11
votes
Digital Distortion effect algorithm
Thanks to the plot in Olli Niemitalo's answer I got convinced that the formula given in the book has a sign error. The non-linearity used for fuzz or distortion is always some type of smoothed ...
- 79.2k
8
votes
Precise 5th and 7th harmonics of a sampled sine wave
This answer discusses the harmonic spectra of the quantized sequence in five cases:
limit $f/f_s \to 0$,
synchronous sampling of a cosine with rational $f/f_s$,
synchronous sampling of a sinusoid of ...
- 12.3k
5
votes
Digital modelling of circuits with diode (i.e. guitar distortion)
One possible tool is Wave Digital Filter analysis which is a type of physical modeling that represents signals as travelling waves. It can also be extended to non-linear elements such as diodes.
...
- 654
5
votes
Can someone explain waveshaping to me?
In the audio domain, waveshaping is simply applying a memoryless nonlinear function to an input signal.
$$ y(t) = g\big( x(t) \big) $$
The waveshaping function, $g(x)$, is most often a continuous ...
- 16.8k
5
votes
Accepted
Looking for pratical quantitative comparison metrics for scaled, delayed and warped Signals
I'm answering the question the way I understood it - How can one find a similarity measure which isn't sensitive to scaling and shifting.
An approach could be borrowed from the Computer Vision world ...
- 39.3k
5
votes
Accepted
Redistributing Color in a RGB Image According to a Gaussian Distribution
After you equalize the histogram you can think of your data as a stream of variables $ {X}_{i} $ where $ X \sim U \left[ 0, 1 \right] $.
Now all you need is to transform samples of Uniform Random ...
- 39.3k
5
votes
Accepted
Identify the Type of Image Distortion (On Lena Image)
Blur
If you want to reverse Blur applied on an image (Using Convolution, namely Linear Spatial Invariant Blur) you should use Deconvolution which, as name suggests, the inverse operation of ...
- 39.3k
5
votes
Accepted
Group Delay for Hilbert Transformer and Resulting Dispersion
A real-valued system that doesn't distort the shape of the input signal must have the following input-output relation:
$$y(t)=Ax(t-t_0)\tag{1}$$
with arbitrary real-valued constants $A>0$ and $...
- 79.2k
5
votes
Accepted
Finding the Transfer Function of a Multiplicative Distortion in MATLAB
Basically the transfer function is given by (Continuous time case):
$$ H \left( j \omega \right) = K \frac{ \left( j \omega - {q}_{1} \right) \left( j \omega - {q}_{2} \right) }{ \left( j \omega - {p}...
- 39.3k
5
votes
Group delay compensation for non coincident drivers
For the first question, given the linear process, what you do to the sum with regards to filtering is equivalent to what you do to each and then sum.
For the second question, the dip is in the ...
- 36.1k
4
votes
Is there such a thing as band-limited non-linear distortion?
A few approaches to alias-free nonlinear distortion (in increasing order of difficulty):
Subband distortion: Use a low pass filter to extract the lower end of the signal. If you choose a cutoff ...
- 4,324
4
votes
Accepted
Create distortion from basic linear (and non-linear if neccessary) DSP elements
Using those four basic elements will allow you to implement linear systems, which can change the magnitude and phase of the input signal, but which will not add the harmonics that are expected from a ...
- 79.2k
4
votes
Group delay compensation for non coincident drivers
I'm not sure whether this is a purely academic exercise or supposed to do something useful in the real world. Assuming it's the later, there are a few additional points to consider
Typically when ...
- 30.8k
3
votes
Accepted
Digital modelling of circuits with diode (i.e. guitar distortion)
if you treat the diodes as having memoryless non-linear volt-amp characteristics and treat the capacitor as linear and having memory, you can use Euler's backward method to represent the capacitors ...
- 16.8k
3
votes
Accepted
If a filter has a non-linear phase lag will the output signal be distorted?
