Help me with a bandwidth calculation. 10 USB video spurces

[tripletopper]

I have a Mac Mini M2 from 2013 that has 40 Gb of USB bandwidth and other wired forms via Thunderbolt

I got two Thunderbolt 4 cables going to two Thunderbolt 3 hubs.

I have four branches of cameras each with a left eye and right eye therefore making two cameras on each branch.

First question is USB A 3.0 considerered fast enough to have two camera share a wire. If it is it's I'm going to have to buy some USB C equipment.

By the way the busiest branch on my thing also contains a microphone and a Bluetooth dongle in addition to two cameras.

In addition to gameplay footage which I have on one capture card I have six perspectives possible three perspectives being shown at once and three different sets of three perspectives on three different scenes.

First of all I noticed that if I manually switch cameras it is usually easier to deal with this as a manual switch than to have multiple scenes stored in memory.

So if I try to connect more cameras at a time but not use them it'll cause more complications so just do the manual switcharoo if I can.

Finally I have unique question with a Belkin Thunderbolt 3 adapter apparently these first generation Thunderbolt 3 devices do not also double as USB C. Could they be transformed into USB A with a thunderbolt 3 to one or more USB A 3.0 slots?

I just wanted to know if converting it to usba would be more useful than trying to use it as a c directly which you can't.

These all these three answers together will probably decide how I'm going to proceed with this.

Just trying to make some shopping decisions based off this.

 

[Lawrence_SoCal]

Maybe others will follow you, BUT, I suspect a little editing of your post will help.
Minor... I assume you meant an M2 from 2023, not 2013 ??
and I don't follow
"I have four branches of cameras each with a left eye and right eye therefore making two cameras on each branch."
- and what type of cameras - USB connected, right? all same model, or mix? what resolution, frame rates, video codec, version of USB supported, etc. Beware a lower-generation USB device can drop chain to lowest-common denominator in some circumstances.

There is no 'sharing a wire'... sharing a motherboard port, via a hub, yes. but this isn't 1980's or earlier and splicing POTS (plain old telephone service) lines. USB 3.0 is USB 3.0, regardless of whether using a physical -A or -C connector

USB-A vs USB-C is a physical connector, and does NOT really impact data transfer at logical layer. It is the version of USB involved (3.0, 3.1, 3.2 (and its many flavors), USB4,; or Thunderbolt 3/4/5, etc) do NOT confuse USB-C with data transport layer... two separate things. I've even seen ads for USB 2.0 Type-C ports (which shouldn't exist).. TB3 and higher, by original spec, uses only USB-C for its physical connector.​

I suspect a picture would help. And that Bluetooth dongle on a TB3 dock may or may not cause issues.

Beware marketing of Thunderbolt and actually available data bandwidth (how to know you are on the right track- it is NOT easy/simple, with lots of 'it depends', caveats, etc) [vs marketing labels on overall bandwidth including video output to monitors]
And then, whether data bandwidth 32gb/s (TB3) or 40, that is still based on a certain data [packet size and number of devices involved. You have WAY more devices involved, so actual usable bandwidth will most likely be MUCH less (this is a thermally constrained, low electric power, consumer system)... no I haven't done detailed testing, but USB Root Hubs get expensive and a bit power hungry when you want to go beyond typical consumer usage, so tend to be in workstations or specialized equipment. Also, consumer grade USB Root Hubs tend not to be designed for consistent latency/jitter across MANY bandwidth heavy video devices...]
all to say ... beware your expectations

Yes, multiple scenes with all those videos sources means ALL of those videos (in all of the Scenes) need to be simultaneously processed (so available at a moment's notice when switching to that scene)... Now, using Referenced Sources means only being processed once, sort of... depend on what you are doing, I suspect, with each source in each scene. I can imagine scenarios that extra CPU /rendering load with extra Referenced Sources (ex unique filters/effects applied)???

As for TB dock... it depends... and I don't know the Belkin specifically. Some TB3 docks could switch to be a USB 3.x dock, but many, especially older/original, cheaper consumer models, were either TB3 or USB 3.x docks.. couldn't be both depending on port plugged into. You'd have to research that specific model... decent chance (though I could just as easily be wrong, I'm only guessing based on other devices) it will only work when hooked up to a TB3 (or newer) port (which by standard is physically USB-C, but could be USB-A or -C, if ignoring power delivery options)

With that much going on, I'd recommend keeping an eye on motherboard and related thermals, as running hot for extended times will shorten its lifespan.

 

[tripletopper]

Never mind, I found the easiest thing to do was don't waste bandwidth by having cameras plugged in you're not going to use.

And I found that two cameras could fit 640x360 two to win USB a 3.0 line so I don't need to spring for the USB C

Also if you split a pair of Thunderbolt 4 ports with 40 GB into 2 Thunderbolt 3 hubs I have enough USB ports and bandwidth through them to do the job.

I did buy a two Thunderbolt 4 hubs, but found out if I use some economy, Thunderbolt 3 would be perfectly fine and maybe the Thunderbolt 4 would be wasteful, so I'm going to sell those on eBay.

Never mind that was a lot of rambling. I was trying to decide what to buy.

Thinking about it more just made me decide to just stick with the Thunderbolt 3.

 

[Lawrence_SoCal]

There is an interesting technical difference between TB3 and TB4 in terms of TB bandwidth switching inside the hub, which the TB3 does more/better than TB4 (which can have a single higher-bandwidth device)... came out a bit after-the-fact... interesting distinction depending on use case ... worth understanding that TB4 does NOT include all features of TB3... very unusual for new tech to do that...

Beware implications of using USB 2.0 devices on a USB 3.x switch/hub (including TB). Sometimes using an older device will slow the line signaling/handshake/whatever {detail tech jargon} doen to lowest common denominator... ie slow USB 3.x devices down to USB 2.0 speed. If there is a hard and fast rule, I don't remember it. I suspect it depends on device, driver, OS, and USB Root Hub (and its driver/firmware)... and probably some other things... Using a USB 3.x webcam at lower resolution is fine.
*IF* you have/plug in a USB 2.0 device (keyboard/mouse, webcam, etc) be SURE to test that it is not negatively impacting performance of other devices. If it is, you may need to change ports, play whack-a-mole to figure out optimal setup for your particular config