HD using HDMI vs SDI vs NDI vs ?

Using the Church Webcasting System, YouTube, etc. Including cameras and mixers.
rknelson
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HD using HDMI vs SDI vs NDI vs ?

#1

Post by rknelson »

For webcasting stake conference we currently use 3 PTZ cameras, but they are SD. We acquired our current setup with a mixer/preview monitors, text overlay, projectors, cabling and so on over a period of several years. About once a year I spend some time considering a switch to HD and weighing the cost vs. benefit. It seems like SDI is being replaced by NDI which allows a PTZ camera to run with a single gigabit Ethernet POE cable for power, control, and video delivery. NDI PTZ cameras are available from several vendors and run about $1500 for 10x zoom or $2300 for 20x zoom. Mixing can be done with inexpensive software (vMix at $60 for the version that appears to have every feature we would use) on a (pretty hefty, $$) computer but with no special interfaces since the video comes in from camera on gigabit Ethernet, and goes out on gigabit Ethernet. An NDI to HDMI output device (~$400) sits on the gigabit Ethernet network and gets you to HDMI, which still needs to be routed to a few places in the building plus the Vidiu. Obviously a gigabit Ethernet POE switch would be needed for these devices. (Our FM group is in the loop, but we install cabling and buy the equipment.)

I know these costs are high, but NDI seems to be the way industry is going. I’m not ready to make the jump yet, but keep considering it. Has anyone considered or used NDI (and NDI|HX)? What are the pros/cons compared to SDI or HDMI camera outputs?
rsix
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Re: HD using HDMI vs SDI vs NDI vs ?

#2

Post by rsix »

Yes, I use a NewTek TriCaster Mini for our stake conferences. (Disclaimer) I worked for NewTek for 7+ years, so I’m a fan of NDI and Tricasters. You’re right, on a tighter budget, I would use the Vmix. I like the PTZoptics NDI cameras better than I do the NewTek branded PTZ cameras. I think the image quality is better. Plus, NewTek is just OEM their cameras fromnsomine else, whereas PTZoptics makes their own cameras. Audi delay is our issue. The head STS for our stake has routed the audio through a different path than the video that comes to the switcher. Thus, there’s a sub second delay in video. I cannot fix it (even though the TriCaster Mini has the ability to do so) because I am only switching the video. Since we only use the switcher twice a year, it’s really not worth the reconfigurations of audio cables.

Overall, I agree, IP video (including the NDI standard) is the way that all audio/video will be produced. I just wish that all building constructions and reconstructions would lay Cat6 cables instead of the old, SD composite cables.
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Mikerowaved
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Re: HD using HDMI vs SDI vs NDI vs ?

#3

Post by Mikerowaved »

rsix wrote:I just wish that all building constructions and reconstructions would lay Cat6 cables instead of the old, SD composite cables.
I use the existing coax to run SDI signals back to the satellite cabinet, works great.
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beegman
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Re: HD using HDMI vs SDI vs NDI vs ?

#4

Post by beegman »

rsix wrote:Thus, there’s a sub second delay in video. I cannot fix it (even though the TriCaster Mini has the ability to do so) because I am only switching the video. Since we only use the switcher twice a year, it’s really not worth the reconfigurations of audio cables.
.
You can use a Behringer FBQ100 to fix your audio sync issue. It was made for automatically catching feedback, but has a delay feature that would get your audio synced back up. It is adjustable from 1 ms to at least 300 ms. I don't know the higher range exactly because I haven't set mine to anything higher. There are $99, but occasionally you can find a demo or used one for a bit less.
beegman
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Re: HD using HDMI vs SDI vs NDI vs ?

#5

Post by beegman »

rknelson wrote:Obviously a gigabit Ethernet POE switch would be needed for these devices. (Our FM group is in the loop, but we install cabling and buy the equipment.)
Have you gotten any grief from your FM guys about a gigabit switch? We bought HDMI over IP extenders for our buildings on the receiving end to distribute the stream through the building, and the boxes need gigabit to work best. We asked FM about replacing the 100m switch and they said it was the church specified one and had to be left in place.
rknelson
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Re: HD using HDMI vs SDI vs NDI vs ?

#6

Post by rknelson »

The latest instructions from FM about installing Meraki MR33's said that switches should be upgraded to gigabit POE switches which can be purchased locally (that is where they specified gigabit and POE) or through the estore that FM uses. This was in an email sent on March 15, 2019 in the FAQ link, but the link is no longer available.
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Mikerowaved
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Re: HD using HDMI vs SDI vs NDI vs ?

#7

Post by Mikerowaved »

beegman wrote:Have you gotten any grief from your FM guys about a gigabit switch? We bought HDMI over IP extenders for our buildings on the receiving end to distribute the stream through the building, and the boxes need gigabit to work best. We asked FM about replacing the 100m switch and they said it was the church specified one and had to be left in place.
I just spoke with CHQ last Friday and the brother there said for those that need more throughput, GigE switches were allowed to be swapped in, as long as they were "dumb" switches. I've seen used 24-port GigE switches for under $30 which he said should work fine.

Most HDMI over IP extenders use a form of multicasting, which will blast the video stream everywhere through dumb switches. That bogs the LAN down and is especially burdensome on the access points. Your IP extenders will most likely need a switch that can do IGMP snooping to tightly control which ports receive the stream. This usually puts it into the category of smart or managed, which the church doesn't want on their network.
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randysteck
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Re: HD using HDMI vs SDI vs NDI vs ?

#8

Post by randysteck »

We've actually found a way to use the coax wired into our older building to transmit HDMI reliably. We found some "HDMI over coax" interface boxes that allow HD to all locations in the building by simply transmitting from one location and adding a receiver for all other locations. This ended up working better than dedicated runs of CAT6 with HDMI adapters and solved our "inside the building" problems where we were limited to lower resolution through the SD modulators for RS and Primary rooms. Now everything is at HD quality without interfering with the existing network.

I can look up the reference to the units if you're interested.
randysteck
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Re: HD using HDMI vs SDI vs NDI vs ?

#9

Post by randysteck »

rsix wrote: Overall, I agree, IP video (including the NDI standard) is the way that all audio/video will be produced. I just wish that all building constructions and reconstructions would lay Cat6 cables instead of the old, SD composite cables.
I would strongly agree. We've been using vMix for 5 years now. One of the things it allows is to delay the video stream for sync with the audio stream which comes through a different delay path. I just made a "flash-beep" box to put on the podium to allow audio/video sync since a single clapboard strike was not very useful....:)

IP cameras have made amazing strides in the last 5 years and it's hard to beat the cost, reliability, low light capability and general image quality for the stake conference use case.
matthewk
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Re: HD using HDMI vs SDI vs NDI vs ?

#10

Post by matthewk »

randysteck wrote:We've actually found a way to use the coax wired into our older building to transmit HDMI reliably. We found some "HDMI over coax" interface boxes
I can look up the reference to the units if you're interested.
How much delay are these introducing? Enough to cause A/V sync issues if we use the in-ceiling speakers?
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