Videonics MX-1 Video Mixer Tips and Tricks

Conversations around originating a webcast for conference, including cameras and mixers.
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JeffTurgeon
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Postby JeffTurgeon » Thu Feb 02, 2012 9:52 pm

Tried a another test today. Failed again even with the "1" added under the unlocked padlock in the advanced setting. The MX-1 output still wants to flash. It does seem that the flashing is when I'm switching to a computer input feed rather than a camera.

The computer output signal to the MX-1 is made by using a "Grandtec GXP-2000" unit that converts by using part of the VGA signal run through a convertor (like a "Y" cable) while also displaying the same information on the computer's monitor.

The Grandtec device provides an array of output options for connecting a TV such as: S-video out, Composite, and Component outputs. I'm been using the composite output of the Grandtec to feed the MX-1.

I don't know if this helps but according to the Grandtec manual these choices for VGA setting are supported by the Grandtec convertor:
720x400 @ 70Hz
630x480 @ 60, 70, 72, 75, 85, 100, 120Hz
800x600 @ 56, 60, 70, 72, 75, 85, 100Hz
1024x768 @ 60, 70, 72, 75Hz
1152x864 @ 60, 70, 72, 75Hz
1280x960 @ 60Hz
1280x1024 @ 60Hz
1600x1200 @ 60Hz

Video Standard Supported:

NTSC, NTSC-EIAJ, PAL-M, PAL-N, PAL, PAL-COMBINATION-N

Functions:
Fine Tune, H-SIZE, V-SIZE, Brightness, Contrast, Hue, Saturation, Flicker, OSD color & Save

Should I change something in the Grandtec or the computer?

Or is there something that I can add to the video signal to clean it to make the MX-1 happy? What confuses me is at first the MX-1 seems to play nice with the computer inputs, but after say 5 minutes or so it starts to act up and begin flashing the output. The computer itself shows a stable image on its monitor but the MX-1 output flashes when the computer is feeding it.

Any advice would be helpful as this is all new territory for me right now.

russellhltn
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Postby russellhltn » Thu Feb 02, 2012 10:09 pm

I'd try a different refresh rate on the computer.
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michaelfish
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Postby michaelfish » Fri Feb 03, 2012 3:07 am

There are video stabilizers the can strip the sync signal and replace it, but the scan converter is supposed to do this. If the scan converter is not outputting a stable sync signal, I'd recommend upgrading the scan converter instead of applying "Band-Aid" fixes.

I'd suspect the problem happens only when you are connected to the computer's signal (poor sync), so let's start with that. Have you tried setting the computer to the 60 Hz scan rate? Here are some other suggestions:
  • Disconnect the monitor (don't split the VGA signal) - splitting video without a distribution amplifier decreases video signal voltages (and also the voltages of the sync portion of that signal). Voltages are critical for sync timing (where to put the picture element). If the video signal has been decreased by splitting the signal, it would make sense that the MX-1 would have issues...
  • Make sure you have high quality cables and good connections. Don't use thin cables, and make sure they are SHIELDED (reasoning goes along with the above)
  • Make sure everything is on before turning on the MX-1 or reboot the MX-1 (the MX-1 scans inputs)
  • Turn off the audio inputs on the MX-1 (through set up)
  • Cycle through and try differenct DISPLAY modes (display the Preview/Next Source/Program/Wipe Patterns on the preview monitor)
  • Is the power adaptor the original? If not make sure the specs state 12 volts A/C, 1 Amp
  • Various display settings and resolutions on the computer (I'd use 640x480 at 60 Hz)
  • Different computer and/or scan converter
  • Use the composite inputs (you are already doing this - I put this in for future readers)
  • Don't split any video signals (cameras, computers, players, etc.) Use distribution amplifiers
  • Turn off unused inputs on the MX-1 through set up
Please keep us posted on your progress. I've seen a lot of (non-LDS) posts with this sort of problem and the opinions of those posts is that their MX-1's are defective. I'm hoping that is not the case since this mixer is an affordable unit which has the right amount of features for Stake Conferences.

I hope we can find a solution...

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Mikerowaved
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Postby Mikerowaved » Sat Feb 04, 2012 2:07 am

Thanks for the detailed tips. It's great to have those who have been already pulled through the knothole help those of us still learning.

michaelfish wrote:
  • Use the composite inputs (you are already doing this - I put this in for future readers)


Just curious... Is there something wrong with using the S-Video inputs on the MX-1?
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Postby michaelfish » Sat Feb 04, 2012 8:03 am


Just curious... Is there something wrong with using the S-Video inputs on the MX-1?
In researching, I found this post (see #11) from another website explaining his solution was converting S-Video to composite.

Although I have never had problems using the S-Video inputs on the MX-1, I put this in as a suggestion to try (no other reason than a suggestion).

