App Designer Text Area "Too many Outputs"

I am trying to make an App that listens to morse code and displays the english text in real time. I have my functions and they work great (thanks to Walter Roberson). The actual listening and decoding is not the issue. The problem I am having is that when I try and display the output from the decoder I get an error saying "too many output arguments". When I try to run the decoder outside of the app with the same recording it works fine, but for some reason MATLAB does not want to print the output to the Text Box, any ideas?

% Callbacks that handle component events
    methods (Access = private)

        % Button pushed function: Button
        function ButtonPushed(app, event)
            recorder();
            app.TextArea.Value = demorse('morseRecording.wav');
        end

        % Value changed function: TextArea
        function TextAreaValueChanged(app, event)
            value = app.TextArea.Value;
            
        end
    end

[Cris LaPierre]

Hard to say without knowing what demorse is doing.

If you are getting an error, it is also helpful to share the complete error message (all the red text) so that we can properly track down the cause.

[Mihai Giurca]

Full error message: Error using demorse

Too many output arguments.

Demorse code: function demorse(wavfile)

fs = 44000;

x = audioread(wavfile);

%zero pad the signal

x = [zeros(fs,1); x; zeros(fs,1)];

% find the frequency of the signal

ff = getChirpFrequency(x);

% use the wavelet as a bandpass filter

waveletSizes = fs * centfrq('morl') ./ ff;

sig = cwt(x,waveletSizes,'morl');

sig = abs(sig);

% do a blur filter five times the frequency length

sigF = conv(sig,ones(floor(10 * fs / ff),1),'same');

% find all places where we transition from background noise to beep

seg = (sigF > (0.25 * mean(sigF))) - 0.5;

segPts = find(sign(seg(2:end)) ~= sign(seg(1:end-1)));

% find the length of each beep or gap

segIntervals = diff(segPts) ./ fs;

beeps = segIntervals(1:2:end);

gaps = segIntervals(2:2:end);

% crude method for estimating length of dots for dashes

[N,X] = hist(beeps,10);

[~,idx] = sort(N,'descend');

thresh = mean(X(idx(1:2)));

beeps = beeps > thresh;

[N,X] = hist(gaps,20);

[~,idx] = sort(N,'descend');

gapThresh = sort(X(idx(1:3)));

gapThresh = gapThresh(1:2) + diff(gapThresh)./2;

trueGaps = (gaps > gapThresh(2)) + (gaps > gapThresh(1));

decoder = getDecoder();

% now we get to interpret the message

letter = beeps(1);

beeps = beeps(2:end);

for n = 1:length(trueGaps)

switch trueGaps(n)

case 0

% dot/dash split

letter = [letter beeps(1)];

beeps = beeps(2:end);

case 1

% letter break

fprintf('%s',decode(letter,decoder));

letter = beeps(1);

beeps = beeps(2:end);

case 2

% word break

fprintf('%s',decode(letter,decoder));

letter = beeps(1);

beeps = beeps(2:end);

fprintf(' ');

end

end

% print the last letter

fprintf('%s\n',decode(letter,decoder));

end

function c = decode(str,decoder)

out(str==1) = '-';

out(str==0) = '.';

if isKey(decoder,out)

c = decoder(out);

else

c = '???';

end

end

function [freq] = getChirpFrequency(sig)

limit = [300 10000]; % frequency range allowed

fs = 44000;

% to save time only do the fft on the first 5 seconds

sig = sig(fs:min(length(sig),5 * fs));

len = length(sig);

cutoff = floor(len * limit / fs);

f = abs(fft(sig));

f = f(cutoff(1):cutoff(2));

[~,idx] = max(f);

idx = idx + cutoff(1);

freq = idx * fs ./ len ;

end

function [decoder] = getDecoder()

text = {'A','B','C','D','E','F','G','H','I','J','K','L',...

'M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z',...

'0','1','2','3','4','5','6','7','8','9','.',',','?','='};

morse = {'.-','-...','-.-.','-..','.','..-.','--.','....',...

'..','.---', '-.-','.-..', '--', '-.', '---', '.--.', ...

'--.-', '.-.', '...', '-', '..-', '...-', '.--', '-..-', ...

'-.--', '--..', '----', '.----', '..---', '...--', '....-', ...

'.....', '-....', '--...', '---..', '----.', '.-.-.-', ...

'--..--', '..--..', '-...-'};

decoder = containers.Map(morse,text);

end

[Mihai Giurca]

Demorse decodes a .wav file to text. Outside of the app the output looks like this:

demorse('morseTest.wav')

MARY HAD A LITTLE LAMB...

Answer 1

[Cris LaPierre]

Your function demorse does not have an output

function demorse(wavfile)

Yet when you use it, you are telling MATLAB to return one.

app.TextArea.Value = demorse('morseRecording.wav');

See this page for how to properly create outputs for a function.