Looking for technical advice on a multichannel audio installation

Smuff · 2024-07-04T07:01:31.567Z

peterb.dmu.ac.uk

Peter Batchelor -- GRIDs

Peter Batchelor (Composer/Sound Designer)

Mo_Frillz · 2024-10-24T01:11:34.043Z

Hello!

For an upcoming project, we intend to create an immersive auditory and visual experience. This will involve establishing a quadraphonic speaker setup for the sound piece, accompanied by moving image animations projected on three walls (front, left, and right).

We would like to establish an efficient way of syncing the playback of all three videos on the projectors with the 4.1 channels of audio. Since the audio material will be synced with the visuals, we require frame-by-frame sync accuracy.

We have access to laptops, BrightSign and 3 projectors. For the audio, I have a sound card with multiple outputs and access to 4 speakers (+ sub).

I am leaning towards using my Motu interface to playback the audio as I’m not sure how good the D to A conversion is on BrightSign, and how effectively it outputs multichannel audio.

We would appreciate any suggestions and help we can get to make this happen!

Thanks in advance.

radioedit · 2024-10-24T07:37:41.385Z

This sounds like it might be a good job for Derivative TouchDesigner - especially when it comes to syncing the playback, having multiple videos and audio channels, etc. It has a Max-like interface for working with, where you connect nodes together. There’s a bit of a difficulty curve in understanding how it works, but it’s super-powerful once you get there.

tt16tt · 2024-10-24T08:01:01.839Z

I’ve recently used a Brightsign for an audio installation with interactive lights with with 4 speakers (although it was just 2 stereo pairs, LR x 2) and found the DA converters in Brightsign to be good. I didn’t notice any weird artifacts or anything else, and it has proven to be rocksolid in terms of continuous playback of audio that played in loop for around 5 hours a day. The sound was just an mp4 file with an audio track, that was send out through the Brigthsigns audio output to an amplifier, that sent the audio to the 4 speakers.

I know that a Brightsign can output multichannel audio (e.g. 5.1) over HDMI, which then needs to be decoded to discrete audio channels. I haven’t tried this, so I’m not sure what gear and not that you need. I would suggest to reach out to Brightsign and ask them. They are quite helpful in my experience

chapelierfou · 2024-10-24T08:18:02.377Z

Which one would be the "master ", audio or video ?
I’m currently touring with a project in which the video is driven via the audio file in Max/MSP. I would recommend to do this if possible.
I used this method as a starting point : mc.jit.movie~ - Jitter Forum | Cycling '74

hallmar · 2024-10-24T08:23:14.787Z

As a former AV installer technician I can attest to Brightsign being rock solid. Only thing that goes wrong is maybe the SD card but as long as you buy a durable SD card then it should last very long.

Nice seeing that someone uses it for art installations!

Regarding multi channel questions, the Brightsign forums seem to be teeming with good info as well. There’s also a Brightsign subReddit

kurogedelic · 2024-10-24T08:28:11.944Z

I used the Pioneer VSA-822 amplifier to build a multi-audio system at college.
It supports HDMI, Analog Inputs, and Optical S/PDIF. Probably BrightSign is also possible.

You can find many inexpensive HDMI-Analog Outputs amplifiers on Amazon and Aliexpress, but I have doubts about their sound quality and robustness.

If you can use S/PDIF or ADAT, you can also use the RME Fireface or Digital Mixer (e.g. O1V).

Mo_Frillz · 2024-11-15T01:47:34.233Z

Hello @chapelierfou.
Thanks for your response. I am familiar with your music! I’ve been a longtime Dimlite/ Dim Grimm fan and I discovered your music through a remix he produced for one of your tracks.

I’m not too familiar with how this Max patch works. In fact, I’m not familiar with Max at all. I just started learning the very basics through M4L and it’s going to take me some time before I can get comfortable with working on Max. Did you write your own Max patch or tweak the existing one to achieve this? And would this process also allow you to sync 3 independent videos to audio (4.1 multichannel)?

I guess in our situation, the master would be the audio. Ideally, I would like to have control over the audio- like handling volume etc.

@tt16tt Thanks for your response!
For the installation that you set up, was it the same audio going to front and rear? Was the audio embedded in the video file?

My concern with sending audio over HDMI is that it will need to be decoded. And I’m not sure about acquiring additional hardware for this process!

I was wondering if this would be easier to do in a software like QLab or Resolume.

