Video System Help

[Matt Riley]

Hi all, I'm afraid this is a bit of a big query really - I'm trying to sort out a video system for my church. We've got a sanyo HF15000 main projector and Sony EX3 cameras at the moment (plus a number of PCs etc). The spec for the project is:

• Able to display song words, keyed over moving backgrounds controlled by Chamsys
  
• Able to display powerpoints/presentations from laptops on stage
  
• Able to stream / live record a feed of services using cameras with overlaid words / graphics
  
• Able to show camera shots on stage with minimal latency (under 120ms)
  
• Easy to control with minimal training
  
• Maintains 1080p resolution into projector.
  
• Best value for money possible
  

 

I have drawn a little google doc drawing of what I'm currently thinking - it revolves around a PDS701 3G to do projector switching/scaling, and then running a seperate blackmagic atem TVS for the cameras and the livestream feed.

 

My big questions are:

• Do you think this would work well?
  
• Will the latency be acceptable? What do you think it will be?
  
• Are there any 'gotcha's' with the kit that I need to worry about?
  
• Am I right in thinking that are there no camcorders that have a 3G sdi output so I can just run the whole system at 1080p and have an easy life?
  
• Has anyone tried libre media server?
  

 

Link to google doc for system diagram.

[Nick Mawer]

Matt, I would suggest the new Kramer VP-770 which has a luma keying function. We are using a different chipset in this scaler from the set in the VP-728/730 etc, and the latency is much reduced and the switch speed is much faster. The one thing that we can't do with this unit from your wish list above is provide a streaming or recording function. The spec of the VP-770 can be found here http://www.kramerelectronics.co.uk/products/model.asp?pid=2628#1

[PatrickSmith]

Hi Matt,

 

Roland do a whole load of options that could be good for you. Why don't you pop up to Reading some time and we can play with some toys? (it's been too long since we had a catch up anyway ;))

 

Have you seen the new VR-50HD? Really powerful product, particularly if you are thinking of streaming.

 

http://www.rolandsystemsgroup.co.uk/articles/110400

[Pete McCrea]

I've been meaning to respond to this for a day or two but have been busy with various stuff.

 

As a system it looks like a pretty good one. The Barco PDS series is solid, and good value for money. You're getting some well designed kit, with a road map for future developments. They're recently added the PIP functionality, and also matrix mode, as well as remote control via built in web interface.

 

The BMD kits is ok, but has it's limitations. There is no scaling in the ATEM, so you need to get all sources in at the same res, but I think you've got that covered.

 

I'd suggest you take up Patrick's offer to go up to Reading and have a look at the other options from Roland. SFL would be a good base to asses the kit as they also have the PDS units in rental stock, and are Barco and Roland account holders, so can put together a good package for you. They also understand the complexities of the Church market.

[Peter F]

Nick,

Can you give us some examples of what the latency is on this new Kramer unit?

I have looked at the pdf spec but can't see this info, perhaps I've missed it browsing on my mobile.

 

Cheers,

Peter

[AHYoung]

I think you are potentially making a very intrinsic mistake in your design as you are mixing the cameras then scaling them through a scaler to the display, This is a bad idea as you are much better taking your cameras through a production switcher to the projector and scaling all the graphics sources to a suitable resolution fo that. Trying to do it the other way round will just mean its unusably latent. The hf15k is pretty slow , and I speak from some experience as Ive got a couple, but the situation can be improved by a couple of frames by switching the video delay mode, but you loose keystoning, so hopefully its in the right place... personally id look at a camera mixer that you use to feed the projector over dvi / hdmi. and Id not get overly caught up as to whether its 1080p or 1080i, as this would rule out the BMD stuff. If you have budget , Im looking at a production unit for our hirestock and my list is remarkably similar. The simple answer is that the thing needed doesn't seem to exist, but currently a Panasonic 410 mixer is favourite as its got all the connectivity and built in multiviewer, and combined with a few hdmi - sdi convertors, should fit the bill.

[Matt Riley]

Hi guys,

 

Thanks for the useful advice so far. Don't forget that there's a link to the in depth system diagram on the post.

 

In terms of what I'm trying to achieve, the IMAG requirement is relatively minimal. We have a studio space, which I want to utilise (very eventually) to do a discreet live streaming mix, and then the main screen (driven by the Sanyo) will normally just display song words keyed over a media server driven by chamsys, with the ability to do a FTB switch to different sources as occasionally needed.

 

AHYoung - thanks so much for chiming in. So you're saying that making the projector scale a 1080i (psf) signal out of a Ross Video Crossover or Panny Vision Mixer would be the way to do it, sending the media server inputs in as 1080 I (psf). My logic was that hopefully using the Barco's built in scaler as opposed to the lower quality one in the projector may reduce latency. In terms of the positioning, we are lucky that the projector is really well positioned so does not need to be keystoned.

 

Pat - will send you an email :)

 

Nick - that product looks very interesting. If the latency query could be sorted out then I will certainly consider it, although it is a bit light on the inputs. I would have loved to have a VP728 with keyer and 3g sdi input.

