Practical Pitch Detection on iPhone

Running pitch detection on mobile

Name

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Methods

• Zero Crossing• AutoCorrelation• HPS ...

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Stack Overflow Suggests

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• FFT and phase shift

What works..

• Window the input signal• Run FFT• Calculate phase shift• Get Peaks• Store the results for a duration• Volume decibel as an indicator for

voiced and unvoiced sound.

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Steps

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Methods

• Limited FFT Range• Noise• Accuracy• Realtime Feedback

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Problems

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FFT

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What is it?

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FFT Bin ~ 43Hz

Fundamental Frequency

Phase OverlapWhy?

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Performance Tips

• Accelerator library• NSThread

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How fast?

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Questions

• <TODO>•

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Did it fly?

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