Re: [music-dsp] Bandlimited morphable waveform generation

[Ross Bencina]

On 24/09/2016 3:01 PM, Andrew Simper wrote:

> "Hard Sync Without Aliasing," Eli Brandt
> http://www.cs.cmu.edu/~eli/papers/icmc01-hardsync.pdf
>

>

But stick to linear phase as you can correct more easily for dc offsets.


What's your reasoning for saying that?

I'm guessing it depends on whether you have an analytic method for 
generating the minBLEP.


Ross.
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Re: [music-dsp] Bandlimited morphable waveform generation

[Andrew Simper]

On 24 September 2016 at 12:06, Ross Bencina  wrote:
> On 24/09/2016 1:28 PM, Andrew Simper wrote:
>>
>> Corrective grains are also called BLEP / BLAMP etc, so have a read about
>> those.
>
>
> Original reference:
>
> "Hard Sync Without Aliasing," Eli Brandt
> http://www.cs.cmu.edu/~eli/papers/icmc01-hardsync.pdf
>

But stick to linear phase as you can correct more easily for dc offsets.
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Re: [music-dsp] Bandlimited morphable waveform generation

[Ross Bencina]

On 24/09/2016 1:28 PM, Andrew Simper wrote:

Corrective grains are also called BLEP / BLAMP etc, so have a read about those.


Original reference:

"Hard Sync Without Aliasing," Eli Brandt
http://www.cs.cmu.edu/~eli/papers/icmc01-hardsync.pdf
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Re: [music-dsp] Bandlimited morphable waveform generation

[Andrew Simper]

Corrective grains are also called BLEP / BLAMP etc, so have a read about those.

If f(x) is your function then I'm defining:

C(0) = f(x) doesn't suddenly jump anywhere, i.e. is smooth in the 0th derivative
C(1) = f'(x) doesn't jump anywhere, i.e. is smooth in the 1st derivative
...
C(n) = f^n(x) doesn't jump anywhere

Now the C^n (where n is a superscript) in papers normally means you
have C(0), C(1), all the way up to C(n)

For example:

saw and sqr are not C(0), but are C(1) onwards (zero)
tri is C(0), but not C(1), but then C(2) onwards (zero)
sin C(n) for all n, which is C^inf

If you function is not C(n) for a particular n then you need to band
limit this transition, which will normally occur at a fraction of a
sample.

Cheers,

Andy

On 22 September 2016 at 18:18, André Michelle  wrote:
> Hi Andrew,
>
>
> I am having a hard time understanding what you are suggesting.
>
> Don't use wavetables!
>
>
> I would be pleased not to.
>
> As you have constructed your desired waveform as a continuous function
> all you have to do is work out where any discontinuities in C(n) occur
> and you can band limit those use corrective grains for each C(n)
> discontinuity at fractions of a sample where the discontinuity occurs.
> Adding sync to this is trivial is you just do the same thing, in fact
> you can jump between any two points in your waveform or waveform shape
> instantly if you want to create even more interesting waveforms.
>
>
> How do I detect discontinuities? It is easy to see when printed visually but
> I do not see how I can approach this with code. Do I need the ‘complete’
> function at once and check or can I do it in runtime for each sample. I
> think so since you suggest that I can jump around within the function
> without alias? Because that would sound like a solution I wanted to have
> from the very beginning.
>
> For example a sawtooth is C(1) continuous all the time, it just has a
> jump in C(0) every now and again, so you just band limit those jumps
> with a C(0) corrective grain - which is an integrated sinc function to
> give you a bandlmited step, then subtract the trivial step from this,
> and add in this corrective grain at a fraction of a sample to
> re-construct your fraction of a sample band limited step.
>
>
> I do not quite get this: C(1). Does it mean I have C(n) values of the
> function where C(1) is the second value?
> What frequency does the integrated sync function has?
> What is a 'fraction of a sample'?
>
> Similarly you can bandlimit C(1) and C(2) discontinuities, after that
> the amplitude of the discontinuities is so small that it rarely
> matters if you are running at 88.2 / 96 khz.
>
>
> I am missing to many aspects of your suggestion. Any hints where to learn
> about this would be appreciated.
>
> ~
> André Michelle
> https://www.audiotool.com
>
>
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Re: [music-dsp] New session of the MOOC on Audio Signal Processing for Music Applications

[Nigel Redmon]

Thanks, Xavier

List: I took the initial session of this course a couple of years ago 
(already?), and highly recommend it.

(If I can spare the time, I’ll monitor this session and see what’s new.)


