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Is SRT output PsF?
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KerryDP  
#1 Posted : Wednesday, November 4, 2026 5:08:03 PM(UTC)
KerryDP

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Forgive me if this is a question that has been asked before... If a Vmix project is 1080i50, and the video input source (and the SDI external output) is 1080i50, then what is the SRT stream configured as? Is it 1080PsF50?

This has always seemed like a bit of a black-box option as a user, because there doesn't seem to be a way (that I can see) to change or check what frame rate/type the SRT output is. We have used 1080p50 projects when we've streamed SRT to online destinations that require a 50fps source. But when we're streaming SRT to a broadcaster, who ordinarily uses 1080i50 in their chain, it is important to sustain the look of interlaced content.
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admin  
#2 Posted : Wednesday, November 4, 2026 11:48:25 PM(UTC)
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SRT in vMix supports only progressive, this includes both inputs and outputs.

https://www.vmix.com/help29/SRT.html

There are a number of reasons for this, but the main one being NVIDIA officially dropped support for interlaced encoding and SRT support in vMix was designed from the ground up to be fully GPU accelerated.
But to answer your question, if you have the master frame rate set to 50i, then the SRT output will just take that and assume it is 50PsF since it can't encode or preserve the interlacing.

In this instance, the best workflow is to set the master to 50p instead, and only specify 50i on External Output or recordings where needed.

This will result in SRT outputting a full quality progressive 50p signal. Even if you eventually connect that to an SRT decoder, often they will support converting that to a 50i SRT output
or if not, a cheap Decimator converter or similar will do the trick.

Hope this helps.

Regards,

Martin
vMix
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