How many NDI sources can be used

[Jbradleypro]

Hello
I'm wondering if OBS requires more PC resources and/or network when adding more than 2 NDI sources?
Is there a basic calculation for this? Based on the information I see so far a 1080p 60fps sources uses 125 to 150meg per second. It's safe to assume this is a network bandwidth calculation and not a OBS calculation. In other words can I use 8 NDI sources all at the same time? I'd like to create 8 separate scenes in OBS. based on 150meg that would be 1.2gig data rate. Please advise if I'm missing something? Thank you in advance

 

[rockbottom]

Some info attached.

Basically correct.

The NDI Bridge can also be used to convert plain old NDI to NDI HX & lower the demand on your LAN.

 

[Lawrence_SoCal]

The NDI Bridge can also be used to convert plain old NDI to NDI HX & lower the demand on your LAN.

From a very basic perspective, and I readily admit I may be way off, my understanding is that the lower bandwidth version of NDI uses more compression, so might that mean more CPU on receiving end to decompress? (the whole, no-free-lunch concept)

Also, beware your camera settings. For example, my NDI camera sends out both a main video feed, but also a low bandwidth (mjpeg? 10fps) to the control center system (which can be turned off). And some camera let you adjust the FPS.. if you aren't using 60fps (and many aren't) then you can save some bandwidth by dropping to 30fps). My Panasonic 1080p NDI PTZ camera send data to my streaming PC using 26->28MB/s

And yes, your computer is going to have to receive, process (decompress) each video stream, all at the same time. So each camera will add CPU, RAM, network bandwidth, etc. In your specific scenario, you could do some hardware resource monitoring with only 1 camera on, then turn on and start using 2nd camera. compare.

As for consolidating network traffic and more than 1gb/s... getting much easier/cheaper nowadays with 802.11bz and 2.5gb/s Ethernet (as well as 5gb/ & 10gb/s). One, you need to know your PC can handle processing that much video simultaneously. If yes, a network upgrade to an ethernet switch with a port > 1gb/s isn't that expensive anymore. These guys have been doing a lot of good reviews on 2.5gb/s switches of late https://www.servethehome.com/category/networking/ though personally I prefer a managed switch, VLANs, etc. Beware the cheapest switches that may not be able to maintain consistent low jitter and latency when driving >1gb/s traffic for an extended period of time

 

[rockbottom]

^^
Nvidia or Intel GPU required to encode NDI HX. Decode cost isn't any higher than NDI. Encode quality is adjustable from near LL to crap.

 

[AaronD]

For another data point:
The rig at my church uses NDI from the projection app on another machine, to send lower-third lyrics to OBS, that are coordinated with the audience displays. That NDI feed is technically full-screen with transparency (and it completely blocks the cameras when we forget to make it blank for new announcement slides), BUT according to the network traffic meter on the receiving machine (the one with OBS), the data rate varies widely depending on how much transparency there is. All-transparent is practically nothing, as if only the visible pixels are actually sent.