DNxHD as rec.709 or RGB

[neiljohnrowe]

Hi,

I am wanting to export my film from Premiere Pro as DNxHD and then create a DCP in DCP-o-matic.

In my first test, I rendered a DNxHD from Premiere Pro as rec.709, I then also selected 'Rec.709' as the 'Color Conversion' in DCP-o-matic. When I tested this in the local cinema the gamma was very dark.

Did I convert to Rec.709 twice?

So my question is what is the correct workflow? should I export from Pemiere as RGB or Rec.709 and then what 'Color Conversion' in DCP-o-matic should I select?

Thanks in advance for any info you can offer.


Neil

[carl]

What you've done should work. The conversion in DCP-o-matic is going from Rec. 709 to XYZ for the DCP. Whereabouts did you specify Rec. 709 in Premiere?

[neiljohnrowe]

Hi, thanks for the reply.

It is in the codec configuration in the export settings (Premiere CS6).

[neiljohnrowe]

If I inspect the properties in DCP-o-matic I get the following-

When exported from Premiere as RGB I get 'Full' Colour Range

RGB Properties.jpg

When exported from Premiere as Rec709 I get 'Limited' Colour Range

Rec709 Properties.jpg

[neiljohnrowe]

After another round of testing at the cinema I think it is clipping the white and blacks to 16 and 235. (so not a gamma issue)

The white and black levels look fine when I play the DNxHD in quicktime, the clipping occurs after the DCP build.

The issue was solved when I rendered the DNxHD with 'RGB Levels' selected in the 'codec configuration' of the export settings in Premiere CS6.

Now everything looks great on the big screen

Hope this helps anyone with a similar workflow.

[carl]

Great, thanks for letting us know.

[Carsten]

Might be interesting to do this once again with a ProRes File from Premiere, Wondering wether that is an DNxHD issue? Bascially, both rec.709 limited and RGB full should work and transform correctly without clipping.

As rec.709 is very important, it would be interesting if you could compare DNxHD with ProRes.

- Carsten

[cloud06]

I have same problem with ProRes 444 from Premiere Pro. There is no way of defining what am I using (limited or full range)... So blacks are lifted. What would be best way to fix this?

EDIT:
It would be best if we could define is it limited or full range. It is easily determined looking at scopes in DaVinci Resolve for example when you set levels to full range.

btw - great software with great features. I was using OpenDCP for long time, but I would like to start using DCP-o-matic exclusively. Too bad there isn't option to pay/donate for special features or some kind of group buy

[carl]

Too bad there isn't option to pay/donate for special features or some kind of group buy

I suggest an informal one on this forum: "I will donate X if Y is implemented, will anybody else"? Feel free to start us off. I could make it a sticky topic and keep it up-to-date.

I do need to investigate what FFmpeg does with regards to this colour range thing.

[Carsten]

Limited colour-range is the norm for rec.709. The question is, why doesn't FFMPEG then treat it as expected. That is, when reading rec.709, it should know that the range is not full but limited. Also, would this behaviour occur with specific fileformats/codecs only?

- Carsten