Panasonic S1/S1H Open Gate

We came across this thread over in the EOSHD forums:

Can’t make decent HDR grade from Panasonic S1 V-Log. What am I doing wrong?

“I’m attempting to make a rec.2020 PQ grade from footage shot on the S1 in 6K open gate 200Mb/s long-GOP 420 V-log mode. I’m cutting in Resolve Studio and no matter what color management methodology I try, I’m consistently getting big macroblock cyan and magenta splotches in certain parts of my image. It’s usually on gray or off-white objects in the picture. These splotches are only clearly visible when viewing in HDR. When the same clips are converted to rec.709 and viewed in that colorspace, the splotches are reduced to just looking like noise.”

A forum member responds,

“1. Why would you ever need to grade for hdr?

2. You are shooting in an interframe codec with 4:2:0 chroma subsampling, youre supposed to expect macroblocking and banding.”

The OP:

“At the risk of feeding the troll, the S1 and S1H share the same 200mb/s 6k 420 10-bit long-GOP V-Log mode. The only difference is the AA filter on the S1H. S1H is “Netflix approved” for anamorphic shooting using the aforementioned open gate mode. Netflix requires all “Netflix Originals” content to be delivered as a Dolby Vision IMF packages. So theoretically the S1H is being used in this interframe 420 mode to produce HDR content for Netflix, and the S1 has effectively the same imaging capability. This tells me they must have figured out a color correction workflow which yields decent looking results. I want to know what part I’m missing.”

The person who replied to the thread might not be very fun at parties, but he’s correct. No one should be capturing 10-bit 4:2:0 for HDR. Netflix’s own published codec requirements specify:

“Lightly Compressed or Uncompressed RAW
or Intraframe Based Codec with 4:2:2 Chroma-subsampling or Greater”

If you dig a little deeper, you’ll see that Dolby Vision specifies a minimum of 12-bits, meaning that the internal 10-bit codec of none of the cameras on Netflix’s approved list is sufficient for HDR production. Unfortunately, external recorders are unable to capture the open gate mode of the S1 and S1H, making the full frame anamorphic mode pretty much useless from an HDR shooter’s perspective.