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Old October 22nd, 2008, 10:53 AM   #1
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Potential Issues using Red Camera with XDR/nano

We discovered a potential issue recording the HD-SDI output from the Red Camera. Using our $25K Tektronix WFM-700 waveform monitor, we discovered that the HD-SDI output from the Red (firmware vr 17) is well outside the SMPTE specs in jitter, rise/fall times and overall signal integrity.

We measured the Red HD-SDI jitter (at 100 Khz filter) to be in the 350 pS range. The max SMPTE jitter allowed is 133 pS, the XDR measures around 120 pS. The Red HD-SDI rise and fall times were in the 400 pS range. The max SMPTE rise and fall time is 270 pS, the XDR measures around 190 pS.

The HD-SDI "eye" opening provides an overall evaluation of the signal integrity. Ideally the eye should be wide open and stable. The Red camera HD-SDI eye shows a lot of reflection issues and has been closed down. The XDR eye is wide open and shows almost no reflection problems.

Regardless of these issues, we were able to record and playback video from the Red camera into the Flash XDR. While the HD-SDI input (from the Red) showed many problems, the loop-thru output from the XDR was clean. We tested with a 1-meter high-quality HD-SDI-cable.

So, while successful, I would caution everyone using the Red camera with the XDR/nano (or other HD recorders) to consider adding an HD-SDI reclocker or keeping the HD-SDI cable length to a minimum.

Red does specify that the HD-SDI output is for monitoring purposes only. However, the current HD-SDI output clearly does not meet SMPTE standards and may be incompatible with any HD-SDI device.
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Old October 22nd, 2008, 11:33 AM   #2
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Excellent bit of research, Mike.

Have you conducted similar tests on HDSDI output from other cameras?

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Old October 22nd, 2008, 12:07 PM   #3
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Originally Posted by Ned Soltz View Post
Excellent bit of research, Mike.

Have you conducted similar tests on HDSDI output from other cameras?

Ned Soltz
Hi Ned-
Every other camera we have tested thus far (Canon XL-H1, Sony EX1 and JVC 250) look great. I would assume that the Panasonic cameras also have excellent HD-SDI performance.

We will continue testing, especially if we encounter any compatibility problems.
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Old October 22nd, 2008, 12:52 PM   #4
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A possible improvement

Jim Arthurs just sent a link to a BNC adapter plate for the Red camera, which may improve the HD-SDI signal integrity and possibly the rise/fall times, but will have no impact on the jitter.

Here's the link: E L E M E N T _ T E C H N I C A - Viewing Product: Video Break Out Box
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Old October 22nd, 2008, 11:04 PM   #5
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Mike,

I have sent you an email... Might be able to help.
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Old October 23rd, 2008, 04:43 PM   #6
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Quote:
Originally Posted by Mike Schell View Post
Jim Arthurs just sent a link to a BNC adapter plate for the Red camera, which may improve the HD-SDI signal integrity and possibly the rise/fall times, but will have no impact on the jitter.

Here's the link: E L E M E N T _ T E C H N I C A - Viewing Product: Video Break Out Box
Mike,

Thanks for the report. We have been using the Sony EX-30 as a video assist for Red work based on a Red Time Base of 25p and SDI preview at 720p/50. The EX-30 has worked fine on that setting.

Following up an inquiry from another Red User we set the camera to 720p/59.94 for preview and were unable to get picture lock at Time Base 23.98, 24 or 29.97, Preview 720p/59.94. The Red camera had the ET VBOB.

As a cross check I hooked up a Varicam at 59.94/24p (23.98) and the EX-30 was fine.

Any idea why we could get lock at 720p/50?
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Old October 23rd, 2008, 08:57 PM   #7
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Hi Scott-
Interesting results. I really have no idea why the 720p60 would not work. I had no problem with this format using our Flash XDR box and the Red camera. We did have a relatively short coax cable, but I doubt that really made much difference.
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