> On Sep 23, 2016, at 12:41 AM, Serra Xavier  wrote:
> 
> A new session of the MOOC on Audio Signal Processing for Music Applications 
> is starting in Coursera on September 26th. To enrol go to 
> https://www.coursera.org/learn/audio-signal-processing
> 
> This is a 10 week long course that focuses on the spectral processing 
> techniques of relevance for the description and transformation of sounds, 
> developing the basic theoretical and practical knowledge with which to 
> analyze, synthesize, transform and describe audio signals in the context of 
> music applications.
> 
> The course is free and based on open software and content. The demonstrations 
> and programming exercises are done using Python under Ubuntu, and the 
> references and materials for the course come from open online repositories. 
> The software and materials developed for the course are also distributed with 
> open licenses.
> 
> The course assumes some basic background in mathematics and signal 
> processing. Also, since the assignments are done with the programming 
> language Python, some software programming skills in any language are most 
> helpful. 
> 
> 
> ---
> Xavier Serra
> Music Technology Group
> Universitat Pompeu Fabra, Barcelona
> http://www.dtic.upf.edu/~xserra/

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Re: [music-dsp] Low Noise Power Supply for audio applications resources.

[Max K]

Cheers Andy,


I'll look into that!



Von: music-dsp-boun...@music.columbia.edu 
 im Auftrag von Andy Farnell 

Gesendet: Donnerstag, 15. September 2016 14:23
An: music-dsp@music.columbia.edu
Betreff: Re: [music-dsp] Low Noise Power Supply for audio applications 
resources.

Hi Max

The usual steps are to use a three termimal regulator
of the 78 series, smoothing capacitors and perhaps
some inductive chokes if you are using USB or unregulated
supplies with high frequency noise on.

Normally you require the input supply to be at least a
couple of volts above the regulated potential you need
and components must be chosen with power/current
requirements in mind. There are many amazing new single
package power conditioning ICs areound these days.

You really should take this to an analogue design list
as music-DSP isnt really the best place, and I am sure
some of the other members can advise you on the best
group to post in. Perhaps start by hanging out on ##hardware
on freenode or similar and asking where you can chat about
PSU design.

cheers
Andy

On Thu, Sep 15, 2016 at 11:43:52AM +, Max K wrote:
> Hi everyone,
>
>
> I'm still working on my digital guitar pedal and now I have to design a power 
> filtering stage to filter the noisy output of a 5V AC/DC power supply. I need 
> clean power for my analog components (pre-amps and DAC/ADCs) as well as the 
> ARM Cortex A9 based 1GHz digital circuitry. I want to "smoothen" the DC 
> current and get rid of all AC components (apparently the correct term for 
> this is "bypassing") and I need to decouple the digital circuit from the 
> analog circuit, so they don't interfere with each other (decoupling). In 
> addition, I have been told that a good ground is also important.
>
>
> I have been googling this topic and found some papers (e.g. this one 
> http://www.designers-guide.org/design/bypassing.pdf) but I'm also interested 
> if you - as fellow "audiophiles" - can point me to any literature covering 
> this topic or have some first hand advice. I tried searching the mailing list 
> archives (which is a pain really) and unfortunately the archives from before 
> August 2015 seem to be gone (404).
Power Supply Noise Reduction - Designer's 
Guide
www.designers-guide.org
Power Supply Noise Reduction Reducing Inductance 4 of 12 The Designer's Guide 
Community www.designers-guide.org inductance can be reduced by decreasing its 
length ...


>
>
> Cheers,
>
> Max
>
> Power Supply Noise Reduction - Designer's 
> Guide
> www.designers-guide.org
> Power Supply Noise Reduction Reducing Inductance 4 of 12 The Designer's Guide 
> Community www.designers-guide.org inductance 
> can be reduced by decreasing its length ...
>
>

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[music-dsp] New session of the MOOC on Audio Signal Processing for Music Applications

[Serra Xavier]

A new session of the MOOC on Audio Signal Processing for Music Applications is 
starting in Coursera on September 26th. To enrol go to 
https://www.coursera.org/learn/audio-signal-processing

This is a 10 week long course that focuses on the spectral processing 
techniques of relevance for the description and transformation of sounds, 
developing the basic theoretical and practical knowledge with which to analyze, 
synthesize, transform and describe audio signals in the context of music 
applications.

The course is free and based on open software and content. The demonstrations 
and programming exercises are done using Python under Ubuntu, and the 
references and materials for the course come from open online repositories. The 
software and materials developed for the course are also distributed with open 
licenses.

The course assumes some basic background in mathematics and signal processing. 
Also, since the assignments are done with the programming language Python, some 
software programming skills in any language are most helpful. 


---
Xavier Serra
Music Technology Group
Universitat Pompeu Fabra, Barcelona
http://www.dtic.upf.edu/~xserra/





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