EPIC compression at 4K?

[Justin Marx]

Hey guys,

I'm shooting 4K for and infomercial and I'm just curious what the best compression would be for HD delivery only.. I will be using a lot of HDRx so the more I can squeeze the better..

Thank you!

[Justin Marx]

No one?

[Mike McEntire]

I have been shooting a lot of 4KHD on my epic and 5-1 compression. Looks great. If I shoot commercials I usually go with 3-1. If you can manage I would shoot 5-1 for sure.

[Justin Marx]

Thanks Mike!

[Peter Lyons Collister, ASC]

Shoot 6:1 with HDRx.....if you can......

[jimhare]

Wasn't Spiderman shot at 6:1 because they found that lower compression wasn't necessary? Good enough for them, probably more than you need for HD!

[Jason Wingrove]

have also shot 12:1 with no discernible issues

[Raphael Varandas]

HAve shot 5:1 too and sometimes 3:1
CHeers

[Mark Andersen]

Correct me if I'm wrong here guys, but one thing to consider is the tonal range of the shot. The darker the scene, night or evening, etc the more low compression is going to help you. If you are shooting bright scenes, day, snow, stuff that is mostly in the lighter tones then you can get away with more compression. Tonite I shot a night time street scene and I set my compression to 3:1 just for good measure.

[Justin Marx]

Correct me if I'm wrong here guys, but one thing to consider is the tonal range of the shot. The darker the scene, night or evening, etc the more low compression is going to help you. If you are shooting bright scenes, day, snow, stuff that is mostly in the lighter tones then you can get away with more compression. Tonite I shot a night time street scene and I set my compression to 3:1 just for good measure.

Interesting.. probably a good test, but I have seen some crappy compressed daytime stuff.. I think it really seems to depend on what your shooting (extreme detail, etc...)

Thanks for all of the responses..

[jimhare]

Very interesting indeed. So you're suggesting the closer to black the lower the compression. Guess this makes sense from the perspective of lifting detail out of shadows, requiring a cleaner starting image. Interesting...


Correct me if I'm wrong here guys, but one thing to consider is the tonal range of the shot. The darker the scene, night or evening, etc the more low compression is going to help you. If you are shooting bright scenes, day, snow, stuff that is mostly in the lighter tones then you can get away with more compression. Tonite I shot a night time street scene and I set my compression to 3:1 just for good measure.

[Dan Kanes]

For HDrx I'd do 10:1 for 4k and for normal 24fps I'd do 5:1. 5k I'd go 12:1 and 6:1 respectively. For high speed work I go to higher compression, like as high as 12:1 for 96-120fps stuff.

[IAN SUN]

This is why it is advisable to expose to the right (without clipping) as each stop has as much data as all the stops below it combined. In a 12 bit image, The last stop has half (2048 out of a total 4096) of all the tonal values that the system is capable of recording. That means that the darkest areas are not just bumping into the noise floor, they are starved for information. The result when you use high compression is that those dark areas that were exposed near the noise floor have very few tonal values to distinguish details. When those tones are compressed along with the noise you can end up with a nasty mess.

This can happen even in daylight shots that have a huge dynamic range. Shadow areas can be quite noisy.

When you are shooting dark skinned subjects in bright sunlight, if part of their face falls in the shadow, you can end up with noise in the face. Not good. Im having to nurse the grading of a shot that was recorded at Redcode 28 right now with just this problem. It is ok with a full debayer and exported at Prores 444 but at 422 with a half premium debayer it was scary.

I am really excited about The Arrival of my Epic (tomorrow!) so that i can jump into some HDRx sweetness. Being able to expose for the face and letting HDRx take care of highlights on those static high dynamic range shots will be digital Nirvana : )