We’re exploring the possibility of using QLab. Would anyone here have any experience with using QLab to handle multiple videos set to different projectors?

chapelierfou · 2024-11-15T08:13:18.087Z

Mo_Frillz:

I’m not too familiar with how this Max patch works. In fact, I’m not familiar with Max at all. I just started learning the very basics through M4L and it’s going to take me some time before I can get comfortable with working on Max. Did you write your own Max patch or tweak the existing one to achieve this? And would this process also allow you to sync 3 independent videos to audio (4.1 multichannel)?

I’ve made my own patch, but the linked patch is a great starting point. It doesn’t have to be much more complicated than that, if I understand your needs well. I’m happy to help, feel free to reach me in PM.

tt16tt · 2024-11-16T13:35:21.063Z

The audio was just a simple 2 channel left-right, where there was two ‘left’ speakers placed together and two ‘right’ speakers placed together (about 1,5 meters apart). Any movement on the sound was just panning from left to right, if that is what you mean by front to rear?

There wasn’t any video for this installation, but the audio playback was just an mp4 file with a black screen in it. The Brightsign has stereo audio out, which I used. If you need multiple audio channels (e.g. 4), you could sync two Brightsign with each other.

kcolf · 2024-11-16T14:56:21.267Z

Just to echo @radioedit above Touch Designer would be a very obvious candidate for something like this - if i could i would try and run it from one machine with the necessary video outputs (a gpu with three outs or an external) then either render the video as a single extra wide video with the multichannel audio (which td handles very welll - or if needed to run multiple machines you could sync them over netowk with a main machine doing sound and managing sync with the other two - you may run up licence costs running across multiple machines and ur budget might be better spent getting the hardware to make ur life easier.

If you can get the means to run it all on one machine it becomes relatively trivial to do basically just striaght video playback split across multiple outputs. Something like a tripplehead2go for example would get you there also.

Qlab is also rocksolid (used to be only in mac world dont know if this is stil true) but i ve never really used it.

Got a lot of Touch D experience though so happy to signpost further

B

Mo_Frillz · 2024-11-16T16:51:06.272Z

Thanks for sharing!

We’re currently exploring possibilities with 3 BrightSign units and maybe sending Front 1+2 to one unit, Rear 1+2 to the second unit and the Sub channel to the 3rd unit (in mono).
Maybe this could work using just the regular stereo out from BrightSign. The HDMI to analog decoding seems to be a laborious process and we don’t have access to an AV receiver.

Although I’m all set to try this approach, I have no experience with using BrightSign. I’m leaning more towards using a Mac computer running QLab. I’m looking into the Mac Mini Pro M2 (2023) as it supports 3 displays. I should have enough USB I/O to hook up my sound card too. Hope I can figure this out. If not, I may have to figure out BrightSign. I’m a bit pressed for time!

kcolf · 2024-11-16T21:47:36.653Z

Just another thought - Depending on ur triggering needs if u have acces to a mac mini with 3 displays the quickest solution could be to render out the video as one ultrawide movie (3 displays worth) with the multichannel audio encoded with it then use something like quicktime player or vlc and just play the movie fullscreen spanning the three outputs - you can do your audio routing in quicktime or the software for the audio interface (something like cuemix if u have a motu) and send it out the correct channels.

Something like qlab or touchdesigner (see my above post) gives you more control and allows for the content to be live or interactive/non-linear but if i understand ur usecase it doesnt have to be much more complicated than playing a movie

Mo_Frillz · 2024-11-17T01:24:21.119Z

Hi @kcolf

Thank you for the your detailed response earlier too. It’s given me a lot to think about.

I could have access to a Mac Mini M2 Pro computer. Do you think this will get the job done?
I plan on hooking up the sound card to this computer as well. Ideally, we want to get the job done with one computer. We plan on using QLab because of its flexibility.

The Quicktime approach also sounds doable. Once we arrive at the space, we would like to tweak the mix and do room correction and then reprint all the audio stems and import them back into QLab. Our videos will be rendered as 3 separate ones.

Essentially our QLab session would have 3 discrete video files- these are 3 separate video files (not mirrored) and 3 discrete audio files- Front L + R as a stereo track, Rear L + R as a stereo track and the Sub channel as a mono track, which will be assigned from QLab to the necessary outputs from the MOTU.

We do not have any live generative tounchdesigner stuff going on. All videos will be final and perfectly in sync with the audio. All video and audio will be of the exact same length and will have to be looped on QLab. The audio will be finalised once we do room correction and basic tweaks to the overall mix on the quad speakers at the space.

My main concern, as I’ve not tried this before, is will the Mac Mini M2 Pro handle this successfully. We’re confident about QLab working well for this installation!

Additionally, we were also exploring the possibility of using a Mac Studio as it gives us a lot more I/O. It gives us 4 Thunderbolt 4 ports, 1 HDMI port and 2 USB C ports on the front.

