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Author Topic: Cat5/6 or Coax for extended video?  (Read 8344 times)

Scott Raymond

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Re: Digital Qam Tuners
« Reply #10 on: January 29, 2011, 10:12:46 pm »

Scott,

I recently implemented a digital CATV distribution setup for a new campus.  I was originally looking at the ZeeVee product, but was steered away from that product by some smart folks.  I came across (and was recommended to) Contemporary Research's QMOD-HD boxes--I have 3 (2X HD, 1X HDSDI).  They work great...and look good--I highly recommend them. 

Kevin

Thanks Kevin,

I noticed some reviews of the 250 running very hot and having some display issues.  Supposedly they admitted it and brought out the 280 that corrected those but running hot is never good for gear.

I see CR products are used in Willow Creek Church in a huge system.  That's a good indication as well.

Scott
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Kevin Hoober

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Re: Cat5/6 or Coax for extended video?
« Reply #11 on: January 31, 2011, 06:04:36 pm »

I actually emailed the guy @ Willow (from the endorsement) as part of my product research.  They actually have both a QMOD-SDI and a ZeeVee (not sure which model number).  Having both, he recommended the QMOD.

Kevin H.
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Brad Weber

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Re: Cat5/6 or Coax for extended video?
« Reply #12 on: February 01, 2011, 08:38:46 am »

I've been using similar Contemporary Research products for many years and have always been quite pleased with the products and support.
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Scott Raymond

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Re: Cat5/6 or Coax for extended video?
« Reply #13 on: February 01, 2011, 03:59:31 pm »

I've been using similar Contemporary Research products for many years and have always been quite pleased with the products and support.

Thanks Brad,

Thanks to everyone's help I feel better equipped to suggest options we may have for now and down the road.

Scott
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Jonathan Johnson

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Re: Cat5/6 or Coax for extended video?
« Reply #14 on: February 28, 2011, 08:18:12 pm »

Just FWIW we are in construction on stage one of a proposed 3 stage expansion.  This stage is an addition of space for a new nursery and conference room, moving and revamping the youth ministry as well as opening up the current entryway and upgrading the whole building with sprinklers.  So new video will be needed in the nursery and conference room in the addition, as well as possibly having video in the enlarged entry.  The other areas are an existing room that's had video and a gym/multipurpose room that might get a feed for overflow or miscellaneous use.  Those involve distances up to around 250 ft. whereas the others are all under 50 ft.  So we aren't talking huge distances at this stage but the second and third phases will involve a separate youth wing and then a new worship center and longer distances involved.  At this point it may boil down to cost and whether they feel the need for any type of digital signage for announcements or messaging etc.  I've seen text over composite from an older computer I have and it definitely "ain't pretty".

Looking at the Magenta hardware I came up with a rough estimate of 1300/1500 dollars for 4 or 5 locations and then whatever Cat5/6 costs would end up at.  With the longer runs it sounds like it might be good to use low skew cable even though it might not be absolutely required at that distance.  Running discrete coax could easily get up in the same area with splitters or matrices involved with that.  The other idea brought up with HD rf was one that hadn't occurred to  me even though we're currently using old analog RF.  Doing a search I ran across an intriguing fairly new product from a company by the name of ZeeVee.  Some of you may have looked into them, they have modulators from around 900$ to maybe around 1800$.  If they are a reliable, quality product they would allow a fairly large distributable system built on standard single rf coax using pretty much off the shelf splitters etc.  They use QAM channels so any off the shelf consumer flatpanel (cable capable obviously) could be used at the receiving end.  Adding another unit and a simple combiner some where down the road would be easy and allow sending different program material to any location.  Seems like a viable option for a ways down the road but I'll welcome any thoughts anyone has on something like this.  Here's the link for anyone that hasn't run across them yet.

http://www.zeevee.com

This has me wondering about something that I haven't taken the time to research (yet): with digital broadcast, what is the latency?

That is, let's say I'm attempting to run live video to an overflow area using HD, and doing it using modulators, splitters, and what have you. What is the best way of delivering the audio: via the digital signal, or a direct feed from the sound board?

Since the audio from the sound board is essentially a pure analog signal and any latency is introduced solely by the speed of light and length of the cable (read: immeasurably low), and digital tends to have measurable delay due to buffering, will the video be noticeably asynchronous with the audio?

OR, should the audio in the overflow room come from the video feed, ensuring synchronicity at the possible expense of degraded audio? (Is the audio quality even a concern?)

