From Amplitude or FFT to dB

From Amplitude or FFT to dB

By : K'Opiyo
Date : November 22 2020, 04:01 AM
To fix the issue you can do A decibel meter measures a signal's mean power. So from your time signal recording you can calculate the mean signal power with:
code :
chunk_size = 44100
num_chunk  = len(signal) // chunk_size
sn = []
for chunk in range(0, num_chunk):
logsn = 10*np.log10(sn)

Share : facebook icon twitter icon
Mean amplitude of a .wav in C#

Mean amplitude of a .wav in C#

By : Rob
Date : March 29 2020, 07:55 AM
Any of those help Here is a snip that reads in a stereo wav and puts the data in two arrays. It's untested because I had to remove some code (converting to mono and calculate a moving average)
code :
    /// <summary>
    ///  Read in wav file and put into Left and right array
    /// </summary>
    /// <param name="fileName"></param>
    private void ReadWavfiles(string fileName)
        byte[] fa = File.ReadAllBytes(fileName);

        int startByte = 0;

        // look for data header
            var x = 0;
            while (x < fa.Length)
                if (fa[x]     == 'd' && fa[x + 1] == 'a' && 
                    fa[x + 2] == 't' && fa[x + 3] == 'a')
                    startByte = x + 8;

        // Split out channels from sample
        var sLeft = new short[fa.Length / 4];
        var sRight = new short[fa.Length / 4];

            var x = 0;
            var length = fa.Length;
            for (int s = startByte; s < length; s = s + 4)
                sLeft[x] = (short)(fa[s + 1] * 0x100 + fa[s]);
                sRight[x] = (short)(fa[s + 3] * 0x100 + fa[s + 2]);

        // do somthing with the wav data in sLeft and sRight
How to get the Amplitude of TTS

How to get the Amplitude of TTS

By : Peter B
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further If you need to synchronize the audio with visual actions, you'll have to set an TextToSpeech.OnUtteranceCompletedListener (or since ICS: an UtteranceProgressListener) to the TTS engine. That way you can determine when a specific piece of text has been synthesized.
Alternatively, you can synthesize the text to an audio file using the synthesizeToFile(String text, HashMap params, String filename) method.
Scaling Amplitude After Windowing FFT to Recover Correct Amplitude

Scaling Amplitude After Windowing FFT to Recover Correct Amplitude

By : Arno Agten
Date : March 29 2020, 07:55 AM
it helps some times The mean value of the von Hann window is (approximately) 0.5, for N=1000 you have
code :
>>> N=1000 ; print sum(np.hanning(N))/N
Amplitude and phase spectrum. Shifting the phase leaving amplitude untouched

Amplitude and phase spectrum. Shifting the phase leaving amplitude untouched

By : Nirina Rakotobe
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further Here is your code with some modifications. We apply a Fourier transform, phase shift the transformed signal, and then perform the inverse Fourier transform to produce the phase shifted time domain signal.
Notice that the transforms are done with rfft() and irfft(), and that the phase shift is done by simply multiplying the transformed data by cmath.rect(1.,phase). The phase shift is equivalent to multiplying the complex transformed signal by exp( i * phase ).
code :

import matplotlib.pyplot as plt
import numpy as np
import cmath

# Generate a model signal
t0 = 1250.0
dt = 0.152
freq = (1./dt)/128

t = np.linspace( t0, t0+1024*dt, 1024, endpoint=False )
signal = np.sin( t*(2*np.pi)*freq )

## Fourier transform of real valued signal
signalFFT = np.fft.rfft(signal)

## Get Power Spectral Density
signalPSD = np.abs(signalFFT) ** 2
signalPSD /= len(signalFFT)**2

## Get Phase
signalPhase = np.angle(signalFFT)

## Phase Shift the signal +90 degrees
newSignalFFT = signalFFT * cmath.rect( 1., np.pi/2 )

## Reverse Fourier transform
newSignal = np.fft.irfft(newSignalFFT)

## Uncomment this line to restore the original baseline
# newSignal += signalFFT[0].real/len(signal)

# And now, the graphics -------------------

## Get frequencies corresponding to signal 
fftFreq = np.fft.rfftfreq(len(signal), dt)

plt.figure( figsize=(10, 4) )

ax1 = plt.subplot( 1, 2, 1 )
ax1.plot( t, signal, label='signal')
ax1.plot( t, newSignal, label='new signal')
ax1.set_ylabel( 'Signal' )
ax1.set_xlabel( 'time' )

ax2 = plt.subplot( 1, 2, 2 )
ax2.plot( fftFreq, signalPSD )
ax2.set_ylabel( 'Power' )
ax2.set_xlabel( 'frequency' )

ax2b = ax2.twinx()
ax2b.plot( fftFreq, signalPhase, alpha=0.25, color='r' )
ax2b.set_ylabel( 'Phase', color='r' )


