Flipping video

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jwax
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Flipping video

Post by jwax » Tue May 03, 2011 7:26 am

I'm looking for a circuit to put between a NTSC video camera and the video monitor that will "flip" the video, left to right, as in mirrored. Any ideas?
No, a mirror won't work! :smile:

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dacflyer
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Re: Flipping video

Post by dacflyer » Tue May 03, 2011 11:25 am

how about switching the polarity on the yolk ?
we have done this many times with video arcade game monitors
typically yellow and green is the vertical coils of the yolk ( flip video top to bottom )
and the red and blue controls the horizontal yolk, ( regular to mirror image )

the red, blue, green, yellow are typical color codes in most monitors by the way this is for CRT monitors, i am sure there might be a way to flip LCD monitors. there might be a option in certain general purpose LCD monitors.

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Re: Flipping video

Post by Dean Huster » Tue May 03, 2011 11:41 am

Oops! Dacflyer's post was a LOT earlier than mine, but wasn't posted on the board when I made this reply. So, there's some unintended duplication here. Sorry. the original reply:

The trick is to reverse the horizontal scan. Anything you put between camera and monitor will effect everything -- e.g., an inverter will invert the entire signal making it incompatible with the monitor. The only "information" in the signal is the video which drives the "Z" axis of the monitor. Anything vertical and horizontal is nothing more than sync pulses. The "easiest" way would be to go into the monitor itself and reverse the horizontal leads on the deflection yoke, possibly even installing a DPDT switch to handle the switch from "normal" to "reversed".

OK. Now that the duplication is done and we've found out that flat screens won't work with the deflection yoke fix, how about just turning it upside down and working on it from the vertical angle? :)
Dean Huster, Electronics Curmudgeon
Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines).

R.I.P.

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jwax
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Re: Flipping video

Post by jwax » Tue May 03, 2011 12:33 pm

Oops. Forgot to mention this is an LCD monitor guys!

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Janitor Tzap
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Re: Flipping video

Post by Janitor Tzap » Tue May 03, 2011 4:42 pm

jwax,

What is it that your trying too do?

If your editing video.
There are lots of editing software available that will do this.

But if this is for live video feed.
Your going to need a Video Effects Board.
And they aren't cheap.
New, they start at $500 and up!
You may get lucky and find one that a school, or small TV station is selling off.
Then is the problem of interfacing the older NTSC camera to the Video Effects Board.
Then from the Video Effects Board, to the LCD monitor. :roll:


Signed: Janitor Tzap

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jwax
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Re: Flipping video

Post by jwax » Tue May 03, 2011 4:53 pm

I'm trying to mirror a live video feed.
There are cameras looking at an assembly line, from the front and from the back. As the line moves right to left, the front cameras show a proper right to left moving line.
(All the LCD monitors are in front of the line)
The cameras in the back however, are showing the line moving left to right- confusing.
I want to mirror the back cameras such that all the monitors show the line moving in the same direction.
Yes, I've found some (Colorado Video) boxes that will do it, but thought we could find a cheaper way. Theirs are $600.

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Re: Flipping video

Post by jimmy101 » Tue May 03, 2011 5:15 pm

You said a mirror won't work. Why not? Just point the camera at a small mirror and point the mirror at the line.

Usually the obvious solution is the best solution.

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Re: Flipping video

Post by jwax » Tue May 03, 2011 5:57 pm

jimmy- The cameras are actually looking through portholes, and lighting becomes a problem with using a mirror.

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CeaSaR
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Re: Flipping video

Post by CeaSaR » Tue May 03, 2011 8:26 pm

Then why not use a mirror at the monitor itself?
Spin it 90 degrees and put the mirror beside it.
Presto! Line moves the other way.

Cheesy, I know, but effective.

CeaSaR
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Re: Flipping video

Post by rshayes » Wed May 04, 2011 12:05 am

The hardware required ti do this is relatively cheap. The design of the hardware will be expensive if only a few units are needed.

The basic problem is that NTSC video is a serial data stream and at any given time the value of only one pixel is available. This is probably not the pixel needed for a reverse output. This will require some storage of the video signal.

These days, this implies an A/D converter, some digital memory, a D/A converter, and control logic for synchronization. The memory required can be as little as two video lines (about 640 bytes per line for 8 bit resolution). This is a trivial amount of memory and probably represents a few dollars in costs.

During one line, the video would be digitized and stored in one line memory. During the following line, the stored line would be read from the first line memory in the reverse order while the next line is stored in the second line memory. In the next line, the second line memory is read in reverse order and the first line memory is written with a new line. The output video would be delayed by the period of one horizontal line (about 63.5 microseconds).

This assumes a monochrome signal. Color would require decoding the NTSC signal to RGB format, three A/D converters, six video line memories, three D/A converters, and the circuits to encode the RGB signals in NTSC format.

Parts and assembly costs per unit might be in the $200 range. However, the engineering costs might be well over $10,000. For a small quantity, the $600 for an already available unit might be pretty good, even if it has far greater capability than needed. If you need more than twenty or thirty units, the design cost per unit may drop low enough for a custom design to be economically feasible.

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Re: Flipping video

Post by jimmy101 » Wed May 04, 2011 3:17 pm

jimmy- The cameras are actually looking through portholes, and lighting becomes a problem with using a mirror.
Why? A mirror reflects better than 95% of the light that hits it so there isn't enough attenuation to be a problem.

The mirror can be within an inch or two of the camera's lens, and the mirror doesn't have to be more than a couple inches across. The focus for the camera is the same, a mirror doesn't change focus distance.

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Re: Flipping video

Post by haklesup » Wed May 04, 2011 3:31 pm

Analog camera and a digital display. YOu either need a PC with a viddeo survellance card and image reversal feature or you need a black box to digitize the analog video and send it to an RGB output

Here is a PCI and USB video capture hardware but the ads don't sday anything about image reversal

http://cgi.ebay.com/4-Channel-CCTV-Surv ... 3367469c99

http://cgi.ebay.com/EASYCAP-USB-CAPTURE ... 4aaade79cf

THis one calls out back up camera application which usually requires reversal. it does composite to RGB conversion.
http://cgi.ebay.com/Composite-video-NTS ... 2561fe9189

ebay has more, search on Composite to RGB or NTSC to RGB or some combination of those terms. Contact the sellers to know if they have image reversal capability.

http://www.ramelectronics.net/audio-vid ... gwodpA2LhA
Here are a bunch more

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Re: Flipping video

Post by MrAl » Fri May 06, 2011 10:18 am

Hi,


If an upside down view is acceptable, turn the camera upside down. That reverses right to left.
LEDs vs Bulbs, LEDs are winning.

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