Why am I getting "Index in position 2 exceeds array bounds. Index must not exceed 1"

This is my import function

When I load the music it says this. However, if i remove these the program works fine. But i need to extract both channels

rightChannel = y(:, 2);

this is supposed to extract the right channel, right? If so, then why am I getting

Index in position 2 exceeds array bounds. Index must not exceed 1.

Answer 1

[Cris LaPierre]

You haven't shared the complete error message, so I'm not sure what line is causing the error, but it is most likely this one:

app.y(:, 2)

The error itself is easy to explain. You are trying to index the second column of a variable that only has one column. Consider the following example.

A = rand(5,1)

A = 5×1

0.1658 0.1431 0.8805 0.6138 0.5775

% Works
A(2,1)

ans = 0.1431

% Doesn't work
A(1,2)

Index in position 2 exceeds array bounds. Index must not exceed 1.

[Rezaul Reza]

i am trying to extract the right channel. when i upload a normal wav file it doesnt show the error and the code works fine. however, after saving the trimmed audio when i load the track it shows the above error that you mentioned.

while initially the track has 2 channels, the trimmed one shows 1 channel. and thats when i get the error.

[Cris LaPierre]

Correct. Somehow when you are trimming your file, your audio is either being combined into a single track, or one track is removed, resulting in the error when you try to extract the right channel.

[Rezaul Reza]

yes the problem is exactly as you described.

How do I fix this issue,please?

[Cris LaPierre]

It looks like when you write your trimmed data, you are not specifying any columns, so you only get data from the first column.

audiowrite(app.IMPORTEditField.Value,y((num_samp*(a-1))+1:num_samp*b),fs);
%                                                                  ^^

Select the specified rows for all columns:

audiowrite(app.IMPORTEditField.Value,y((num_samp*(a-1))+1:num_samp*b,:),fs);
%                                                                   ^^^

Since you shared your app...

I strongly recommend you avoid using global variables. The proper way to share variables between callbacks is to make them properties of the app. You can then access them using app.varName. See here: https://www.mathworks.com/help/matlab/creating_guis/share-data-across-callbacks-in-app-designer.html

[Rezaul Reza]

it works!!

thanks!

[Cris LaPierre]

1. give it a different name

2. Generally in an app, it is preferable to not use 'input', as the whole idea behind an app is to have everything be contained there. Use an Edit Field component and query the value.

startpnt = app.StartEditField.Value

Generally speaking, once an answer has been accepted, it is best to ask a new question, especially if the new questions are unrelated to the original.

[Cris LaPierre]

That was made up example code. You have to use your actual variable and component names. Capitalization matters.

app.startpnt = app.STARTEditField.Value

EDIT: This thread may now seem confusing to follow. The OP has deleted several comments and reworded those that are still here, making it so the replies no longer appear to align with the questions.