Thursday, January 23, 2014

Omnivore Field Kit Issue

A lot of people have seen the Omnivore Field Kit Detailed Demo on YouTube since it was uploaded a few months ago.

A reader sent me the link and asked an interesting question about what was seen on the screen. He saw today's webinar and went to the web site for more information. The scenario here is that there's no digital output, thus you need the Field Kit. Here's the Field Kit Viewer's screen (from the video).

What jumped out at our eagle-eyed reader is the recorded size setting displayed on the screen, CIF. CIF, or Common Intermediate Format, "is a format used to standardize the horizontal and vertical resolutions in pixels of YCbCr sequences in video signals, commonly used in video teleconferencing systems. It was first proposed in the H.261 standard." The dimensions for a CIF sized video is 352x288.

But, the size of the VGA output, as shown in the video is different. The Viewer is reporting the source as 1024x768. How many times does 352 go into 1024? How many times does 288 go into 768? Are the results a nice, round number? If not, what does that mean?

If the video is recorded at 352x288, and sent to the VGA port at 1024x768 - what's happening? Is aspect maintained? What should you do? Unfortunately, when you examine the spec sheets of DVRs, you'll find this a lot. 720x480 or 640x480 is pushed out the VGA, regardless of what the recorded size setting happens to be.

If you choose the Set Display Dimension option (by clicking on the blue Display/Source link) all you do is resize the viewer screen. This doesn't change what's coming out of the DVR? Does it change the amount of pixels captured? No. It seems that the adjustment just makes the Viewer window smaller/larger.

So, here's a problem for folks using this solution. How many know the source video dimensions, or made a note of the dimensions in their report? How many know what's being pumped out of the VGA port into the Field Kit? The Field Kit Viewer is supposed to detect the signal and adjust accordingly. Did you remember to write this info in your report?

But even so, when this happens in the example video, it's still not divisible.

As with any tool, validate it for use before you put it into action. Forewarned is forearmed, right?

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