Pixel Format Issue

[Nick Doyle]

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,

[Steve Bentley]

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.

[Walter Soyka]

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   |   RenderBreak [blog]   |   Profile [LinkedIn]

[Chris Wright]

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

[Nick Doyle]

Sorry for the slow response

Thanks everyone for your responses. Very much appreciated.

I’ve managed to get to Uncompressed YUV 4:2:2. It’s coming out at over 13GB in size. Is there anyway to reduce that?

Thanks,

[Walter Soyka]

[Nick Doyle] “I’ve managed to get to Uncompressed YUV 4:2:2. It’s coming out at over 13GB in size. Is there anyway to reduce that?”

You need to get full delivery specs, including the codec that the recipient wants.

“Planar 4:2:0 YUV” is a pixel format that a number of different codecs could use. Maybe it’s H.264, maybe it’s uncompressed…

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