How much highlight recovery can be reasonably expected from HLG video?

[js47]

I may have taken ETTR a little too far, and admittedly this is my first time ever trying to edit a video, but adusting the exposure of this video feels like editing a JPG image. There is almost zero adjustability to it. I expected it would be nearly as editable as a DNG from the same sensor (which doesn't have great highlight recovery either to be fair, but it is much better than this). The file I am using is 5.1k HLG H.265, 59 seconds long, and 1.05 GB — large enough that I think it should contain more data.

I am using Davinci Resolve 17, which is the latest version that will work with my hardware. I'll attach a screenshot where the only adjustments made to the clip were highlights and shadows. Original is on the left and "edit" is on the right.

There are a few possible issues I can think of:
1. I don't have any idea what I am doing in Davinci Resolve, and I am doing something terribly wrong.
2. I burned the highlights when recording the video.
3. A combination of the above.

Any ideas are very welcome.

 

[js47]

For comparison, here is a photo I took 2 minutes later. The exposure settings were different, but the relative exposure is -1.67 EV compared with the video. Unless video is totally different than photo, at least some of that overexposure should be recoverable.

 

[Dave Maine]

Look at your scopes. The top flat lines are clipped highlights in the sensor data. Once digital data is clipped, you can never recover it. The only solution is less exposure in the beginning. HLG does not impact exposure directly, it simply adjusts the contrast curve between the high clip and low clip levels.

 

[js47]

Look at your scopes. The top flat lines are clipped highlights in the sensor data. Once digital data is clipped, you can never recover it. The only solution is less exposure in the beginning. HLG does not impact exposure directly, it simply adjusts the contrast curve between the high clip and low clip levels.

Thanks for your reply Dave. Would you say that if the highlights looked clipped in the preview on the controller/Fly App while recording the video, they will end up clipped in the final product?

 

[MavicAir2Marc]

There is a histogram in DJI Fly that will let you better check your exposure. There are also zebra stripes to show overexposed areas. Use those tools to get yourself a correct exposure and then your DaVinci Resolve output will be much better.

 

[Filmarik]

There is a histogram in DJI Fly that will let you better check your exposure. There are also zebra stripes to show overexposed areas. Use those tools to get yourself a correct exposure and then your DaVinci Resolve output will be much better.

Since arrival of digital cameras there has always been more data "hidden" in shadows than in highlights. I know that the general rule is to expose with histogram weighed more to the right but that is to minimise noise. When dealing with high contrast situations it is better to expose to the left to make sure data is preserved in highlights because as said in the other post, once the highlights are clipped they are unrecoverable. As for your comment and comparison to JPEGs, you are right. Unless recording RAW video which Mavic 3 is unable of, you are dealing with string of JPEGs as that is what you get when recording in HGL h.265 MP4 or MOV. Shooting video in D-log will give you more latitude in post but it is not a magic bullet either.

 

[js47]

As for your comment and comparison to JPEGs, you are right. Unless recording RAW video which Mavic 3 is unable of, you are dealing with string of JPEGs as that is what you get when recording in HGL h.265 MP4 or MOV. Shooting video in D-log will give you more latitude in post but it is not a magic bullet either.

Thanks Filmarik, that actually makes a lot of sense. 1.05 GB for 59 seconds sounded like a lot, but at 25 FPS that is only 0.7 MB per frame — orders of magnitude smaller than the raw files from the same sensor.

I’ll “shoot for jpeg” when in video mode. And I will look into why D-Log yields better dynamic range — if the videos are just strings of jpegs anyway I’m not sure why that’d be. The “flatness” of D-log footage is definitely one of the reasons I assumed Mavic 3 videos were in a raw format.

 

[MavicAir2Marc]

Unless recording RAW video which Mavic 3 is unable

My Sony FX-30 won't even record in RAW. I have to record on a recording monitor to enable RAW on it.