Just some thoughts. Yours?
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Brad Weber

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Re: Cat5/6 or Coax for extended video?
« Reply #15 on: March 01, 2011, 11:16:40 am »

This has me wondering about something that I haven't taken the time to research (yet): with digital broadcast, what is the latency?

That is, let's say I'm attempting to run live video to an overflow area using HD, and doing it using modulators, splitters, and what have you. What is the best way of delivering the audio: via the digital signal, or a direct feed from the sound board?

Since the audio from the sound board is essentially a pure analog signal and any latency is introduced solely by the speed of light and length of the cable (read: immeasurably low), and digital tends to have measurable delay due to buffering, will the video be noticeably asynchronous with the audio?

OR, should the audio in the overflow room come from the video feed, ensuring synchronicity at the possible expense of degraded audio? (Is the audio quality even a concern?)

Just some thoughts. Yours?
Any added latency in the transmission aspect might also depend on the signal formats involved, for example if there is a D/A conversion out of the video system and then an A/D conversion into the transmission system versus a straight digital path.  However, chances are pretty good that any live video or video through a production system may already have some noticeable latency, so that could be an issue even without consdering any transmission latency.

I can see that it could be desirable to add some delay to the remote audio signal either prior to transmission or at the receiving end.  I often include such signals in the system processing so that delay, limiting, etc. can be applied.  Having a digital board in the overflow room with delay on each input would also be a nice solution!  ;D

A bit off topic, but the same issues can apply to other sends such as ALS and interpretation.  It is often desirrable to add some delay to those signals to both better sync with the video images and to reflect the natural delay that would occur for someone sitting out in the middle of the listener space.
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Brian Ehlers

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Re: Cat5/6 or Coax for extended video?
« Reply #16 on: March 01, 2011, 07:12:19 pm »

Just to expand on Brad's comments a bit:

The human brain is quite tolerant of audio lagging video, because that's what we're used to seeing in real life.  But the brain is extremely intolerant of the video lagging the audio even a little, because it's so unnatural.

Even if you use the audio which is transported with the video, there's no guarantee that it will be synchronized.  Every piece of equipment is different.  And since audio codecs and processors typically use smaller, shorter frame sizes than video codecs and processors, there's a good chance the final video will be later than the final audio -- exactly what you don't want.  For this reason I'd always design a system so that I can add more delay to the audio somewhere.

Since overflow seating is often within earshot of the main room, I like to delay the audio to the overflow seating even if there is no video.  That way the bleed from the main room is perceived as a little extra ambience, not a late echo.
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Kevin Hoober

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Re: Cat5/6 or Coax for extended video?
« Reply #17 on: March 03, 2011, 05:20:30 pm »

This has me wondering about something that I haven't taken the time to research (yet): with digital broadcast, what is the latency?

That is, let's say I'm attempting to run live video to an overflow area using HD, and doing it using modulators, splitters, and what have you. What is the best way of delivering the audio: via the digital signal, or a direct feed from the sound board?

Since the audio from the sound board is essentially a pure analog signal and any latency is introduced solely by the speed of light and length of the cable (read: immeasurably low), and digital tends to have measurable delay due to buffering, will the video be noticeably asynchronous with the audio?

OR, should the audio in the overflow room come from the video feed, ensuring synchronicity at the possible expense of degraded audio? (Is the audio quality even a concern?)

Just some thoughts. Yours?

For simplicity's sake, I'd use the audio from the modulator (it is quite good as long as you watch your levels).  There is a bit of latency in the digital modulators (I only have experience w/ CR's digital modulators)--150-200mS, maybe--but they do a good job of keeping audio and video synced together.  (that's not to say your tuner will do the same--as Brian alluded to; adjustable audio delay is a good thing)

If you ran audio separately, you'd definitely need to delay the audio back to the video.

Kevin H.
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Jonathan Johnson

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Re: Cat5/6 or Coax for extended video?
« Reply #18 on: March 04, 2011, 12:30:13 am »

For simplicity's sake, I'd use the audio from the modulator (it is quite good as long as you watch your levels).  There is a bit of latency in the digital modulators (I only have experience w/ CR's digital modulators)--150-200mS, maybe--but they do a good job of keeping audio and video synced together.  (that's not to say your tuner will do the same--as Brian alluded to; adjustable audio delay is a good thing)

If you ran audio separately, you'd definitely need to delay the audio back to the video.

Kevin H.

It seems to me that it would be wise to have the delay box at the location of the remote video monitor so you could visually sync it.
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