Blackmagic Forum

Hello everyone,

I'm encountering a strange problem on a HDR project graded in PQ Rec 2020 limited to P3. I have occasional gamut errors after checking the scopes. Strangely, QScan and Transkoder don't see any errors. I'm wondering whether I've got some kind of ‘false positive’ or whether there's a real default?

I get the same result with RCM and ACES color managment.

I've also tried converting my export to P3 and then converting it back to 2020 limited to P3 but I'm still getting gamut overruns.

Here's a small test export: https://www.swisstransfer.com/d/c48e084 ... e2c0311e22

If anyone has a clue. It would be very helpful.

It seems like a false positive. Here is the result from Iris QC Pro:

Interesting. I wonder what is causing that.

Thank you very much Lucius for taking the time running a test.
This would confirm a false positive. Nevertheless, I wonder why Resolve's scope behaves so badly?

It could be interesting to have the point of view of someone at Blackmagic.

Resolve expands gamut to one set for the "timeline".
In order to preserve clip gamut you have to either process it in this gamut (color processing setting) or limit it on output. This defeats purpose of a testing if Rec.2020 exported clip gamut is limited to P3 or not.
QC tools simply displays what they see (once file is interpreted properly). Resolve always processes it in working gamut and then converts to output gamut. This makes hard (impossible?) to see "native gamut" of the clip in Resolve.

Andrew Kolakowski wrote:Resolve expands gamut to one set for the "timeline".
In order to preserve clip gamut you have to either process it in this gamut (color processing setting) or limit it on output. This defeats purpose of a testing if Rec.2020 exported clip gamut is limited to P3 or not.
QC tools simply displays what they see (once file is interpreted properly). Resolve always processes it in working gamut and then converts to output gamut. This makes hard (impossible?) to see "native gamut" of the clip in Resolve.

But the setting is Rec2020. Your explanation seem insufficient.

Yes, this is why I don't know exactly what is going on.
If you interpret clip and set all other settings to Rec.2020 then in theory it should work, but it doesn't.
Maybe limiter on export is broken, but if other tools show it's within P3 then no idea
Maybe Resolve always expands it internally to something "big".

Is it definitely within P3?
It needs to have last frame checked in Iris as this one apparently goes out.