For community engagement, I advise against streaming to multiple platforms.
- With 'Scheduled' Facebook Live events, you can get a consistent URL that non-Facebook users can watch (and see other comments).
- As much as I detest Facebook practices, YouTube isn't much better and the prior benefit of YT being able to stream 1080p vs FB's 720p is no longer the case (FB previously (2020) allowed a select group of gamers to stream at 1080p but not everyone else. I'm not sure when that changed, but streaming to FB at 1080p now with nothing done other than changing my OBS stream settings.
When you ask about PC power, some other considerations would be other sources/plug-ins you expect (or should be thinking about) to use
- What else beyond camera view? ex if liturgical style, a Service Bulletin? or lyrics/music, readings, etc
I use PowerPoint, in Windowed Slide Show mode.
- Then there is your audio interface, effects/filters etc. Some can be CPU demanding, though video filters/effects are more so.
As for GPU, general recommendation is to get a nVidia Turing based card or better for its much better NVENC for GPU encode offload (ie reducing CPU load). That used to mean a GTX 1650 Super. Supposedly some newer base 1650 models 'not Super) _may_ have changed chipsets and use Turing? not sure, so be careful.
With recent publishing of yet another Intel vulnerability (BIOS 6th-11th gen), I really wanted an AMD CPU, but also wanted a business class PC (for better build quality, and warranty/support) so ended up with an Intel i7-10700K with a GTX 1660 Super and 16GB RAM, and 5 yr next business day onsite, US call center support (for $1,500 delivered fall '2020). For reference, with a Panasonic NDI camera, and PowerPoint, plus browser session to monitor stream, and camera control software, my CPU/GPU usage is a little over 10% (1080p stream and record at different 1080p settings). I expect this PC to last a full five years, and be able to run DaVinci Resolve in case any video editing needed (ex Baptism, Wedding, Funeral, marketing material, etc) [So PC was equipped with a DVD burner as well]. To make sure hardware lasts, PC is connected to an Auto Voltage Regulating pure Sine wave output UPS (battery backup unit).. Why? unclean electrical power is common cause for failed motherboards/components.
Now, with crazy GPU prices, you could get a CPU (APU) with built-in graphics, and simply use CPU encoding for a year or so. When GPU prices return to normal, pick up a GPU add-in card then?? Though thermal throttling can be a consideration, it is possible to run OBS to livestream a service using a laptop. I don't necessarily advise it, and more care is required in model, GPU option and cooling design, but it is doable if need be.
As for NDI:
- Your PC has to process incoming video feed (decode). It has to do this regardless if USB, SDI, HDMI, or NDI. What would vary is in a multi-camera setup, with NDI, OBS processing every camera. *IF* using SDI/HDMI and an external video switcher, then PC only seeing/processing a single video feed (less processing, but then can't do picture-in-picture, fades, etc... so like most things it is a trade-off)
So, do you need a really powerful CPU/GPU for a basic House of Worship livestream setup? No. Will an NDI camera materially impact hardware resource demand? No. Do I recommend NDI for the single cable simplicity? Yes, though don't forget to account for PoE in getting switch/router. For security and reliability, I put streaming PC behind its own firewall (protect from rest of Office PCs). A SMB router, with PoE would work nicely, or a managed switch with VLAN routing might suffice.
Then, don't forget to account for your audio interface. Though we had a contractor who didn't follow statement of work, and require a largely do-over (grumble), to keep things simple in our Sanctuary, I placed OBS PC on a shelf in sound mixer closet. I then ran a 50ft DisplayPort fiber optic cable + a 2nd 50ft powered USB cable into choir/organ loft. With DisplayPort MST, I run 2 monitors off the single cable. 1 larger 1440p monitor used for OBS, PPTx, browser, etc. 2nd monitor is used for camera control software. Using PTZOptics OBS plugin, and a larger monitor, probably doable on a single monitor. Then a Aux audio output on mixer into gain adapter into 3.5mm TRRS cable into PC. Awaiting opportunity to switch to using digital (USB) connection and getting access to each mixer channel on OBS PC (Mute certain mics when not needed, etc).
As for camera, beware that most Sanctuaries aren't that well lit. So quality optics for low-light performance can be important for many. And some PTZ cameras use cheaper motor controls (for ex older PTZ Optics cameras couldn't move in the diagonal... ie could pan or tilt, but not both at same time... I believe latest models have changed that, though I suspect the knock-off PTZ cameras on Amazon, etc may have the older mechanics).
Finally, on a side note, be aware that your audio mix for in-person audience and that for remote viewers is likely to need to be different. For us, piano, pipe organ, and choir don't need mics for in-person audience, but mics are needed for remote viewers. So we have mics that are not amplified/output as part of Main Out but is setup for Aux Out. And minor tweaks beyond that to levels, to account for usually mobile device speakers for remote viewers (so Compression may be desirable)
I hope that helps
