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Weird interlacing with vMix14
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thomas  
#1 Posted : Sunday, September 28, 2014 1:47:12 PM(UTC)
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I recently did a new stream-production with vMix 14. I was hoping the new interlacing-method in Vmix14 would handle interlaced throughput, but there is something weird going on.

The input was 576i50, broadcast standard. Input via decklink quad. When i output via SDI, also in 576i50, the feed had jaggy edges and the picture looks horrible with fast motion, panning and tilting (vast amount of motion blur).

The master framerate was 50i. I'm in the TV-broadcast business and have to use interlaced sources.

I changed the settings to 1080i50 and just upscaled the sources. The jaggy edges went away, but the SDI-output was still horrible and really motion-blurred when it was fast motion, panning and tilt.

I've also tried to take the feed as throughput on the decklink quad and straight to a SDI-monitor. Then the interlacing is fine. Same when i output interlaced from Premiere to a SDI-monitor. This means that vMix does something with the interlacing..

Can you please look into this, Martin? We're doing streaming AND broadcast, and i really like vMix.It's really stable, flexible and great to work with, but as of now, I can't use it for broadcast..

And deinterlacing is not an option for us..
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jkmakela  
#2 Posted : Sunday, September 28, 2014 2:58:02 PM(UTC)
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I did the first tests with vmix 14 and 1080 50i and it seems to work well. We use matrox vs4 for input and decklink mini monitor for out (sdi ). Text ticker runs smoothly, cube transition runs smoothly, live feed from camera runs smoothly, slow-motion/videodelay is fairly good (after some tuning with multicoder codec which affects also the video delay codec).

First I got poor results but the reason was BMD desk top video software where was selected "reduce flickering when video paused" or something like that. After I removed that check box - interlacing became perfect.

Stability tests not done yet.

Thank You Martin this was major update for us! Now I would call this really a broadcast software which is usable also in traditional tv-production etc....
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thomas on 9/30/2014(UTC)
jkmakela  
#3 Posted : Sunday, September 28, 2014 3:12:09 PM(UTC)
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I keep the master framerate (display ) as a 50p and interlacing in decklink mini monitor out is perfect. I do not understand (or it seems to have no effect) the relationship between display framerate and size to the sdi out because also the 720 50p works fine even the master display size is 1920x1080. Of course the decklink out card has to be in right format (in case of 1080 50i) in BMD desk top video software (1080 50i) and in external out settings in vmix (1080 50i)
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admin  
#4 Posted : Sunday, September 28, 2014 6:24:51 PM(UTC)
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Hi Thomas,

I asked for some additional information including sample files in the vMix 14 thread, did you get a chance to upload something?
Could you confirm what settings you have selected for these three areas:

Camera,
Settings (Master Frame Rate)
External Output

Also can you confirm the Render Time in vMix. A decent graphics card is needed for correct interlaced playback.

Also try resetting all settings to default and setting everything up again. For example as jkmakela mentioned turning on the "reduce tearing" option
makes things much worse for interlacing. In fact it really never should be enabled.

Regards,

Martin
vMix
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admin  
#5 Posted : Sunday, September 28, 2014 9:22:16 PM(UTC)
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I have added some additional documentation to describe how interlacing works in vMix 14.

http://www.vmix.com.au/help14/index.htm?Interlaced.html

It can be a little daunting to understand at first, as vMix supports many different input and output formats simultaneously
both progressive and interlaced with automatic conversion back and forth.

Regards,

Martin
vMix
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thomas  
#6 Posted : Tuesday, September 30, 2014 7:00:28 AM(UTC)
thomas

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Sorry about the delay, I did as you guys said, reset to default and removed the "reduce flickering when video is paused" in blackmagic settings.

Did a quick test and now it works like a charm, thanks Martin and jkmakela!

But I`m not sure why it works, but both the changes seems to have done the trick.

Even the MXF-files now playback correctly and I`m able to restart and scrub through the files. I was hoping the interlaced-issue was a user-error, cause vMix is awesome :)

Camera was: 720x576/interlaced
Master Framerate: 50i
External output: 720x576i50

The rendertime is on average about 12ms. I have a 680 TI-displaycard installed. I forgot to check if tearing was checked before i restarted to default.

This is awesome, Martin. Thank you for great software. I will benchmark further and hope it will stay interlaced :)

Can drop-frames and sudden change in rendertime cause wrong field-order with interlaced sources, Martin?


admin wrote:
Hi Thomas,

I asked for some additional information including sample files in the vMix 14 thread, did you get a chance to upload something?
Could you confirm what settings you have selected for these three areas:

Camera,
Settings (Master Frame Rate)
External Output

Also can you confirm the Render Time in vMix. A decent graphics card is needed for correct interlaced playback.

Also try resetting all settings to default and setting everything up again. For example as jkmakela mentioned turning on the "reduce tearing" option
makes things much worse for interlacing. In fact it really never should be enabled.

Regards,

Martin
vMix
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admin  
#7 Posted : Tuesday, September 30, 2014 7:12:31 AM(UTC)
admin

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Glad to see it is working now.

vMix ensures correct field order regardless of the systems performance.

This means when the top field of a video is ready to play, vMix will always wait for a matching top field
on the output before playing it.
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