Routing more than 4 Channels of Audio to Plugins

Allow Bitwig to address all input channels of hosted plugins, beyond the existing stereo Main Input and stereo Sidechain Input.

Solutions could be:

  • Make available additional Sidechain inputs
  • Restructure Sidechain page to allow setting which plugin channels are used for Main Input + Additional Inputs to the limit of the hosted plugin

What problem(s) would this feature resolve?

Currently, hosted plugins in Bitwig can only be provided with:

  • 1 Stereo Audio Input
  • 1 Stereo Sidechain

This is particularly restrictive when using plugins with many input channels available e.g.

  • VCV Rack Pro 2 (16 Channels)
  • Plogue Bidule (up to 64 Channels)
    … and many others.

How does this feature fit in Bitwig as a product?

Bitwig puts an emphasis in the interoperability with plugins, as shown with the Circle and various campaigns with partner plugin developers. This feature would improve the interoperability of certain Bitwig devices with hosted plugins. Additionally, the same would apply for connections between hosted plugins.

The Grid is a characteristic part of Bitwig, and this feature would particularly benefit it, for instance allowing Grid signals to be sent to any and all the available input channels of third-party plugins that support multi-channel input.

Is there already an alternative way to achieve this on Bitwig?


Could it be implemented using Bitwig components or APIs, without Bitwig team’s support?


Could it be provided by a VST or something else reasonably integrated with Bitwig?


Are there other products that offer this feature?

The ability to route more than 4 channels of audio to hosted plugins is a common feature in most major DAWs.


5 posts were split to a new topic: [Draft discussion] Routing more than 4 Channels of Audio to Plugins

The question would be how to implement that. The best would be to get multichannel tracks!
To use the side chain input is a bit of a hack anyway, because its meant for a different purpose. And the side chain could remain unaltered…
Of course this would be not a quick change as the whole engine and the user interface needs to be adapted for that. Much to digest for the developers and UI designers. But it would be a Bitwig way of doing things differently.
Though this could be a feature request on its own, it would completely cover this one. Maybe we could modify the title to reflect it…?


Hey, thanks for taking a look and contributing!

I probably differ a little in perspective on whether use of Side Chain to send any type of signal into a plugin, to be used for any purpose, would be considered hacky.

While the most prominent use of Side Chain is, as we can probably all observe, designating an alternative source of audio during dynamics processing, I don’t think “Side Chain” is necessarily a term synonymous with dynamics processing, or any other particular kind of processing - it has just as correct a usage in amplitude modulation and ring modulation, to give a couple of examples.

A multi-band dynamics processor with individual Side Chains servicing each band is certainly a valid scenario too.

Ultimately, the way any requested solution ends up being implemented is very much a Bitwig thing - I don’t wish to be proscriptive on how things should be laid out, labelled etc. The essence of the request is (hopefully) clear, and the suggested solutions are only suggestions :slightly_smiling_face:

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I agree, I wouldn’t mind to get as well multichannel side chains. The purpose of a side chain is to route signal from a different place. Whereas multichannel itself can happen on a single track. Bitwig is a bit special in that regard, as everything is stereo, a mono signal is carried also on two channels. One could not simply turn everything into multichannel without sacrificing the CPU.
There are also different purposes for multiple outputs. The one I use often is to send my signals to 8 speakers others do cinema 5.1 mixes. The multiple outputs of a drum machine are meant to allow to mix them individually. Maybe the solution is a device which simply changes the number of channels in the chain. That would allow to get also true mono to minimize processing power at places where it isn’t needed. But all native devices would need to deal with this intelligently.
In my Max patches I do that automatically, I have multichannel patch cords, and if I connect one which carries 8 tracks to a filter, the filter would create 8 instances of itself. If it is mono my filter would be mono as well. I don’t know how VSTs deal with this. Are they aware of existing connections and can they deal with the resources accordingly?


I think this would have to be done if multchannel sound is ever added to BW (which I hope it is soon). I typically work in 5.1 surround, and there are many plugins that work in that fashion, including meters, reverb, etc., that are useless atm. These would all require the ability to accept the inputs from the multchannel track itself or another track, in the case of a bus.

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With the flexibility of Bitwig’s routing it’s actually relatively trivial to create your stereo track and then a related psuedo mutlichannel bus (either as the output sub or simply the mutlichannel receiver for the mutlichannel VST outputs). Bitwig could e.g. expand on the ‘Group’ feature and have a ‘Spatial Group’ option so that e.g. you build your 7.1 bus out of 8 tracks that get grouped to behave as one submix bus/multichannel track. From there, all you need is an Audio Receiver on each VST input chain and for Bitwig to open the VST device inputs up beyond the 4 channels possible at the moment. The Audio Engine almost supports working in spatial audio already, it’s just the VST side is limited to stereo in, spatial out.


I thought this section was interesting in Bitwig’s .dawproject XML project file when I had a snoop. This describes a track with polysynth on it and there is data describing how many audio channels that track uses (yes I tried changing it and opening again, but it’s still 2.0 haha!)

Probably means nothing other than bitwig saying its own channel configuration is 2.0, but clearly there is a need to define number of channels on a track, so I am hopeful multichannel tracks or at least multichannel I/O for devices & VST beyond 2.0 will be realised (one day).

<Track contentType="notes" loaded="true" id="id2" name="Polysynth" color="#ff5706">
            <Channel audioChannels="2" destination="id10" role="regular" solo="false" id="id3">

Signed up just to say this is the one feature holding me back from Bitwig. I work primarily in quad, and all of the workarounds have kept me from jumping in. If the Grid and audio channels started to work natively in quad+ formats, I’d be all-in. Here’s hoping!


Would be great to see this coming. Really would like to do 3D Audio stuff like Ambisonics in Bitwig.

This could also be an inspiration: Free Tools for Live Unlock 3D Spatial Audio, VR, AR | Ableton


Need this!