OBS Program to SDI/NDI Questions

[LecheL]

Hey y'all!

I am currently building a setup with a bunch of computers where people would stream in the same room together, but I will also want to have each of their Program feeds as SDI so I can plug it into my Blackmagic ATEM Switcher. I've heard and see places that OBS is able to output its Program to Decklink Cards, but its not on my Computer when I go to tools on my home OBS. Does the Decklink output option only appear if I have one installed on my computer? Are there better alternatives for this?

I am worried about not being able to get the audio off of the SDI since it would go into a switcher, would I need to split it and convert some to work in a mixer?And if so does anyone have advice for that? I was thinking about having a mixer computer that has a Large Decklink for inputs as well just to get the audio into somewhere.

NDI doesn't seem to work well in this Building, so that's why I am asking about the Hardware solution and wanted to know if anyone had advice before I buy one to trial especially if this wouldn't work. That being said, I am using the OBS NDI plugin, and it seems like its having problems because its using SO much up/down, much more than a normal stream.

Any advice appreciated. Thank you!

 

[Lawrence_SoCal]

your comment about NDI bandwidth would possibly imply you don't understand what NDI is doing, and how its configured, etc.
Personally, with my networking background, I'd make sure network is solid, and not create a secondary SDI network.
But, that does require all of the computers to have the spare processing capacity to create/handle the NDI stream (yes, higher bandwidth as it is typically MUCH higher quality than typical stream rates, which are HIGHLY compressed/lossy). But, there are certainly some scenarios where SDI may make sense ... like most things technical.. it depends. You did NOT mention # of people/computers, and average and peak network traffic (without NDI)
Certainly, a typical 1GbE network, properly configured managed and maintained, should handle plenty of NDI streams (up to a point), and higher NDI stream bandwidth may well require separate networks (if approaching/exceeding 1GbE peak bandwidth usage), but 10GbE simple switches are relatively inexpensive, but if at/exceeding 1GbE in NDI traffic, that is going to take a well engineering solution to process all of that, especially within reasonable latency timing). I haven't priced something like this out, so couldn't say if a > 1GbE NDI traffic solution would be more or less expensive than SDI.
And unfortunately, NDI is not built into OBS Studio (I presume due to NewTek licensing reasons)

 

[LecheL]

I thought I understood how NDI works but I could be wrong. I have mostly used it for just a few computers, but this project would be 7-8 NDI Feeds as those computers are also streaming out to Twitch. My understanding (for NDI) is since its all on the same network your ISP up/down doesn't matter and it's only limit is your router's capacity for it, is that correct? Or where could I find resources to help provide clarification on that if I'm wrong?

The feeds would all come into another OBS or vMix computer for help with Switching and splitting it to get the audio from each into a mixer.

The computers are good enough to send the feeds no worries while they stream, but I am slightly worried about the computer that is receiving them all. If not using OBS/vMix to take them all, what other good options could there be?

I am using the DistroAV plugin to OBS for sending and receiving.

NDI seems like the easy choice for this setup, but due to previous comments by the venue I am a bit worried and wanted to make sure the hardware solution I had in mind made sense.

 

[Lawrence_SoCal]

I thought I understood how NDI works but I could be wrong. I have mostly used it for just a few computers, but this project would be 7-8 NDI Feeds as those computers are also streaming out to Twitch. My understanding (for NDI) is since its all on the same network your ISP up/down doesn't matter and it's only limit is your router's capacity for it, is that correct? Or where could I find resources to help provide clarification on that if I'm wrong?

Uh, that networking understanding is, unfortunately, WAY to simplistic to be accurate.

Whether on same network or not really isn't an issue (technically) as issue is bandwidth, jitter, latency, routing, etc. The reality is that in typical consumer flat network, it is fast enough for typical usage scenarios. One can route high bandwidth over Internet just fine, if one knows what they are doing, and have the right setup. it all depends.

For a typical 1GbE consumer Ethernet network, 7-8 computers and NDI would be a non-issue, assuming reasonable/typical traffic levels. However, cheap routers can be bad at handling higher traffic levels. So, a quality Switch all PCs connected to would possibly help. If 8 PC, you also need uplink port (to router), so you usually need at least 1 more connection than # of PCs
And then, if you have all PCs independently streaming (outbound/upload traffic) and then also sending higher quality NDI stream to a central video receiving (OBS Studio) PC, which then composites those feeds, and send out its own streaming feed, that could easily overwhelm some routers. And that has nothing to do with whether you are using NDI or not. But if using NDI, and some of that traffic is traversing router ports from gaming PC to OBS Studio PC... that could potentially impact router performance

The feeds would all come into another OBS or vMix computer for help with Switching and splitting it to get the audio from each into a mixer.

The computers are good enough to send the feeds no worries while they stream, but I am slightly worried about the computer that is receiving them all. If not using OBS/vMix to take them all, what other good options could there be?

Things like Killer Network driver has been known to cause havoc. Plenty of folks don't understand networking and make ill-advised changes/'optimizations' to their setups that can cause havoc. Or certain security software/settings. Beware assuming anything... maybe the PCs can handle it, maybe not. Without real-time monitoring on both PC and LAN, you don't KNOW

I am using the DistroAV plugin to OBS for sending and receiving.

NDI seems like the easy choice for this setup, but due to previous comments by the venue I am a bit worried and wanted to make sure the hardware solution I had in mind made sense.

I'd be inclined to provide my own managed switch, with monitoring setup (its own things to learn) such that venue is ONLY dealing with outbound stream traffic (and little else). But that may not be an option depending on layout, etc. And would only help if someone actually knew what they were looking at in terms of network traffic

NDI vs SDI - each approach has its own Pro's & Con's