Still no update about Windows 11 being supported? There is a post on the Birddog User Group about Windows 10 having bug from an algorithm dealing with congested networks affecting NDI on 10Gb workflows. Apparently Windows 11 22H2 has specific features to fix the bug and also manage 10Gb connectivity better. Birddog confirmed the issue and also confirmed it is fixed in Windows 11 22H2.
This would seem to advance the urgency of getting Windows 11 support for vMix.
Here is the text and response from Birddog about this issue:
*** NDI and 10Gb Workflows on Windows ***
TL;DR If you don't want to read too much, and you are having issues with any WINDOWS workflow with 10GB, just update to Windows 11 22H2.
****
I've been working most of the weekend to drill into why we see so many issues with 10Gb NDI and Windows Machines.
It started when Dan Miall posted an update about the QUAD. How strange there was an issue with 10GB I thought? 1GB works fine? He went on to say in the comments that OSs such as Linux and MacOS don't appear to have this issue. Further, you may recall me posting here some weeks back pulling my hair out over a frame drop issue using a Flex 4K Out. I was able to reproduce it regardless of what brand Decoder I used. Instead, I stick a Mini on an HDMI output to do the decoding and moved on... Anyway, when Dan posted the QUAD update, there was something clearly broken - and it wasn't the Birddog Products, and it wasn't my network (reproduced with UBNT *AND* M4250s).
Beginning at least with Windows 10, Microsoft introduced a new algorithm [1] for dealing with congested networks. Its important to understand that even if you have sufficient bandwidth, there may be congestion elsewhere in the system (network buffers, switches etc). So NDI places a strong load on the network. This algorithm though contains a bug that under heavy load creates massive TCP retry storms. The retry storms compound on each other and ultimately lead to hugely degraded network performance, and manifest as dropped or stuttering frames.
The pattern during times of TCP connections that stall (while perhaps under high load to longer latency) look like this:
TCP spurious retransmission (SPUR) --> DUP ACK --> SPUR --> DUP ACK --> SPUR --> DUP ACK --> ............... --> RST
This pattern can be easily reproduced with NDI easily, or in fact *any other* network load causing high congestion. My testing involves artificially lowering the TCP buffers and other parameters [2] on Windows to expose this bug faster and more quickly.
Perhaps the best write up on this I've seen, in more detail is posted at [3] however this writeup doesn't discuss NDI at all, instead perhaps more correctly discussing it at a generic level.
Whats perhaps most amazing is that this issue has been posted about in NewTek Forums [4] most generically, however the common denominator is Windows.
Another note here is that this failure or bug isn't detectable normally. From the switch perspective, this is just TCP doing its thing (retrying under load), and from the host side, its just business as usual. NDI is a unique workload that exposes this bug visually.
Microsoft believes this issues had been corrected in previous releases however, there were remaining other issues. Not until the Windows 11 22H2 updated from October 2022, does it appear this issue been demonstrably fixed. There is a Windows 10 22H2 Update, though I've not been able to see if its been fixed there personally.
Its important to acknowledge my conversation with Dan Miall in all of this. This is gnarly and hard. They clearly have a world class engineering team, so despite that I'm posting this, the credit should at minimum be shared with the great
[1]
https://techcommunity.mi...he-internet/ba-p/2347061[2]
https://learn.microsoft....-performance-tuning-nics[3]
http://gary-nebbett.blog...-congestion-control.html[4]
https://forums.newtek.co...onment-is-10gpbs.166848/[5]
https://forums.newtek.co...eads/ndi-and-10g.165762/-----OK We have done quite a bit of testing here at BirdDog HQ over the weekend as well as today and we have seen a major improvement in the Windows output when updating to Windows 11 22H2. We have been able to receive 4 x 4K60 video streams from vMix over 10Gb from this machine to QUAD in Decode mode. We can also use this machine as NDI Bridge to receive NDI from other sources and 'reflect' them (no transcode) to QUAD successfully receiving them (Think TriCaster which might not be able to be updated immediately).
Please see below a screenshot from my machine showing the update that resolves this issue.
We will be releasing a follow-up firmware this week that gives field order selection for interlaced workflows, at this point there should be a workable solution for nearly all workflows.
Once again a massive shout out to Josh Bernstein and the amazing engineering team here at BirdDog for their continued work on this.
