Two shows in a row, I've had major problems with audio dropping out on NDI sources between vMix instances. These are running on AWS in the same subnet of the same VPC.

On one show, we tracked the problem down to too much NDI network traffic. As soon as we closed a few VPN-connected streams, the problem cleared up. We had big audio dropouts on NDI video sources and audio-only NDI sources.

My very next show, we had huge audio dropouts again. Again, it affected both A/V and audio-only sources. But this time, it was a very small show between two instances. We never figured out the cause, and we suffered with bad audio for over 4 hours.

Any ideas of what I can do to reduce the fragility of NDI?

Mavik, thanks so much for your insight.



I haven't tried this. I can certainly do that for the sources that are outputs. Calls and audio busses will have to remain NDI, however.



An interesting question. I will have to dig in on AWS and see. But I can't imagine on my second show I was anywhere near saturating the subnet (the machines have 25Gbps NICs).

Again, I appreciate your reply! Thank you!

Hi Geoff - any update or progress on this for you? We're planning a similar setup in AWS.

JB

Nothing new to report. Hoping to do some testing midweek with someone who knows networking better than me.

I can tell you that I have successfully had 5 vMix instances running on AWS with the main machine having 9 NDI video sources in and 6 out (plus 7 audio busses in & out). But I've also had failures with far smaller operations, so I would like to have a better understanding of what causes it to break.

Thanks for the tip on the analysis app. I'm going to check that out for sure.

In the U.S., AWS offers multicast only in the N. Virginia data center. My big show is migrating there for that very reason.

Which one ?

Not sure if this is (tangentially) related or not. I too have had dropouts of audio using NDI between two vMix instances on two laptops connected by hardwire to a gigabit switch on the same network over the last few weeks. To be clear, I am not using AWS, but rather, a LAN.

In my case, on the first computer, I'm doing switching, streaming and encoding with graphics and a vMix Call or two and on the second computer, I am bringing in a Zoom meeting using Virtual Audio Cables on both computers as outlined in the instructions on the vMix website for using two computers to bring in a Zoom call.

Both laptops have very similar specs -- the primary one for streaming, encoding and switching has an i7-9750 CPU, 32DB RAM, nVidia 2060 GPU and the second one has an i7-8750H CPU, 16GB RAM, nVidia 1060 gpu -- and I'm running separate instances of vMix on each laptop.

The audio works for a while without a hitch, but then suddenly, I'll get a dropout for like a minute where the remote guest on Zoom can't hear any audio from the master production, or vice versa, or both. It's very disconcerting. I'm using an unmanaged 5 port TP-Link Gigabit switch and I'm providing video Output from the first laptop and Bus B audio from the first laptop to the second laptop via NDI. In return, I'm making the Zoom video (two screens -- one of the guest and one of their PowerPoint), as well as the guest's audio, available via NDI.

I've experienced this issue several times and have been working to try to identify the source of the problem. I posted a note on the NDI Facebook group because I suspected the issue was possibly related to NDI (and, more specifically, possibly related to the switch I'm using) and Kane Peterson there mentioned that he's using a switch that is a slight upgrade from the one I'm using and that it's worked well for him. I realize this won't help you in an AWS situation but thought I'd mention it here. I just purchased the switch he suggested (model TL-SG105E) and will be testing it very soon and will report back here on what I find. I had been using model TL-SG105.

In comparing the feature descriptions for the two switches, the TL-SG105E mentions "IGMP Snooping optimizes multicast applications" whereas the feature description for the model TL-SG105 mentions "Supports 802.1p/DSCP QoS and IGMP Snooping". Not sure if there's a difference between the IGMP Snooping capabilities between the two units (or what that means, for that matter).

Thank you! Very helpful!

Can it be that your PCIe lanes are the problem. Usually a GPU spike should not have any results but if the data can't be transfered internally who knows what the symptoms would look like.

I assume you are using the Quadro setup and not the eGPU. The latter is just connected over the network if I understand the AWS setup correct. That would not be the prefered usage. The Quadro should be the better option. Is Cloudwatch providing some more insights?

Generally sharing is caring. I have learned so much from all here and there and still do everyday. For me it's a no-brainer to pass on my knowledge and get others up and running.