NDI network - wifi problems and solutions?

#1

Hey guys, i’m very happy with NDI implementation, its great for performances that need wireless movable cams, but have some observations and problems with framerates, and would love to learn others experiences / solutions, in particular regarding which networks / routers to use.

I’ve been developing and performing a set that uses three wireless NDI cams (current gen ipod touch). In studio and rehearsal, i can have all three running in SD on its own wirless network, provided by a Google Wifi, or also just using my normal home network, a router provided by Deutsche Telekom. Also using an old Apple Aiport Express works fine. I get stable 24-30 fps framerates with acceptable low latencies, they are mostly equal to wired video inputs, and uses appearantly less CPU on my system, wieghts NOTHING, so a win win for touring.

When touring I’ve been using the Google Wifi. Up until this weekend, all performances have been smooth sailing. However, this weekend, framerates fell to between 0 and 6 per sec and I could use at most one camera, maybe two (one camera seemed to linger around 12 fps, the other between 0 and 6). They never disconnected but often was just a frozen frame. Nothing I did changed anything, the network (I assume) was “clogged”?. System CPU and VDMX was working fine and responsive. This was in a huge public building, but there weren’t a lot of other wireless networks, as far as i could see. No other wireless equipment in use on stage.

The Google WiFi has no “settings” to inspect or change, it is designed to “optimize” the network itself automatically. And I don’t know enough about network tools or setups to be able to figure out what went wrong.

Does anyone have more experience working with NDI, and have tips for “best practices”, either to set things up so this never happens again, or if it happens, a way to find out what the problem is and correct it? Is there anything in MacOs I can do or look into to help figure out why the network is so slow?

Of course now back in the studio, it works fine, i can’t reproduce the problem. But I’ll be touring extensively with this setup so I fear the problem will appear again, and need to find a workaround/solution, or eventually disregard NDI and look for other video inputs (which I’m soooo tired of…).

Thanks for any advice or input or thoughts!

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#2

Hey gmm,

I’ve not used Google WiFi at all, so I can’t speak to the robustness of that as a means to work with NDI streams, but here are a few notes that might be helpful:

  • Off the bat I have to say that to get the best results with NDI® it is strongly recommended to connect devices over a network using gigabit ethernet or similar high speed connections whenever possible; I’m sure you are using WiFi because that isn’t an option here, but worth noting for people who come to this thread for tips – use ethernet if you can!!!
  • NewTek provides a free set of useful NDI Tools applications for testing purposes. If at any point you think there is a problem that has to do with VDMX, give these a try to see if they have similar connectivity issues.
  • Some general notes on WiFi…
    • WiFi essentially works over radio waves; this means that physical structures (such as walls, mountains, trees, etc) as well as electrical interference can diminish the range or otherwise degrade the transmission quality.
    • The antennas on most WiFi routers are optimized for broadcasting horizontally – for example, a WiFi router may work very well between rooms that are on the same floor of a building, but will typically not work well between different floors within a building, even if the rooms are directly above / below each other. If this is the case, you can look into directional wifi antennas.
    • Like radio broadcasts, WiFi routers broadcast on different channels (different frequency ranges). In order to avoid conflicts, WiFi routers will automatically negotiate which channels each is using; in some cases routers will let you manually specify a channel to use. When routers switch channels (say because another router appears that conflicts with it) you can get a momentary drop while the router reconfigures itself. The way this is handled might be something that varies between different routers. (it doesn’t sound like this is the case here, but again, worth mentioning for anyone who stumbles into this thread)
  • If you haven’t already done so, I’d also suggest asking on the NewTek forums (https://forums.newtek.com/), particularly if you can recreate the issue using the NDI testing tools. If this is a general issue related to WiFi streaming, the NDI community at large may have some good suggestions!
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#3

Hi GGM,

David pretty much covered it, I’m apart of a touring project that uses wifi and OSC commands. Instead of a dropped frames or frozen images, if the single OSC message doesn’t go through, then it messes with the timing of the show. I also defer from using NDI over wifi because of the bandwidth requirements for HD video. In the past for wifi video, I’ve primarily used other wifi IP cams with URL links and MPEG compressions. While it looks much better, NDI can eat up a lot of resources quick.