From my experience observing other stake's use of poor quality cables and adapters, combined with the distance of cable runs, the loss of the quality of the signal could be an issue with the MX-1. In addtion, adding baluns increases the number of connections, so bad connections or possibly a poor quality balun could have possible contributed to the poster's problem. Going RCA all the way would eliminate bad balun connections or poor quality baluns.

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JeffTurgeon
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Postby JeffTurgeon » Tue Feb 07, 2012 7:23 pm

I took the suggestions of trying different internal settings in the Advanced menu of the MX-1 without success. I also tried to change the monitor settings to all 60Hz settings to no avail. I appreciate the suggestions; keep them coming.... The picture still flashes on the output from the Grandtech video converter (used to conver VGA signal to composite to inject into the MX-1 mixer) when using a computer as the source.

I did another test with good results which makes me think I may be getting closer to a solution.

- I remembered years ago there were Video Stabilizers designed to prevent a flashing recording on a copied VHS tape.
- I believe it was called removing some copy protection called macrovision.

Anyway, I picked up one of these filters and put it on the computer's video output signal (coming out of the Grandtec VGA converter) leading to the mixer's input. To my amazement the video stabilizer removed the flashing of the mixer's output. Everything looked perfect and clean.

My thinking in now that somehow there must be some flashing or inconsistency of the output from the computer (similar to the old macrovision encryption) that my eyes can't see and the MX-1 mixer is amplifying. When the video signal runs through the stabilizer though, after coming out of the Grandtech VGA to composite converter, no more flashing is experienced on the MX-1 output.

I called Grandtech (MFG of the Grandtec output device I'm using to convert VGA to composite) and they were baffled too. They talked about interlacing and some other things relating to how they transfer the VGA signal from the computer to composite within the Grandtec device. They are now suggesting that I try changing the video monitor settings to some of the 75Hz options to see if this works without the need for an extra video stabilizer circuit. They also indicated that the Grandtec device was designed to feed a TV and that the mixer may be more sensitive than what they anticipated the need would be. I'll try the 75Hz choices because I'd like to eliminate the need for adding additional video stabilizer circuits to the outputs from the computers.

If the 75Hz setting do not work, at least I have a band-aid work-around until I get this problem solved.

If anyone know some other tricks, send them my way...

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Postby russellhltn » Tue Feb 07, 2012 7:59 pm

JeffTurgeon wrote:I did another test with good results which makes me think I may be getting closer to a solution.[/B][/color]
- I remembered years ago there were Video Stabilizers designed to prevent a flashing recording on a copied VHS tape.
- I believe it was called removing some copy protection called macrovision.

Anyway, I picked up one of these filters and put it on the computer's video output signal (coming out of the Grandtec VGA converter) leading to the mixer's input. To my amazement the video stabilizer removed the flashing of the mixer's output. Everything looked perfect and clean.[/color][/B]


Interesting, since what I know of Macrovision is that it messes with the gain, not the timing. My best guess is that the output of the device is weak and/or doesn't match normal video levels.

You mentioned splitting the signal. Perhaps that's what's causing the problem.
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michaelfish
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Postby michaelfish » Tue Feb 07, 2012 8:13 pm

...just a suggestion. Perhaps you could borrow a different (hopefully better) scan converter and test it. If the problem goes away, consider upgrading the scan converter.

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JeffTurgeon
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Postby JeffTurgeon » Wed Feb 08, 2012 3:46 pm

michaelfish wrote:...just a suggestion. Perhaps you could borrow a different (hopefully better) scan converter and test it. If the problem goes away, consider upgrading the scan converter.


What would be better scan convertor than this unit? (On the cheap of course our current setup has 2 computers feeding the MX-1 images/video clips as well as the 2 cameras.)

The Grandtec worked well with the manual switch until I decided to go fancy and add a higher piece of equipment to the mix (the MX-1 video mixer).

I thought the Grandtec units were good. They sure are easy for my crew to setup. The manufactures packaging said it "is the best choice for connecting your computer to any TV, Plasma, LCD TV, or Projector. The versatility of the PC to Video Component makes it the ideal choice for every application, from big-screen gaming to professional presentations. The muti-format output provides conversions of resolutions up to 1600x1200 into standard video, S-video or high-resolution component video (y.Cb.Cr-480i)."


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This is a:
Grantec
Model: GXP-2000
- PC to TV
- PC to Video Component

[color=blue]As a test...
[/color][INDENT] - What could I use to boost the output signal from the Grandtec to see if this was the problem?
[/INDENT][INDENT]- Do you think running it in and out of something like a common old school VCR would do the trick?
[/INDENT]

russellhltn
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Postby russellhltn » Wed Feb 08, 2012 4:08 pm

JeffTurgeon wrote:The computer output signal to the MX-1 is made by using a "Grandtec GXP-2000" unit that converts by using part of the VGA signal run through a convertor (like a "Y" cable) while also displaying the same information on the computer's monitor.


I think a couple of us have raised this issue - how is the signal being split? Are all the devices involved intended to be used this way? If done wrong, you could end up with a weaker signal.
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