Screenshot 2024-11-17 at 6.53.38 AM1674×1292 109 KB

kcolf · 2024-11-18T08:59:23.880Z

I would have thought the mac mini would be more than adequate - processing wise ur really not doing that much (i mean quantatively not qualitatively) its just three videos and three audio clips - i/o wise u only need 1 usb for the motu - by all means go for the mac studio if u need but the mini should be more than adequate

Making sure ur videos are at the correct resolution for ur projectors on export and using the proper codecs (not sure what works best on mac/qlab these days but i generally go with mp4 h.264/265 when in doubt) so qlab doesnt have to do any rescaling will also improve peformance

We ve been using an old 2013 mac mini as a set-and-forget multichanel output machine (16 outs) for years and never had any issues so i would be surprised if the one u ve specced isnt totally fine

Good luck

chapelierfou · 2024-11-18T21:00:11.330Z

Just want to chime in with some semi-technical semi-knowledge :
(I pretty much don’t know anything about video, but) I’ve run my patch in a quite bit venue, with a very high-end video projector. At first, it wasn’t working because of so-called “HDCP” (High-bandwidth Digital Content Protection - Wikipedia), that’s apparently inherent to the newish Macs.
In the end I used a cheap USB-C to HDMI dongle, but with the Mac (Mac Mini M2, bought in September 2024) HDMI port, it was not working.
That said, I have no idea what I’m talking about, and maybe the guy at the venue told this because he was lazy. Just a word of semi-warning !

Mo_Frillz · 2024-11-25T13:20:54.384Z

@kcolf

Thanks!

Actually, the concern was not so much about the processing capabilities of the Mac Mini. I’m more concerned with the I/O. We need 4 independent video outputs. 3 to the projectors and 1 for our display monitor, to operate QLab. The Mac Mini allows 3 simultaneous displays, but if we have to use a display monitor, one of the displays would have to be mirrored. Unless there’s a workaround, we were hoping to get a Mac Studio as we would have additional video outs.

Please let me know if I’m right about this!

@chapelierfou
Thanks again!
I don’t know video at all! So this has been challenging to say the least.

What you’ve mentioned about HDCP is slightly concerning. Thanks for the warning. I will look into this more.

I’m trying to understand this better… Did you end up using the Mac Mini for your setup?
The Mac mini has thunderbolt video outputs as well. So are you saying that only the HDMI port wasn’t working with the projector? Or do you think it was a faulty port?

For your reference, this is the projector that we will be using. 3 of these:

Panasonic Connect

PT-VZ580

Bring native Full HD video to big screens in small places. Designed for education and corporate applications

Shiftr · 2024-11-25T14:01:19.641Z

Mo_Frillz:

1 for our display monitor, to operate QLab

You could operate Qlab from the remote app on an Ipad or Iphone.
Or even trigger it from any device that can send midi or OSC.

aroom · 2024-11-25T20:49:40.418Z

for this I’ll use a Blackmagic Decklink Duo 2 card connected into a Sonnet Thunderbolt 3 case: 4 3G SDI outputs (or inputs). And Decimator MD-LX SDI to HDMI converters.

blackmagicdesign.com

DeckLink – Tech Specs | Blackmagic Design

DeckLink are high performance capture cards for Mac, Windows and Linux with support for 12G-SDI and 8K.

sonnettech.com

Echo Express SE I (Thunderbolt to PCIe Card Expansion System) - SONNETTECH

Compact, desktop 40Gbps Thunderbolt adapter box with 1 slot and space for daughter card. Supports low-profile PCIe cards. For Thunderbolt 4 and 3 computers.

https://www.decimator.com/Products/MiniConverters/MD-LX/MD-LX.html

sns · 2024-11-25T21:47:16.357Z

Mo_Frillz:

Actually, the concern was not so much about the processing capabilities of the Mac Mini. I’m more concerned with the I/O. We need 4 independent video outputs

I think you (or some of you in this topic) would be interested in this device : HA5-4K by AJA.
It allows to split a 4K HDMI signal to 4x 3G-SDI, ie you can get 4 HD quadrants from a single 4K signal, all you need is to compose your video feed accordingly.

I did not used it yet but I started a new job where they used it quite a lot for video installations, they run 3 video screens from a single MacBook Air without getting bothered with having a computer supporting 4 screens or syncing things another way.

This device from AJA converts a 4K HDMI signal so 4x3G-SDI so you may need SDI-to-HDMI converters depending on what projectors you use, but other quadsplit boxes exist (search for Decimator 12G-CROSS, Datapath HX4, QuadHead2Go Q185).