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nicademus  
#1 Posted : Sunday, June 7, 2026 9:24:31 AM(UTC)
nicademus

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We upgraded from .46 to .48 having seen a reference to long SRT stream framing issues.

Yesterday we had 3 Inbound streams going and 7 outbound.

2 of the Inbound were via SRT - one from an Atomos Connect, and the other was from our Main VMIX OB PC. We've moved to SRT as the commentary for the most part seems to be it is more stable, more resiliant to network drops, Jitter, etc.

The atomos connection dropped right toward the end of the stream - but had been going for around 5.5hrs - so all told not bad.

The VMIX Broadcast, per another question I have asked about having SRT Stream options - is instead just working with the SRT output - using 10Mbps, the usual 2 second keyframes, and pushing to a specific Path on our SRT server. Then that SRT server pushes to the RTMP Server that has the Youtube and Facebook RTMP details.

That stream had been going for around 3.5 hrs at the time, and AI has mostly identified "timing drift / pacing instability"


2026-06-07 09_19_51-vMix Pro - 29.0.0.48 x64 - VLogStreaming.vmix.png (3,092kb) downloaded 5 time(s).

Should we still use this method to push our Streams? or go back to relying on RTMP Custom pushes... Which for the most I even think seem to have better Quality if I'm honest, but seems to be that when they Drop...they drop more savagely and take longer to get back online to the RTMP server, as we need to reset NGINX...

Or even - is there some means to add into a hidden config to be able to make sure the SRT data itself is definitely these settings:

enable strict CFR
fixed GOP
keyframe exactly every 100 frames (50fps = 2s)
no adaptive GOP
no dynamic bitrate.

Cheers in advance
ckvideo  
#2 Posted : Friday, August 7, 2026 4:03:40 AM(UTC)
ckvideo

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Originally Posted by: nicademus Go to Quoted Post
We upgraded from .46 to .48 having seen a reference to long SRT stream framing issues.

Yesterday we had 3 Inbound streams going and 7 outbound.

2 of the Inbound were via SRT - one from an Atomos Connect, and the other was from our Main VMIX OB PC. We've moved to SRT as the commentary for the most part seems to be it is more stable, more resiliant to network drops, Jitter, etc.

The atomos connection dropped right toward the end of the stream - but had been going for around 5.5hrs - so all told not bad.

The VMIX Broadcast, per another question I have asked about having SRT Stream options - is instead just working with the SRT output - using 10Mbps, the usual 2 second keyframes, and pushing to a specific Path on our SRT server. Then that SRT server pushes to the RTMP Server that has the Youtube and Facebook RTMP details.

That stream had been going for around 3.5 hrs at the time, and AI has mostly identified "timing drift / pacing instability"


2026-06-07 09_19_51-vMix Pro - 29.0.0.48 x64 - VLogStreaming.vmix.png (3,092kb) downloaded 5 time(s).

Should we still use this method to push our Streams? or go back to relying on RTMP Custom pushes... Which for the most I even think seem to have better Quality if I'm honest, but seems to be that when they Drop...they drop more savagely and take longer to get back online to the RTMP server, as we need to reset NGINX...

Or even - is there some means to add into a hidden config to be able to make sure the SRT data itself is definitely these settings:

enable strict CFR
fixed GOP
keyframe exactly every 100 frames (50fps = 2s)
no adaptive GOP
no dynamic bitrate.

Cheers in advance


Hi,

the picture looks like some bandwith issue on the transmission line. Make sure you use CBR, it is in the advanced settings of the encoder popup menu. Unfortunately, it is off by default. Make sure your SRT latency is 2x or better 4x the ping time between your vMix PC and the target server. Make sure the signal uses only 75% of the link capacity, leaving 25% for error correcting. Watch the SRT stats in the stats window (Rainbow colums icon bottom right in the vMix window.

It is not clear, where the error comes from. Check the parameters, stick to SRT and learn how it works. RTMP is dated and not up to todays sometimes difficult network conditions.

Picture quality is no SRT issue, SRT is codec-agnostic, you can put through it whatever you want. Encoder settings are the issue here. It could well be that your encoder settings on the SRT output were other/worse than on the RTMP out.


Good luck,

Chris
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