Ask Alex - The 411 on 4:4:4

[Dunantar]

Very good explanation. But could you tell me if I'm right or wrong if I say that the 4:2:0 in the first line takes 2 samples of blue and from the second line takes 2 samples of red. This is what really is 4:2:0 subsampling? I mean, it takes half the U info and 0V info from the first line and 0u info and half V from the second line? Am I right?

[Spawn4ever]

Very well explained and illustrated. Thank you for taking the time to explained this technology and for sharing your knowledge.

[DylanPenev]

Hi Alex

Great tutorial. Thanks. :)

[benjaminbode]

Thanks. You are a gift to humanity.

[5DFilmSchool]

@benjaminbode Thanks. You made my day!

[SOEINEGAUDI]

sooo helpful :)

thanks a lot !!!

isn't there a single dslr with 4:2:2 in video mode ??

[5DFilmSchool]

@SOEINEGAUDI The only way to get 4:2:2 out of a DSLR is to use a standalone video recorder like the Atomos Ninja.

[SOEINEGAUDI]

@5DFilmSchool Thank you ! This seems like a great concept, but how can i know

if the dslr truly puts out 4:2:2 ? couldn't it be that the hdmi output already is compressed ?

[Hrehorowful]

Thanks. great vid.



[ronoc9]

Literally just sat down, watched this, and now I'm that much smarter. Clicked subscribe :D

[oregonhockyfan]

Thank you for this video. You described this better than my film teachers did in class.

[LRCProductionsUS]

very, very nicely done. but it would have been so easy to add the luma value explanation to this video, all you had to do was dim and brighten one of the pixels to demonstrate it. That would have made this video 100% to people that still don't understand. by the way, awesome lighting, sound, and quality! just found your channel and you guys are the truth! :)

[Tweek5470]

So in 4:2:0 the pixels have a luma value but only the 2 pairs on the top get a chroma value and the ones on the bottom have to share that chroma value?

[Toddyyyyyyy]

Can the dumb guy just ask - can't you still then get a good key on 4:2:0 by using just the luminance data ?

[HoneycombHouse]

@Toddyyyyyyy Not a dumb question at all. A lot of keying software packages use the luma channel to help figure out detail around the edges. However, that's in conjunction with chroma info. A luma key by itself only really works if you're shooting on a white background. A luma key won't work on a green screen, because the green tone is a more medium-light shade, and you can't really isolate it from anything else.

[outdevo]

easily the best basic explanation of this I have yet seen (and I have done a lot of searching)

Thanks Alex!

[5DFilmSchool]

@outdevo @cgxphoto Thanks for the kind words ... I'm very glad that you liked the video!

[MarcoStarink]

Hi Alex, thanks for this very helpful vid. Can you help me out on this one. I'm planning to purchase a D5m2. I do some ChromaKey vids using Datavideo CKL-200. How would the Choma subsampling on the D5M2 affect this in quality-terms?

[5DFilmSchool]

@MarcoStarink Hi Marco, thanks for the comment. In my experience, 5DMk2 footage is okay to key with, but not great. It's certainly better than DV or HDV, but definitely not as good as a less-compressed HD format. Aside from the chroma subsampling, the overall compression tends to give you a lot of blocky edges. With that said, it's most definitely true that the better your software, the better your results. Good luck!

[RossCharnock]

Thanks so much for the explanation!

I saw a post on a forum about converting 5/7D footage to 4;4;4. To me this doesn't a make sense as you're trying to get the computer to create date/detail that isn't there... Am I mistake? Or does it have some clever other purpose?

[5DFilmSchool]

You're right, you can't create data that wasn't there to begin with. However, the idea is that you can add NEW data in 4:4:4. So, for color grading, there's a theoretical advantage to converting to 4:4:4. I'm a little skeptical about the cost/benefit of filling up my harddrives with uncompressed versions of footage that was highly compressed to begin with, but some folks seem to swear by it.

[shiksastudio]

does Canon 5D Mark II record 4:2:0?

[5DFilmSchool]

I'm 95% certain that the answer is yes. I've seen some people talking about it recording 4:2:2, but I believe they are mistaken.

[cgxphoto]

I was just asking a friend about this yesterday, thanks so much Alex! Perfect explanation!