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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How sensitive is the Videonics MX-1 mixer when it comes to Video Input signals

Postby JeffTurgeon » Wed Feb 08, 2012 5:14 pm

RussellHltn wrote: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.


MX-1 from Grandtec.jpg
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I've connected the Grandtec GXP-2000 exactly as the manufacturer instructed (see photo above).
1) VGA cable (long[color=black][/color]) connects to back of computer
2) Red Y-VGA connector goes to Grandtec converter
3) VGA cable ([color=black]short[/color]) goes to monitor so you can see what you are transmitting
4) USB cable provides power from the same computer
5) Composite cable goes to a TV/Projector or in my case the MX-1 video mixer

The Videonics MX-1 can except composite video or S-video inputs. I am using the composite.

The Grandtec device can output composite, S-video, or component.

The Grandtec is powered by USB from the computer so the signal, I'm assuming-yes I know this is bad, should have its strength being regulated to some standard.

When I spoke to Grandtec on the phone they too wondered if the MX-1 wanted a stronger video signal. But what would I use to see if this really was the problem? That's why I'm wondering if feeding through a VCR would act as a video signal amp for me to test this theory.

russellhltn
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Postby russellhltn » Wed Feb 08, 2012 6:24 pm

JeffTurgeon wrote:The Grandtec is powered by USB from the computer so the signal, I'm assuming-yes I know this is bad, should have its strength being regulated to some standard.


I don't know if it's still true, but some laptops had "low power" USB ports. Meaning that they were unable to deliver "full power" to some USB devices, causing some of the more power-hungry ones to not work properly.

One thing you might do, is since you're saying the USB is just for power, perhaps you can power it from something else. Perhaps a cell phone charger.

JeffTurgeon wrote:When I spoke to Grandtec on the phone they too wondered if the MX-1 wanted a stronger video signal. But what would I use to see if this really was the problem?


Do you have access to a O'Scope?


JeffTurgeon wrote:That's why I'm wondering if feeding through a VCR would act as a video signal amp for me to test this theory.


Worth a shot.
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michaelfish
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Postby michaelfish » Wed Feb 08, 2012 7:15 pm

Your idea of using a VCR may work, similar to adding a video enhancer to remove and restore the video synchronization portion of the signal. Anything you can think of to help with diagnosis is on the right track however, the root of the problem will still be in the mix, so if you want to find out what is causing the blinking, I would recommend further research. Let's also not discount the fact that the MX-1 may be faulty too.

I personally think that the scan converter's signal is not up to the MX-1's requirement for proper synchronization (a VERY significant signal needed in order for the MX-1 to do its job correctly). A video signal is a combination of many different kinds of signals (B/W picture, Color information, Synchronization information, Color timing signal...just to name a few) and they are all put together (thus "composite" video signal) that totals only 1 volt peak-to-peak. The portion of the signal that is most important to mixing video signals is the lowest 0.0 volts to 0.75 volts IRE (in a good signal). Among the many things that can cause problems with that portion of the signal are; long lengths {1) VGA cable (long) connects to back of computer}, a Y cable spitting the signal {(2) Red Y-VGA connector)}, radio frequency interference (RFI) {many VGA cables are not shielded}, etc.

In either case, the Grandtec manufacture states it works great with any TV, Plasma, LCD TV, Projector, but they did not mention video mixers. Video mixers must synchronize two or more video signals oscillating at 3,579,545 cycles per second from a voltage about 1 tenth of a volt, which is QUITE A TAST. There are no consumer TV's, Plasmas, etc. that mix two video sources, thus the video synchronization standard of the Grandtec does not have to be as perfect as what the MX-1 may require.