 

Out of interest, there aren't any reasonably priced little HDMI/DVI chroma keyer boxes which I could use in the interim are there?

[AHYoung]

My view is process the cameras as little as possible to minimise latency, as ive seen many a "professional " design where the cameras get mixed then sent through a scaler then scaled again by the projector. the latency is total comedy stuff. You will be running through the projectors hardware no matter what, but on a hf15k, you can turn most of the processing off, you wont improve anything by sticking a barco in the signal path, it will just degrade the signal a bit less than a cheap unit. You don't actually need to scale to make 1080i 1080p, its that you get the odd field then the even, so its the same amount of lines, but less often. If you want a cheap interim hd mixer that does keying, get a tvone 750 dual scaler and if you want live control get a spark defuser controller. Its a great little unit and does all the keying you could want, its just that its horrendous to use via the osd, so download the corio tools software.

[Matt Riley]

That's cool - I was wondering whether something with a form factor akin to a decimator MD-DUCC / BMD mini converter which could just do a simple key from 2 sources of the same resolution and spit out a keyed image with no scaling requirements.

[AHYoung]

The tv one 750 will take any analogue or digital video signals up to 2k on 2 inputs and scale them to anything up to 2k with all the options you will ever need. If it wasn't so horrific to use you see them everywhere as its powerful , the results are good quality and its about 500 quid. The spark mixer is a little hardware controller that makes it a lot more usable as a 2 ch mixer with keying controls amongst other things, have a look - http://sparklive.net/dfuser/ .

[Tim gregory]

Hi Matt,

 

We have almost identical requirements to what you are trying to do and in the end I went with the Atem 1ME

I looked at various seamless switchers but they all added too much latency for live cameras.

 

Our kit list is as follows:

 

Inputs

Computer running Resolume for video backgrounds and slides (HDMI)

Laptop feed from stage for song words, running custom software (HDMI via Cat5)

Hyperdeck Studio for video playback (HDMI)

4 x JVC HM600's (SDI)

 

Processing

Atem 1ME Mixer

 

Outputs

2 x Christie LX605

Various Plasmas

Hyperdeck Studio for recording

Small musician screens from Aux out showing just song words

 

One of the requirements that we had was that we needed to record a clean feed without the song words as this has copyright issues.

 

The Atem is a great bit of kit as long as you are aware that it does no scaling. The fact it does no scaling helps reduce latency.

 

Given that your camera's are all genlock, if you run in in sync then the Atem latency would be a couple of lines rather than frames.

When I worked out the latency on our (non genlocked) system it was roughly as follows:

 

Camera - up to 1 frame

Atem - 1 frame

Projector - 3 frames

Total 5 frames (200ms)

 

I reduced this by turning the projector to video delay mode which saved almost 2 frames (80ms).

 

I have also found that running everything in 720p reduces latency. This is because any frame buffers are running at 25 FPS on an interlaced signal but 50 FPS for progressive. So everything is held in frame buffers for half the amount of time.

 

I think we are well within 120ms now overall but have no easy way of easily measuring this and have not bothered as I am happy with the result

 

720p is fine for us as our native projector res is 1024x768. That may not suit your setup may be worth trying.

 

Tim

[Nick Mawer]

Hi guys,

 

 

Nick - that product looks very interesting. If the latency query could be sorted out then I will certainly consider it, although it is a bit light on the inputs. I would have loved to have a VP728 with keyer and 3g sdi input.

 

Out of interest, there aren't any reasonably priced little HDMI/DVI chroma keyer boxes which I could use in the interim are there?

 

From CV or YC to 1080p I believe it is 48ms for the VP-770/771 but I am double checking with the factory. The VP-728 was around 97ms

[Matt Riley]

Hi Tim

 

TBH - I don't envisage IMAG to be a significant part of the proceedings. The sightlines are good in the building and I have a passionate dislike of IMAG, it just needs to be acceptable when it does happen. Everyone's thoughts about this seem to be heading in one direction... which is very interesting actually as I happen to have a Broadcast Pix slate 1000 with control panel sitting in its box which I was frankly quite keen to sell up until this discussion.

 

In terms of a revised plan, now I know about the TVone box, I can set this up as a standalone keyer with a media server and words pc. I can then send a keyed feed through the Bpix to the Aux out (with a nice neat rackmount controller at FOH to switch to the main bus or to an alternative input at will), then run the main bus as the recording feed.

 

M

 

AHYoung - you don't happen to know the latency on the HF15000 do you? We've got the RGBHV(?) and the DVI inputs on ours if that makes a difference.

[AHYoung]

If I was running a video in an average size venue where the middle position was 15m from the speakers / screen, id add about 100ms to the audio delay to get it looking right. at a guess that means that its a total delay of 150ms? if you go to video delay, you can speed it up but you lose the keystone and Nr and a few other things, but id expect that in that mode its about 3 frames in to out at 50p.