Professor Butts Teaches Us About Stereo (Interleaved)

Today, I must regale you with the life story of an incredibly important man who has certainly touched your life – Professor Lucifer Gorgonzola Butts, A.K.

Now, before you start laughing and say to yourself “Adam, I don’t know anyone by THAT ridiculous name!” – I assure you that you know his work very well. Professor Butts was an inventor who began his work in 1929 and retired in 1931, only to come out of retirment briefly in 1934 to work alongside his friend Boob McNutt until their funding ran out shortly thereafter.

And no, I’m not joking about any of this.

You would know him for his famous inventions which took simple tasks such as swatting flies, shining shoes, and putting stamps on envelopes and turned them overly complex. Today, you know Butts’ inventive machines by the name of Butts’ creator – comic artist Rube Goldberg.

Just like Professor Butts’ machines, you and I often have the mental skill to take incredibly simple things and re-imagine them as overly complex. We certainly do this all the time when imagining how audio inside of a computer works, and an easy example of this is what some DAWs refer to as an “interleaved” stereo audio file.

What Does Audio Look Like in a DAW?

In a computer, audio is just represented by a series of numbers with a decimal point between positive and negative one. If you’re looking at a sine wave – positive one is the maximum amplitude, negative one is the minimum amplitude, and zero is silence.

A single channel of audio is usually represented by a set of these numbers, usually in an object called an “array” (this is a fancy programming word for “a set of items of the same type”). While it’s not always like this, you can usually think of an array of numbers as representing a channel of audio. If you’ve got three channels, the DAW is probably handling three separate arrays.

If you’ve got a stereo file, by that logic, you’ve got two separate arrays. Right? Well, not always.

When Are Separate Channels Not Separate?

While it’s usually easier for us to think of an array as equivalent to a channel, oftentimes that’s not as efficient as sequentially stored data. The more we can reduce complexity, we can often reduce file sizes and processing requirements as well.

Therefore, when writing stereo audio files to disk and sometimes reading them – the data of a stereo audio file is stored as one sequential array (or “set”, remember). This is referred to as “interleaved” in programming as the left and right channel information is mixed together just like cards in a deck.

You can visualize this by thinking about what it’s like if you were to shuffle a deck of cards perfectly. You would have half the deck in your left hand (left audio channel), half the deck in your right (right audio channel). When you go to shuffle the deck perfectly, you lay down a card from your left hand followed by a card from your right hand, over and over, until the deck is fully shuffled. In this example, each card you lay down is a single sample from either you left channel (left hand) or right channel (right hand).

Write that to a single file on disk and you have a “Stereo (Interleaved)” file. Get it?

Not as Crazy as you Thought, Right?

I hope you’re sitting there thinking “huh… that’s it?!” because yes – that is indeed it.

Now, unlike our good pal Professor Lucifer Gorgonzola Butts, A.K., I really enjoy breaking down both complex and seemingly complex things into explanations that are easier to follow. If you’ve been reading my articles in the last few months, you’ll know I’ve spent quite a bit of time doing this on my programming streams.

While these have previously been on Twitch, as of this weekend I’ve made the official move over to YouTube! While I wouldn’t expect regular short videos from me on that platform, I plan to stay over on YouTube for my weekly programming (and soon music/interview) streams for the forseeable future.

I’m live on YouTube every Saturday from 2pm-4pm PST, and if you miss out on the live stream you can catch the shows on VOD as well! I hope to see you there soon.