Axtell's Notes: June 21

Today, I added some more features to BigGUI. First I worked on labeling the x-axis of the peak graph with units of time in samples. That was easy enough and works nicely. I'm considering adding an option to switch into time in seconds since the FFTGUI call takes a specific second, not sample.

The points on the peak graph now are different colors through the spectrum depending on their amplitude. An example (using a440.wav):

That picture also shows that I added a zoom function. It can now show as few as ~1380 Hz or as many as 22050 Hz. That is controlled by two new buttons under the Show Peaks button on the BigGUI controls.


The last piece I got working today is that the FFTGUI now opens with the same buffer and window as the BigGUI had selected when Get FFT was clicked. Tayloe got the Get FFT to read the time in seconds from the text field and do the FFT on that specific part (I was still working with the whole file). I still am working on making the FFT and sine curve graph as soon as FFTGUI opens. To do this, I have to tell FFTGUI that those buttons have been pushed even though they haven't. Hopefully that will be working tomorrow.

Lastly, I found an equation for volts to decibels (I decided that the raw data was in volts as that made the most sense), but I got oddly large numbers, so I'm not sure the given formula is accurate. The formula is 20log(V) for dBV, meaning 0 dB = 1 V, and 20log(V/0.7746) for dBu, meaning 0 dB = 0.7746 V. I assumed that it was log base 10. I will try using ln tomorrow to see if it looks right. I am also going to look at the website that I got it from again to see if they explain any more.

I also gave up on using the dialog box to show status and stop the splitting because it was taking a long time and is not that important. I will still be using dialog boxes to explain errors though.

So tomorrow I'll be working on the FFTGUI call a bit more and adding in the error dialog boxes. I also want to look into closing windows. I want to be able to close one of the graphs and then bring them back if I click the button that calls it again.

Hopefully we'll be adding in a constant Q option soon. That will probably be a check box in both BigGUI and FFTGUI. Since the constant Q is based on the FFT, we do not need a whole other button.