Question / Help Network Speed dropping when recording/streaming with NDI (please read)

TomPilot

New Member
Not sure why, but my posts are being removed before anyone can see them. Same with reddit. I just want some support. Mods, please dont remove this post.

Hi, all. I'm having an issue using the NDI plugin for local recording and streaming. I have had a dual PC setup for a couple months now, and it worked fine for local recording. I have my gaming PC and encoding PC connected to my router with the same gigabit cables, and I haven't changed any kind of settings since then.

What is happening now is that the incoming NDI signal on the encoding PC is stuttering and freezing every couple seconds. This only happens when I'm recording. I have Task Manager open on both PCs and I'm monitoring the Ethernet usage under the Performance tab. The "Send" speed on my gaming PC stays at around 140Mbps when I have OBS open, but not recording. When I record, however, it will drop down to around 10Mbps for a second or two, then jump back up. I'm not sure what caused this to start happening.

To be clear, I know this isn't an encoding issue. I have a webcam connected to the stream PC that doesn't drop any frames when this happens, and it shows a constant 60fps with no dropped frames in OBS. Also, my gaming pc is 100% capable of recording and streaming. I use a 2 PC setup to remove the encoding load for better fps in games. So its not a hardware issue.

If anyone has an insight or info on what can be causing this, please let me know.

Here is a log file of what is happening. I started and stopped recording a few times to see if there is something going on. Thanks in advance!

Log File: https://obsproject.com/logs/xOcgR7hbQ_I-Owbd
 

carlmmii

Active Member
What does task manager say your CPU usage is on your encoding PC? An i5-3470 being asked to encode 900p60 at veryfast is asking a lot, and it may be causing NDI processing to be sacrificed due to OBS encoding priority.

What happens if you change your preset to ultrafast, or reduce your resolution?
 

FerretBomb

Active Member
I'd also recommend checking the Networking tab on both machines. It's entirely possible that one of them may have auto-negotiated down to 100B-T levels instead of full gigabit, and NDI can easily use more than 100mbps on a 900p60 video source. Just a sanity check.

You might also use something like Crystal DiskMark to check the write speed capabilities of the disk you're recording video to; I've had drives go 'bad' with no explanation in the past, and top out at 20-30mbps write.

Also, NEVER record directly to MP4. It causes problems. Lots of them. Record to MKV and remux to MP4 from there.

I also have to ask, what are the specs on your gaming machine? With an encoding machine as frankly low-end as the i5-3470, it's very likely that just running a 1PC setup with NVENC, and running OBS as Administrator on the gaming system to take advantage of the GPU priority workaround added in 24.0.3 could give you better performance and visual quality, depending on the GPU in the machine. The NVENC provided by an nVidia 10-series GPU would be a strong step up from x264 VF, and a 20-series would blow it out of the water.
 

TomPilot

New Member
Sorry for the late reply. To answer carlmmii's question, my CPU usage is always below 60%. It can encode just fine. Its the communication between my gaming PC and encoding PC that is the issue. My NDI transfer speed drops from 150mb/s down to about 10mb/s, and that is when the video feed stutters on the encoding PC. So I guess I should be more specific and ask if there is some type of network configuring I must do to combat this? I'm using a Sagecom Wave2 router from Spectrum to connect the 2 PCs. Does NDI require a dedicated network switch?
 

teteuzen

New Member
Hey Tom! I was having the same issue, NDI dropping upload speed only when start streaming. Found out that it was OBS process priority taking all cpu resources on the streaming pc. Setting below normal process priority did the work for me. Hope it helps!
 

Dihelson

Member
Sorry for the late reply. To answer carlmmii's question, my CPU usage is always below 60%. It can encode just fine. Its the communication between my gaming PC and encoding PC that is the issue. My NDI transfer speed drops from 150mb/s down to about 10mb/s, and that is when the video feed stutters on the encoding PC. So I guess I should be more specific and ask if there is some type of network configuring I must do to combat this? I'm using a Sagecom Wave2 router from Spectrum to connect the 2 PCs. Does NDI require a dedicated network switch?
Yes, but did you test your write speed on the network destiny disk ? Use Crystal Diskmark for that and look at what speed your lan can sustain. As a friend told some lines above, sometimes, some disks go bad and write speed drops to around 20Mbps. By coincidence, I have an SSD here that write speed drops out of nothing.
 
Top