Quick RED Compression Ratio Comparison

[Mike P.]

Quick little test comparing 6:1, 12:1, and 18:1... I wanted to see how noticeable the differences would be at the delivery stage (generally compressed and 1080p, not 4k/RAW). Figured there would be some soon-to-be-Scarlet owners (or 32gig SSD owners) that would want to check it out in order to maximize their REDmags. I cover most of the details in the video's description.

Must say I was pleasantly surprised seeing as how we're dealing with approximately ~3gigs/min vs. ~2gigs/min vs. ~1gig/min... Holds up extremely well in the grade, too. Granted there was tons of ambient ~5600k light, which definitely helps, but it's good to see that you aren't sacrificing too much quality whilst literally getting 3x the amount of recording time out of the same REDmag. It certainly doesn't seem to be 1/3rd the quality at the deliverable end (they all look pretty much the same, which I guess is to be expected when they end up being crammed into the same 10mbit h264 codec regardless of the source ratio, but still).

[Nick Pasquariello]

If anything, in post, I've noticed that a higher compression ratio = more visible noise. Perhaps the compression ratio needed is situationally dependent? Recording in a darker setting could mean you'll want to bump your compression ratio down?

[William Dempsey]

Hi Mike,

Most of the frame is static. I bet you will see more of a difference if there is more motion as a greater percentage of the frame. I had done a quick test of a talking head set up and found 18-1 held up really well but also not much change per frame. Motion like a pan would probably show issues. Thanks for the test.

[Jaakko Rinne]

A windy wheat field in the rain is a brilliant go to for compression tests.

[Marc Wielage]

Water and smoke are also good torture tests for compression issues. Another good one is a stadium shot, with lots of little teeny-tiny people in the grandstands. I've seen certain MPEG images just completely fall apart with motion artifacts and dropped frames with complex shots like that.

[Gunleik Groven]

What used to be compression stressing for the R1, would be something like a shot in a forest with high contrast, tons of detail (leaves and branches) and some motion.

The field and the stadium and smoke sounds good, too...

[Nick Wernham]

You've gotta love the distillery district as a location though. Such an interesting place to shoot!

[Bob Gundu]

I remember the day they had a casting call for tall skinny dudes when they were shooting the concentration camp scene for the first X-men here. My friend got a part as an extra. Not sure why I didn't??? Oh yeah, I'm not white, tall, or skinny! Ha ha!

[Uli Plank]

What used to be compression stressing for the R1, would be something like a shot in a forest with high contrast, tons of detail (leaves and branches) and some motion.

Hi Gunleik,

why do you think it needs motion? RED's compression is strictly Intra.

[Gunleik Groven]

Hi Gunleik,

why do you think it needs motion? RED's compression is strictly Intra.

Sure! But with tons of small motion in leaves or grass or waves in the sea, the difference in compression between high-detail frames, used to be a stress test. Early on, you could even make the camera go down under such conditions, because it didn't handle them... :) (Looooooong time ago).

I am in no way sure of this (!!!), but I have been wondering that as it is a VBR codec, sometimes the "next" frame could suffer if the "1st" was "hard" to get right...

Haven't run these tests on Epic, and my guess is (again due to all the computing overhead apparantly available inside that box) that it won't be an issue at all! But yoy could trigger t at higher compressionratesm still... as the wavelet "evens out" stuff. Add motion, and that could differ from frame to frame...

Maybe I should try! :)

G

(Just contemplating ways for breaking beauty...)