I think your question comes from several misunderstandings. The fact that the phase lag of a system becomes more negative for large frequencies does not mean that there's more distortion of larger ...
- 79.2k
3
votes
Accepted
Regarding the advantages of generalized linear phase filters
Note that with the definition of generalized linear phase $\phi(\omega)$ according to
$$H(e^{j\omega})=|H(e^{j\omega})|e^{j\phi(\omega)}\tag{1}$$
and
$$\phi(\omega)=\alpha\omega+\beta\tag{2}$$
the ...
- 79.2k
3
votes
How to model Tape Saturation (Audio DSP)?
Saturation can be modeled to first order as a symmetrical distortion of the signal, but it also has history dependence--hence the term hysteresis in describing magnetic response to a field that is ...
- 81
3
votes
Precise 5th and 7th harmonics of a sampled sine wave
The harmonics will be in the range of -150dB to -170dB. The exact value will depend on exact frequency, phase relationship to sampling frequency, phase locked or unlocked, rate of phase drift, ...
- 30.8k
3
votes
Accepted
Fixing integer overflow in wave file
What you have there is "wrap around" and a bad case at that.
It's easy enough to fix though. Let's call your samples $x[n]$ and your max amplitude $x_{max}$, so your signal is currently ...
- 30.8k
2
votes
Digital Distortion effect algorithm
You can write the body of the function directly into Wolfram Alpha and it plots it:
It looks like a waveshaper to me, and those can be used as you describe. But there was an error in the formula, see ...
- 12.3k
2
votes
Algorithm(s) to mix audio signals without clipping
Lower the global volume. Impulse tracker classically outputs channels at about 33% volume max by default.
That seems to be both loud enough for music with few channels (4 channel Amiga MODs) and soft ...
2
votes
Camera Calibration using Single Input Image
Take a look at this paper here: "Straight lines have to be straight" by Faugeras et al.
http://link.springer.com/article/10.1007/PL00013269#page-1
It is straight forward to implement, but essentially ...
- 61
2
votes
What is done to minimize distortion due to the hold operation?
I agree with Jim Clay's answer, but I think it is important to point out two things. First of all, there are no phase distortions due to the hold operation, just a simple delay of half a sampling ...
- 79.2k
2
votes
What is done to minimize distortion due to the hold operation?
What you are describing is the distortion introduced by an ideal digital-to-analog converter (DAC) in the analog domain. Two things are typically done to reduce this distortion:
Analog filtering
...
- 11.8k
2
votes
Accepted
Total Harmonic Distortion calculation and its origins
You can create non-linear digital systems (an example would be a system that finds the absolute value of the input). You can also simulate an analog non-linear system using DSP. The easiest way is to ...
- 13.6k
2
votes
Distances In a Single Image With Some Real References
Well, you can have an approximation. Due to the forms in the image are non regular, completely plain, its hard if not impossible to know the camera distortion. But if you know the size of the wheels ...
2
votes
How to estimate radial distortion from lens characteristics?
There is a lot of variability because distortion can be compensated for optically and lens designs differ. Some lenses are marketed as rectilinear, most not. You would be making the distortion worse ...
- 12.3k
2
votes
Accepted
How to analyze image quality?
You are apparently in the context of no-reference, reference-free or blind image quality assessment. The topic is quite active, and I am not sure people have already a completely accepted framework ...
- 29.7k
2
votes
Accepted
Can IR emitter signal be distorted by curved glass housing around receiver?
Short answer: No.
Long answer: you can of course create shadowing that way, and that would disturb operation. And of course, a glass wall will refract infrared just as it refracts any other light. ...
- 25.8k
2
votes
Accepted
Norm MPEG-1 Layer III (Mp3) Filter banks distortion
I have tested your code.
There are problems with the decimation and upsample stages. When you run the analysis and synthesis filters at the undecimated rate, then you get the perfect reconstruction (...
- 26.6k
Only top scored, non community-wiki answers of a minimum length are eligible