Bjorn Roche
  • Member for 9 years, 7 months
  • Last seen more than 1 year ago
Algorithm(s) to mix audio signals without clipping
7 votes

the formula $$\text{result} = A + B - AB$$ doesn't make any sense, even if you mean something other than $AB = A*B$. One thing you need to think about is that sound varies above and below zero. A ...

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What audio effects, filters, distortions, etc. create a "vinyl" effect?
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7 votes

I don't know the precise formula for 1920's gramophone, but this is the general process for audio antiquing and should get you started. Depending on the exact settings, you can get vinyl, telephone, ...

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Controlling audio high/mid/low in frequency domain
4 votes

while you could do this in the frequency domain, there are many problems with this approach, some of which are outlined here. A better approach is to use a time domain filter. There is a tutorial ...

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Help implementing audio dynamic range compression
4 votes

Here are some suggestions: There are plenty of opensource implementations (Sox, Audacity, etc). Even if you don't understand them, you might be able to translate the code from C to javascript. I'm ...

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Harmonic errors in acoustic instruments
4 votes

A few things: Not all instruments have partials neatly defined by the $h_n = nf$. Kettle drums would be an obvious example, but bells are another. In this case, you will be way off looking in the "...

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Measuring the "frequency stability" of a signal
4 votes

Your technique might work, provided you window and so on correctly, but it does not really strike me as the right approach for pitch vibrato for a lot of reasons, mostly that the change in pitch is ...

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SineWave generation and BandPass filter : Audio
3 votes

As someone suggested in the comments, filtering a sine wave is just a change in amplitude and possibly phase, although you will have some edge effects at the beginning. I assume this is not simply an ...

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Preparing audio data for FFT
3 votes

I know the signal could be passed through a low pass filter, and then windowed before the FFT. Yes, it could be, and it's usually advisable to use a window, but these are not just things you do ...

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Simple beat detection algorithm for microcontroller
3 votes

I think you can accomplish this pretty easily: start with a low sample rate (simply because there is no reason for a high sample rate). use a low pass filter to eliminate signal above ~100 Hz. (You'...

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Filtering PCM data in java
Accepted answer
2 votes

Audio EQ in by FFT?!? Please don't do that. CPU usage will be the least of your worries. http://blog.bjornroche.com/2012/08/why-eq-is-done-in-time-domain.html There was also a related discussion ...

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How do I go about detecting whistles, pops and other sounds in live audio input?
2 votes

While I agree with one of the comments that using speech recognition techniques might be a good start, these sounds are different and I'm not aware of anyone having done any research into categorizing ...

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Piano pitch detection
2 votes

Another answer suggests PLL. I think you should stay away from PLL: most literature on pitch tracking focuses on auto-correlation (search for "YIN Pitch Tracking" -- YIN is a modern pitch tracking ...

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Audio Signal Noise Filter Problem
Accepted answer
2 votes

Wiener filtering is one approach. It might even be the best approach. A Wiener filter is designed to minimize the noise (in the least squares sense) and invert the effect of the impulse response, ...

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Recorded an audio file using microphone via Windows Sound recorder, but has 2 channels that are slightly different. Why are they different?
Accepted answer
2 votes

I am not %100 sure, but it sounds like you are recording the file in stereo. If this is the case, then Windows Sound recorder is taking stereo input, which means it's accessing 2 AD converters which ...

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Most efficient way to extract frequency components of audio signal with near-human accuracy in real time
2 votes

There are many alternatives, but it depends on what you are doing. Physically, I would argue our ears are more like a parallel filter bank than an FFT, which gives them good time resolution, and a ...

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Is there an existing feedback elimination algorithm that can be implemented in iOS?
1 votes

I've never implemented this myself, but here are my (possibly incorrect) thoughts: The general method of feedback elimination is to Detect the frequencies that are feeding back Tune a filter to ...

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Audio Watermarking in MATLAB - How to choose frames to embed in?
1 votes

Loudness is defined as human perception of volume. In general, there is a very good correspondence between the two. Therefore, you can often use one as a proxy for the other. In this case, you can ...

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How to determine ALPHA, smoothing constant, of a LPF?
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1 votes

All formulas I'm using come from the wikipedia page you cite in your code. First, calculate RC. We have, fc = 1/(2*pi*RC) so RC = 1/(2*pi*fc) Now, ALPHA is simply: ALPHA = dt / ( dt + RC ) ...

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Goerzel algorithm - increasing accuracy
1 votes

There are two things you can do: Use a different algorithm, like autocorrelation. Use the phase information! This technique is discussed in chapter 9 of DAFX. You can find matlab source here. DAFX ...

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Generate buzzer sound
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1 votes

Based on the spectrum, it looks to me like this was generated by FM synthesis. The mathematics of starting with a sound and working backwards to generate it using FM synthesis can be time consuming. ...

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How to create an echo effect in audio samples?
1 votes

As hotpaw2 said, you are not going to hear an echo or delay effect unless your signal changes, so you are not hearing it because you are sending in pure, unchanging signal. You might want to try ...

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How to amplify sound wave
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1 votes

The first and best solution is to increase the input gain which should be possible on most platforms. If not, then read on... If multiplying by a constant caused distortion then either: it is too ...

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Rough estimate of how close a human speaker is to a microphone?
1 votes

One possible approach would be to use an echo cancellation algorithm to do the heavy lifting of telling you where the echos were coming in. Just make sure the code you use is able to give you that ...

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FFT doesn't always have frequency in all frames
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-1 votes

Not sure I understand your question exactly, but make sure to take the magnitude not just the real/imaginary components. Also, it will probably help to window your incoming data, and it sounds like ...

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