On vacation, but thought I'd comment on this topic before getting on the Harley to go run some errands in the cold Pacific Northwest. As pointed out in someone else's recent blog post, MPEG-4 can leverage what is referred to as a Sample Aspect Ratio (SAR)...not to be confused with Storage Aspect Ratio (SAR) or Signal Aspect Ratio (SAR). It's important to note that in the case of MPEG-4, the Sample Aspect Ratio is the Pixel Aspect Ratio (PAR); they are one and the same.

It's also important to note, again, that regarless of any of these numbers, the shape of the samples from an analog source ARE NOT DEFINED BY THE NUMBER OF LINES.

Oh, one more thing...most multimedia NLE and encoding applications provide precise control of all of these settings. Just an FYI. All the best my friends.

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Consider this: If the DOJ forces Apple to create a new method to access this data in JUST this case, more than one Apple employee will need to be intimately familiar with it. It will need to be well documented, and protected by the very same US Federal Government privacy and security rules and regulations the DOJ is asking Apple to breach (think HIPAA, etc). Cool, Apple can do that, they have been more than helpful putting policies and procedures in place to accommodate government access legally from day one.

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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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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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