Since there is a lot going on, professionals use devices such as time base correctors (TBC) and yes, expensive scan converters, costing hundreds to thousands of dollars, in order to produce what the MX-1 does, only they do it better. The MX-1 is about the lowest quality there is on the TBC-assisted-video-mixer-scale and was never designed to synchronize computer VGA signals. It uses S-Video or composite video. That is why a scan converter is needed - to take a video graphics array (VGA) and convert it into a composite video signal. Computer's graphics are not based the National Television System Committee (NTSC) signal, and thus an intricate conversion must take place. If the MX-1 is fed a video signal is not just right...well, hopefully I have described why there may be issues such as what you're describing surface.

I'd like to help. If I were you, I would start at the most basic and cleanest set up (short cables lengths, only one or two devices connected) and look for problems. If everything is OK, add a device and test again. It's a pain, but continue until the problem resurfaces. Then replace the last component added and retest. Does the problem go away with the replaced device? If the problem goes away, great. You've found what needs to be replaced. If the problem resurfaces, try eliminating one device or cable and test again. Hopefully you will be able to narrow down the culprit and find a solution.

Try this: How does the MX-1 test with only 6' shielded cables (camera to MX-1, 6' VGA to the scan converter, 6' shielded cable from the scan converter to the MX-1), no splitting of wires, and a different scan converter?

barataj
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Postby barataj » Fri May 25, 2012 10:22 am

H,

I was wondering if you know a way to make the multiviewer screen jsut the 4 channels of video. I don't have any use for all the wipe effects and I'd rather use the whole screen to just preview all 4 channels of video

michaelfish
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Postby michaelfish » Fri May 25, 2012 6:59 pm

Unfortunately, there is no way to do this on the MX-1. It was not an included feature. Don't give up though. You have options...

In order to monitor 4 video inputs of the MX-1, try using a quad splitter such as the Ultrak KQ7340CU. Used ones can usually be purchased off of eBay for about $20 - $30. The KQ7340CU is a professional digital video processor which has loop through video outputs for all channels so the cameras can feed through it and then loop out to the MX-1. I use a 20" monitor so when the pictures are split into 4, they're about 9" each. You can also select a single video input and display it full screen.

Wiring diagram:

Multicamera Wiring Diagram.jpg
(84.2 KiB) Downloaded 1513 times


Another option could be to use the MX-1 preview output to display the "Next-Source ABCD" selection instead of the quad/wipe-patterns screen. Although this only previews one camera at a time, you could use it to display any Preview video source (full-screen). Just set up the MX-1 by pressing the Display button until the preview ouput jack shows what is selected on the bottom "Next-Source" bus. The display feature toggles from Quad/Wipes to Preview output to Main output. Pressing any of the ABCD buttons on the bottom previews that camera on the preview monitor.

dustinaleksiuk
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MX-1 with a projector

Postby dustinaleksiuk » Mon Sep 17, 2012 1:31 pm

This is an amazing thread. We just had stake conference, and I wasn't able to use my new MX-1 because I did all my testing with normal televisions. When I hooked the mixer up to the projectors we use for stake conference, I got lots of jittering on the top 15% of the screen. So any of the televisions and monitors I used worked fine, just not our stake projectors.

I got the mixer here in town used for $150 with a monitor and a custom-build road case.

I was googling today to try to figure it out and I came across this thread. I'm going to try some of the things mentioned here, but the big difference for me is that my inputs are 2 video cameras and 2 DVD players. There are no digital inputs at all. There are 3 projectors in our stake centre and I webcast to 2 towns in the stake.

Any ideas about that would be great, but maybe I should start a new thread. If that is preferable to people, I'll start a new one and post the link here. I'm hoping to catch the attention of all of you who are using this mixer. I love it and I was disappointed I couldn't use it this weekend. Thank you.

michaelfish
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Postby michaelfish » Tue Sep 18, 2012 5:29 am

First, great price on the mixer...and it included a monitor and custom case! Anytime I find those kind of deals I'm always worried something may be bad. I hope you can find a solution.

