@agatestudio

Sound Processingdengan FFT

Edi SyaputraKnight

Agate Studio

@agatestudio

DISCLAIMER

AS3, based on “FFT Based Spectrum Analyzer” (by : Gerry Beauregard)

Processing, bukan Recognizing (apalagi pake voice)

Less technique!!!!

Yang presentasi buta nada

@agatestudio

Sound Processing?

• Bukan “masukin suara ke game”, tapi “menggunakan masukan (input) suara ke game

• Input suara -> store -> tweak/process->...

• Image Processing : Manipulating array of pixels

• Sound Processing : Manipulating “array” of samples

What For?

• Alternatif input, selainkeyboard/mouse/joystick/tombol-tombol lainnya

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FFT

• Fast Fourier TransformFourier Transform, yang cepat... :v

DFT (Discrete Fourier Transform) yang cepat

• Fourier : fungsi yang dibentuk dalam sejumlah fungsi sinus cosinus.

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FFT – How?

• Raw Input (berupa sinyal suara/time domain)

• Proses

• Output (Frekuensi/frequency domain)

Konversi dari time domain ke frequency domain,

Analog ke digital

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FFT – How? (2)

• Di AS3, Input microphone (sample) di-store kedalam variable

• Store sample ke buffer, lalu lakukan perhitungan

• Output bisa berupa magnitude atau frekuensi

Gampang, kan? :D

:D

computing the DFT of N points in the naive way, using the definition, takes O(N2) arithmetical operations, while a FFT can compute the same DFT in only O(N log N) operations.

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Applications

• Game berbasis suara (ya iyalah)

– Karaoke (frekuensi/pitch)

– Dll

• Manipulasi suara

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Pros

• Faster than DFT

• Yang sudah dijelaskan sebelumnya (itu yang diatas juga sih...)

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Cons

• Slow/Heavy sometimes, may cause a little latecoming of information (delay)

• Sensitive!

Thanks!

• http://www.audiostretch.com/spectrum/

• http://gerrybeauregard.wordpress.com/2010/08/06/real-time-spectrum-analysis/

• http://gerrybeauregard.wordpress.com/2010/08/03/an-even-faster-as3-fft/

• http://www.aes.org/sections/pnw/pnwrecaps/2012/jj_jan/fft.pptx

Demo, yay!