Red (and only red) jagged in H.264 footage

[Walter Soyka]

H.264 may be using 4:2:0 or 4:2:2 chroma subsampling (depending on profile). That will give you really hideous stair-stepping — especially if the original has undergone multiple generations of lossy encoding.

If it’s possible to get a higher-quality original, that’s the way to go. If not, you can exchange some of the stairstepping for softness by blurring the chroma (Channel Combiner for RGB -> YUV, Channel Blur for increasing Green and Blue (now U and V) blurriness, then another Channel Combiner for YUV -> RGB).

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events

[Walter Soyka]

[Walter Soyka] “H.264 may be using 4:2:0 or 4:2:2 chroma subsampling (depending on profile). That will give you really hideous stair-stepping”

I should clarify — chroma subsampling will result in hideous stair-stepping on drastic diagonal color boundaries like these diagonal green/red transitions.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events

[Corrado Carlevaro]

Thank you,(Field Order is set to Off), but if you can clarify more I have some questions.
I can get a better original, but this chroma subsampling stuff is not very clear to me: which kind of sampling should be used? 4:2:2 is not supposed to be “good”? Or those artifacts are a “side effect”?
Moreover, in AE in H.264 Video Settings window, under “Profile” I can choose between Baseline, Main and High and under “Level” from 1.0 to 5.1: what is supposed to be used?

Corrado Carlevaro