Cinema DNG vs. Prores 4444 workflow- post-production advantages and disadvantages

[Wladimir Bonsegnori]

Hi there,

 

I am new to the cinema DNG workflow and I just started working with the Ikonoskop a-cam-dii.

Although I have been doing a lot of research on the subject, I would like to have some advice from someone with some experience in the field.

My questions is the following: for projects that do not need massive color correction, would it be acceptable to throw away the DNG files after transcoding them to Prores 4444 or Prores HQ 422 and use these Prores files as the master files? What would the disadvantages be in this case, if any?

 

Thanks

 

 

Edited April 17, 2013 by Wladimir Bonsegnori

[Alan Rencher]

I wouldn't throw the DNG files away, but yes, the ProRes 4:4:4 files are excellent for grading; and you can use them for your masters.

Edited April 17, 2013 by Alan Rencher

[Brian Raftery]

Hi Wladimir and Alan,

 

I am looking to create a workflow to transcode CinemaDNG files to Apple ProRes 4444 before any editing and grading will be done on them. Essentially I want to create new master files that are supported by my systems NLE.

 

Can you recommend the best/fastest program(s) to transcode the clips to ProRes for a mac that will to the retain the maximum original quality and colour?

 

Thanks!

[Chris Burke]

Compressor is the best program for a Mac to do that job. If you do not need lots of color correction, ProRes HQ may be all you need and not ProRes 4444. Archive the CinemaDNg files, edit and master with the ProRes HQ. I would think that the CinemaDnG and ProRes4444 are so close in quality as to be redundant.

[Alan Rencher]

DaVinci Resolve (or DaVinci Light) or Adobe Media Encoder

[Brian Raftery]

Thanks for the responses guys. I have tried DaVinci Resolve Lite and had high hopes for it. But unfortunately when I try to bring up the DNG files and play them back live in Resolve, they're broken and look like they have static. It might be an issue with the system we're using not being powerful enough since an error message comes up when I open the programme; "Your GPU memory is full". Anyone have any ideas about this?

 

I also tried a trial of Adobe Speedgrade which after some familiarising with the controls, I got the clips in and exported, but it presents me with another problem; the clips come out looking very green. I can open the individual frames in preview app and see what the colour is meant to look at, but when I open it in Speedgrade it looks very green.

 

I am not a colour grader and don't want to start messing with the grade before we hire someone to do that. But as well I don't want the clips to remain looking green while we're reviewing the footage because it's very distracting. Does anyone have a solution for this?

 

Thanks again!

[Phil Connolly]

Da Vinchi on paper looks like the best option as it has a good round trip workflow from DNG files. But I also encounter some weird artifacts on Ikonoskope footage - basically odd green noise over most of the images.

 

I'm going to try davinchi again as the project I'm working needs conforming and grading. I think the other option for transcoding DNG files is adobe after effects but this is painfully slow.

 

When you transcode RAW to prores from the Ikon your always going to get strong colour casts - you usually need to do a one-light type grade during transcode to get your footage in the ballpark of looking normal - or your not going to have enough information to edit.

 

I'm really hopeing I can make davinchi work or its going to be a painful grade on my current project. I hugely regret using the ikon - its been a complete pain to work with so far and the post process is problematic and clunky.

[Frank Glencairn]

DaVinci is pretty picky regarding the hardware - look at the specs on the Blackmagic site.

 

The "static" may be caused by an old version of you OS - you need to update, if this is the case (both Resolve and OS)

DNGs are greenish, because they consist from 50% green pixels but only 25% red and 25% blue.

You need a LUT to get this to REC 709.

 

Alternative workflow is CineformRaw. You get the speed and file size of ProRes, but better quality and you keep all the raw options.

I wrote this article for BMC CinemaDNGs, but basically it covers all DNGs:

http://frankglencairn.wordpress.com/2012/10/07/post-workflow-for-the-blackmagic-cinema-camera/

Edited May 20, 2013 by Frank Glencairn

[Brian Raftery]

Hi all,

 

Thank you for your responses. My apologies for the difficulty in getting to the bottom of this, but I am learning as I am going a long, so I really appreciate your help.

 

I achieved a much better result by changing the colour space default. Since I am new to Speedgrade, I didn't know to do this. I changed it to "Cinema DNG" and then loaded a preset for "Ikonoskop A-Cam Daylight" and bingo it improved the image significantly. However there was still a problem with the over exposed areas of the image being very red. I solved this by lowering the input saturation in the Highlights tab of the Look.

 

I understand what you said Frank about there being twice as many green pixels than red or blue and if I right that is because the image is run through a bayer filter. I have heard that I need to debayer the footage. This is something else I am not familiar with, so my final question and piece to the puzzle is how to I debayer my CinemaDNG files and can I do this in Speedgrade?

 

Thank you again!

[Phil Connolly]

Thanks Frank

 

I'll try that - hopefully that will fix the green noise thing.

 

Phil