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1.5 Second delay of RTSP video feed into OBS

Our church just bought the 20x -SDI camera. We currently use OBS to live stream our services. The problem we are having is rather than just the normal couple hundred millisecond delay in the video feed, we are having a latency of about 1.5 seconds. No amount of adding latency to the audio can seem to compensate for such a large lag. We have brought the RTSP stream into ONVIF, IP Capture Viewer, and even downloaded a trial of vMix, and in all of them, the video feed was almost real-time or only a few milliseconds delayed. 


It seems to be something with OBS. Has anyone else ever run into this problem, and have you found a solution? Thanks.


Hello Dwight,


This is something we have been hearing and seeing recently. It turns out OBS leverages VLC for pulling in RTSP feeds. Whether you bring them in as a media source or VLC Video source. And it seems like the same issue occurs in the latest version of VLC. We are in the process of testing things out with older versions of VLC to see if that solves the issue. If we find anything that can fix this delay in OBS I will reach back out on here. 

Thanks for letting me know! Will be watching for a resolution!


Any update on this issue? I'm also experiencing something similar. Wondering if OBS has this limitation, should we look at other options like Wirecast will have a better performance.

Hi James,


Yes, this appears to be becasue OBS leverages VLC to do the RTSP feeds. This adds a good bit of additional latency that would otherwise not be there in Wirecast or Vmix. You can always get a trial of Vmix to test it out and see if it shows less latency for you. 

We are having a similar issue using vMix, so it isn't strictly an OBS problem


Hi Lee,


IP latency can come from a number of different sources and the ways that VLC, OBS, vMix implement use of the FFMPEG solution.


I would be curious with your setup in vMix how much latency you are seeing and how the stream(s) are being configured.


Please see an example of achieving the lowest possible latency within vMix, outside of using NDI, for our RTSP feeds.


Note that we would not recommend running a professional production with no buffer as shown above.


What this should enable though is for you to see, without buffering, how low of latency is possible given the current PC, Network, etc...


One other thing to be aware of is the x264 decoder selected within vMix settings can also impact the final latency experienced.


If you have any additional questions relating to this or otherwise please do not hesitate to return to the forums.

Has anyone figured out a fix for this latency issue? I had my audio dialed in and just used presets, but now the latency seems to be variable and this week was almost 3000ms instead of the 1100ms it has been since I set it all up. 

Hi Josh,


While I cannot speak to the exact latency you will see via OBS I can likely assist with the "drift" issue you are experiencing.


On our network I typically see latency around 800ms - 900ms in testing in OBS using the VLC input option for RTSP.


Our network is a Unifi solution, top to bottom, that uses the following setup guide to for configuration for IP video 


Unifi Setup Guide for mDNS and Multicast


In the knowledgebase entry shared below you will learn how to leverage the NTP options on the camera, you PC and network to minimize video drift and allow for better synchronization of multiple cameras and audio feeds.


https://help.ptzoptics.com/en/support/solutions/articles/13000083024-synchronizing-multiple-ptzoptics-ip-video-streams-audio


If you do not see the NTP option on your camera please proceed with updating the firmware using the PTZOptics Firmware Finder.


https://ptzoptics.com/firmware-finder/


If you combine this tutorial with the audio synchronization test you should find a much more reliable presentation for day-to-day use with little to no modifications required.


We hope this information is helpful towards improving the synchronization between audio and video for your productions





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