SoundWave | Illustrate your sound waves on the fly | iOS library

You need to add () for commands.Cog.listener:

I think the answer here is nearly equivalent to this answer I gave several years back. As time goes up, the floating point accuracy declines for computing pitch*2π*time. Adjust your code such that time resets back to zero or is and offset from zero after you complete a full wave of data.

Something like this:

EDIT: Turns out that I misunderstood the question. Anyway, leaving this answer here because it answers "how to blink without blocking" which may be useful too.

The answer for the main problem would be: You are using pulseIn which also blocks until the pulse is received. The default timeout for pulseIn is one second, so if there is no object in view of your parking sensor, you are blocking for 1s every time! Since you are probably only interested in reasonably small distances anyway, you could just set a timeout of, say, 10ms (10000us):

You will need an array of PCM values which you will use to calculate the sound wave values, and an array of bytes which will hold the values to be written to the SourceDataLine.

The size of the PCM array is set to the period of the wave you are creating. So, if you want to make an A 440, the period (based on a sample rate of 44100fps) would be 100 (a tad sharp of 440).

The first step is to fill the PCM array with random numbers (floats suffice, ranging within -1 to 1). Then loop through the following two steps (starting with the second step):

• Calculate the next set of PCM values based on the formula you cited.
• Convert the PCM buffer values to bytes per your audio format and append it to the byte array that will be written to the SourceDataLine.

When the byte buffer for the SourceDataLine is full, write the buffer and start refilling it for the next write operation.

There is an article here that also describes some refinements to the algorithm. Details on converting the PCM to bytes per the audio format have been covered in other posts.

Following is a quick and dirty implementation. The code only plays a 200-pcm note. Obviously one would want to rewrite this to make it work for other notes. But it does show the algorithm in action and it does play.

You can add a scatter and update its data in a loop by using .set_offsets().

You can use Udacity visualizer to preview XML layout files.

But not all features are available like Gravity or layoutDirection.

Better use an array of char to record raw data. But to answer your question:

I have figure out a temporary solution thank you to LaurentMaquet. At some point I will post the final soundWaveView as it is in development at the moment.

The changes made are:

1- Create a custom class for soundWave.

The problem stems from the fact that your lambda captures by reference. In soundWave both dAmplitude and dFrequency are scoped to the life of the function so when you capture them by reference and return the lambda, the lambda is referring to objects that no longer exist and using them is undefined behavior.

What you need to do is capture by value, so the lambda gets its own copy of the function parameters, and those will live for the life of the lambda. Changing soundWave to