xmephestox
Carbonite Member
Thanks for the explanation and clarification, but not sure I understand your concept of oversampling. As an engineer, I understand how you can oversample an analog signal, for example use a 12-bit A/D converter to produce a very accurate 10-bit digital result. But this same concept does not apply to a digital signal like HD-SDI.
By definition, HD-SDI always has a 10-bit word length. However, the actual video signal is not required to have 10 effective bits. In the case of many (most) cameras, the lower two-bits are simply set to zeroes. So if you capture 8-bit video using a 10-bit CODEC, all you will do is compress the lower two zeros, there is no gain on the quality of the video. You can't oversample data that does not exist in the first place.
Mike Schell
I'm not saying you are gaining information that isn't there, in the form of oversampling i'm describing here comes from a workflow where you overshoot the existing source quality and information so when you start pushing it around through the vigors of post, it has more room to get pushed around.
8 bit color gamut gives you a 0-255 amount color information, 10 bit gives you about 4x more. Converting your 8 bit source to 10 bit, will stretch out the 0-255, it's the same amount of color, but when you start let's say, adding blue to balance your very warm scene. Working natively with a 8 bit codec a slight nudge and you may move let's say for the sake of saying it, 20-30 increments in the color. Stretching it out will let's say let you move in increments of 5 rather than 20. (the math is not exact i'm just saying it as a brief example) Now the you may not have as many shades of blue, but you have finer control over what you do have.
It's the same when it comes to your shadows and luminance. You gain more control, not information, which is why in a lot of VFX software, they work in 32 bit float with their filters, plugins, etc. even when they are only work with a 8, 10, 12 bit source. They need the extra head room to make finer calculations, they are clear and proven results.
You can say well you can convert in post, and that's true, but that's transcode time you could have got in one step, on set, without redundant hard drive usage, and adds a generational loss. Now you can sit there and just look at the footage comparison, and start at avchd native, nanoflash xdcam intra frame, and pro res all day and not see much of a difference if any, nor am I saying that you will. But as an editor, and colorist I always want to be working with the highest quality footage I can, which every weapon in my arsenal as allowed, and it's my firm belief that productions if solid high standards should want that as well.
Even if you bring 8 bit footage to a finishing house to get it color corrected, they'll always convert it to 10 bit before working on it. The advantages are there, even if it's just a technical stand point.