Ability to adjust exposure on Sony XAVC files

via email:

One production changed the ISO on their cameras (exterior shoot) from the default setting down to 500 ISO. This production is shooting XAVC. After we processed this footage through Cortex, the DP/DIT said that everything looked overexposed. So I started looking into it.

When I bring the clip into RAW Viewer, the app reads the metadata that it was shot at 500 ISO and automatically turns down the exposure setting (see attached).

But in Cortex, I don’t have this option. There is no dialog to adjust anything with XAVC (not like Sony RAW clips). My understanding is (and correct me if I’m wrong) XAVC already has been decoded and all the exposure, SLog, gamma settings have been “baked” into the XAVC file. So I guess my questions are:

  1. Are the XAVC files being recorded in a raw-ish mode and expect the dailies app to interpret the modified ISO and apply it?
  1. Or is XAVC really a flat image and RAW Viewer is simply adjusting some brightness/gamma settings to mimic an exposure change?

We’ll be looking into this in the near future. There isn’t anything ‘RAW’ about the data in an XAVC file, so this must be just some controls to manipulate the image after the fact (not unlike applying CDL values). We’ll see what is involved to add the same controls for Exposure, etc in Cortex

more info:

So it turns out that the SLOG3 or SLOG2 XAVC recorded on the F55 as XAVC does NOT get an EI change baked in UNLESS you choose to record the MLUT on the SxS card.

You can have the change in EI applied IF you choose to record the MLUT that is applied and you can choose JUST SLOG3 or SLOG2 as the MLUT.

However, in this case (and likely others that we’ll encounter in the future), the production has applied an MLUT (Rec709) for onset viewing only….and is not recording rec709, but leaving the camera and recorder in SLOG3. So…Slog XAVC with NO EI change embedded is what we got.

Thus we need a way to read the metadata that the EI has changed AND apply a scaling adjustment to compensate for the change in EI….

Quick update @24pdailies - @hans has started to investigate this, but its not clear yet how best to do this. We are in contact with the Sony SDK team and will let you know when we have a better sense of when such a feature could be made available. It could take a little time to sort out the details.

OK - keep us posted. If you need us to test anything, you know where to find us.

We are pretty close here. It’ll be in v1.5.4. I’ll make a beta available early next week.

1 Like

v1.5.4 beta b5342 includes this feature and is available to test now.

1 Like

We threw some XAVC footage at this new beta version, adjusted the exposure to different values and rendered out DPX files. We did the same with Sony RAW Viewer (same exposure levels). Then we compared the DPX files. Everything was spot on and exact. No variation on the scopes. This is wonderful! Thanks for adding this feature!

Additionally, we imported a clip that we knew had different exposure settings than normal. Cortex interpreted the exposure change in the metadata and automatically applied the correct exposure change. Again, this is awesome!

Two items that need addressed before final release:

  1. the decimals need removed from the exposure and kelvin fields. For example, the exposure might read 1250.0000 or the kelvin might be 5500.0000. Simply 1250 or 5500 should suffice.
  2. With these changes, I’d suggest you add six columns in the bin. Three for exposure, kelvin, tint as it was shot and three for applied exposure, kelvin, tint (as applied by Cortex). Of course these columns could be turned off by the user. This kinda goes hand-in-hand with the request to show all metadata columns.

@hans, can you make the change above?

This one may have to wait until we determine the best way to technically address the earlier request:

The slider values should look better now in v1.5.4 beta b5390.