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1500 questions
8
votes
1 answer
What's the correct graphical interpretation of a series of MFCC vectors?
I'm studying speech-recognition, in particular the use of MFCC for feature extraction. All examples I've found online tend to graph a series of MFCC extracted from a particular utterance as follows (graph generated by me from the software I'm…
jotadepicas
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8
votes
3 answers
What is the difference between phase noise and frequency noise?
I'm reading Audoin and Guinot's The Measurement of Time: Time, Frequency and the Atomic Clock, and ran across a confusing an interesting passage (Section 5.2.5, pp 72-73):
The physical origins of white phase and frequency noise are
understood.…
mpdonadio
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8
votes
3 answers
Is sampling at double the desired reproduction frequency accurate?
This is probably a general principles question, though I'm thinking specifically in relation to sound, which is commonly sampled at a rate of 44.1 kHz in part because the maximum frequency the average person can hear tops out at around 20 kHz.
Given…
aroth
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8
votes
1 answer
Adaptive filtering: Optimum filter length and delay
I'm trying to find the optimum filter length for an Adaptive Filtering, using RLS Algorithm.
I'm using this design:
So the "error" signal is the signal without noise (and that's the signal that I want).
If I have $e(n) = d(n)-y(n)$ but $d(n)$ is my…
Unnamed
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8
votes
3 answers
MP3 Filterbank + MDCT: Why?
What is the rationale for the two-step process the MP3 format performs, first decomposing the input into 32 subbands of 6/18 samples each then performing MDCT on each subband individually?
Why not simply perform a single MDCT?
Is this simply due…
Justin Olbrantz
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8
votes
3 answers
Digital delay effect: avoiding clicks on delay time change
I'm implementing a digital audio delay effect using a simple circular delay line. Changing the delay time by making the delay line longer or shorter introduces discontinuities in the audio signal, resulting in clicks.
What would be the best (most…
Bram Bos
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8
votes
2 answers
Which image filter can be applied to remove gridded pattern from corrupt jpegs?
I have around 1,400 jpegs that have been corrupted somehow and have lost the backup images. They all seem to have the same gridded pattern of lines over each (i.e. the gridding does not shift from image to image.
Here's what one of these images…
Stephen E
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8
votes
2 answers
YV12 to RGB - What is wrong with my algorithm?
I am attempting to convert YV12 to RGB using the following fragment shader:
precision mediump float;
uniform sampler2D tex0, tex1, tex2;
varying vec2 v_texCoord;
void main(void) {
float r, g, b, y, u, v;
y = texture2D(tex0, v_texCoord).x;
…
Error 454
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8
votes
4 answers
Monotonic, symmetrical soft-clipping polynomial
Okay, I intend to answer this question myself, but I would like other folks to pipe in on it. The issues or requirements are this:
Input to soft-clipper is $x(t)$, output is $y(t)$.
Output $y(t)$ limited in magnitude to $1$: $|y(t)| \le…
robert bristow-johnson
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8
votes
2 answers
Evaluating loudspeakers
If you don't have a lot of money to spend but you want to estimate the frequency response of different loudspeaker setups what is the best way to do it?
I bought a very nice microphone and built a box with foam on the inside. My idea is to place the…
John
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8
votes
7 answers
Design of a digital A-weighting filter with arbitrary sample rate
I want to A-weight a time series with arbitrary sample rate.
An analog A-weighting filter is defined exactly by IEC 61672-1. But there's no definition for a digital filter. One method is to use the bilinear transform (BLT) to convert the analog…
user2561747
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8
votes
2 answers
Non-negative matrix factorization for audio separation - why does it work?
Non-Negative Matrix Factorization aims to factorize a matrix $\mathbf V$ into the product of two matrices, $\mathbf V = \mathbf W\mathbf H$, where $\mathbf W$ represents a set of basis vectors and $\mathbf H$ their activations or weights. Applied to…
Samyukta Ramnath
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8
votes
1 answer
Digital Biquad filters
The only 'authoritative' web reference (=very often linked) for calculating the coefficients for digital biquad filters seems to be this:
http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
Does anywone knows if there is out there any othe good…
Yozek
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8
votes
1 answer
Causal system and Physical Systems
According to the Paley-Wiener criterion, a system is causal if satisfies:
$$\int\limits_{-\infty }^{+\infty }{\frac{\ln (|H(f)|)}{1+{{f}^{2}}}}df<\infty$$
So I want to know
This equation is related to LTI system only?
Only casual system is…
Ehsan Zakeri
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8
votes
3 answers
Shape of structuring elements for morphological gradients
I am looking to understand recommended shapes of structuring elements used in calculating morphological gradients. According to Pierre Soille: Morphological Image Analysis:
Only symmetric structuring elements containing their origin are considered.…
penelope
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