Too much data forced thru the TB cable?

[N9JIG]

Could I possibly be trying to force too much data thru my TB cable?

I am getting video glitches popping up on my video during live-streams. Last night they popped up every few minutes, I hadn't them before.

My current setup starts with a new M1Max MBP 14 inch in clam-shell mode with a TB cable going to a CalDigit TS4 dock. To the dock are connected 2 32-inch 2560x1440 monitors, Ethernet, my USB desk mic, a 4K webcam, speakers (via the audio jack) and my backup hard drive.

I am using the TB4 cable that came with the TS4 dock. It also charges the laptop so it is the only cable connected to the computer. I restarted my computer a few minutes before the stream and it was just the video in the stream that flickered. My internet is 1 GB up/ 1GB down fiber to the home and SpeedTest shows a 2 ms ping.

I wonder if I am trying to put too much data thru the single TB port, could this be possible?

 

[joevt]

What's the refresh rate of the displays? If they are 60Hz then they should use only 14.5 Gbps which is less bandwidth than a 4K60 display.
What speed is the backup hard drive?

 

[N9JIG]

both are identical 60Hz. IPS panels, one connected to a TB port on the dock and the other to the DP port on the dock.

The hard drive is a LaCie USB-poered drive with USB 3.1 Gen 1 using a USB-C port.

 

[joevt]

I think you should have plenty of bandwidth for all the devices. What USB speed is the webcam and mic and speakers? You're using all of them during live-stream?
14.5 Gbps + 4 Gbps + 1 Gbps = 19.5 Gbps of 40 Gbps total.

DisplayPort has precedence over USB and PCIe though. Have you tried connecting the displays to a different Thunderbolt port of the M1 Max MBP to see if it makes the problem go away?

 

[N9JIG]

I do use all the devices during the stream. The line-up on the TS4 dock was:

• USB-C port to the Time Machine HDD
• TB1 to the MBP
• TB2 to one of the monitors
• TB3 to the Logitech Brio webcam
• USB-C to the Samson Q9U Mic
• USB-A 1 to the Le Cie Time Machine HDD
• USB-A 2 to Lightning cable for my iPhone, Air Pods, Magic I/O charging etc.
• USB-A 3&4 vacant
• DP Port to the second monitor
• Ethernet port to my router
• Audio to my speakers

I swapped out to my OWC Thunderbolt Dock for now and will try to see if the same issue arises with it on the next LiveStream next week. I prefer the CalDigit TS4 dock since it has more ports. I had to connect the mic to a USB-C to USB-A adapter since I ran out of ports on the smaller OWC dock.

Would there be any problem using BOTH docks at the same time, perhaps splitting the monitors up between them? I have 3 TB ports on the MBP after all.

 

[joevt]

Would there be any problem using BOTH docks at the same time, perhaps splitting the monitors up between them? I have 3 TB ports on the MBP after all.

I don't think there should be a problem using both docks at the same time (connected to different ports of the MBP).

 

[N9JIG]

Well, I tried the OWC on tonight's livestream and again had the random video glitches. Midway thru the show I stepped off and unplugged the camera from the dock and directly into a TB port on the MBP. No glitches occurred after that.

Upshot is that it has something to do with the dock, since it occurred on 2 different ones from two different manufacturers and plugged into two different TB ports says something. What that something is though I do not know.

Next week I will leave the camera plugged into it's own TB port and make sure it doesn't continue.

 

[N9JIG]

Well, there might be an answer to the question now and if correct it is not a direct issue with the dock but rather the TB4 ports on the computer. According to this article (https://9to5mac.com/2022/04/18/m1-mac-thunderbolt-4-ports-speed-tests/) it appears that the TB4 ports on M1's do not provide the expected thru put. I suspect that is why things tend to work better when I separate the camera to it's own TB4 port.

I am going to try that this week and next week try putting one of the monitors on a separate TB port. If it all works well then, then I will have to assume that the TB4 ports just cannot support 2 monitors, the mic, hard drive, Ethernet, audio and the camera all at the same time.

 

[joevt]

Well, there might be an answer to the question now and if correct it is not a direct issue with the dock but rather the TB4 ports on the computer. According to this article (https://9to5mac.com/2022/04/18/m1-mac-thunderbolt-4-ports-speed-tests/) it appears that the TB4 ports on M1's do not provide the expected thru put. I suspect that is why things tend to work better when I separate the camera to it's own TB4 port.

I am going to try that this week and next week try putting one of the monitors on a separate TB port. If it all works well then, then I will have to assume that the TB4 ports just cannot support 2 monitors, the mic, hard drive, Ethernet, audio and the camera all at the same time.

Here's a thread that discusses the same problem as that article:
https://forums.macrumors.com/thread...ally-10gb-s-also-definitely-not-usb4.2269777/
I don't know if your problem is at all related.