Add audio channels

Separate audio channels

Lets say you wanted to make a multi-track recording, with different patterns playing at the same time, but recorded separately.. Or wanted to route the audio from some patterns into external effects processor. How is this possible? Tidal’s audio engine is (most often) SuperDirt, and the key to routing audio channels is understanding how to configure and use orbits. You can think of each orbit as an audio output, with its own set of global effects (by default, reverb and delay).

Have a look at SuperDirt’s documentation, in particular the example superdirt_startup.scd file. You’ll want to paste the setup code into the SuperCollider editor window. If you save it in your SuperCollider startup file it will automatically run when you open SuperCollider - you can find that file via the menus.

There are probably only two bits that you will want to change in the setup code. If you wanted six stereo outputs, that would require 12 channels in total, so you would set the number of output bus channels accordingly, i.e.:

s.options.numOutputBusChannels = 12;

You assign the orbits to separate stereo channels by offsetting each one, like this:

~dirt.start(57120, [0, 2, 4, 6, 8, 10]);

You might also be tempted to change the number in this line:

~dirt = SuperDirt(2, s);

However if you want to work in stereo, you should keep this number to 2, i.e. the number of channels per orbit.

If your editor plugin (and therefore BootTidal.hs), then d1 will automatically be sent to orbit 0, d2 to orbit 1, and so on. Or you can be explicit by using the orbit control, e.g.

d1 $ sound "bd" # orbit 3

You’re now free to route the audio to a DAW for e.g. effects processing or recording, or record all the channels straight from SuperCollider into a single multichannel file.

Multichannel sound

In general, we deal with stereo sound, i.e. we use two speakers and pan between them. Sometimes it’s nice to work with four or more speakers though, and enjoy that surround sound experience. We set up for multichannel sound in a similar way to how we do [separate audio outputs](##Separate audio channels). With separate outputs we are probably sending multiple stereo outputs though, whereas with multichannel sound we generally send one output, but with multiple channels.

Here’s an example supercollider startup file, for panning across four channels:

(
s.options.numBuffers = 1024 * 256;
s.options.memSize = 8192 * 16;
s.options.maxNodes = 1024 * 32;
s.options.numOutputBusChannels = 4; // total number of channels output
s.options.numInputBusChannels = 2;

s.waitForBoot {
~dirt = SuperDirt(4, s); // pan across four channels
~dirt.loadSoundFiles;
~dirt.start(57120, [0, 0, 0, 0, 0, 0]);
};
s.latency = 0.3;
);

Have a look at SuperDirt’s documentation for more details, in particular the example superdirt_startup.scd file.

This line sets the number of output channels coming from supercollider:

s.options.numOutputBusChannels = 4; // total number of channels output

This sets the number of channels to pan across. For multichannel sound, this will generally be the same number as above.

~dirt = SuperDirt(4, s); // pan across four channels

Each 0 in the below represents one orbit, giving us six orbits. You probably want to keep these as zeroes, so every orbit starts from the first channel.

~dirt.start(57120, [0, 0, 0, 0, 0, 0]);

That’s it! You can save this code in your supercollider startup file (which you can find via the supercollider menus) so you don’t have to run it manually when you start supercollider.

Then to use it, you can use things like:

d1 $ sound "bd*16" # pan saw

The above will play kick drums in a ring around all the speakers. If you had four speakers, by default they’d be in position 0, 0.25, 0.5 and 0.75. Therefore 0.125 would be halfway between the first two speakers, and 0.875 would be halfway between the first and last speakers. Once you get up to 1, you’re back to the first speaker again.

Because 0 and 1 are the same speaker, the jux function doesn’t work well (as it will play the original pattern in position 0, and the transformed pattern on pan position 1, which in multichannel sound, are the same speaker. Instead, you can use juxBy 0.5 , or jux', which distributes a list of functions across a multichannel ring.

d1 $ juxBy 0.5 rev $ sound "bd cp sn:2 mt*2" # pan saw

d1 $ jux' [id, rev] $ sound "bd cp sn:2 mt*2" # pan saw

d1 $ jux' [id, rev, fast 2] $ sound "bd cp sn:2 mt*2" # pan saw

Hack the audio

Have a look around the SuperDirt hacks folder for more fun with orbits:

• Orbit routing
• Sound spatialisation
• Audio looping
• Adding global / local effects

Audio mixing and mastering

StageMaster, made by Calum Gunn, is a light mastering chain for use during live coding performance in SuperCollider. It adds light compression, EQ and limiting to all output.