[LAD] Determining Phase
Hi, Can anyone point me to a simple code example for how to determine the phase at a specific time in a waveform? ex. if I have a sample that is 5 seconds long and want to know the phase at 2.5 seconds I'm open to code in any language or a scripted example if such a tool exists. If there is an ui which has that feature I am also interested. Cheers -- Patrick Shirkey Boost Hardware Ltd ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Tascam US-1641?
2011/6/22 Jeremy Jongepier autosta...@gmail.com: The US-1641 still appears to be unsupported. http://www.google.com/search?q=tascam+1641+site:mailman.alsa-project.org Also it appears superseded by Tascam US-1800 http://tascam.com/product/us-1800/ ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
On 06/25/2011 04:23 PM, pshir...@boosthardware.com wrote: Hi, Can anyone point me to a simple code example for how to determine the phase at a specific time in a waveform? ex. if I have a sample that is 5 seconds long and want to know the phase at 2.5 seconds talking about the phase at some particular point in time doesn't make sense. first you would have to do an fft (whose resolution is bound by the window size), and then you'd have to look at each frequency bin separately, because they will all be at different relative phase. when you talk directly into my ear, the voice/ear system will be roughly zero phase. when i move away even a few inches, there will be a linear phase distortion due to the fact that i'm now one wavelength away at some mid frequency, but several wavelengths at high frequencies. so phase is not really a meaningful thing unless you are talking about recombination of strongly correlated signals. another example: if your sample consists of a sine at 100hz and one at 200hz, after 10ms the first component will be at 0° while the second is at 180°, iff both started at 0° in the first place. but why would anyone care? with real-life sounds, this whole exercise becomes meaningless. what are you trying to accomplish? ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
On Saturday, June 25, 2011 09:23:29 am pshir...@boosthardware.com wrote: Hi, Can anyone point me to a simple code example for how to determine the phase at a specific time in a waveform? ex. if I have a sample that is 5 seconds long and want to know the phase at 2.5 seconds I'm open to code in any language or a scripted example if such a tool exists. If there is an ui which has that feature I am also interested. Do you mean... for a very simple sine wave? Assuming yes: p = asin( x / A ) Where: A is the amplitude of the sine wave x is the value of the sample (-A = x = A) p is the phase of the wave in radians (-pi/2 = p = pi/2) If not this... then... what Jörn said! :-) -gabriel ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
On Sat, Jun 25, 2011 at 04:23:29PM +0200, pshir...@boosthardware.com wrote: Can anyone point me to a simple code example for how to determine the phase at a specific time in a waveform? ex. if I have a sample that is 5 seconds long and want to know the phase at 2.5 seconds I'm open to code in any language or a scripted example if such a tool exists. If there is an ui which has that feature I am also interested. phase can mean a lot of things, and there is no such thing as the phase of a waveform. Maybe you could explain what you want to do. Ciao, -- FA ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
On Sat, Jun 25, 2011 at 01:55:05PM -0500, Gabriel M. Beddingfield wrote: Do you mean... for a very simple sine wave? Assuming yes: p = asin( x / A ) Where: A is the amplitude of the sine wave x is the value of the sample (-A = x = A) p is the phase of the wave in radians (-pi/2 = p = pi/2) And what if the phase is -pi/2 or +pi/2 ? -- FA ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
On Saturday, June 25, 2011 02:49:39 pm Fons Adriaensen wrote: p is the phase of the wave in radians (-pi/2 = p = pi/2) And what if the phase is -pi/2 or +pi/2 ? then you set phasers to stun. :-p Hey, at least I pointed out the limitation -gabriel ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
