Errors with audiorecord function

Hello everyone, I've written the below code so far.

Need Matlab to record(function to be running/active) for as long the button is pressed.

Then use the above running time as an input for the record function (screenshot).

Imagine it being like a play/pause button.

Gives me some errors

Can I use while (as long the state button value is True) instead of if(skips some code parts)?

Thanks in advance

[Nikos Korobos]

Is it possible to replace the if with a while?

Answer 1

[Walter Roberson]

Yes, it is possible. However, you cannot achieve your goals by doing that.

You are in the middle of a callback that fires every time the state of the button changes -- which can mean that it was pressed to start or can mean that it was pressed to end.

You should have your app store the current status, currently recording or not. You should have your app store the recorder object (at the app level).

When the button is pushed, have the value changed function check to see if it is a request to start recording or to stop recording.

• If it is a request to start recording and you are already recording, either discard the press or else stop the existing recording and continue on as if you were not already recording.
• If it is a request to start recording and you are not already recording (or you "fell through" after stopping an existing recording), create the recorder object and store it at the app level, and set your state to "recording", activate the record() method of the recorder, and return from the callback.
• If it is a request to stop recording and you are not already recording, discard the press
• If it is a request to stop recording and you are currently recording, stop the recording, grab the data, remove the recorder object, set your state to not-recording, and enable any actions that should not be possible to perform until you have recorded data, and return

When you activate the record() method, I recommend that you put in a maximum length, to prevent it from overflowing the memory.

[Nikos Korobos]

Thanks for your input so far, its a state button the one im currently using here.

[Nikos Korobos]

Also what do you mean by:

You should have your app store the current status, currently recording or not. You should have your app store the recorder object (at the app level).

[Walter Roberson]

app.currently_recording = true;
app.recorder = audiorecorder(fs, bits, ch);

[Nikos Korobos]

Got one more question.

Should app.currently_recording have the value of app.RecordButton.Value or not?

If you could explain a bit more what you sent above it would be great.

Seems like the recording starts by itself with the code above.

Thanks in advance

[Nikos Korobos]

I would like the recording to start when the value of the button is equal to 1 or True

[Walter Roberson]

Assume that somehow the program might have lost track of events or receive them out of order. You might receive two callbacks to Start in a row, or two callbacks to Stop in a row. It is not good programming practice to assume that the events generated by the user interface perfectly match the program state.

It is better for the program to keep track of whether it believes that it is currently recording or not. When it receives a Start event it should check its own memory of what it is doing in case it got a Start while it is already started. Likewise if it got a Stop event it should check its memory of what it thinks it is doing in case it is already stopped.

[Walter Roberson]

https://www.mathworks.com/help/matlab/ref/matlab.ui.control.statebutton-properties.html

Your current code tests if the value is "True". However uibutton style state has value 0 or 1. Instead of

if value == "True"

code

if value

[Nikos Korobos]

I get what you 're saying, but isn't this condition supposed to get values such as 1 or 0?

[Walter Roberson]

In MATLAB the test

if Value

is equivalent to

if all(logical(Value(:)) == true) == true

To phrase that a different way:

• the Value must be convertible to numeric
• the converted value must not be NaN
• all converted values must be non-zero

So even a single zero leads to the test being considered to fail, and NaN leads to error, and otherwise the condition is considered to succeed

So you do not need to explicitly

if value == 1

What you care about is that it is non-zero and just naming the variable without a relation operator automatically tests for non-zero

[Nikos Korobos]

I think i got a grip on what you are saying.

Would you point out any mistakes in my code (according to your directions)?

Sorry for spamming but I'm a total beginner on Matlab.

Thanks in advance

[Walter Roberson]

Do not do the

app.currently_recording = true;

at that point. At the place you initialize your other variables you should initialize it to false and leave it like that until you are switching into recording mode.

In the case for

if value & app.currently_recording == false

you have

    app.currently_recording == true;

but that should be

    app.currently_recording = true;
    

Then in the "if it is a request to stop" case, you currently have

    if value & app.currently_recording = true

and you should change that to

    if ~value & app.currently_recording = true

and change the

        app.currently_recording == false;

to

        app.currently_recording = false;

Remember that == is comparison, and = is assignment.

[Nikos Korobos]

Hello again, so I've done some testing with your suggestions and my code is currently like this.

Although it does run and the Record button wont give me any errors, it doesn't seem to record anything.

Any ideas?

Thanks in advance

[Nikos Korobos]

I have also added a Properties section