AC160 guidance needed on 4.2.0/4.2.2 --Barry

R

Rod Pike

Well-known member
Hi Barry, 160A owner here.
I have recently been asked for time coded 4.2.2 format for a TV ad. I have read your book and your other website article on this subject and know that 4.2.2 can be output by the sdi socket. But two questions remain for me:

1. Does the camera upscale the 4.2.0 output to get to 4.2.2 ? You state it is lossless so I would appreciate a better understanding. If it is true 4.2.2. is there a technical reason why the internal resolution need be 4.2.0?

2. As the cost of say a samurai and ssd is significant, is the improvement worthwhile, (I suppose I mean visually significant) I undersatnd that green screen keying is cleaner but generally, would there be any noticable improvement over 4.2.0 on say a blu ray on a 42"screen? (if so it might be worth investing and shooting permanent 4.2.2.
thanks in advance for any info:
Rod
 
1. It is pure 4:2:2 out the SDI and HDMI ports. No up scaling.

The recording format is limited to 4:2:0 because that's what the standards committee decided for it, back in about 2007 or so. All AVCHD cameras records 4:2:0 because the AVCHD format is inherently 4:2:0.

2. Most people don't see any difference. 4:2:2 is definitely better, especially for keying or grading or compositing, but in terms of overall look, most peoPle don't seem to see the difference. Blu-Ray is 4:2:0 and is shown on large screens all the time, and few complain. But it is better, it is twice the color info.

But if your client specifies it, you should deliver it.
 
thanks so much Barry, that is now very clear. The TV co specify 4.2.2 but when I called them they said that although it is their preference, they would ,and have accepted high quality 4.2.0 material and the 160A can certainly do that!

I had not thought about the 4.2.0 specification of blu ray though for my non TV industrial customers. So, other than for cleaner chroma keying etc, are the advantages really lost when converted back to 4.2.0 for blu ray out ?
Rod
 
Well, yes and no. Better source will lead to better results in the end, if you do any manipulations on it. If you're just directly rendering the source footage out to a blu ray then no, it won't make any difference.
 
Thanks for your prompt and concise (as usual!) response Barry, greatly appreciated by me and everyone else who you take the time to help,
I am now very clear on my understanding of 4.2.0 v 4.2.2.- and it's nice to know I actually have a full 4.2.2 camera if I really need it!. (Well, if I buy an external recorder -another project I guess)
Cheers!
Rod
 
But don't you have to output HD-SDI as you shoot (live) vs play it out after recording to SD card.
 
Yes, if you want to get the full quality the camera is capable of. Once it has been recorded, it will always be 8-bit compressed 4:2:0.
 
Related question here:

Probably going to be shooting for a bird hunting show shortly with the AC-160. Other camera(s) will likely be HVX200. While not required by my client, would recording to a Hyperdeck Shuttle increase the quality of high-motion scenes? Or is it mainly a 4:2:2 color thing? Would 60i through SDI to ProRes be better than 60p to AVCHD? Kind of a hard choice - I don't think there will be a ton of color grading but the background will likely be quite snowy. Maybe do both at the same time and see what works? Any thoughts on the value of the external recorder would be appreciated.

p.s. I have all the gear already for use with other cams, so no additional costs involved, just inconvenience and effort... :)
 
4:2:2 is more data, but when you are talking about quality of high motion scenes such as movement I dont think it will matter. What will matter is the frame rate you are shooting at. So 60P or 60i should allow you to move the camera around quickly and not have too many issues. If you are going to be moving the camera around allot I would use 60i. If you will be just on a tripod then 60P would be good. All 4:2:2 will give you is more information, its not a bad thing but I dont think for what you are doing it will matter. Less gear you have to mount outside the camera the better off you are IMHO.
 
I would never use 60i when 60p is available ... unless your deliverable is 60i. If your client demands 60i, then sure, go ahead and shoot 60i, but if you ever have the choice, 60p is just better in all ways than 60i.

I wouldn't send 60i out the SDI to ProRes, because you're going to be throwing away half your vertical resolution when you do that. Sure, 4:2:2 would be nice to have, but not at the expense of losing half the vertical res!

When external recorders support 60p, it might be a better option, but until then I'd use in-camera 60p.
 
Thanks guys, I think 60p AVCHD is the way to go then. Any thoughts on scene files for outdoor daytime shooting in substantial snow field conditions?
 
Snow tends to make everything underexpose, so you really want to use cine-D to keep the highlights yanked down and give you enough room to expose up a bit. If using automatic iris you may want to crank the a.iris level up a little to bias the exposure a little hotter than it may otherwise want.

If using manual exposure, use the zebras or the waveform, try to keep the caucasian faces no hotter than about 70 IRE, and don't let the snowy white go hotter than about 100 IRE.
 
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