Developers Notebook-Digital Signal Processing

From WxWiki

Contents 1 Digital Signal Processing 1.1 Fourier Transforms 1.1.1 Fast Fourier Tranform (FFT) 1.2 Head Related Transfer Functions (HRTF & HRIR) 1.3 Sample Rate Conversion 1.3.1 Interpolation 1.3.1.1 Linear 1.3.1.2 Cubic 1.3.1.3 Guassian 1.3.1.4 X-Point 1.3.2 Decimation 1.4 Pitch 1.5 Terms 1.5.1 Envelope

Digital Signal Processing

[Yehar's digital sound processing tutorial for the braindead!]

• The best intro to dsp
• Understandable with only knowledge of basic math

Fourier Transforms

Fast Fourier Tranform (FFT)

GPL - http://www.fftw.org

• These guys are really full of themselves and their testing is skewed (I.E. BS), but it is one of the fastest and best.

Public Domain - http://netlib.org - check out fftpack

• RN - the best one I know of...

A listing of FFTs - http://ourworld.compuserve.com/homepages/steve_kifowit/fft.htm

Head Related Transfer Functions (HRTF & HRIR)

http://interface.cipic.ucdavis.edu/CIL_tutorial/3D_home.htm

Sample Rate Conversion

Interpolation

Linear

Cubic

Guassian

X-Point

Decimation

Throw out samples then lowpass filter above nyquist frequency...

Pitch

• Time Scaling == Pitch Scaling + Resampling.
• Pitch Scaling == Time Scaling + Resampling.
• Final Report for Project Group Blue

Terms

Envelope

Change of sound over time....

• sample to sample?