Hello friends,
with this extension we can obtain the peak value, the rms value, the decomposition of a signal through FFT and the waveform emitted by a Player, obtain and change the sound volume.
com.KIO4_Visualizer.aix (13.2 KB)
Blocks.
1.- MIT Companion and permiss MODIFY_AUDIO_SETTINGS.
This extension needs MODIFY_AUDIO_SETTINGS permission. MIT Companion doesn't have that permission, so we can't emulate it in MIT Companion.
Installed it should work.
If you want to emulate it in the MIT Companion you must add the mentioned permission.
In this topic I have put information about it:
Add permissions to MIT Companion with APK Editor Studio
In this page a MIT Companion with MODIFY_AUDIO_SETTINGS:
http://kio4.com/appinventor/127G2_androidmanifest.htm
3.- Example app.
p299I_Visualizer.aia (1.8 MB)
(better installed)
Down / Up volume = Decrease / Increase volume (16 levels)
Tests with a Wave (.wav, .mp3) file, Song file and Tone.
Get peak and rms in mB (milli bel (B)). Get peak and rms in levels. Get frequency step.
Draw Wave form or FFT.
3.- Basic FFT (Fast Fourier Transform).
FFT is a mathematical process to decompose any signal into a series of sinusoidal signals.
Instead of representing the graphical result of the waves in the time domain, it is represented by traces in the frequency domain. Each trace represents the amplitude of a wave and its frequency.
The decomposition of any signal usually generates an infinite number of sinusoidal signals.
If we add all those sinusoidal waves, we would obtain the initial signal.
If we add the first sinusoidal waves, we would obtain the initial distorted signal.
If the initial signal were formed by a certain number of pure sinusoidal signals, in its representation we will have that certain number finite of traces.
In addition to the graph of Amplitudes in the frequency domain, we can also obtain another graph with the phase shifts of each of the signals, we will not see that in this tutorial.
FFT is used in telecommunications, sounds, music,...
This is very basic information, check out other tutorials on this topic.
4.- Comments.
peak and rms in millibel, I do this conversion in the code.
can i get the .aia for example
(better installed)
Is there a way to use mobile's microphone as source for real time fft;
I believe Tarsos DSP is the thing you are looking for.
Am I right?
Thanks @vknow360 for the quick replay. You mean that I must build an extension based to TarsosDSP. I'll give it a try.
But, is there any easy/easier way to use mobile's microphone instead of the audio file that is emended in the @Juan_Antonio app, as input to the fft ;
There should be.
I can make your job easier.
Created a long time ago.
com.sunny.pitcher.aix (278.9 KB)
