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!
 

nottooloud

Member
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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