Re: [music-dsp] Sampling theorem extension

2015-06-11 Thread robert bristow-johnson
On 6/11/15 5:39 PM, Sampo Syreeni wrote: On 2015-06-09, robert bristow-johnson wrote: BTW, i am no longer much enamoured with BLIT and the descendents of BLIT. eventually it gets to an integrated (or twice or 3 times integrated) wavetable synthesis, and at that point, i'll just do bandlimite

Re: [music-dsp] FFTW Help in C

2015-06-11 Thread Bogac Topaktas
The following link provides lots of detail regarding implementation: http://www.codeproject.com/Articles/6855/FFT-of-waveIn-audio-signals You can find the FFT code written by Don Cross, which is used in the above article at: http://web.archive.org/web/20020221213551/http://www.intersrv.com/~dcro

Re: [music-dsp] Sampling theorem extension

2015-06-11 Thread Sampo Syreeni
On 2015-06-09, robert bristow-johnson wrote: so the way i resolve it in my head is say that (among other facts like there really aren't any signals, remaining non-zero, that go off to t = +/- infinity) i will model, in my imagination, the ideal impulse function in time as having area of 1 (and

Re: [music-dsp] FFTW Help in C

2015-06-11 Thread Richard Dobson
If it is purely for graphic display, the interesting aspect coding-wise will be timing, so that the display coincides closely enough with the audio it represents. In this regard, the update rate for a running display rarely needs to be more than 60 fps, and can often be slower - so you would on

Re: [music-dsp] FFTW Help in C

2015-06-11 Thread Danny van Swieten
When setting up the audio callback for PortAudio you can give it a void* to some data. Set up the fft plan and set the fft object as the void*. In the callback you can use a cast to get the fft object from the void* Good luck Sent from my iPhone > On 11 Jun 2015, at 16:20, Connor Gettel wrote:

Re: [music-dsp] [ot] other than sampling theorem, Theo

2015-06-11 Thread robert bristow-johnson
On 6/11/15 1:20 PM, Sampo Syreeni wrote: On 2015-06-11, Theo Verelst wrote: [...] I don't recommend any of the guys I've read from here to presume they'll make it high up the mathematical pecking order by assuming all kinds of previous century generalities, while being even more imprecise abo

Re: [music-dsp] Sampling theorem extension

2015-06-11 Thread Sampo Syreeni
On 2015-06-11, vadim.zavalishin wrote: Not really, if the windowing is done right. The DC offsets have more to do with the following integration step. I'm not sure which integration step you are referring to. The typical framework starts with BLITs, implemented as interpolated wavetable loo

[music-dsp] [ot] other than sampling theorem, Theo

2015-06-11 Thread Sampo Syreeni
On 2015-06-11, Theo Verelst wrote: [...] I don't recommend any of the guys I've read from here to presume they'll make it high up the mathematical pecking order by assuming all kinds of previous century generalities, while being even more imprecise about Hilbert Space related math than already

Re: [music-dsp] Sampling theorem extension

2015-06-11 Thread vadim.zavalishin
Sampo Syreeni писал 2015-06-11 15:55: On 2015-06-11, Vadim Zavalishin wrote: So they can be considered "kind of" bandlimited, although as I noted in my other post, it seems to result in DC offsets in their restored versions, if sinc is windowed. Not really, if the windowing is done right. Th

Re: [music-dsp] FFTW Help in C

2015-06-11 Thread Bjorn Roche
The important thing is to do anything that might take an unbounded amount of time outside your callback. For a simple FFT, the rule of thumb might be that all setup takes place outside the callback. For example, as long as you do all your malloc stuff outside the callback, processing and so on can

Re: [music-dsp] FFTW Help in C

2015-06-11 Thread Athos Bacchiocchi
You may find this article useful: http://www.rossbencina.com/code/real-time-audio-programming-101-time-waits-for-nothing It deals with the things to do and not to do when processing audio in realtime using callbacks. Athos On 11 June 2015 at 16:20, Connor Gettel wrote: > Hello Everyone, > > M

Re: [music-dsp] FFTW Help in C

2015-06-11 Thread Phil Burk
Hello Connor, If you just wanted to do a quick FFT and then using the spectrum to control synthesis, then I would recommend staying in the callback. If you are doing overlap-add then set framesPerBuffer to half your window size and combine the current buffer with the previous buffer to feed into t

[music-dsp] FFTW Help in C

2015-06-11 Thread Connor Gettel
Hello Everyone, My name’s Connor and I’m new to this mailing list. I was hoping somebody might be able to help me out with some FFT code. I want to do a spectral analysis of the mic input of my sound card. So far in my program i’ve got my main function initialising portaudio, inputParameters,

Re: [music-dsp] Sampling theorem extension

2015-06-11 Thread Sampo Syreeni
On 2015-06-11, Vadim Zavalishin wrote: So they can be considered "kind of" bandlimited, although as I noted in my other post, it seems to result in DC offsets in their restored versions, if sinc is windowed. Not really, if the windowing is done right. The DC offsets have more to do with the

Re: [music-dsp] Sampling theorem extension

2015-06-11 Thread Theo Verelst
HI While it's cute you all followed my lead to think about simple continuous signals that are bandwidth limited, such that they can be used as proper examples for a digitization/synthesis/reconstruction discipline, I don't recommend any of the guys I've read from here to presume they'll make

Re: [music-dsp] Sampling theorem extension

2015-06-11 Thread Vadim Zavalishin
On 11-Jun-15 11:00, Sampo Syreeni wrote: I don't know how useful the resulting Fourier transforms would be to the original poster, though: their structure is weird to say the least. Under the Fourier transform polynomials map to linear combinations of the derivatives of various orders of the delt

Re: [music-dsp] Sampling theorem extension

2015-06-11 Thread Sampo Syreeni
On 2015-06-09, Ethan Duni wrote: The Fourier transform does not exist for functions that blow up to +- infinity like that. To do frequency domain analysis of those kinds of signals, you need to use the Laplace and/or Z transforms. Actually in the distributional setting polynomials do have Fou

Re: [music-dsp] Sampling theorem extension

2015-06-11 Thread Vadim Zavalishin
On 10-Jun-15 21:26, Ethan Duni wrote: With bilateral Laplace transform it's also complicated, because the damping doesn't work there, except possibly at one specific damping setting (for an exponent, where for polynomials it doesn't work at all), yielding a DC Why isn't that sufficient? Do you