Hardware Recommendations? - Low Latency setup for Online Music Lessons over Zoom

[Michael Berry]

I have a setup that I threw together for my wife to teach online music lessons a year ago when Covid was sprung on us. Our setup has been working pretty well but the computer I used is pretty old and I'm looking at buying some newer hardware for a dedicated setup mainly to keep it reliable and reduce latency. We mainly use OBS as a video switcher and sending the video to Zoom. Looking for some input.

Our Goals/Needs:

Low Latency (By latency I mean time to render between real time and when zoom sends the video. I feel like its around 300-500ms right now)​

Reliability​

Easy Setup on a daily basis​

Dual Cameras​

Chroma Key​

Interface with Zoom​

Current Hardware and Setup:

Dell Optiplex 770 with i7 2600 Processor, SSD and 16GB Ram​

NVIDIA GTX 1650 Super OC graphics card​

Logitech C922 and C910 cameras​

Behringer UMC202HD Audio Interface (Need 2 channels, one for keyboard, one for a mic)​

Streamdeck Mini​

USB Document Camera​

We are routing audio and video from OBS to Zoom via NDI virtual input (I'm open to trying the newer ways that are now available if its faster)​

We also do some screen captures from onscreen for sheet music, pdfs, etc.​

New Hardware and Setup I'm looking At:

Dell Precision workstation with i7 Processor (T3640?)​

Keep my GTX 1650 Super graphics card - unless something would do substantially better​

Keep my UMC202HD audio interface (Unless something would improve latency)​

Switch to a video capture card instead of Logitech?? -- I've had random issues with these cameras and it seems like they have lots of latency with the capture.​

Would getting an hdmi capture card with other cameras improve latency? If so what is my best bang for my buck on a capture card and cameras. One camera is a face camera that we also do a chroma key background on and the other is a camera that looks down on the keyboard. Or would I better off going an entirely separate route like a hardware video switcher?

Thank you and I appreciate any input that you all might have. We want to keep latency to a minimum as it is distracting to the student and teacher having to make sure they don't talk/play over each other.

 

[PASS Studio]

FYI LESs the 1000 ms is good look at what other programs can be disable include a SSD seems to me ssd dont get the credit they need pcie is better

 

[Reaby]

I assume you don't need any audio from obs video sources - if so - you could just use the recently added virtual camera, which has - if not exaclty 0 latency - but very few for routing the program out to other apps, like zoom. If I remember right, zoom has some sort of hq/music mode, which you should enable when working with program sources like yours. If your behringer can mono the incoming signal, it would be it's easier for the studen to listen. Othervice a 4 channel soundcard might be a good call, so you get stereo sound from your instrument and an external mic.

You should disable all audio from obs, see settings and disable everthing there. then setup the zoom to pickup mic directly from the usb interface and also output to the usb interface. I don't know which options the zoom has... if you can use ASIO, that's the most less latency option out there. MME and directX are slower. Anyway doing so, your video is kind of nearly direct from webcameras, with only small delay of obs processing the chromakey etc.... and audio direct from the usb interface with the latency it has... consider if you can use asio, it's then 5.7ms to 10ms.

Notable still is, that your audio and video comes from different sources, I would recommend you to take a moment to sync your audio with video, since there *will* be different latency between the sources. There is so many options to do so: search youtube for audio/video sync or use recently added loistosync from the tools section of this forums (shameless selfpromotion ^_^). You wish to record the zoom session output and see the sync from there. Video you can delay, but audio not so easily... So wish that the video is ahead of the audio when syncing, then you can apply some offset to the videos using video delay filter.

Random tips: make sure your obs output match with the screen size of zoom. Use nvenc if possible for recording, but if you dont' need to record the lessons, then it doesn't matter, virtual cam handles the encoding its own.

Stay safe, and with best regards,
Petri

 

[Michael Berry]

I assume you don't need any audio from obs video sources - if so - you could just use the recently added virtual camera, which has - if not exaclty 0 latency - but very few for routing the program out to other apps, like zoom. If I remember right, zoom has some sort of hq/music mode, which you should enable when working with program sources like yours. If your behringer can mono the incoming signal, it would be it's easier for the studen to listen. Othervice a 4 channel soundcard might be a good call, so you get stereo sound from your instrument and an external mic.

You should disable all audio from obs, see settings and disable everthing there. then setup the zoom to pickup mic directly from the usb interface and also output to the usb interface. I don't know which options the zoom has... if you can use ASIO, that's the most less latency option out there. MME and directX are slower. Anyway doing so, your video is kind of nearly direct from webcameras, with only small delay of obs processing the chromakey etc.... and audio direct from the usb interface with the latency it has... consider if you can use asio, it's then 5.7ms to 10ms.

Thanks so much for your input!!!! We are currently using audio through OBS mainly for convenience as its nice that OBS just handles all the audio mixing and video switching together. Plus we occasionally share content on screen with audio (like a youtube video for instance) with the student. So I would prefer to keep audio routing inside of OBS. I believe OBS has a new virtual cam that does some audio routing also. I haven't tried that because our setup with NDI has been running smoothly and I haven't wanted to rock the boat.

Right now I keep our audio pretty much mono. I use the 2ch Behringer box. One channel Keyboard, the other channel Microphone. It likes to present itself inside of OBS as a stereo pair. So, inside of advanced audio properties I select the interface and pan it all the way left or right to just get one of the channels. I am using OBS to put a limiter on the mic and a noise gate also. It doesn't seem to have added much latency looking at the logs though. From OBS everything goes through the NDI pipe with audio and video to Zoom. On Zoom I have "Original Sound" enabled and I have turned off as much audio processing as I can. The audio seems to work pretty good this way. The only other audio tweak is that I have to set the level on the NDI to +10db or so in order to bring my audio up loud enough for students to hear. I'm not exactly sure why this is but it works ok.

What do you think of trying to bring ASIO direct into OBS to reduce latency? I've read about it but haven't tried it.

Notable still is, that your audio and video comes from different sources, I would recommend you to take a moment to sync your audio with video, since there *will* be different latency between the sources. There is so many options to do so: search youtube for audio/video sync or use recently added loistosync from the tools section of this forums (shameless selfpromotion ^_^). You wish to record the zoom session output and see the sync from there. Video you can delay, but audio not so easily... So wish that the video is ahead of the audio when syncing, then you can apply some offset to the videos using video delay filter.

I do have my audio synced right now. I did mine with a sync video from youtube and then I watched the zoom stream to get it right. I'll check out your tool for sure though.

Random tips: make sure your obs output match with the screen size of zoom. Use nvenc if possible for recording, but if you dont' need to record the lessons, then it doesn't matter, virtual cam handles the encoding its own.

Yeah, I have the screen size set the same for OBS and Zoom. I'm running at 720 but Zoom likes to dumb it down to 480 over my internet connection. I'm trying to keep my webcam capture, canvas resolution, output resolution all to be the same to minimize processing of the video. We don't record or stream anything so OBS is purely a video switcher for us.