At its base, it is a system that takes a programmatic score, as well as programmatic descriptions of synthesized instruments or processors, and produces audio output. Other tools in this category include CLM, Supercollider, and STK, though Csound has a history that predates all of them.

What makes it different from popular music tools is that you are in control of the instruments' guts, and can create custom instruments, so you can apply virtually any form of synthesis, any type of audio transformation or generation, you can imagine. This makes it ideal for experimenting with synthesis and algorithmic composition.

"Electro-acoustic" is an academic term that encompasses various forms of experimental music and research involving artificial sound sources, including electronic music, electric instruments, tape loops and manipulation, computer-generated music, and so forth. Roughly: "any avant-garde music that requires loudspeakers to perform." You can of course use Csound for more popular music applications as well, but you would typically find traditional DAW tools to be more convenient in those cases.

Basically it's for creating music programmatically, conceptually it's solid although it does lack some major features (you have to convert frequencies to notes, and as far as I'm aware there's no inherent option to use the note itself).

You can use different ways to enter pitch [0]. A common way is to use the "octave.pitch" format, such as 08.04, where 08 is the central octave (if I remember correctly) and 04 is the note E. It's common to use a score generator such as PythonScore [1, 2], and some people (myself included) like to use a regular programming language to generate the scores. I've used Common Lisp, Tcl, and Python in the past. Csound has a few frontends [3] that people may like. AFAIK, Csound can read notes from a MIDI keyboard as well.

[0] http://www.csounds.com/manual/html/PitchTop.html

[1] http://jacobjoaquin.github.io/csd/pysco.html

[2] http://write.flossmanuals.net/csound/methods-of-writing-csou...

[3] https://csound.com/frontends.html

EDIT: remove some repetition

This is one of the reasons why many of us in this field have moved on to SuperCollider[0] since the late 90s.

[0] https://supercollider.github.io/

If you've ever seen a modular synth, like a Moog, it's basically a programmatic version of that. You wire the outputs of signal generators to the inputs of others to create instruments. Then you create a score, which triggers the instruments with input parameters at specified times, simulating the performance of your instruments or conducting of your orchestra. The output is either live sound or a sound file.

You often find it in the heart of VST/AU plugins, within ios and android apps. Now it can work from the web. Its also heavily used in games for programmatic sound effects. But its more of a library or framework for audio/midi rather than a full blown user facing system like Max/MSP.

VST/AUs are more likely to be written from scratch, often inside a wrapper like JUCE to abstract away the OS-specific details.

CSound is a grab-bag of mediocre DSP algos hacked together from various sources by academics who have no interest in professional production values.

While you can build your own synths with Csound, they don't usually sound very good.

Games are actually more likely to use PDLib, although there's also a lot of custom C++ in some games.

There's a significant difference in sophistication between the crude algos in Csound and the algos in successful commercial VSTs like Serum, Uhe's synths, the Roland Cloud collection, SoftTube, UAD, and FabFilter mixing tools, and so on.

> There's a significant difference in sophistication between the crude algos in Csound and the algos in successful commercial VSTs like Serum, Uhe's synths, the Roland Cloud collection, SoftTube, UAD, and FabFilter mixing tools, and so on.

I don't know about "crude," but yeah. And honestly? There is no comparison between the components in Max/Pd/sc/ChuCK and any of this stuff either (I joke with my art-music friends that I like everything about Max except the sound ;). You'll never hear something like Cytomic's The Drop (a filter that can crush your CPU) or serious tape saturation, or sophisticated EQ curves with lots of warmth and character.

It's true that you could create any kind of filter, oscillator, DSP-whatever you want with these systems, but in practice, the people working with these tools are not U-he-level DSP programmers, and it shows.

I wish that weren't true, because I'd much rather code stuff csound-style than work in a DAW with a bunch of expensive plugins.

But is it true that you can run VSTs in csound? Could you use commercial VSTs, but write fancy controllers in csound?