

>>

>> r b-j

>>

>>

>>  Original Message 

>> Subject: [music-dsp] High quality really broad bandwidth pinknoise

>> (ideally more than 32 octaves)

>>

From: "Seth Nickell" 

>> Date: Mon, April 11, 2016 12:57 pm

>> To: music-dsp@music.columbia.edu

>> --

>>

>>

>>

>> > I'm applying an iterative function to an input signal, in this instance

>> > pinknoise. Because of the iteration, spectral characteristics in input

>> > signals tend to "blow up" really quickly, so I'm looking for a really

>> high

>> > bandwidth and high quality source of pink noise.

>> >

>> > My understanding is that most of the approaches like the supercollider

>> > PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As

>> the

>> > number of octaves grows, the accurcary drops. Is my understanding

>> correct?

>> >

>> > I'm hoping to find a way to generate pink noise that is:

>> > 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves

>> > 2) Tractable to generate an arbitrarily large number of samples

>> (billions,

>> > so can't fft the whole thing in one pass)

>> >

>> > Any suggestions? I've read through

>> > http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems

>> > focused on fast-generation of pink noise of moderate quality and a

>> > relatively narrow bandwidth. I'm sort of looking for the other side of

>> > things... what's the most ideal pink noise I can generate en masse?

>> >

>> > Thanks,

>> > -Seth

>>

>>

>> --

>>

>> r b-j r...@audioimagination.com

>>

>> "Imagination is more important than knowledge."

>>

>>

>> ___

>> dupswapdrop: music-dsp mailing list

>> music-dsp@music.columbia.edu

>> https://lists.columbia.edu/mailman/listinfo/music-dsp

>





--
r b-j � � � � � � � � �r...@audioimagination.com
"Imagination is more important than knowledge."
�
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[Al Clark]

I presented a solution at the comp.dsp conference in 2010

It uses the pole zero approach that rb-j mentioned earlier. 
I used a magnitude squared approach to calculate the 
coefficients. You can make it as good as you want although 
math precision issues are probably going to be an issue at 
very low frequencies.


Here is the link:

http://compdsp.com/presentations/Clark/Magnitude%20squared%20method%20to%20solve%20a%20collection%20of%20arbitrary%20functions.pdf

Al Clark











On 4/11/2016 7:26 PM, Evan Balster wrote:
I haven't yet come across an automated process for 
designing high-quality pinking filters, so if someone can 
offer one up I'd also love to hear about it!


Seth -- as you say, "the error from 1/f can't be corrected 
by increasing the number of iterations".  Adding octaves 
to the Voss-McCartney algorithm only lowers its bottom 
frequency.  But do consider my suggestion above...  The 
ripple in VM noise has a logarithmic periodicity of 1 
octave in the frequency domain...  You could eliminate it 
by way of destructive interference if you generate the 
pink noise at equally-spaced sampling rates between N 
(inclusive) and 2N (exclusive).  With this approach you 
could get an arbitrarily flat slope -- if you're willing 
to pay the cost!


Your project sounds totally bonkers, but I'll give you the 
benefit of the doubt on that.  :)


– Evan Balster
creator of imitone 

On Mon, Apr 11, 2016 at 6:59 PM, Seth Nickell 
> wrote:


Hi Robert,

I know very little about filter design (hazy undergrad
memories, you know the type), is this something I
could sanely rig for myself, or is that total madness
as a filter novice? Could you point me toward the
right terms I need to read up about to learn more
about this?

-Seth

On Mon, Apr 11, 2016 at 10:47 AM robert
bristow-johnson > wrote:

being that this is a discussion group about music,
which is a subset of audio.  and being that our
hearing is at best 10 or 11 octaves, why do you
need 32 octaves?

and then how closely, in dB, does your pink noise
need to conform to the 1/f power spectrum?  +/-
0.1 dB?  0.01 dB?

all this can be done with a good white noise
source and a filter alternating real poles and
real zeros placed at just the right values.  for
32 octaves, i would hate to guess how many
pole/zero pairs you would need.  maybe 10.

r b-j


 Original Message

Subject: [music-dsp] High quality really broad
bandwidth pinknoise (ideally more than 32 octaves)
From: "Seth Nickell" >
Date: Mon, April 11, 2016 12:57 pm
To: music-dsp@music.columbia.edu


