How can create a .wav bar based spectrogram on matlab?

Question

How can I create a bar based spectrogram that updates as a .wav file is playing. This is commonly found in music players. Here is an example below:

I am able to display a amplitude/frequency graph that updates as the .wav file is being played using this code below:

function syncPlayerDemo()
%some example music
%set up audio player
%player = audioread('test.wav');
[y,Fs] = audioread('test.wav');
player = audioplayer(y, Fs);
[samples,channels]=size(y);
%calculate timeline
t=linspace(0,1/Fs*(samples-1),samples);
%initialize full plot, update will only move the visible area using xlim
h=plot(t,y);
%set up callback to update every <TimerPeriod> s
player.TimerFcn=@timerFcn;
player.TimerPeriod=0.1;
player.playblocking()
end
function timerFcn(source,data)
%an area of length <area> s will be visible
area=1;
position=(source.CurrentSample-1)/source.SampleRate;
%move visible area, current position is in the center
set(gca,'XLim',[position-area/2,position+area/2]);
%used a waitbar for testing, might be commented in
%waitbar(source.CurrentSample/source.TotalSamples);
end

Which results in an updating graph:

How can I get the bars like above, any suggestions?

Answer 1

You can get the bar based spectrogram by decomposing the signal segments into fractional-octave subbands. Try octaveFilterBank and then compute signal power level by pow2db(sum(abs(signal))). This will result in a logarithmic frequency scale.

You can also use pwelch to estimate power spectral density, which brings you a linear frequency scale.

Answer 2

I guess you can simply change the command "plot(t,y)" to "bar(t,y)" and customize the plot more!

If you want the visual to look good, try dspSystemToolbox. This is much easier and allows frame based processing (it will process particular number of samples each time) with more smoother response.Especially "the time scope" looks much better and allows "stair plotting"(check doc dsp.TimeScope). I feel it suits more for your need, although there is no problem with the present code.

If you are not familiar with this and If you have already installed dspSystemToolbox, you can type on command line "testbenchGeneratorExampleApp", the GUI there after appears will allow you to configure sources and sinks and generate the respected MATLAB code directly for you. You can modify this code little to appear the data in bars and you can customize this bar plot also. I suggest customizing the Timescope.
Hope this helps :)