2011/6/25 Fons Adriaensen f...@linuxaudio.org: On Sat, Jun 25, 2011 at 01:55:05PM -0500, Gabriel M. Beddingfield wrote: Do you mean... for a very simple sine wave? Assuming yes: p = asin( x / A ) Where: A is the amplitude of the sine wave you mean the maximal amplitude (-MAX = x = +MAX) , I guess ? x is the value of the sample (-A = x = A) p is the phase of the wave in radians (-pi/2 = p = pi/2) And what if the phase is -pi/2 or +pi/2 ? since x = A (always), that result is not possible -- E.R. ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
On 06/26/2011 12:04 AM, Emanuel Rumpf wrote: 2011/6/25 Fons Adriaensenf...@linuxaudio.org: On Sat, Jun 25, 2011 at 01:55:05PM -0500, Gabriel M. Beddingfield wrote: Do you mean... for a very simple sine wave? Assuming yes: p = asin( x / A ) Where: A is the amplitude of the sine wave you mean the maximal amplitude (-MAX= x= +MAX) , I guess ? x is the value of the sample (-A= x= A) p is the phase of the wave in radians (-pi/2= p= pi/2) And what if the phase is -pi/2 or +pi/2 ? since x= A (always), that result is not possible ?! it seems you have just proven that the maximum duration of any pure tone is 1/f. that is quite extraordinary. might it even be the explanation of the almost mythical 1/f noise? all those tones suddenly realizing they have to stop or violate rumpf's lemma :-D sorry, couldn't resist... but seriously, it does make a lot of sense to talk about arbitrarily large phase angles. take a look at a real-life speaker system: it's not uncommon for the HF to lag behind the subs several complete cycles after passing through the crossover. even a perfectly phase-linear theoretical speaker exhibits them: in fact, if you stand 3.4m away from a speaker, the phase angle of a 100hz tone at your ear will be 360° relative to the membrane, while a 200hz tone will be at 720°, and so on. that's where delay becomes group delay, i.e. the same constant time delay implies different phase angles depending on frequency, pretty much arbitrarily large as the frequency rises. ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
2011/6/26 Emanuel Rumpf xb...@web.de: since x = A (always), better: abs( x ) = abs( A ) that result is not possible, with that function at least ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
On Sun, 26 Jun 2011 00:22:58 +0200 Jörn Nettingsmeier netti...@folkwang-hochschule.de wrote: that's where delay becomes group delay, i.e. the same constant time delay implies different phase angles depending on frequency, pretty much arbitrarily large as the frequency rises. Bingo! Which is why it is quite insane for people to worry about phase shift in amplifiers. As long as all channels are the same so there is no phase *difference* it's quite irrelevant. -- Will J Godfrey http://www.musically.me.uk Say you have a poem and I have a tune. Exchange them and we can both have a poem, a tune, and a song. ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
On Sat, 25 Jun 2011 16:23:29 +0200 (CEST), pshir...@boosthardware.com wrote: Hi, Can anyone point me to a simple code example for how to determine the phase at a specific time in a waveform? ex. if I have a sample that is 5 seconds long and want to know the phase at 2.5 seconds I'm open to code in any language or a scripted example if such a tool exists. If there is an ui which has that feature I am also interested. in general, theory i mean, phase equals delay; it can be computed deterministically iif the signal is a pure tone (sinusoidal) otherwise you must have a reference signal and referring to its fundamental frequency (1st order harmonic) or, when in-the-field, you can pick one conventional signal tone (i've been told that a 1khz is a usual choice:) and compare to that. if you are to compare two known signals (often input vs. output of some lti transformation, eg. filter), than the computation to do is correlation. well, you should use fft for that, but i'm sure you know that:) cheers -- rncbc aka Rui Nuno Capela rn...@rncbc.org ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
2011/6/26 Gabriel M. Beddingfield gabrb...@gmail.com: *headdesk*. Yes... should have been the half-amplitude of the signal... p = asin( 2*x / A ) I.e. MAX = A/2 and MIN = -A/2 ? Try with φ = ∆t * f * 2π(rad) -- φ = 1s * 1Hz * 2π = 2π (rad) φ = 0.5s * 1Hz * 2π = 1π (rad) φ = 0.25s * 1Hz * 2π = 0.5π (rad) = 90 (deg) φ = 0.125s * 1Hz * 2π = 1/4π (rad) = 45 (deg) -- E.R. ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
[LAD] Yoshimi Midi Learn: 1st testing release
