Some more offline comments and testing recently have raised a critical issue; the use of Square Pixel Sampling and Non-Square Sample Formats. Before that though, let's talk about validation testing. When we get to this level of detail especially, it is important to validate our processing, tools, and complete process. Correcting Aspect Ratio is certainly no exception. In fact, I think we would all agree that when this level of detail really matters, you must validate. Lot's of great resources out there about that topic.

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There ARE Non-square samples, and their shape IS NOT dependent on the # of scanning lines. There are also Non-Square picture elements in CCD and CMOS image sensors, but their electrical charge is never converted to digital in an analog CCTV camera.

If you are aware of a standard that defines the shape of 480i (NTSC) or 576i (PAL) non-square samples differently than through the use of the luminance sampling frequencies, please bring that to my attention. Thank you.

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I probably should’ve just dropped the mic after the last post, but we’re going to continue on. I’m not one for dropping names, and in this case I don’t have to either. Everyone has gotten this wrong at some point, and I mean everyone. The people working on related standards; the people making the world’s leading non-linear professional editing systems; the people who make a living professionally processing and transcoding video; the people making multimedia playback software; the people making DCCTV systems; the people making operating systems; and yes, even forensic video and digital evidence technicians and analysts. We’re all human, my friends. It is a long, convoluted, complex process with its very foundation based on sampling an analog signal.

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Have you ever worked with somebody who is clearly smarter than everyone else around them? I have, and still do.

View entire post on LinkedIn.

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I was hoping I’d be able to wrap this series up with this post, but it’s clear to me now that I won’t be able to. There’s simply too much to cover and I’m certain that at least a few are still scratching your heads (like I was), wondering why we shouldn’t just rely on the pixel matrices to calculate Pixel Aspect Ratio (PAR) from analog sources. It is critically important to understand that I am approaching this topic from a forensic perspective, with the goal of standardizing the methodology used for forensic processing, interpretation, and presentation.

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