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markleman  
#1 Posted : Friday, March 3, 2017 7:04:34 PM(UTC)
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Hi folks,
I am streaming an event at the London Aquatic Centre (the 2012 Olympic swimming pool), all my cameras are 16:9 720p50 and my output stream matches this and there is a gigabit internet feed - all good so far :-)

At the pool there are two large video walls which are used as score boards, during intervals between swimming and medal presentations I take over these and show live video of the presentations or twitter feed from the teams,

Unfortunately the video walls are 4:3 - I think the resolution is 800x600 from trial and error last time

I would like the second output from vmix to be a 4:3 cropped version of the main 16:9 (loosing the left and right vertical columns), can anyone think of a way to achieve this?

At the moment I have display 1 set to 1280x720 and display 2 set to 800x600, vmix squeezes/distorts the image on display 2 but I want it to crop leaving the centre.

There is a video scaler in the equipment rack that drives the video wall, which I am sure is capable of achieving this if I simply fed the 1280x720 video to it, however I don't like adjusting the settings on kit which is not mine, in case I can't get it back to the correct settings when I pack up!

Regards,
Mark Leman
kol0  
#2 Posted : Friday, March 3, 2017 7:20:30 PM(UTC)
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NDI is an answer.


Get the laptop with Vmix. And feed that laptop NDI from main production machine.
Set laptop Vmix to 800x600 quality and fullscreen output to VGA or something what that system get.

Or use second instance of Vmix with SD quality, but... its not officially supported.
DWAM  
#3 Posted : Friday, March 3, 2017 7:28:39 PM(UTC)
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Hi Mark

you might be able to do it with external renderer outputting to a BMD card (for example) set to convert to SD PAL(720x576). You should then have 2 options: pan&scan or letterboxing
thanks 1 user thanked DWAM for this useful post.
markleman on 3/3/2017(UTC)
markleman  
#4 Posted : Friday, March 3, 2017 7:42:14 PM(UTC)
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DWAM wrote:
Hi Mark

you might be able to do it with external renderer outputting to a BMD card (for example) set to convert to SD PAL(720x576). You should then have 2 options: pan&scan or letterboxing


That is a good idea, particularly as I use a BMD Decklink Duo 2 card with my three cameras, so have a spare output at the moment.

Last time I feed the output of my graphics card into the 8x8 DVI video cross point switch that is part of the sites equipment rack. I have an SDI to HDMI converter and an HDMI to DVI cable which could be used to achieve the same effect from the BMD SDI output.

Regards,
Mark Leman

markleman  
#5 Posted : Saturday, January 19, 2019 6:31:41 AM(UTC)
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Reviving my old question/topic but with an answer, so hopefully someone else will benefit from the solution.

Summary..
I use vmix to stream swimming galas and as all my camera are 16:9 720p or 1080p I use those formats.
I am wanted to also output to a local video wall which is 4:3 800x600.
So how to get a cropped version of the vmix output for the video wall without affecting the main output?

I had not solved this and had put up with the distorted image the video walls built in scaler gave.

This year I had a thought..... how about using the 'external output' feature of vmix?

I first tried ffmpeg/ffplay...

ffplay -f dshow -i video="vMix Video" -an -x 800 -y 600 -vf "crop=960:720:160:0, scale=800:600" -noborder

which is perfect but does not allow me to move the 'no border' window to the correct monitor, I have raised this on the ffmpeg users mailing list to see if it could be fixed.

One suggestion that came back was to try mpv, so I did....

mpv av://dshow:video="vMix Video" --osc=no --screen=1 --no-border --geometry=800x600 --panscan=1 --profile=low-latency

and it works on my monitor at home and tomorrow I will try it at the venue.

I also tried VLC and it did work but it had a lot of latency (probably fixable but I did not dig too deep).

Hope that helps someone other than me :-)

Regards,
Mark Leman
mjgraves  
#6 Posted : Saturday, January 19, 2019 9:20:14 AM(UTC)
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I'd be inclined to bring the HD 16:9 feed into a second instance of vMix. Could be SD. Probably easiest via NDI to another host.

On that system you can crop and reposition as necessary to fit your video wall. Even add panels top & bottom if you want to show the whole stream.

Feed the video wall via fullscreen output.
ask  
#7 Posted : Saturday, January 19, 2019 11:24:58 AM(UTC)
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Yu will probably find that you have to use the video wall scaler anyway. My bet is, if it is like the units I have had to interface with, that it will do the cross conversion for you, usually by letterboxing the output. What you want to do is rather than trying to get vMix to solve the issue, work with the suppliers of the video wall. They usually understand/have the answer...
markleman  
#8 Posted : Thursday, January 31, 2019 10:09:47 PM(UTC)
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Originally Posted by: ask Go to Quoted Post
Yu will probably find that you have to use the video wall scaler anyway. My bet is, if it is like the units I have had to interface with, that it will do the cross conversion for you, usually by letterboxing the output. What you want to do is rather than trying to get vMix to solve the issue, work with the suppliers of the video wall. They usually understand/have the answer...


If I was hiring a video wall for a my own event I would fully expect the scaler to be able to do all this.

However in the equipment rack at the pool there are 4 scalers, an 8x8 video switcher and 3 PCs which should do anything I need, unfortunately there is no system architecture diagram or any documentation at all! We arrive, do a weekend gala and leave. Because of this I try to change the minimum to reduce the risk breaking anything. I found early on that injecting my video into an unused port on the video switcher and selecting that input got something on the screens, so my aim is to pre-distort my video feed to give an un-distorted display, not ideal but given the situation the best (least risk) option at the moment.

This year while the gala was on, I spent some time tracing the video flow and have a better idea how it works. I have the option to go back another weekend when there is not a gala on and spend some more time exploring the system, so by next years gala I might be able to use the systems scalers to solve the problem.

In the mean time it is useful to know how to take the vmix live output and crop/scale it to arbitrary sizes :-)

Regards,
Mark Leman
NHT  
#9 Posted : Friday, February 1, 2019 2:45:04 AM(UTC)
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Another option for this using the normal Full Screen option is to add your output back to your project using NDI.

Then go into the NDI input and change the aspect ratio to anamorphic.

Then assign the NDI input as the Full Screen output.
ProSonas  
#10 Posted : Friday, February 1, 2019 5:50:00 PM(UTC)
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We just finished up the IHF Handball World Cup and had the exact same problem: all production was (of course) in 16:9 but the large screens (the "cube") in the 6 stadions across Denmark and Germany, was somewhat 4:3'ish.

Not 100% 4:3 but somewhere in that region.

Fortunately, we didn't have to output in both aspect ratios, so we ended up making one 4:3 screen with the 16:9 in the upper region of the 4:3 screen and the bottom part of the 4:3 area was then used for graphics / scoreboard.

For some reason, uploading pictures here didn't go well for me, so if you'd like to see pictures and a few videos, have a look at:

https://www.prosonas.dk/portfolio-items/kundecase-vm-i-haandhold-storskaermsproduktion-og-bandereklamer/
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