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Sonic visualiser spectrogram6/5/2023 ![]() The smoothing window is because your Fourier transform - a thing which matches up sinusoids of different frequencies against a signal to identify which ones would add up to it - operates on an infinite signal, consisting of the input you give it repeated forever in both directions: this will have a discontinuity each time it wraps around, and the smoothing window removes some of the frequency artifacts from these discontinuities. The short slices are because you want a fixed, smallish number of output bins, and you have various tradeoffs - time and frequency resolution and computational efficiency - to consider in that. For a programmer, a spectrogram comes from taking short overlapping slices of a sampled signal, multiplying each by a smoothing window shape, applying a short-time Fourier transform, and taking the magnitudes of the complex output bins to get one column of the spectrogram per slice of input. I have since realised this is partly because it isn’t all that clear with its notation, but there is also a big gap between the naive programmer’s view (that’s mine) of a spectrogram and the mathematical analysis used in the paper. I read this paper about 15 years ago and didn’t understand it. Illustration from Auger & Flandrin (1995) This crunchy publication (21 pages, dozens of equations and figures) took a pleasing idea - replacing the familiar grid-format time-frequency spectrogram with a field of precisely localised points calculated using both magnitude and phase of the frequency bins, rather than only magnitude as a traditional spectrogram does - and set out the mathematics of applying it to a number of different time-frequency and time-scale representations. It's a very user-friendly app that all musicologists should be familiar with.Patrick Flandrin is a physicist and signal-processing researcher whose name I first encountered as co-author (with François Auger) of a 1995 IEEE Transactions on Signal Processing paper called “Improving the Readability of Time-Frequency and Time-Scale Representations by the Reassignment Method”. ![]() Luckily, Sonic Visualiser comes to the rescue. ![]() The most prominent editing software to come to mind is Audacity, which is an absolute pain to use, what with the constant crashing and total non-user-friendly interface. In conclusion, this software is much better and much, much easier to use than other programs for music viewing and editing. Never crashes, and it's much easier to use than previous applications I've used in the past. Once I got to use it, I couldn't believe I had never heard of it before, and couldn't fathom why anyone would use any other program when this one exists. It was all it was cracked up to be and more. Upon downloading it, though, I was so relieved. A music app that was easy to use didn't crash and was free? It almost seemed like a prank. ![]() Once I heard about it, it seemed too good to be true. Because I thought it was the best free program available for download, I figured I should just get used to dealing with it and all of its pros and cons. It would always crash, I had to look up tutorials for every small thing because the program was just so cluttered and hard to navigate that I'd find myself lost a lot of the times. I'd been a user of that program for a while, and it quickly became a pain. To me, when I think of music programs available right now on the internet, the most prominent, and the first one that comes to mind for me is Audacity. ![]()
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