  • 1 x stream SD video = 20 Mbps
  • 1 x stream 1080p50/59.94 video = 125Mbps
  • 1 x stream 720p50/59.94 video = 90Mbps
  • 1 x stream UHDp30 video = 200Mbps
  • 1 x stream 1080i50/59.94 video = 100Mbps
  • 1 x stream UHDp60 video = 250Mbps

I’m assuming you are using a 2.4GHz connection. While 5G would be faster, its range is also shorter. When I’m working with wifi devices in close proximity and free of obstacles, I’ll use 5GHz if the devices support it.
That being said, I’m also working on a touring project that has been in the works for over 2 years. Wifi was fine while it was in a smaller city or in the studio, but for venues in Philadelphia, D.C., and NYC. I have converted as much of the setup to hardwired ethernet (RJ45) as possible. The main reason is wifi interference. In Philly, there were about 20+ wifi networks floating around. With cross city wifi networks such as ATT, Comcast Xfinity, hidden ones for government operations, cell phone companies, etc. the 2.4GHz band can look pretty ugly. I use wifi analyzer on my android phone when I get to the venue to determine if a 2.4GHz band channel is free. Since most consumer wifi networks are set to auto channel, it is a roll of the dice whether they will switch over to the one you are using an interfere. 5GHz isn’t as bad because of the range limitations, but there is a range of factors that can make any wifi underperform.

Some odd things to think about_-

-Crowd interference or hacking. Ok, the hacking aspect is less likely, but if someone wanted to run a deauth attack on your google wifi router while you are in the space, it wouldn’t take more than a $5 device plugged into a cell phone to do it.: https://github.com/spacehuhn/esp8266_deauther Seriously, it can happen and has.

I’ve also stumbled across a wifi pineapple setup that would auto duplicate my host network name, deauth it, and capture the connection from the Raspberry Pi’s I was using. They were mainly sending OSC data, but the fact that someone set it up in a public space was pretty alarming.

-Stupid cell phones. Everyone seems to have a cell phone these days, some even work with a form of city-wide wifi services that don’t broadcast an SSID, but are on the same channel of your setup and tear it apart as they live stream to their Instagram.

Could the camera’s own wifi be competing with itself? When I use multiple wifi Raspberry Pi’s I make their channels static.

I could think of a few other reasons, but unfortunately, wifi is an overcrowded medium.

You could try to direct your router: https://hackaday.com/2017/11/18/3d-printed-wifi-reflectors-custom-designed-for-the-building/

Hope this helps

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#4

Thank you both, David and ProjectileObjects. This is very very helpful, thanks a lot for taking time to share your knowledge and experiences! I have two weeks studio rehearsals now to do art and tech updates, one of the steps is to try more customizable routers, that also gives me better stats and monitoring tools, one annoying thing with the Google Wifi was that its so “simple” there was no way to force units to use 5 ghz (or 2.4 if 5 really was the problematic one). I would really prefer being able to force all units to be on the 5 Ghz connection, the router and devices will be in short distance from each other.

We’ll see. I will follow up in a few weeks with my experiences, notes and decisions, thanks again!

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#5

In today’s date, wifi is mandatory to use to get a strong Internet and that will be fine for all. Also, browse some different tricks like you will use Netgear router and that will be fine for all.
I always prefer to use a netgear router, by using this you will not face any type of problem. From browsing netgear wifi extender wn3000rp setup, you will get it properly.

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#6

Got much better/great results,
when deactivating receiver or senders WLAN…
to force a cable Network Connection…

if wlan activated…
even with a direct thunderbolt bridge…
lag connection… :(

Love the wireless Universe… but on events… it fails/lags so often… :(

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#7

Hi everyone, thanks for input and observations, very helpful in developing this. I’ve now been touring/performing with this setup for about a year, in lots of various stages/venues/etc, and I now have a stable, always-working wireless + wired multicam solution, just thought to follow up with what works for me, and what didn’t, this could be helpful for others struggling with this.