It sounds to me that the projectors need a more stable signal than the TV sets. I have had the same problem but it was caused by our PC's capture device. We had to go through several different capture devices to solve the problem. I also helped other stakes in my area, and they had flagging of the picture and artifacts due to splitting of the video cables (instead of using video distribution amplifiers) and using the thin RCA cables.

Is the power supply the original? The unit requires a 12 Volt A/C, 1 Amp power supply.

May I suggest a couple of things to try?

Start with the bare minimum and use the best quality, short length cables/connectors. Connect only one input and the projector all by itself. Don't use any splitters and use good quality, thick video cables. Keep the cables short, so bring the equipment together in the same room. Experiment with other video sources as well (live TV/Satellite, etc.) If the problem is still present, go to the advanced setup settings (SHIFT-SETUP). Try changing the value of the Frame Rate Lock Setting (2nd), Noise Filter (3rd), Black Level (4th). The Headphone Volume (1st) and Composite Chroma (5th), won't help your situation. Some of the adjustments are independent of any other source, so you may need to adjust additional sources (as you add them).

Remember, any settings are reset if the unit it powered off.

If you do not have success, try adjusting the settings on the projector. Sometimes pushing settings to extremes can over-process the signal and cause other circuits to go whacky (especially SHARPNESS and CONTRAST). Does it happen with every projector? Are all of the projectors the same make/model? Are they old? Experiment with other projectors (if you have access).

If you cannot get the problem to go away, I'd suspect something is wrong with the MX-1.

If you have success, then add one source and try again. Repeat until the problem comes back and then try swapping the order of the inputs connected on the back. Since the time base corrector (TBC) locks a second signal with the first, the second TBC will sometimes not work properly when the first source's signal is unstable or weak.

Another possible solution could be to connect and run the output of the MX-1 through a video stabilizer.

Hope this helps...

scottperkins4@gmail.com
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Postby scottperkins4@gmail.com » Thu Oct 11, 2012 6:50 am

Thank you for this conversation. I am having the same flicker problem on the upper third of the picture when I output from the MX-1 mixer through a Grass Valley (canapus) ADVC110 analog to digital video converter. You mentioned in a post that you had to experiment to find a converter that worked with the MX-1. Can you tell which product(s) you ended up using. Thank you very much.

michaelfish
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Postby michaelfish » Thu Oct 11, 2012 8:28 am

For capturing video and audio, I use the Roxio Easy VHS to DVD USB dongle (about $50). I've used this on about 6 or 7 PC's with success although sometimes there have been problems getting the capture program to switch inputs, but selecting another input and going back to the Roxio usually works. When that doesn't, I pull the USB dongle out and plug it back in again. I use this device almost every week to record the talks (audio only) via the hearing impaired receiver and the quality is excellent. It also works great with the webcast communicator with no audio sync problems (audio and video).

BlackMagic Design's line of BlackMagic Design Instensity Procapture devices are also excellent and many on this forum have recommended their internal card.

For more information, check out this thread devoted to finding capture cards that work: Webcasting Video Capture Cards that Work

dustinaleksiuk
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Re:

Postby dustinaleksiuk » Sat Jan 26, 2013 9:43 pm

scottperkins4@gmail.com wrote:Thank you for this conversation. I am having the same flicker problem on the upper third of the picture when I output from the MX-1 mixer through a Grass Valley (canapus) ADVC110 analog to digital video converter. You mentioned in a post that you had to experiment to find a converter that worked with the MX-1. Can you tell which product(s) you ended up using. Thank you very much.


I think I just figured it out tonight. If you hold down the shift button and then press "setup" you can change a parameter represented by a padlock. Change the "0" to a "1". All flicker is gone. I got the information here: http://vjforums.com/showthread.php?t=14817

I found another thread here on the LDS forums talking about other side-effects of turning on that lock parameter, but I tested for about 45 minutes tonight and I didn't see the problem. I'll be using it live tomorrow morning so I'll see. If it fails, I'll have to quickly flip back to my old push-button selector.


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