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Nick Doyle
Pixel Format Issue
on Apr 17, 2018 at 11:43:42 am

Hi there,

Would really appreciate some advice on this problem.

I'm producing an animation for a client and they've given me the spec they want said animation to be produced in. It all makes sense apart from they've asked it be encoded with pixel format Planar 4:2:0 YUV. I've not heard of this particular format and haven't been able to find many answers on the internet.

Would anyone be able to explain what it's used for and if Media Encoder outputs to this?
Many thanks in advance,
Nick


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Dave LaRonde
Re: Pixel Format Issue
on Apr 17, 2018 at 2:14:13 pm

There's a missing piece of information: the media container.

Mp4? Mov? AVI, God forbid?

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Nick Doyle
Re: Pixel Format Issue
on Apr 17, 2018 at 4:44:45 pm

Ah! of course sorry about that.

They've said it can be in either .avi, .mov or .wmv format. I'll most likely be outputting in .mov format.

Many thanks,


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Dave LaRonde
Re: Pixel Format Issue
on Apr 17, 2018 at 6:33:50 pm

Since it's YUV, I'll guess it's going to broadcast.

Quicktime should have the codec, but NOT if you did the April update -- Adobe killed off support for a lot of QT codecs. You'd have to revert to the previous update.

Personally, I render in a lossless codec out of AE, and use Adobe Media Encoder for the transcode.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Steve Bentley
Re: Pixel Format Issue
on Apr 17, 2018 at 7:49:28 pm

I wonder if they mean "Linear" instead of Planar (as in a linear color space), or I wonder if the Planar media player has a special codec or requirement. Usually these branded media players use a run of the mill codec with a wrapper, just like an mp4 can be a wrapper for an H264.



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Walter Soyka
Re: Pixel Format Issue
on Apr 18, 2018 at 10:32:50 am

Let's break "planar 4:2:0 YUV pixel format" down.

First, a "pixel format" defines the way the computer will use numbers to encode the pieces of a digital image, and the way it will store them in memory.

"YUV" refers to a way of encoding an image. Instead of describing color in terms of red, green, and blue, we describe it in terms of a single channel of brightness (luminance, or Y) and two channels of color (chrominance, or U and V).

"4:2:0" refers to a chroma sub-sampling method. Because the human eye is more sensitive to changes in brightness than it is to changes in color, we can reduce the amount of memory or bandwidth an image requires by "sub-sampling" the color channels, or using fewer color samples in our image than brightness samples. 4:2:0 chroma sub-sampling means that our color channels will be 1/2 the horizontal resolution AND 1/4 the vertical resolution of the brightness channel. (In case you're wondering what the heck 4:2:0 means, it says we're looking at a sampling width of 4 pixels, that we'll do 2 horizontal color samples in that space, and that 0 of those samples will change in the second row of pixels we sample.)

"Planar" means that once we have our YUV samples, we'll store them in planes in memory; first, all the Y, then all the U, then lastly all the V. Contrast this with "packed," where we'd intersperse and store all three values together by pixel group, instead of by channel per frame.

Nerdy diversion aside... you also need to know what codec they want delivered. For example, H.264 uses the "yuv420p" pixel format you want by default.

Walter Soyka
Designer & Mad Scientist at Keen Live [link]
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
@keenlive [twitter]   |   RenderBreak [blog]   |   Profile [LinkedIn]


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Chris Wright
Re: Pixel Format Issue
on Apr 18, 2018 at 12:49:17 pm

9/10 they also want 16-235 video levels when asking for yuv. but not necessarily. you'll need to ask that one too.


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