Month: September 2014

Notes:

Audio Signal Processing Course: https://www.coursera.org/course/audio

By Xavier Serra and Julius O. Smith

This is a free course offered by Stanford. It starts at the beginning of October. I will be taking the course and would be happy to help you if you are interested in taking it too.

Pd weekend 2014: Katja Vetter Microphone design: http://libguides.lib.siu.edu/puredata

Part I – Pitch detection

How would you construct an ‘Autotune’ effect that works in real time?  The first requirement is accurate pitch detection:

Frequency domain:

FFT and STFT: Find frequencies where the signal has greatest energy. Tradeoff between frequency and temporal resolution. Moderate latency.

Max examples: https://reactivemusic.net/?p=11202

Also look at the builtin Max tutorials on the fft~ and pfft~ objects

3rd party Max/Pd objects:

• fiddle~, sigmund~, centroid~ (CNMAT) http://cnmat.berkeley.edu/downloads
• pitch~ (Tristan Jehan) http://web.media.mit.edu/~tristan/maxmsp.htm

DSP code

• DIRAC (Stefan Bernsee) http://www.dspdimension.com/category/tutorial/ 
• Audiograph (iOS) http://zerokidz.com/audiograph

Time domain:

Zero crossing: Measure the period of waves by counting rate of zero crossings. Doesn’t work with complex waveforms.

Max objects: fzero~ and zerox~

Autocorrelation: Compare a signal with a time shifted copy of itself.  Low latency but CPU intensive. Can be improved by using lower sample rates and other tweaks. (Helmholtz)

Example patches: https://reactivemusic.net/?p=17169

(note: gbr.yin~ is a 3rd party object from IRCAM, but is built into Max)

Pd examples from Katja Vetter: (helmholtz~ external)

• “Helmholtz finds the pitch” http://www.katjaas.nl/helmholtz/helmholtz.html
• SliceJockey: http://www.katjaas.nl/slicejockey/slicejockey.html

We also looked at Katja’s new app: InstantDecomposer. If you would like to try this patch, please contact me. I will need to get permission from Katja.

Wavelet transform:

• The Wavelet tutorial by Robi Polikar: http://users.rowan.edu/~polikar/WAVELETS/WTtutorial.html
• Multi Resolution Audio Transforms by Graham Wakefield: http://www.grahamwakefield.net/MAT-F04/201b/
• wavelet~ object (From CNMAT)

Other methods:

• phase locked loop
• human pitch matching (what is the latency?)
• Neural networks?
• Statistical methods (pattern matching)?

Part II – Prototyping

Muse development case study: https://reactivemusic.net/?p=16187

Assignment

Next week we will listen to your music from the future.

Ways to approach a project:

Make machines that make art

Twitter streaming example:

 

 

https://reactivemusic.net/?p=5786

Infinite Jukebox by Paul Lamere at The Echo Nest

http://labs.echonest.com/Uploader/index.html

Reverse engineering

Designing Sound

By Andy Farnell http://aspress.co.uk/sd/index.php

automax https://github.com/tkzic/automax

Use the wrong tools

Ok-Go https://reactivemusic.net/?p=7971

Luke Dubois: http://lukedubois.com

Abstraction and destruction

Picasso: http://www.slideshare.net/sotos1/pablo-picasso-bulls-111

David Tinapple: https://reactivemusic.net/?p=7537

Do something backwards, extreme or opposite

Connect two things

Orange Plantation Lego

From an Interview of Mike Will At Bloomberg Business Week by Devin Leonard

http://www.businessweek.com/articles/2014-08-07/mike-will-made-it-hip-hops-hottest-producer-is-crossover-king#p1

“(Mike) WiLL didn’t know Cyrus, but (Peter) Edge did. She was signed to RCA. WiLL talked her into recording We Can’t Stop, coaching her through it. “I was like, ‘Yo, use that country twang,’ ” WiLL recalls. “ ‘I hear it, but you are trying to hide it.’ So she started using her country twang. That made it all-the-way dope.”

 Processing sound with pictures in Max/MSP by Tadej Droljc:

https://reactivemusic.net/?p=16887

(basic_patch.maxpat)

I’m thinking of something: http://imthinkingofsomething.com

auctioneer: https://reactivemusic.net/?p=7140

politician: http://digg.com/video/guitarist-plays-along-to-sobbing-japanese-politician

 Ask questions

Google: http://google.com