mic's blog

I was prompted the other day to write a review of SongDasher – a piece of software for the iPhope or iPad from Far Out Notions, LLC. What I got in an e-mail was: "SongDasher is a streamlined song crafting tool with six tracks of audio, programmable drum beats, and flexible section-by-section composition. SongDasher allows musicians to quickly and easily capture musical ideas, and share their compositions with friends and bandmates through a variety of social media and cloud services". And so it does.

We have been collecting some posts DSP and some DSP related wiki topics. Although we have a lot, we have been putting everything together a bit haphazardly. Anton Kamenov was nice enough to organize a lot of the DSP information on this website into a book: Digital Signal Procession for Audio Applications. The book is a very solid foundation for anyone who wants to know more about how DSP in audio comes about. It is well organized and derives a lot of the DSP operations that we take for granted in a simple and transparent manner. It also adds a lot of useful information – some that we have already started adding to this site and some that is still not up.

Here are some topics of interest in the book.

Filters and other DSP operations for audio are discussed at length on this site. There are various DSP operations and the discussion below applies to all, although when engineers talk about DSP errors, they usually discuss filters – finite impulse response filters, infinite impulse response filters, etc.

I use the words "simple delay" to describe the simplest of practical recording effects – an effect that produces one repetition of the input signal with some delay in time and usually with some decay in amplitude. More complex delays can have additional parameters: feedback, delay and decay sweeps, multiple "taps" to output, etc. Even simple delays, however, can be very interesting and the following are example settings that can produce great results.

We were working recently on version 3 of Orinj. We wanted to improve the graphs of several of the DSP effects in Orinj to include the actual magnitude response of the effect. This included effects that have graphs with some equalization or some frequency type filters – the graphic and parametric equalizer, the reverb (because of its parametric equalizer), and the notch filter. This post is about computing the actual magnitude response quickly and efficiently.

I just watched CDBaby's video on one-sheet. I admit that I am not very good at marketing and the thought of having a one-sheet never occurred to me.

Distortion in music compresses the peaks of the audio signal. In the analog world this can happen when the signal begins to overload internal circuits. Digital distortion is similar.

I just watched the 2009 documentary "The Musical Brain" – various neuroscientists studying the responses of the brain to the listening, composing, and dancing with music. Most interestingly, one professor (Daniel J. Levitin) studied what happens in Sting's brain when he listens to or composes music. Also interesting, Wyclef Jean was talking, using the sleepiest voice and expressions that I have ever seen, about how his eyes lighten up and how excited he gets when he hears or plays music.

The catholic church has done many interesting things during the centuries, some bizarre, some just plain stupid, and some that are both. One of those is the excommunication of the tritone – the topic of this article.

Everyone knows some scales and can talk a bit about modes. A scale is a collection of notes in some ascending or descending order. The A minor scale for example is A, B, C, D, E, F, G. This scale has modes: Aeolian or natural minor (A, B, C, D, E, F, G), Locrian (B, C, D, E, F, G, A) and so on. There are seven modes of the natural minor scale in fact, one of which is the major scale itself. All modes contain the same notes though, so why do we care about modes?