[jsyn] Pitch Detection using JSyn

[jsyn at music.columbia.edu]

Hello,

That code looks fine.  I saw in that old thread that someone suggested 
adding highpass and low pass filters in series between the input and the 
detector. That reduces energy outside the range of interest. That will 
help. Start with 40 Hz cutoff for the high pass and 1500 Hz for the 
lowpass. Set Q=1.0.

Also reduce the confidence threshold to 0.1 and print the confidence 
along with the frequency.  That will give you a better idea of what is 
happening.

Confidence is a measure of how accurate the period detector thinks its 
answer is. It will always return a value for period but sometimes the 
input is just noise or silence so the confidence in that value will be 
very low. Or the input may be varying a lot from vibrato or enharmonic 
partials. That will also reduce confidence.

Phil

On 10/22/10 5:17 AM, jsyn at music.columbia.edu wrote:
> Hello!
>
>
> I am fairly new to JSyn as well as the audio signal processing field so I hope
> that I will be able to learn eventually in the field. I am currently trying to
> implement a Pitch Detection module for a project using JSyn and so far, I was
> able to stumble upon this
> thread http://old.nabble.com/Pitch-Detection-From-LineIn-td3309520.html. As
> such, I implemented the code in the thread and tried to test it but I am not
> sure if it is working  properly.
>
> Here is the code (I omitted the try catch since it takes up space):
> {
> Synth.requestVersion( 140 );
>          Synth.startEngine(Synth.FLAG_ENABLE_INPUT);
>
>          pitchDetector = new PitchDetector();
>          lineIn = new LineIn();
>          lineIn.output.connect(0, pitchDetector.input, 0);
>          lineIn.start();
>          pitchDetector.start();
>
>          while (true)
>          {
>               double confidence =  pitchDetector.confidence.get();
>               double period = pitchDetector.period.get();
>               double frequency = Synth.getFrameRate() / period;
>
>               if (confidence>  0.99)
>                   System.out.println("F:"+frequency);
>
>               Thread.sleep(200);
>          }
> }
>
> I have a few questions. The setup that I am doing is that I attach a mic to my
> laptop and run the code. I then position the mic in front of my Casio Keyboard
> speakers and play a note. The result is sometimes, I am able to get a reading
> for the frequency and sometimes not.
>
> So I am confused: what does the confidence  variable do? Also, is my setup ok?
>
> Hope you can help! Thank you!
>
>
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