Fluctuant delay between audio and video using NDI for video (2 PC Setup)

Whooley

New Member
Hey!

So I use a fairly complex setup for my stream. I use two machines, one for streaming and one for the rest. In my case, it's not gaming, but mostly music production.

My music production PC is a Windows machine, my streaming computer is a MacBook Pro from 2019. I use NDI to get the video data from the music production PC to the MacBook. However, for audio I use a seperate setup in which I take two outputs of my music production PC's audio interface, re-route them into the inputs of another interface that is connected to the MacBook. This is necessary because with my music production, NDI wouldn't pick up all the sounds I need due to different drivers. Also this way, I can be sure that the stream can hear exactly what I hear.

Unfortunately, there seems to be a very annoying issue with this. When I stream (or even just record), the video (transmitted via NDI) and the audio (transmitted via the interface chain) are out of sync. I recorded a bit of an audio-video-sync-test and figured out how much of a delay there was. But when I fix it and restart the recording, there seems to be a whole different delay. So it's like a game of cat-and-mouse of me trying to fix the constantly changing delay.

This happens as well when both machines are not anywhere close to maximum workload. The MBP is connected via 1 Gbit/s LAN.
I'm new to this, but I hope these are the log files you need. Please let me know if you need anything else to help me.

MacBook recording with fresh delay adjustment: https://obsproject.com/logs/l66zj4aAJSSxtNYQ
PC session running at the same time: https://obsproject.com/logs/p7zbD7u1mcQzIJn_

Second MacBook recording with same delay settings but now out of sync: https://obsproject.com/logs/UsVnFDjPq8Vl5aNe
PC session running at the same time (restarted in between): https://obsproject.com/logs/e03hR3xRwwUtdWeM


I hope someone can help me figure this out since this is driving me and my community nuts. Thanks for your support!
 
Looking at the two Macbook logs,

first one:
16:38:51.981: [obs-ndi] started A/V threads for source 'PC-ROBIN (Desktop)'
16:38:51.981: [obs-ndi] A/V thread for 'Desktop' started
16:38:52.068: coreaudio: device 'iO4' initialized
16:38:52.112: adding 23 milliseconds of audio buffering, total audio buffering is now 23 milliseconds (source: Desktop)
16:38:52.112:
16:38:52.144: [obs-ndi] started A/V threads for source 'DESKTOP-KBR62TD (Acer Laptop)'
16:38:52.144: [obs-ndi] A/V thread for 'NDI™ Source' started

second one:
16:41:27.798: [obs-ndi] started A/V threads for source 'DESKTOP-KBR62TD (Acer Laptop)'
16:41:27.798: [obs-ndi] A/V thread for 'NDI™ Source' started
16:41:27.888: coreaudio: device 'iO4' initialized
16:41:27.904: [obs-ndi] started A/V threads for source 'PC-ROBIN (Desktop)'
16:41:27.904: [obs-ndi] A/V thread for 'Desktop' started

Is that 23 ms your corrective delay? It wasn't added to your second session.
 
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