Ambisonic audio using IEM plugin suite

[gklimmt]

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Hello all,
I am trying to have the IEM plugin suite (https://plugins.iem.at/ (https://plugins.iem.at/)) for ambisonic audio work under Bitwig for Linux (but this should be no different under Windows or Mac as the plugins are cross-platform).
Basically I am trying to reproduce under Bitwig 4 (which is my DAW of choice) the steps detailed here for Ardour : (which work fine for me with Ardour), using the IEM StereoEncoder and BinauralDecoder plugins.
But concepts of buses and tracks might be a little different under both DAWs. For instance, I can't create buses with four channels under Bitwig, as is demonstrated in the video.
Would someone have some experience with the IEM plugins under BW, or be so kind as giving it a try and tell me how I could set up the whole thing under BW4 for Ambisonic audio?
Many thanks in advance.
Best regards,
George.

[TheYke]

To my knowledge HOA is not possible with Bitwig as it stands. As you already saw, the routing is not flexible enough.
I really would love to use Bitwig for Ambisonics projects. However, I doubt that this will happen (soon), as this is still quite an (academic) niche.

[minortom]

To my knowledge HOA is not possible with Bitwig as it stands. As you already saw, the routing is not flexible enough.

I you may be giving Bitwig's routing less credit than due. It's true that a single track has only 2 channels, but you can always use multiple tracks to represent multichannel busses. Things are more possible than they seem on the surface.

Would someone have some experience with the IEM plugins under BW, or be so kind as giving it a try and tell me how I could set up the whole thing under BW4 for Ambisonic audio?

I don't have experience with IEM plugins per se, but if you ask a more specific question around what you're trying to achieve in most cases an answer will be found.

One thing that will be difficult is feeding more than 4 audio channels into a plugin, but 4 is easy (2 directly and 2 as sidechain). Seeing that Ambisonic signal is 4 channels, using IEM should be fairly straightforward.

An example of an ambisonically panned track:

image_2021-08-05_102050.png

[minortom]

Explanation of ^^:

Encoder outputs 4 mono channels, Bitwig treats each one as a stereo channel and outputs a sum, which is not usable. Instead, we make two stereo splitters with an Audio Receiver in each side, to recombine each stereoized pair back into one L/R signal. That is:

* Stereo split 1-2 puts Encoder output 1 into L and output 2 into R (by injecting the plugin output signal directly from the plugin's output chain via an Audio Receiver)
* Stereo split 3-4 does the same for outputs 3 and 4

Now we have two stereo pairs containing the outputs 1/2 and 3/4. The 1/2 pair is fed directly into the decoder (note that all Audio Receivers are set to full wet, meaning the output of 3-4 splitter is blocked by the 1-2 splitter), and 3/4 pair is brought into the decoder as a sidechain.

[gklimmt]

Waoo.. thank you for so detailed an answer. This is pretty technical for my level of expertise though.
I have not been able to reproduce it for the moment, but it is a measure of my ignorance.
Especially, what is not clear to me is:
- the exact sequence of clics on either the blue or the white crosses, but also Left and Right buttons within the Splitter, to get the correct chain.
- how to rename the StereoSplit as 1-2 or 3-4 to be able to select them later?
Sorry, these are very elementary questions.
George.

[minortom]

No problem.

First, in Encoder you need to expand the output chains: click the rightmost button at the top of the device, then click "Add missing chains".

Then in the splitter the "Left" and "Right" things are what's called an FX slot. Clicking on the slot expands its contents to the right, and that's indicated by the colored bracket at the top — the color will match the color of the slot, if the slot is empty the bracket just looks like a little square. The blues pluses under the bracket add devices to the slot.

So, you want to add a splitter after the Encoder, then click on Left, then click on the blue plus to the right, add Audio Receiver and set it to "Encoder Chains > Output 1", and so on.

Selecting any device shows its inspector in the left panel, there is a field for a name — that's the most straightforward way to rename something. There is also a hot key that depends on your OS, I think.

[TheYke]

Hm, nice explanation there. However, I was talking more about like 5th-order Ambisonics and up. This needs busses with more than 30 channels into one plugin. Would be an awesome feature to make this possible.

[minortom]

Hm, nice explanation there. However, I was talking more about like 5th-order Ambisonics and up. This needs busses with more than 30 channels into one plugin. Would be an awesome feature to make this possible.

It most certainly would be, multichannels would make a useful feature request (-> support@bitwig.com).

[Tj Shredder]

Lets mail bomb Bitwig with requests for multichannel to be again way beyond Live… I usually play on 8-channel setups, at my bedroom I have 2*5.1 thus 10 channels… But if Bitwig would be open for unlimited channels, it would simply cover that edge case of 5th order ambisonics…
I guess it would need some changes in the core of the engine lets hope for Bitwig 5… ´til then Reaper is your friend…

[gklimmt]

I agree. Ambisonic is becoming omnipresent. Once you have experienced it, you want this space feeling in all your productions.
I definitely vote for this feature. In the meantime (and despite your very kind and helpful explanations), I switch from Bitwig to Ardour just to get this spatialization.
Best,
George.

[Tj Shredder]

Have you tried Reaper?





(Though this is a running gag, it can do ambisonics)

[gklimmt]

Any advantage of Reaper over Ardour as regards ambisonics?
G.

[ThomasHelzle]

For Reaper there also is the ATK: https://www.ambisonictoolkit.net
Some very nice nodes in there, I especially found the Super-Stereo encoder quite cool - it does a very good job in creating ambisonics out of stereo material. I only have a 5.1 setup but this sounded marvelous with some well mixed songs - would actually be my audio-player of choice if it weren't too cumbersome. I haven't found a good audio player that has a mode for upmixing at that level of quality.

I simply don't gel with Reaper as a window into sound and music.

So I keep using Bitwig and my Surround Panner in Quad/5.1 for the time being.
Or Resonic Pro and simply duplicating channels to the back...

Cheers,

Tom