Bitwig Studio doesn’t support Surround Mixing natively, but with it’s extremely flexible routing one can come up with quite interesting solutions.
I personally work in surround all the time. For me it’s so much more natural than stereo – adding another dimension to the sound allows you to sit right in the middle of it. Just playing some slow notes on a guitar with a huge reverb floating all around you is a wonderful experience IMO.
My projects are mostly Soundscapes and Environments, targeted more at installations and exhibitions with flexible speaker positions and setups than towards classical movie surround, so don’t expect this to be the guide to industry-standard surround mixing, although that should be possible too.
My main goal with this article is to show you some ideas and techniques I came up with to do basic surround in Bitwig Studio 1.1 – feel free to enhance and build upon those concepts and adapt it to your needs and ears.
I personally mainly use the four surround speakers and a sub. For convenience I mix to 5.1 since that is the most used format, although I often have no use for the center channel.
I won’t go into every detail of Bitwig Studio in this tutorial and assume that you already know your way around Bitwig and it’s basic functionality and workflow.
Right out of the box, Bitwig Studio 1.1 is an audio software that offers stereo tracks, and stereo tracks only.
Instrument tracks hold note information (and feed that to factory and plugin instruments), Audio tracks hold audio information and Hybrid tracks can hold both. In addition there are Effect tracks (usually called return tracks in other software) which I use a lot in this article and finally one (and only one) Master track, which I don’t use at all for surround.
All these are stereo.
The basic elements I use to make this into a surround environment are:
- Audio Receiver Devices for routing everything from everywhere to wherever it’s needed.
These things are hot! You can pick the audio from anywhere inside elaborate device chains with many layers and substructures. Awesome!
- FX-Layer Devices which I basically use as submixers inside of tracks. They are not ideal since you need to open the device chain to mix, but hopefully the group tracks in Bitwig Studio 1.2 will make this easier (EDIT: They did, see part two of the tutorial for that).
The Surround Panner
One major component we need to position sound in surround space is a panner.
Thankfully Bitwig Studio has XY devices that we can use to make this very intuitive:
The main element of this device chain is the XY Instrument device where for us each corner represents one speaker ( BTW. you could use the XY Effect just as well, doesn’t really matter). I use corner “C” as front-left, “D” as front-right, “A” as rear-left and “B” as rear-right.
Other than you might think I don’t use any of the four lettered FX slots though, since those are only mixed down to stereo according to the position of the XY pad.
This is an important basic concept with all Bitwig Devices to understand: Only the output/sum of the device is altered by for instance the layer volume fader in a FX Layer device, inside each layer it’s always playing at full throttle. This is the reason why my setup is a bit more elaborate than what you might first expect.
Instead of the four corner slots, I only use the X and Y modulators of the device to control additional devices inside of two layers of a FX Layer Device that is nested into the Post FX slot of the XY Device. Lets look at a screenshot:
These are the parts:
- First you see the XY Instrument device that is used only as a XY pad modulator.
- Inside it’s Post FX slot I have a FX Layer device with two (basically identical) layers for the Front and Rear channels.
- Inside of each layer there is first another FX Layer device, which is only used for it’s Mix knob.
- Next is a Tool device that is only used for it’s panning knob and as a clear “endpoint” for the chain (for the Audio Receiver further down the road).
(I can’t use the Tools Amplitude knob here since it does not go down to -inf in volume but only to -36 dB, therefore I have to use the FX Layer).
Let’s set this up step by step:
- When we drag the dot in the XY Instrument device between the upper left and right corner, we want the sound to pan between the two front speakers:
This is the X-axis, so activate the modulation arrow under the X (looks like this: o-> ) and drag the Pan knob of the Tool in the Front layer up to a modulation value of +1.00.
Deactivate the modulation arrow and the panning should now follow when you move the X/Y dot.
- We want the same to happen for the two rear speakers so repeat the same for the Tool Pan knob in the Rear layer.
- Now that we have the left-right modulation set up for all four corners, we want a similar effect for front-rear modulation:
Set the Mix knob of the FX Layer nested inside the Front Layer to it’s centre position (50%).
Activate the Y modulation arrow of the XY Instrument and drag the Mix knob modulation to a value of -0.5.
Deactivate the arrow and see if the Mix knob follows your movement.
The front speakers should get full signal when the dot is dragged to the top and no signal when it’s dragged to the bottom.
(Since the FX Layer is blocking sound when Mix is at 100% we had to invert the modulation).
- Finally we do the same for the rear speakers, but the other way around so that they get full signal when the front is silent:
Activate the Y modulation arrow again and drag the Mix knob of the FX Layer nested inside the Rear layer to +0,5.
Deactivate the modulation assignment.
(Right now this won’t do anything “surroundish”, since we first need to set up the outputs).
