gTune Documentation

This program and all its documentation are released under the terms outlined in the LICENSE file released with this program. See README or LICENSE files for more information.

The FFT routines included with this program, however, are not distributed under the terms of this license and instead the terms included within the package. The FFT routines encompass everything in the fft2/ directory as well as realfft.a and fft.a which appear in this program's directory after installation.

1. Introduction

gTune is a Guitar tuner that uses FFT routines to represent incoming sound on your microphone as the musical note it refers to. I did not write the audio end of this so I am unsure of exactly how this is done, but one of the major drawbacks in this is that FFT is very slow.

2. Using

gTune should work "out of the box". Below I will illustrate the usage of gTune.

Below the menu bar, is a letter. This is the letter which the most recent tone can be most closely associated with. In this case someone has hit an E. Below the label is a slider bar. This bar represents how far from that note the last tone was. When the slider is to the left, you have struck a note below the tone, when the slider is to the right, you have struck a note above the exact tone. The purpose of tuning an instrument is to arrange the slider dead center on the note you wish to tune to.

On the status bar is the output the original gTune produced. This is for users who may prefer the original program's output, it is not neccesary to understand, and in itself it is quite self explanatory. For more information, consult the copy of the original gTune README.

3. About Tuning a Guitar (or potentially any instrument)

Using a tuner such as this is great, it's a good way to accurately tune your guitar when you don't have access to a piano, signal whistle, etc., or alternatively, you are a beginner learning guitar. There is a major drawback to just about every available guitar tuner out there: because computer microphones are cheap little 10$ pieces of junk, you may get some out of the whack values. Generally it will be ok, I've tuned my guitar with this tuner and it worked perfectly fine (and my microphone is the definition of POS). By out of the whack values, I was saying that when you first strike a note, the tuner will not display it immediately (this depends on your interval and computer speed), and you may be surprised at the initial output. Often you will so some note that is nowhere neer the note you are tuning to appear first, then the proper note. This is perfectly normal, it happens with both computer guitar tuners I use (one is semi-commercial!). Ignore the initial out of the whack value, it's meaningless. To attempt to prevent that, just use your mixer and set down the volume just a bit, it won't be perfect but will help. The other problem is as the note slowly quiets, the tuner may display the tone as lower than its original value. This is again normal and a problem encountered by both tuners. I generally trust the first or second displayed value, but usually the change will be very slight anyways.

This in mind, using a computer guitar tuner is still very nice. It can tune anything from guitars to coke bottles (yes I've done it!), and with very good accuracy. I hope gTune proves itself to be a very useful tool with an attractive interface, however if you have any gripes about the interface or think features should be added, just mail me at michael_celli@hotmail.com

In case you are unsure, the strings on the guitar are (from 6 which is the lowest to 1): EADGBE. On every string, the fifth fret is the same as the next string except for the G string where the 4th fret is B. A common tuning (this was used on neerly every song in Mellon Collie and the Infinite Sadness by the Smashing Pumpkins), is half step down tuning where every note is a half step down, meaning E becomes Eb. Also remember that Eb is the same as D#, seeing how the tuner uses sharps as opposed to flats (I may soon make this an option). Another common tuning is "drop D tuning" where the low E is brought down a whole step to a D. Many musicians try experimenting with tunings to produce new sounds.

What's New?

Well there are quite a few new things, I rewrote most of my side of the code. This is much simpler now. The nicest new feature is that you don't have to fiddle around setting intervals, it's done for you (that's what the 7 second wait is). Also, gtune comes with its original console version for textmode enjoyment. I removed the preferences, if you think those features were useful (I didn't), mail me and I'll reinstate them and release it.

Troubleshooting

If this program seems to be running unbelievably slow, or you get a message about being unable to open yada yada file, run the program and check and make sure that there is a .gnome-gtune-status file in your /usr/local/etc directory. If not, you must get yourself access to that directory from your sysadmin or whoever.

If the program crashes on startup, mail me, it's a glitch that will only happen on machines with very slow hard drives, I'll explain how to overcome it.

If gTune reports wild notes that aren't being hit, even in silence, then your microphone volume is too high and your best bet is to use a mixer (I reccomend GMix) to correct this. Alternatively, if you get no response to any sound through the microphone, you must turn up the microphone volume in the mixer. If either of these two problems seems to be any more than this (I can't imagine how it would), contact me.

Acknowledgements

I merely wrote this docs and threw a cool Gnome interface on gTune. Harold C.L. Baur a.k.a. "Bo" (bo@bikerider.com) wrote the original gTune program. gTune was based on a tool called "tune" which was written by Kirat Singh . His code doesn't compile on mine or Bo's system though. The FFT routines were written by Peter Valkenburg , and he kindly allowed the redistribution of them.

If you have any suggestions comments or anything, just mail me at michael_celli@hotmail.com and tell me what's on your mind, I'm also very willing (at this point) to add any features to this program that one may be interested in.