--



> I'm applying an iterative function to an input
signal, in this instance
> pinknoise. Because of the iteration, spectral
characteristics in input
> signals tend to "blow up" really quickly, so I'm
looking for a really high
> bandwidth and high quality source of pink noise.
>
> My understanding is that most of the approaches
like the supercollider
> PinkNoise.ar ugen are mostly accurate, but over
a limited bandwidth. As the
> number of octaves grows, the accurcary drops. Is
my understanding correct?
>
> I'm hoping to find a way to generate pink noise
that is:
> 1) Accurate over an arbitrarily wide bandwidth,
at least 32 octaves
> 2) Tractable to generate an arbitrarily large
number of samples (billions,
> so can't fft the whole thing in one pass)
>
> Any suggestions? I've read through
>
http://www.firstpr.com.au/dsp/pink-noise/#Pseudo,
but everyone seems
> focused on fast-generation of pink noise of
moderate quality and a
> relatively narrow bandwidth. I'm sort of looking
for the other side of
> things... what's the most ideal pink noise I can
generate en masse?
>
> Thanks,
> -Seth


--

r b-j r...@audioimagination.com


"Imagination is more important than knowledge."

___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu

https://lists.columbia.edu/mailman/listinfo/music-dsp


___
dupswapdrop: music-dsp 

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[Ross Bencina]

On 12/04/2016 10:26 AM, Evan Balster wrote:

I haven't yet come across an automated process for designing
high-quality pinking filters, so if someone can offer one up I'd also
love to hear about it!


Last time that I  checked (about a year and a half ago) the following 
was the best reference that I could find. Unfortuately I'm not yet 
sufficiently initiated to follow the Hardy-space methods.


"Simulation of Fractional-Order Low-Pass Filters"
Thomas Hélie (IRCAM)
IEEE/ACM TRANSACTIONS ON AUDIO, SPEECH, AND LANGUAGE PROCESSING, VOL. 
22, NO. 11, NOVEMBER 2014


Abstract:

"""
The attenuation of standard analog low-pass filters
corresponds to a multiple value of decibels per octave. This
quantified value is related to the order of the filter. The issue
addressed here is concerned with the extension of integer orders
to non integer orders, such that the attenuation of a low-pass filter
can be continuously adjusted. Fractional differential systems are
known to provide such asymptotic behaviors and many results
about their simulation are available. But even for a fixed cutoff
frequency, their combination does not generate an additive group
with respect to the order and they involve stability problems. In
this paper, a class of low-pass filters with orders between 0 (the
filter is a unit gain) and 1 (standard one-pole filter) is defined to
restore these properties. These infinite dimensional filters are not
fractional differential but admit some well-posed representations
into weighted integrals of standard one-pole filters. Based on this,
finite dimensional approximations are proposed and recast into the
framework of state-space representations. A special care is given
to reduce the computational complexity, through the dimension
of the state. In practice, this objective is reached for the complete
family, without damaging the perceptive quality, with dimension
13. Then, an accurate low-cost digital version of this family is
built in the time-domain. The accuracy of the digital filters is
verified on the complete range of parameters (cutoff frequencies
and fractional orders). Moreover, the stability is guaranteed, even
for time-varying parameters. As an application, a plugin has been
implemented which provides a new audio tool for tuning the cutoff
frequency and the asymptotic slope in a continuous way. As a
very special application, choosing a one-half order combined with
a low cutoff frequency (20 Hz or less), the filter fed with a white
noise provides a pink noise generator.
"""


There is an AES paper by the same author:
http://dl.acm.org/citation.cfm?id=2693064

HTH,

Ross.
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[robert bristow-johnson]

being that this is a discussion group about music, which is a subset of audio. 
�and being that our hearing is at best 10 or 11 octaves, why do you need 32 
octaves?
and then how closely, in dB, does your pink noise need to conform to the 1/f 
power spectrum? �+/- 0.1 dB? �0.01
dB?
all this can be done with a good white noise source and a filter alternating 
real poles and real zeros placed at just the right values. �for 32 octaves, i 
would hate to guess how many pole/zero pairs you would need. �maybe 10.
�
r b-j

 Original Message 

Subject: [music-dsp] High quality really broad bandwidth pinknoise (ideally 
more than 32 octaves)

From: "Seth Nickell" 

Date: Mon, April 11, 2016 12:57 pm

To: music-dsp@music.columbia.edu

--



> I'm applying an iterative function to an input signal, in this instance

> pinknoise. Because of the iteration, spectral characteristics in input

> signals tend to "blow up" really quickly, so I'm looking for a really high

> bandwidth and high quality source of pink noise.

>

> My understanding is that most of the approaches like the supercollider

> PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As the

> number of octaves grows, the accurcary drops. Is my understanding correct?