Amplitude of input wave is massively different to Fourier coefficient amplitude

Amplitude of input wave is massively different to Fourier coefficient amplitude

By : user2572308
Date : March 29 2020, 07:55 AM
wish of those help As I described in another answer, there is an approximate relationship between the amplitude in the time-domain and the frequency-domain, which I stated under the usual Discrete Fourier Transform definition. Since R's fft follows the same definition (see the documentation), you may expect a similar approximate 0.5*N scaling of the amplitude when going from the time-domain to the frequency-domain.
Note that since you clearly do not have a pure sinusoidal signal, the different frequency component may start to interfere and make the relationship more approximate than absolute truth, but it should still be in the right order of magnitude.
Related Posts Related Posts :
  • keycloak.exceptions.KeycloakGetError: 404: b'' using Python 3.7
  • How to modify a column in a SQLite3?
  • VS Integration Services: flat file source to OLE DB destination - detect new data columns in file, add columns to table,
  • Customize xticks in matplotlib plot
  • How can I show the image in a labelframe which is inserted through askopenfilename?
  • Boxplot with distibution size histogram on top (and median regression)
  • Fit differential equation with scipy
  • ModuleNotFoundError: Correct setup
  • How to pass rendered plot to a html file through render_template?
  • Create flat ndarray from DataFrame column containing arrays
  • Bring radial axes labels in front of lines of polar plot matplotlib
  • Python3: Unable to split word from parsed data
  • Using Python to login to a website and web scrape
  • Customise shift in matplotlib offset
  • Combining and Reshaping rows and columns of 2 dataframes in R or Python
  • Regex condition after and before a known phrase
  • subplots based on records of two different pandas DataFrames ( with same structure) using Seaborn or Matplotlib
  • find numpy array in other numpy array
  • Print Triangle Pyramid pattern using for loop python
  • Python Script Running through Command Line Not Creating CSV
  • Questions about Subclassing
  • Creating list with dictionary instead of multiple dictionaries in python
  • Sorting queryset results in a template
  • Django Rest Framework allow not authenticated access to a view in certain cases
  • How do I efficiently map integers to URIs in a multidemnsional array?
  • Installing Python packages for Visual Studio Code
  • How to merge two columns into one in pandas dataframe
  • Decompose string of different symbols in python
  • pandas merge and group concat
  • How to traverse tree for making binary code from a HuffmanTree?
  • Check if IP is in network on Python3
  • non equally spaced points along x-axis in a plot
  • Concatenation of text files consisting list of lists?
  • Use regex to parse characters on a line of text
  • pandas df.fillna - filling NaNs after outer join with correct values
  • How can I undo a time series conversion of a pandas dataframe?
  • Virtual environment is not working in Django
  • FileNotFoundError in Python during Arabic text analysis
  • How to read email using python and smtplib
  • How to write a function which takes a string and turns into a single digit?
  • Linear Regression without Least Squares in sklearn
  • Matplotlib - Box plot with number of occurrence of data?
  • Finding the numbers in a given range who have a perfect square for the sum of their divisors and returning them with the
  • How do I put y(a) and y(b) initial conditions in odeint(python) instead of y(0) and y'(0)?
  • Import Error in Tensorflow in Jupyter Notebook
  • How to convert a mapping of ranges into a dictionary
  • lxml scraping overwrite error due to missing element
  • How can I run different codes from different editor tabs on the Spyder on the same console (as opposed to different tabs
  • urllib3 connectionpool - Connection pool is full, discarding connection
  • How to change django-filter filtering key?
  • Python Google Sheets API Limit 429 Error with Loop
  • How can I turn this DataFrame into a DataFrame with average score by Index Value?
  • summing element in a range for all element in an array
  • pm2 json file format for python script
  • Mask dataframe column based on datetime index
  • Brute force stable marriage, How to implements all possible pairs between 2 lists?
  • Rounding hours of datetime in PySpark
  • Show data only from one cluster
  • ValueError: Cannot feed value of shape (64,) for Tensor 'x:0', which has shape '(?, 128, 128, 1)'
  • Python try except not working with np.arccos
  • shadow
    Privacy Policy - Terms - Contact Us © bighow.org