Current working setup:
-Macbook Pro Retina 15" 2016, 16GB RAM, Radeon Pro 460 4 GB for video (VDMX)
-Macbook Pro Retina 13" 2019, 16GB Ram, for audio/sequencing/signal routing (Ableton Live/Max4Live)
-Netgear Nighthawk XR500-100EUS AC2600 Dual-Band Pro WLAN Router
-Two Apple ipod Touch, running NDI Cam
-Apple iPhone6, Apple iPhone8+, running NDI Cam
-Logitech C920 and Logitech C922 webcams
-ELP Webcam 720P Fisheye H.264 USB
-Two cheap Microsoft 720p webcams as backup incase network problems
-Internal Facetime camera
-Laptop cooling pad with max amount of fans (a gaming one)

Most important, magic first tip: CLEAN YOUR MAC FOR DUST REGULARLY. I had endless problems with throttling (kernel_task) when using VDMX, even with simple setups that wasn’t taxing the GPU much. Turns out the problem was, as a touring artist, playing everywhere from outdoor festivals to grungy basements, my laptop quickly gathered a lot of dust and particles stuck inside the ventilation system, and wasn’t able to ventilate itself properly. And under stagelights, it gets super hot super quickly up there. I opened it, and holy shit, it was PACKED with dust, I was shocked. Cleaning it out with airspray, and VDMX instantly runs with zero problems, if it throttles now it is because I obviously reach max CPU/GPU, not because reaching max temperature. So if kernel_task is going amok, clean your mac. I’m sure many of us has this “laptop lifestyle” and are completely unaware of this problem!

The router is operating only the 5 gHz band, all devices and machine is connected to this 5 ghz network. Router is never connected to the internet, it is just providing a LAN for the wireless cameras. Devices are never updated, they are only used for this exact setup. The router is placed on stage, in the same height as laptop and all wireless cameras, if possible. The wireless cameras (ipods, iphones) are powered, because they would run out of battery for the one hour show, but placed around or outside stage so outside cabled reach for video signal. They can’t be toooooo far away, the 5 ghz network is not strong over long distances. All cameras broadcast or shoot at SD or lower (800 x 648 or 640 x 360) and are often active (output) simultaneously in the main projection (this works for my visual aesthetic, where multiple sources are shown as smaller images within a larger collage and a lo-fi style with heavy processing). The network will struggle if even just ONE of the devices are broadcasting HD.

NDI has been super stable for me - even more than USB. If a VDMX source is set to an NDI input, this device/input consistently comes back exactly as intented when disconnected or moved or setup at another stage etc. Maybe latency increases now and then, but the signal is always THERE. I can trust it. This is not the same with USB cams which I’ve found can be finicky and always needs to be “touched” somehow to get back to work, and often appear with strange new random names in the system, needing me to go through every single proejct and reconnect the device with its new name.

I’m not always using all 8 cameras, on average 6 cameras are active; three wireless and three wired. When using more than 3 wired cameras, they need to be distributed to separate sides of the Mac (can not have all cams on one bus).

MIDI and sync I’m running cabled between VDMX and Ableton Live. The “physical” network is stable, theoretically networked MIDI should work, but I’ve found the macOS network MIDI operation itself to be unstable, the connections can suddenly drop. That experience is based on several years of trying it, so i’ve given up trying it since macOS 10.13, maybe that has improved in later updates now, but the cabled solution is rock solid, always the exact same latency and weights nothing in transport, so it works for me.

Things I tried and refused:
Apple Airport, Apple Airport Express, not strong enough network.
Google WiFi, not strong enough, unstable and no control over device.
Bluetooth MIDI, very finicky and unstable.
Marshall CV502 USB 3 cameras, visually great but super unstable, particularly when more than one.

Generally I’ve found that high-end, good quality gear for gaming seem to actually be the best for working-class artist visual graphics work. Its made for high performance computers and low latency and its not super expensive.

Hope this helps, this is of course something that works for my specific setup and artistic aestethic / message, it is no universal recipe and i’m sure others will have different experiences and opinions, but maybe some of this info can help others.

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#8

Turning off wlan just on one Maschine helps a lot… never got probs anymore… :)
For wlan cam using a wired iPad’s… so this devices do the network than + good resolution preview…

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