Hello everyone, Every one knows Yoshimi, the fork of ZynAddSubFx. One thing was lacking to yoshimi to be perfect: to be nearly fully controlled by midi controls ( no OSC, sorry ). ZynAddSubFx had possibilities to control a few parameters with complicated NRPN, Yoshimi recently had ( in the test versions ) some features too. But now I'm proud to announce you the work of licnep ( not me, I'm just a bug reporter ) who made the midiLearn function for yoshimi. It's not stable for now because it's recent, and not full, but here are the present features: * Control System effects, Part Insert Effects * Master/Part Volume, Pan, System Effect Sends * Most of ADsynth parameters * Add/Remove controller * detect the channel and the number * reset the knob ( its position ) I think it's a feature that's very useful and could help many yoshimi/zyn users. To use it, that's simple: connect your controller to yoshimi, right-click on a blue knob ( yellow are ones which are not supported for now ) and click midi Learn move your controller, it detects automatically the controller. To see and modify controllers, go to the Yoshimi MIDI controllers menu. To erase midi control of a knob, simply right click on it and click on remove midi control Here is the gitHub repository: https://github.com/licnep/yoshimi To download and install it, follow the explications link ( gitHub ): https://github.com/licnep/yoshimi/wiki/How-to A light page to understand how to control others not implemented controllers: https://github.com/licnep/yoshimi/wiki/Source-code Pages to follow the news of the project: Facebook: https://www.facebook.com/pages/Yoshimi-midi-learn/224823617534934 Twitter: http://twitter.com/#!/YoshimiMIDI So if you're interrested, all bug requests are deeply recommended. Cheers, Louis CHEREL. ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
On Sun, Jun 26, 2011 at 12:22:58AM +0200, Jörn Nettingsmeier wrote: it seems you have just proven that the maximum duration of any pure tone is 1/f. that is quite extraordinary. 0.5 / f actually, which is extraextraordinary. Both Joern and I have invited the original poster to explain more clearly what he wants to achieve. Because as it stands his question doesn't make sense and can't be answered. If the purpose of this list is to let people help each other with audio software related problems, then the other replies so far are, to put it gently, 'unfortunate'. To put some things right: - Absolute phase response *does* matter. It's quite easy to create e.g. a filter that has a perfectly flat amplitude response, modifies only the phase, and sounds as a e.g. a resonance or even a reverb. You won't hear the relatively harmless phase response of a tyipcal amp, but that doesn't mean you can't hear phase errors in general. - Phase is related to delay but it is not the same thing. Group delay is again something different. Mixing up all these is not going to help anyone understand things any better. Ciao, -- FA ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] Determining Phase
From the long list of answers, I see lots of speculation about Mr. Shirkey's question. Some time back he approached me on the work that had been done a very long time ago on phase-modulation to achieve panning. He never replied to my subsequent information or queries. I suspect that this question is really all about the phase of the signal being transported through any given audio driver, ALSA, JACK or whatever, so the analysis is somewhat germane. I think that a phase demod analyzer might be his attempt to solve his real problem. I speculate that Patrick didn't actually ask his real question. So, perhaps any Haas-effect plugin would satisfy Patrick's needs. Other than that, I'd make a really cool spectrum analyzer that ran the Fourier analysis on two channels, correlated their phases then made a +/- line vs. frequency for all to see so that the phase of the components of the spectrum could be watched for phase relationships. Suggestions? On 06/25/2011 09:23 AM, pshir...@boosthardware.com wrote: Hi, Can anyone point me to a simple code example for how to determine the phase at a specific time in a waveform? ex. if I have a sample that is 5 seconds long and want to know the phase at 2.5 seconds I'm open to code in any language or a scripted example if such a tool exists. If there is an ui which has that feature I am also interested. Cheers -- Patrick Shirkey Boost Hardware Ltd ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
