"muting" HDMI signals

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TimStannard
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"muting" HDMI signals

Post by TimStannard »

Hi. First post from me. I'm Comp Secretary at Staines CVS.

I've searched and asked this among other clubs and on other forums and as yet no-one seems to have a solution. I post here in "just in case".

I'm talking here about our projection setup. In the days of MiniDV, we took two signal outs - one went to the monitor by the operators and one via a colour processing unit to our projector. After a film finished we could fade down the signal (via the colour processor) going to the projector and cue up the next film using the monitor, before fading up the signal to the projector again. All fine and dandy and helps give a professional presentation.

Enter high definition and HDMI. As HDMI requires a signal of some sort all the time, a straightforward fader is not feasible, we'd need something which will not so much fade the signal but "mix" the image we want to fade with an image of "black". Such equipment is available, but it seems it would cost many £1000s - overkill for the task required.

So, the next option is simply to "kill" the signal to the projector between films. We attempted this using a variety of two way HDMI switches (switching between the "live" signal and no signal). This "sort of " works, but the problem is that it takes several seconds (unacceptably long) for the signal to become "live" again. We need to be ready to go as soon as the presenter announces the film.

The other option is to use the "blank" or "no show" option on the projector. Although, like the solution above, it would mean no fade, this can be made to work (and is, indeed how we currently present).

However there are two problems. It relies on infra red remote control (from the back of the room to where the projector is situated towards the front) which requires line of sight and there is no indication on the back of the projector (Epson TW3500) that the signal has been received. As there is something like a 1.5-2 sec gap between the IR signal being received and the projector switching on (not ideal but acceptable) the projectionist often switches "off" again thinking the original command has not been received.

Sorry for the long post.

How are other clubs coping with this?
Tim
Proud to be an amateur film maker - I do it for the love of it
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Dave Watterson
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Re: "muting" HDMI signals

Post by Dave Watterson »

One sophisticated club - that might prefer to remain anonymous - sits its projector on a baseboard with a groove in front of the lens. Between films they slide a solid black DVD case along the groove to block the light!

If that notion seems worth following, try this. In the early days of "slide-tape" shows with two or more slide projectors people often rigged up mechanical irises in front of the lens ... ranging from giant versions of the irises in camera lenses to an almost equally effective cut-out of a "hand" with "fingers". (You can try this with your own hand ... as the fingers cross the lens the output dims and as the palm of the hand arrives it goes black.)

Since your projector is some distance from the operators such mechanical devices might need to be triggered by long pieces of string (!) or simple low-voltage motors and cables.

-Dave
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TimStannard
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Re: "muting" HDMI signals

Post by TimStannard »

Dave Watterson wrote: Since your projector is some distance from the operators such mechanical devices might need to be triggered by long pieces of string (!) or simple low-voltage motors and cables.
Indeed the distance is the problem. However your suggestions prompt me to consider a contraption with pulleys and levers which just might make an interesting club film project - a sort of Wallace and Grommit with humans.
Tim
Proud to be an amateur film maker - I do it for the love of it
Chrisbitz
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Re: "muting" HDMI signals

Post by Chrisbitz »

Thsi is about the cheapest one I'm aware of..

http://www.markertek.co.uk/Catalog/HD-S ... /DV-SE2000

Old analog signals were easy and cheap to manufacture, but as soon as you go digital, there's a lot of electronics to get in the way.
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Michael Slowe
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Re: "muting" HDMI signals

Post by Michael Slowe »

As one who has, in past years, been honoured by an invitation to present films at Staines, I can vouch for their professionalism with regard to presentation. I can't see them being satisfied with 'sliding a box' in front of the lens but they certainly have highlighted a problem. There must be a 'techie' out there with a brilliant idea (Tom ??).
col lamb
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Re: "muting" HDMI signals

Post by col lamb »

We supply our HD HDMI input projector via our new AV amplifier, the feed to the projector stays live and we just use the many inputs into the amp to switch sources between Bluray player, MiniDV, camcorder etc.

The AV amp is a standard home cinema type, if anyone is interested in getting one then do take care when you are researching as most do not have s-video inputs. I saw s-video on the back of a review of ours when I was researching but it was only later after we bought it that we found that it was only for an ipod docking station and would not work when our MiniDV player was connected.

The AV amp also upscales our DVD and MiniDV sourced material into HD, the results do look pretty good
Col Lamb
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TimStannard
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Re: "muting" HDMI signals

Post by TimStannard »

Thanks for the suggestions gents and the kind words from you Michael.
Whilst the 2.5K unit is a comparitively good price, I'm not sure members woyld consider this good use of our limited funds.
I'm interested in the AV amplifier solution, Col.
We put everything through a Pioneer BLU-RAY recorder which effectively performs the same task as you describe (it has S-video in for our MiniDV deck and upscales as well). However, it is not the perfect solution because (a) it takes a few seconds to switch between inputs and, more importantly, (b) as that provides our main signal to both monitor and projector, this does not give us the facility to preview.
So, maybe the solution is an AV amplifier next it the chain. Thanks for the suggestion.
Out of interest, what amp do you have?
Tim
Proud to be an amateur film maker - I do it for the love of it
col lamb
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Re: "muting" HDMI signals

Post by col lamb »

Tim

We have a Pioneer, it was the end of line and so it has been superceded (probably twice)

It cost us £290 (original list price c£450) and it had the best review in the up to £500 price range
Col Lamb
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TimStannard
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Re: "muting" HDMI signals

Post by TimStannard »

col lamb wrote: We have a Pioneer
Thanks Col. That at least gives me an idea of the sort of cost we might be looking at.
Tim
Proud to be an amateur film maker - I do it for the love of it
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