Here you can download this device as a Bitwig preset if you should get stuck:
This basic panner can be used to automate panning or become the basis for more advanced things, like automatic movement where you modulate the X and Y axis for instance with LFO MOD devices. To do this, click the gear icon in the XY Instrument GUI to have access to the X and Y knobs for modulation by other devices:
(If you want to test the panner right away, you can add an Hardware FX device at the end of each of the two layers and output to the Front and Rear speakers directly).
The Output Section
To make the panner work as expected, we now need to set up our output channels. For this I rely heavily on the Audio Receivers that were introduced in Bitwig Studio 1.1 and which together with the Note Receiver make the software extremely powerful for any non-standard routings (EDIT: See part two of this tutorial for an even easier setup with groups in 1.2+).
I set the outputs up as effects tracks since we can only have one master track (which I don’t use for surround) and I find the visual distinction of the effects tracks helpful, but this is up to your personal preference.
This is how my output section looks:
The “Front” channel accumulates everything going to front left and right, the “Center” channel collects everything for the center speaker and pans it hard left. The “LFE” combines everything that should contribute to the subwoofer channel and contains a splitter to cut off higher frequencies, then pans everything to the hard right. The “Center & LFE” channel combines those two into one stereo channel for easier file handling and export and finally the “Rear” channel receives everything meant to to the the rear left and right speakers.
This setup assumes the typical Windows 5.1 channel order where you have:
Front Left, Front Right, Center, LFE, Rear Left Rear Right.
Feel free to adjust it to your needs.
Center and LFE don’t send anything out, but the outputs of the Front, Center & LFE and Rear channels are set to output to the corresponding speakers.
Now that we have the (Effect-) tracks for our surround channels set up, let’s see how they work internally.
This is the first part of the Front channel device chain:
As you can see, I use a FX Layer device with Audio Receiver devices to collect the audio from all over the project. The FX Layer device acts as submixer where I can adjust the levels for each input. With the Audio Receivers “Source” dropdown you select what audio you want to use, in the case of our panner above, we would for instance navigate to the Tool output of the Front Layer:
As you can see, these dropdowns can become quite involved with larger chains ;-)
This can make it hard to find out where audio is coming from if you dive into a project a month later again, since you can’t open that path for inspection (as in: the dropdowns when opened again do not show you the used path), so make sure you name the receiving layers in the FX Layer device with meaningful labels.
I guess over time the Bitwig team has to come up with some way to show the path of these receivers…
Allright, now we have all the input sounds collected. If you want to treat one of the inputs with effects, you can put devices directly behind the Audio Receiver device. For effects that are meant to affect all the inputs the same, I put another FX Layer device behind the first one (not nested) and put for instance a Reverb in one layer and a simple Tool device (for the dry part) into another, again using the FX Layer device as a kind of submixer. Alternatively you can just put your effects in the FX Layer device and use it’s Mix knob for wet/dry balance.
At the end of each channel I usually put a Peak Limiter device to be safe while experimenting, but I leave that to your taste and working habits.
The setup for the Rear channel is pretty much identical, we just have to select the “Rear” layer from the panner in the Audio Receiver dropdown.
You should then be able to use the panner and move your sound input around your speakers.
Finally let’s have a look at the two remaining special channels:
The Center channel is similar to the Front channel, but depends a lot on what you want to appear there. The main thing is that you have to put a Tool device at the end that is panned hard left, so that the output is mono:
For the LFE channel, it again depends on what you need. It seems not to be cast in stone what one should send there, depending on the surround standard and source, I found a lot of different suggestions. Some cut out everything above 120 Hz, some above 180 or 200 Hz and some recommend to leave the audio alone and let the target system do the cutting, depending on the subwoofers specs.
But as an example, you could either use one of the filter devices in Bitwig Studio, a VST plugin of your choice or the Multiband FX-2 device if you want to cut out the high range:
Notice the Tool device at the end panned to hard right to make the channel mono.
Finally you combine the two in the Center & LFE channel for easier export:
As you may be able to see from the meters in the screenshot, the two layers only receive on one of their stereo channels and the FX Layer device combines that into one stereo signal.
Almost done :-)
There you have it, a basic surround setup.
When finished and everything is set up to your liking, do an “Export Audio”, selecting “Front”, “Rear” and “Center & LFE” from the list:
Then, combine the three files for instance in Audacity into a multichannel FLAC, WAV, AC3 or whatever you need for your output system:
Be sure to set the Audacity preferences to “Use custom mix” to be able to export to surround formats instead of Stereo:
When you now go File -> Export Audio you get an overview how your channels get exported and can adjust the connections when needed:
Part two of this Tutorial will show how to make the surround routing even easier with the help of groups and their local and will go through an example project with different kinds of sound sources.
I hope this was helpful and will encourage you to step into the wonderful land of surround and doing things your DAW isn’t supposed to do.
If something should be unclear, let me know in the comments and I’ll try to address it in part two.
BTW: I recently released a first environmental/soundscapish surround piece on Bandcamp that I created this way: