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#1 Posted : Tuesday, July 21, 2020 12:17:22 AM(UTC)

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I understand interlaced over SRT is not supported.

Most broadcasters still are bounded to interlaced for multiple reasons and this will be a strong feature need to integrate with different workflows.

At the moment we are testing sending interlaced sgnals from a Makito encoder into vMix (1080@50i) and they show up in vmix as 540@50p which makes sense but it´s unuseable.

Is there any paln to support for incoming (and outgoing) interlaced SRT?
As said it is critical to integrate with existing workflows in the broadcast world.

Is there any workaround that would allow to convert in vMix from this 540@50p into 1080i?
#2 Posted : Wednesday, August 5, 2020 6:34:57 PM(UTC)

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Asking this question here makes no sense! vMix is not in charge of the evolution of the SRT protocol, you'd better ask your question to the SRT Alliance.

However I can give you my personal opinion : it is very unlikely to see interlaced signals supported by SRT one day. Interlacing is a thing of the past, even if broadcasters still use it.
This being said, you can still stream progressive SRT to a TV station, they just need to process it before use so that it conforms to their requirement. This can be done in realtime with a basic ffmpeg script or whatever signal processor they want to use.

For this, I'd push a 1080p50 feed to them (shot with a correct shutter speed) so that they can get a 1080i50 conversion simply by making each frame interlaced. Or you can check this:
#3 Posted : Thursday, August 6, 2020 1:43:32 AM(UTC)

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Asking this question here makes absolute sense, so let me explain further.

"it is very unlikely to see interlaced signals supported by SRT one day"
SRT does indeed support interlaced signals or, to put it more accurately, SRT doesn´t care at all about your signal flavor as it is a data transfer protocol and thus why it is agnostic to anything you send inside of it.

The problem with vMix supporting interlaced OVER SRT (note the difference) has to do with vMix handling already interlaced signals that use SRT as a means of transmission.

As I learned, this is a problem at the decoder level on vMix that is not easy to solve.

While this is a problem with the codec that vMix uses, it does present a problem unique to vMix since other receiving ends like hardware SRT receivers or even VLC player do handle interlaced video OVER SRT.

"it is very unlikely to see interlaced signals supported by SRT one day"
I can partially agree with your statement, given the fact that unless you still use a CRT display, your signal indeed will be deinterlaced at some point (probably at the TV in a way that is not controlled) so whenever possible you should go for something like 50P.

There is a ton of hardware at the source, middle and destination that cannot support 50P.
This is particularly true for most broadcasters not just because they are OLD but because the underlying infrastructure rely on other signal processing stages that cannot support 50P or even 25P sometimes (and even if they do 25P does present other issues on moving images).

It is fairly simple to integrate this interlaced workflow on a vMix workflow based on SDI as conversions to 50P and/or back to 50i can be done by the capture cards.
This solves downconverting to 50i at the delivery but I still have not found a fully working reliable workflow from hardware encoders sending 50P over SRT to vMix either (working on further testing on that).

While vMix might eventually work reliably for anyone using 50P signals over SRT, that is not always possible when your source is indeed 50i (like most existing broadcast cameras and several other hardware), or it involves undesired steps and gear to upconvert the signals.

For a broadcaster, changing all the infrastructure to 50P requires a huge investment that is not a simple change, and one I can promise, no one is going to do to be able to use vMix in the mix.

On the contrary, if there were a simple way to add interlaced support (even by converting it to 50P on arrival) on Vmix end, it will hugely improve the ability to integrate vMix with existing hardware, which is specially useful for (but not limited to) broadcasters

Unfortunately, this I am told this is not possible so I am still trying to find a workaround it since at the moment even while trying to use 50P over SRT, I have not yet been able to integrate vMix into an existing infrastructure that is heavily based on interlaced workflows.

Arguably, this might not be a problem with vMix itself, but so far it is indeed limiting it´s possible use on this kind of scenarios so I still think it would be very useful to add some level of support for it on vMix itself.

Progressive segmented frame is a way to use PROGRESSIVE SIGNALS ON INTERLACED SYSTEMS, which is completely the other way around of this specific problem.

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