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Kona - Random Green Flash Frames

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MTrubac
Kona - Random Green Flash Frames
on Nov 15, 2007 at 3:31:11 pm

Hello, I have a video edited in FCP 6 inside a HDV 1080i60 sequence, rendered to ProRes. Actually this sequence is about 19 sequences, all HDV 1080i60 rendered to ProRes, that have been nested.

I am trying to downconvert my HD to SD for DVD. Seeing bad results through software, like Compressor 3, I decided I would try to use my Kona to downconvert. The Kona is faster, and I am seeing a much better result. However, I keep getting random green flash frames. I am not sure if it is a timing issue, a bad cable, or if the Kona card has an issue, and hope someone here might be able to help. More details follow

Here is a still frame pulled from my downconverted file that shows the problem. I have only seen this happen on two frames in the entire 90 minute program. It happens randomly. I can redo the downconvert and I won't see any flashes, or if I do they will happen in different places.

I am accomplishing this downconversion by doing a 'Print to Video' from one of my Macs. This mac is outputing through the HD-SDI output of a Matrox MXO. The MXO is fed by an 8-core Mac Pro. The Output runs to the SDI Input of my Kona LH. The Kona is installed in a PowerMac G5 dual 2.7. I have the Kona set to 525i29.97 as the Primary, and 1080i29.97 as the Secondary format. This causes the control panel to show a 1080i29.97 signal coming in through SDI, being downconverted before reaching the 525i29.97 frame buffer. The Genlock setting on the Kona control panel is set to Video in.

I am capturing on the PowerMac/Kona system by choosing the 'AJA Kona LH- NTSC 8bit to DVCPro 50' setting, changing device control in Audio/Video settings to 'Non-Controllable Device,' opening up the Log and Capture window, starting the output from the MacPro/MXO and hitting Capture Now on the PowerMac/Kona.

I am always using the same cable. It is just 50 feet of 75 Ohm coax cable connected to the MXO and Kona Box with BNC adapters.

Both Macs are running: OSX 10.4.10, FCP 6.0.1, and QT 7.2

Matrox MXO driver is 2.0.0.21
Kona LH driver is 4.0

Ideas?




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JeremyG
Re: Kona - Random Green Flash Frames
on Nov 15, 2007 at 3:43:08 pm

I have seen green frames when using 1080 ProRes material, but I can't seem to to track it down or repeat it consistently. What if you just played out you HDV timeline, does it happen then?

Jeremy




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MTrubac
Re: Kona - Random Green Flash Frames
on Nov 15, 2007 at 4:05:09 pm

I will try this later today, and report back. I wish that I didn't have to sit and watch this so closely over and over to make sure I am not getting flashes.


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JeremyG
Re: Kona - Random Green Flash Frames
on Nov 15, 2007 at 4:14:57 pm

Yes, reviewing long form is long.


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MTrubac
Re: Kona - Random Green Flash Frames
on Nov 15, 2007 at 10:41:37 pm

I changed all of my sequences back to render same as sequence codec (HDV 1080i60), rendered, and tried another print to video (in other words output MXO to KONA). I still had green flash frames. I actually had more of them than I have seen before, but none of them were full frame. Just the bottom third, or the middle section of the frame, etc.


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Gordon Gurley
Re: Kona - Random Green Flash Frames
on Nov 15, 2007 at 9:26:43 pm

Can you use a shorter cable? Cable quality, type and length are all important with HD.


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MTrubac
Re: Kona - Random Green Flash Frames
on Nov 15, 2007 at 10:54:19 pm

I suspect the cable may be to blame. The cable I am using consists of two of these 25 footers connected with a barrel connector, and then I have BNC adapters on each end to connect to the MXO and Kona.

Trying to do the best I can with what I have available. :)

however, I am willing to purchase new cables/gear to make this work reliably.


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MTrubac
Re: Kona - Random Green Flash Frames
on Nov 16, 2007 at 12:12:34 am

99% sure it is a bad cable.

found a spot in the cable that I can wiggle and the signal cuts in and out, the Kona Control Panel flips back and forth between 1080i29.97 on the SDI in, and no video. The audio also pops and crackles.

I'll be out to purchase cable, bnc connectors, and a crimper in the morning, and will give this another go. I will report back.


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Gordon Gurley
Re: Kona - Random Green Flash Frames
on Nov 16, 2007 at 7:33:44 am

My goodness, are you kidding? Use video cable designed for HD use, try Belden. Any barrels or adapters cause signal loss. Avoid them if you can.


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MTrubac
Re: Kona - Random Green Flash Frames
on Nov 16, 2007 at 1:39:36 pm

hey thanks.

I purchased Remee RG6 Quad. Hopefully this will have it fixed.


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MTrubac
Re: Kona - Random Green Flash Frames
on Nov 16, 2007 at 4:44:44 pm

I made a new cable, just the right length, bnc connectors, no adapters or funny business. Tried the down convert process again, and everything looked good!

always use quality cable, and never trust it!


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