>

> I'm hoping to find a way to generate pink noise that is:

> 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves

> 2) Tractable to generate an arbitrarily large number of samples (billions,

> so can't fft the whole thing in one pass)

>

> Any suggestions? I've read through

> http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems

> focused on fast-generation of pink noise of moderate quality and a

> relatively narrow bandwidth. I'm sort of looking for the other side of

> things... what's the most ideal pink noise I can generate en masse?

>

> Thanks,

> -Seth





--
r b-j � � � � � � � � �r...@audioimagination.com
"Imagination is more important than knowledge."
�
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

Re: [music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[Evan Balster]

Hey, Seth --

Check out the Voss-McCartney algorithm on that page.  It's wonderfully
cheap and you can extend it to as many octaves as you like without an
increase in operations per sample.  Obviously the resulting noise isn't
perfect -- it's a little distorted near Nyquist and has some ripple between
the "octaves" of white noise -- but additional octaves do not (as far as I
understand) degrade quality.

The ripple could be mitigated by mixing independent sources of pink noise
generated at different sampling rates between N and 2N, and the top-end
could be fixed (if necessary) by a process of high-quality downsampling.
Combining these solutions, one could imagine an process whereby we generate
wideband white noise using the Voss-McCartney algorithm at rates of, say,
96K, 112K, 128K, 144K, 160K and 176K, apply a high-quality downsampling
algorithm to produce 48K versions, then amplify and mix them according to
the -3dB trend.

– Evan Balster
creator of imitone 

On Mon, Apr 11, 2016 at 11:57 AM, Seth Nickell  wrote:

> I'm applying an iterative function to an input signal, in this instance
> pinknoise. Because of the iteration, spectral characteristics in input
> signals tend to "blow up" really quickly, so I'm looking for a really high
> bandwidth and high quality source of pink noise.
>
> My understanding is that most of the approaches like the supercollider
> PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As the
> number of octaves grows, the accurcary drops. Is my understanding correct?
>
> I'm hoping to find a way to generate pink noise that is:
> 1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
> 2) Tractable to generate an arbitrarily large number of samples (billions,
> so can't fft the whole thing in one pass)
>
> Any suggestions? I've read through
> http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems
> focused on fast-generation of pink noise of moderate quality and a
> relatively narrow bandwidth. I'm sort of looking for the other side of
> things... what's the most ideal pink noise I can generate en masse?
>
> Thanks,
> -Seth
>
> ___
> dupswapdrop: music-dsp mailing list
> music-dsp@music.columbia.edu
> https://lists.columbia.edu/mailman/listinfo/music-dsp
>
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

[music-dsp] High quality really broad bandwidth pinknoise (ideally more than 32 octaves)

[Seth Nickell]

I'm applying an iterative function to an input signal, in this instance
pinknoise. Because of the iteration, spectral characteristics in input
signals tend to "blow up" really quickly, so I'm looking for a really high
bandwidth and high quality source of pink noise.

My understanding is that most of the approaches like the supercollider
PinkNoise.ar ugen are mostly accurate, but over a limited bandwidth. As the
number of octaves grows, the accurcary drops. Is my understanding correct?

I'm hoping to find a way to generate pink noise that is:
1) Accurate over an arbitrarily wide bandwidth, at least 32 octaves
2) Tractable to generate an arbitrarily large number of samples (billions,
so can't fft the whole thing in one pass)

Any suggestions? I've read through
http://www.firstpr.com.au/dsp/pink-noise/#Pseudo, but everyone seems
focused on fast-generation of pink noise of moderate quality and a
relatively narrow bandwidth. I'm sort of looking for the other side of
things... what's the most ideal pink noise I can generate en masse?

Thanks,
-Seth
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp

[music-dsp] A DAC improvement experiment I did

[Theo Verelst]

Hi all,

There's been a bit of discussion here at times about Digital To Analog Conversion that 
inevitably follows a lot of DSP experiments, and the lack of complete accuracy that might 
make music sound less good than intended. Depending on the POV and varying opinions of 
course, but it's my opinion things are far from perfect and nice, as yet.


So I did this experiment, and for good types of music recordings (like HDTracks high 
resolution audio from well known artists) I can get a lot more pleasant results when I put 
my large and good quality audio system loud.


So if you're interested, here's a page on my server about what I did:

   http://www.theover.org/Dsp/Simpleundistort/

Enjoy, and discuss if you feel like it, though this is not part of an attempt to start a 
deep science discussion about the subject, even though I'd probably prefer it i that were 
possible; it's a practical experiment, and there's a download containing all the DSP blocks.


Theo V.
___
dupswapdrop: music-dsp mailing list
music-dsp@music.columbia.edu
https://lists.columbia.edu/mailman/listinfo/music-dsp