Pd-list June 2006

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138 participants
210 discussions

Re: [PD] deconvolution in pd
by Charles Henry 21 Jul '06

21 Jul '06

Yes, I see....the signal with compact support can have zeros outside of ROC...It's clear why, now. I'm not sure what to do differently yet.... my idea was this: given alpha <=1 (an adaptation coefficient) we do: 1. Fourier transform of 3 things: reference signal (length 2N), received signal from microphone (length 2N), and the weights (length N, padded with N zeros at the end). 2. divide (FT of reference) by (FT of received) 3. unwrap phase; take result of (2) as phase and magnitude 4. multiply (FT of weights) by mag^alpha*( cos (phase*alpha) + i sin(phase*alpha) ) 5. take IFT of weights, and throw away final N samples Maybe there's an eigenvalue/vector trick that I'm missing... chuck On 4/8/06, Piotr Majdak <piotr(a)majdak.com> wrote: > Hi Charles, > > Charles Henry wrote: > > >2. Fourier deconvolution: The only restriction here is that the > >signal spans the entire frequency range (which in terms of wavelets, > >is just an octave chirp). > > > Dividing by a spectrum, every zero become a pole. Thus, dividing by a > spectrum of a signal with zeros outside of ROC will result in unstable > signals. To avoid this problem you can try to calculate a minimum phase > version of your ref-signal and divide by that one. Of course, the phase > information won't be deconvolved perfectly in this case :-( > > br, Piotr Majdak > -- Charles Zachary Henry anti.dazed.med Med student who needs a Mickey's

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PD latency and timing accuracy with HID
by rubber glove 21 Jul '06

21 Jul '06

Hi: I am currently developing a system using PD will record users' responses to audio and video files. Essentially, the subject (this is for psychology experiments) will turn a knob indicating their like/dislike (or whatnot) of an audio or video file. For input, I am trying to use a Griffin PowerMate knob with the HID object ( http://at.or.at/hans/pd/hid.html ). I have written a simple external which keeps track of timing (using a timer from flext), and writes the data to a text file. Timing is important to the researcher. She has a system called the 'black box toolkit' http://www.blackboxtoolkit.co.uk/ and I have done some tests to determine the latency and timing accuracy. For the test, I have a puredata playing an audio file consisting of noise bursts at regular intervals, while I periodically press the knob. The 'Black Box' listens to the sound output and is also wired into the knob. I expected to see the values recorded by my PD external to be offset by 50ms (the latency setting) in comparison to the Black Box recorded values, but I was a bit surprised to see the offset vary between 48 and 62 ms (especially the 48ms!), which gives an uncertainty of 14ms. I was hoping for less than 10ms. The latency is not a problem at all, I am more concerned with accuracy and consistency (so that I can simply compensate for the latency) Where I should begin to try to improve this uncertainty (would I call it jitter?). What are the likely and most significant factors? Currently I have only tried the test under OS X, with the powermate knob. I will try again under linux, when I can get a LiveCD that will install easily on the old eMacs present in the lab. I will also try with a midi controller, when I find one that I don't mind soldering some test leads onto. Is the timing error most likely in PD, the HID object, the knob hardware (I know, probably), or just usb? Would a midi controller knob be expected to perform better? And really, what would be the limit of this kind of timing accuracy? Is 10ms as good as I can hope for? Thanks a million. -martin

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Feature Request: trigger editing
by Chuckk Hubbard 18 Jul '06

18 Jul '06

What if adding an element to an existing trigger object shifted all the outputs to the right of where the new one was inserted, instead of adding outputs to the right? Maybe a similar thing for deleting elements, instead of deleting outputs past a certain number, it could delete them from the middle? I can't think of any reason the current way would be better, but I may be missing something. -Chuckk -- "Far and away the best prize that life has to offer is the chance to work hard at work worth doing." -Theodore Roosevelt

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Gem - CPU usage 98%
by klaas de Baas 16 Jul '06

16 Jul '06

Hello, I am working on a patch, in which I use a webcam as a motiondetector, to drive another video (AVI, DV). (Every detected motion forwards a frame of the movie playing in pix_movie). I want this patch to be playing fullscreen in an exhibition for two months, non-stop. The problem is that I am worried about the CPU load - it hovers above 90% in Task Manager. (OS=WinXP) My concern is that the computer will not hold out on that load for that long. I had hoped to solve this by buying a new graphics card, which I thought would have taken over the processing load. I have been experimenting with the Asus n6200 256 MB (a Nvidia Geforce 6200 card) and the Hercules ati Radeon 9000 128 MB. I'm aware that my Mobo does not support 8X AGP bus speed, but since I am mainly looking for 2d acceleration I hoped it would be ok. CPU utilization is still high. My questions: - was I wrong in supposing that the GPU would take over processing tasks of the CPU? - what would be a realistic cpu load for 24 hours a day, 2 months? - Does anyone on the list have experience with running fullscreen gem-patches with specs such as pentium III, 800Mhz, 384 Mb, and do they have any pointers on how to optimize (such as using a different size video, codec, etc..?) I am also working on another computer (faster pIV, 512MB etc, etc...). I noticed that playing a video in mediaplayer requires less than half the cpu load of playing it in pix-movie or pix-film. - Can anyone explain why this is? Looking forward to hear from you. Klaas windows XP, pIII 800Mhz, 384 MB, Abit VL 6 Mobo, Hercules ATI Radeon 9000 128Mb

