Since the Covid-19 lock down I'm getting quite a few requests for help (I've now seen screenshots of Octave in Chinese and German). The bulk of the problems are around running Octave. As Gimp is to Photoshop, or Open Office is to Microsoft Office, Octave is the free open source clone of Matlab ($$$). Octave/Matlab is basically a very fancy programmable scientific calculator that does matrix algebra.
However, Matlab has its roots in Unix (now Linux) and is a very old user interface. It looks pretty strange to someone with only experience with Windows or Mac OS.
You know who you are :~). Let me know if this is worth putting up on Cuki's website as a tutorial.
Thanks!
Jon
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Before getting started with Octave download my script script jf45ir.m. Place it in the same directory as your guitar sample WAV file (60 seconds long, pickup left, mic right, no clipping, mic and pickup about the same volume). Install Octave. All the links are here:
http://acousticir.free.fr/spip.php?article136
Step (1), You want to start the GUI (not command line) version of Octave:
Step (2), Change the
Current Directory to the one with your sample and jf45ir.m.
Step (3), Change the file browser window to the
Current Directory.
In this example the current directory is C:\Users\jonfi\Google Drive\jf45irdemo
The sample is named mgit.wav (it is my RainSong CH-PA & HFN).
Step (4), Select the command window for the right half of Octave.
Step (5), Type the command jf45ir('mgit') and carriage return.
For this last screen shot I increased the Octave window to full screen. You can see the output files in the browser sub window. My script evaluates eight three second segments of your sample and processes the first 4 acceptable ones it finds (no clipping, decent SNR). It will tell you if it found fewer acceptable segments or none at all. The zero count is more academic, but if you were suspicious that RainSong guitars and HFN pickups are brighter the proof is here. I am using 65,536 frequency bands and most of them are above the output frequency of a guitar (at DVD 48 kHz sampling the top frequency is 24 kHz which is approaching 3 times what an acoustic guitar produces). A typical "average near zero" count is closer to 40K for a wood guitar.
