Help encoding Ambisonic B-Format to Mono files using B-Dec and Nuendo etc

[karen elliott]

Hi there Folks.
I have reasked my question with reference to B-format. I am new to this forum and apologise if I have posted this message to the wrong section. I have read most of the "Stereo to Surround" thread but can't really find the answer I need. I fully intend to mix further but I want to listen to these files as mono LF/RF/LR/RR feeds first.

I have my B-Format audio on 2 stereo files, which are WX & YZ: (blank for Z). I want to use B-Dec to play these files out as 4 mono files corresponding to my speaker feeds, so that I can monitor before mixing down. I can listen to the process through my Audio & Design Ambi-8 but due to the extremely quiet nature of the audio in some sections of the track, going back through analog is not clean enough for a pre-production mix.

The B-Dec help file, such as it is presupposes that I know Nuendo but I don't really although I comprehend the principle. I'm not even sure if I also need to use B-Pan as well. Could some kind soul please talk me through the B-Dec & the Nuendo surround busses configuration? I've been going round in circles for over 48 hours and I'm a bit fraught. I've looked at all the ways I could find to do a simple conversion but they all seem to require a multitude of programs or procedures. Anyone done this procedure successfully? I do not have C-Sound installed, nor do I want to tackle another software chain if avoidable. Nuendo and B-Dec should produce excellent results if I can get it configured and I want to

When I originally asked this question I was redirected to the 'Stereo to Surround' sticky, but I'm trying to find a way whereby I can always either monitor the mono feeds of my B-format recordings before deciding to mixdown. Packing files and then finding out that they're of no use is not my way: I want to here the result as if it were through the line ouputs of my Ambi-8 so that I can work on then in a live situation but with the benefits of remaining in the digital realm where possible.

This is not the first surround project I've done but it's the first where I need to make the B-format into mono feeds by software.

Thanks for listening and thanks to those who tried to reply to my less than informative first request.

Karen. (for Kymatik)

[ursamtl]

Hi again Karen,

Ok, I understand now that you need a bit more than splitting files. I don't have Nuendo, but I have worked with it on a friend's studio and I have lots of notes, so between my frazzled memory cells and my notes, let's see if I can put something useful together for you. Perhaps someone with Nuendo on his or her system can let us know if I have any errors in here and I'll be happy to edit this post to correct it.

Loading the files
As I wrote last night, to split the files into four: Create a new blank project in Nuendo. Choose File > Import then open your WX file. Check the box next to Split channels when prompted. When asked if you want to insert objects on one track or each on a different track, click the Different tracks button. Repeat this procedure for your YZ file. Note that if your Z channel is empty (a horizontal-only encoding), Nuendo may not add the empty channel. This gives you four wave files on four tracks from top to bottom, W, X, Y, Z (if available).Setting up your outputs
Now you mentioned four speaker feeds, so the following will add four channels for monitoring. Press your F4 key to bring up the Nuendo VST Connections - Outputs dialog box. Click the Add Bus button. In the Configuration dropdown list, choose More... then choose Quadro from the menu that expands out of it. Click OK and notice that Nuendo added a Quadro Out bus to the list of busses. Now, since the channel order in a standard or traditional Ambisonic definition of a square is Front Left, Front Right, Rear Right, Rear Left (rears reversed from what's onscreen), you have to reverse the output Device Ports for the Left Surround and Right Surround channels. Simply click on the device port listing for each channel and set it to the others. for example, if they were listed as A05, and A06, you should change them to A06, and A05. Once this is done, double click on the "Quadro Out" bus name and change it to "Ambisonic Square" or something else meaningful to you. To save this configuration for future use, click the little icon with a + sign on it next to the Presets list. Give the setup a name and click OK.Routing your channels
Now you have to route your channels.Press your F3 key to bring up the Nuendo mixer. From left to right, you should have your stereo input fader, then four faders for each of the channels you added earlier. For each channel, look at the two black lines above them. These represent the input and output routings. Click the second from the top for each and route W to the Left channel of Ambisonic Square (or whatever you called the bus you added), X to Right, Y to Left surround, Z to right. Note: Don't worry that this doesn't match what I told you above about reversing the rears. You need to add your decoding plugin before everything will work. You are simply using the four channels to route the W, X, Y, and Z channels to the four inputs of your decoder.Adding your decoder
Ok, to get this thing working, you need to decode the W, X, Y, and Z files with a proper Ambisonic decoder. On your Nuendo mixer (press F3 if you closed it), find the fader corresponding to your output connections. It will have Quadro on the top and whatever name you have it on the bottom. Click on the icon with the small letter "e" about half way down to the left of the Quadro fader. In the resulting VST Output Channel Settings dialog box, notice that there are two set of eight horizontal black lines. These are effects slots. The ones on the right are the sends, which you don't want to use. On the top left, click the black line labelled "i1" (for insert slot #1). Navigate to the Ambisonic decoder VST plugin you wish to use, B-Dec for example. Once you add it, the plugin's interface should appear onscreen. Adjust it as necessary.If all is well, then pressing the spacebar should give you the sound you're looking for. As I mentioned in my reply last night, just yesterday, Dr. Bruce Wiggins from the University of Derby release two excellent Ambisonic decoding plugins called the Wigware Ambisonic Decoders (WAD), one for 1st order Ambisonics and the other for 2nd order. My initial tests of these in Plogue Bidule with some B-format files I downloaded form http://www.ambisonicbootlegs.net/ were very good.

Anyway, I hope this works. As I said above, I don't have Nuendo on my system so working from notes and memory may have introduced errors. Let me know if this worked for you.

Regards,
Steve.

[karen elliott]

Hi. Thanks Steve. I'm still trying to fathom B-Dec in Nuendo. There is no Quadro bus in this version: it just divides the Quadro channel setup over 2 buses. I can't quite get my head round the 4 in 4 out display for the plug coming up on 2 buses and how to configure it yet, but from what I have got I would say the software is not as good as my Ambi-8 box. I ramped up the output gain on my RME Multiface and fed the B-Format out through the Ambi-8 and back in and I would say the phase cohenrence is way above what I can get out of B-Dec. I think the idea of a frequency for frequency interpolation really emphasises the mid range over everything else, but I could be just messing up the setup. I'll keep posting to the thread if I get better results. B-Dec has to have 2 stereo files as input sources so wouldn't even benefit from a WAVE-EX format Nuendo - if it exists. It's not a program I know as I said. I'm going to try B-Dec in Plogue Bidule: something else I've never tried before as I think the interface may be less confusing in a live type context. Nuendo is a bit steamroller and peanut for a simple file conversion. Failing that it's back to 3 different processes and in & out of the command prompt. How tiresome eh! Still, I'm learning, that's for sure.

I'll get on to AmbisonicBootlegs when I have time. Some of our stuff - Kymatik - is up there, but not much. There will be other field recordings going up when I can borrow a DAT to transfer them.

K (for K)

Thanks again.

[ursamtl]

Hi Karen,

Sounds like you're working with an older version of Nuendo. What I wrote was based on v2.x and 3.x.

I would strongly suggest you check out the Sursound mailing list (https://mail.music.vt.edu/mailman/listinfo/sursound.). The people who contribute to this list daily are the world's leading experts on Ambisonics. They can help you much better than any of us can! Membership is free and the discussions are quite fascinating at times.

Regards,
Steve