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Re: [PD] converting decimal to binary
by adam armfield 11 Jul '06

11 Jul '06

<pre>thanks chaps, chuck, yeah, i'd been thinking with this one to use the larger numbers as is (instead of chopping them to 8 beat length), so that the original part loops every 8 beat, and part 4 for instance, is much longer... i've had some success with using prime numbers as the lengths for sequences, i got the tip from a flash book years ago, with animation it works well with several elements looping at the same time, it creates longer sequences that don't repeat the same way twice... at least not for a long time in sound terms i like using clock dividers set to prime amounts, then feeding both signals into a logic gate, with a bit of care this can make really nice rhythms (using several such units) the bitwise gates in pd don't really lend themselves to this, but more straightforward gates do... i've had a quick look at your tribalhaus generator andy, looks really good from here (didn't get much joy sound-wise from this machine, pd audio in win98 isn't all that great anyway, i'll hopefully try it on a mac at some point, should be much better)... i had been thinking about using mathematical whatsit to create wavetables that could be kind of morphed or reshaped easily, what you've done there looks quite similar to what i had in mind. i had been wondering how primitive beatboxes store their rhythms, i assumed it was all hard-wired... all the best adam </pre> ___________________________________________________________ To help you stay safe and secure online, we've developed the all new Yahoo! Security Centre. http://uk.security.yahoo.com

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object name in GOP abstraction
by Federico 10 Jul '06

10 Jul '06

hello list(s), I have a problem: must create a small graph-on-parent abstraction. but I can't keep it small, because the object name and it's creation arguments enlarge the effective graph size. so if I set 20x20px as GOP size, but the object instance is: [myobj $0 foo bar 0 0 0 1] the instantiated object is too wide. is it possible to hide the object name (for GOP abstractions) or force it to not overflow dimensions set in canvas properties? (i write CC to the developer list, because i think if this is not possible, would be nice at least discuss about it... my little C programming skills don't help me in looking at the code and submitting an appropriate patch, but i think it won't get too difficult to change this... just want to see if other people experienced similar problems) bye -- Federico

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Abstractions from jmmmp
by João Miguel Pais 10 Jul '06

10 Jul '06

Hallo list, I just made available a small group of self-made abstractions, which I use myself a lot. Most of them require the GOP capabilities of Pd 0.39, and some other some external libraries. Please feel free to go to https://puredata.org/Members/jmmmp/ and download them and try them out. They are enough documented, and any remarks about them will be welcome. Greetings, JoÃ£o Miguel Pais -- Lugostr. 14 79100 Freiburg i. Br. Deutschland +49 (0)761 7074997 jmmmpais(a)googlemail.com http://www.puredata.org/Members/jmmmp

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state object
by glerm soares 09 Jul '06

09 Jul '06

I couldn't find a [state] object help not even in cvs. Is it there anywhere and i'm blind (or my locate is)? the object is loading. but I miss the help (if there's one). Could anyone could pass me a .pd abs using it(or the help file)? thanx -- _________________gLeRM SoAreS.......: baixem o album do matema 17mp3 num pacote--> http://www.organismo.art.br/matema

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anyone want OSC (or other externs) compiled for ppc-linux?
by Kevin McCoy 09 Jul '06

09 Jul '06

Hello, Thanks to some help from the list and the ever-useful pd-list archives, I was able to successfully compile OSC externs for PowerPC linux; I'm planning to do many many more externals soon. It took a while though, and I would like to save other ppc users the trouble if I can (especially for reinstalls, etc). As I go through and compile these, is there any constructive place to be putting them to share with others? I didn't find anything like that during my searching, and it appears to me (though this may be completely unfounded) that ppc-linux has a slowly growing base of users as more distros support Apple processors. I suppose I could make my own page, but I have no server at the moment. Or is Hans (or anyone else) interested in getting a pd-extended ppc Linux release going? I would be happy to help in any way I can. Kevin

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command line arguments for Pd 0.39 on OSX
by chris clepper 06 Jul '06

06 Jul '06

I would like to pass the -open argument to 0.39 so I can use a shell script to open Pd with specified patches. I can only get -open to work in the settings dialog.

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Pd-list June 2006