Handling 6k BRAW Footage

Hi,

I’m thinking of buying the Blackmagic Pocket 6k for short films and narrative work. I was planning to shoot BRAW 3:1 or 5:1.

However, I’ve just done a BRAW speed test and it seems my CPU can’t support 3456p but it can support 2160p. I’ve attached a screenshot of the test results and also the spec of my iMac.

Does this mean I’d be better off opting for the pocket 4k instead or is there some kind of workaround using proxies etc..?

Sorry if that’s a silly question, I use Davinci Resolve for both editing and grading but I’m not familiar with the BRAW workflow (or any RAW workflow for that matter).

Any help greatly appreciated?

Many Thanks,
Matt

For easing the load with RAW media, by preferred method is reducing Decode resolution.

For easing the load with RAW media, by preferred method is reducing Decode resolution.

Hi Jim,

Thanks for getting back to me. I just want to check I've understood correctly: Should I change the "Decode Quality" to something like "Quarter Res" and then when it comes to exporting the project I tick "Force debayer to highest quality"?

Thanks,
Matt

I'd doubt that machine is any joy working in a UHD timeline. I'd do all the editing and grading in HD and switch the timeline to UHD before rendering. BRAW seems to be some type of DCT, not Wavelet. It doesn't profit much from reduce debayering, other than R3D.
Before you decide on a camera, get some BRAW test files and try if the render doesn't crash with a few grades and effects you'd normally use. The camera to buy doesn't matter that much, you can always profit from 6K for some re-framing, stabilization, or push-in. But first, make sure that you don't need to invest in a better computer.

Yes, Matt.

Hi Uli and Jim,

Thanks for getting back to me. I downloaded some sample footage; both 6k BRAW and 4k ProRes.

If I switch the project to HD then the editing, playback and colour grading is smooth without any crashes or dropped frames.

When switching the project back to UHD for export, the render out to a ProRes master file is very slow for the BRAW; around 15 mins for 1 min of video. The ProRes renders out pretty much in realtime (1 min for 1 min video).

For projects where I don’t need the maximum flexibility for grading, I’d be quite happy to record in 4k ProRes to save huge render time with the final grade as I’m not due to upgrade my Mac for another few years.

Thanks,
Matt

[CaptainHook]

It doesn't profit much from reduce debayering

While mostly true for the Pockets and 4.6K cameras, the new Blackmagic RAW version in the 12K camera does benefit a lot from reducing the decode resolution and you will find significant performance gains there. This helps make editing 12K clips on a MacBook Pro a reality etc. I know its not directly relevant to the OP but just pointing out this has changed and a lot of work went into it.

You of course still reduce the overall overhead working in a lower resolution timeline though even with the other cameras.

Thanks for that info, Captain, much appreciated.

To Matt:
You won't lose much by recording ProRes, but I wonder about such a massive difference in rendering times.
You may want to try and switch off BRAW decoding by the GPU (since that one is pretty weak) and see if it improves. Oh, and render to another storage than the one with your BRAW files.

Thanks for the suggestions Uli. Unfortunately it's not making much difference to the export time.

It's not too bad because the performance editing and grading the BRAW files is fine, if I switch the project to HD. If I want to export a rough cut or fine cut in HD then the render time isn't bad, but when I come to export the final version in in UHD ProRes HQ then it's really slow. Hopefully in a couple of years when I upgrade my machine it won't be a problem.

Also, I downloaded some BRAW clips for the Pocket 4k and these export pretty quickly to UHD ProRes. It seems the 6k BRAW files are a lot for my 5 year old iMac to handle. I'm still leaning towards the 6k and just shooting in ProRes for longer projects where I don't want a long export time.

Be glad you have a Mac, even if it's slow! A PC might not render those files with the same GPU at all.

Be glad you have a Mac, even if it's slow! A PC might not render those files with the same GPU at all.

Yes, in the future I may look at buying an external eGPU but I've been put off slightly as Apple doesn't officially support or recommend it with devices that only have thunderbolt 2. A few people seem to be using thunderbolt 2 to 3 adapters, but I'm still mulling it over. May be better to wait until I upgrade my computer further down the line. I'm a bit gutted that I upgraded my mac just a little before thunderblot 3 came out.

[Dwaine Maggart]

As you note, Apple does not support eGPU's on systems with TB2 ports.

Simply adding a TB3 to TB2 adapter to a TB3 eGPU won't help.

The only way to make an eGPU work on a TB2 system is some sort of OS hack.

Not to say that might not be an option, particularly for Trashcan users with horizontal render artifacts.

While Dwaine is right (of course) regarding the 'Trashcan', IMHO you shouldn't invest further in that iMac. You won't get the gains you may expect from an eGPU via TB2. Be glad it works, albeit slow, and wait until the dust settles around M1.

A 6-year-old iMac is gonna be rough with 6K. You might be able to do OK with a recent-vintage iMac Pro with a TB3 eGPU, but a lot will depend on what specific processor, RAM, and so on.

The reality is these super-high-res projects require hefty hardware.

An iMac 2017 (non Pro) with an eGPU might be cheaper. Mine is very stable.

Thanks for all the feedback and suggestions. I’ll probably end up waiting a while and getting a new machine further down the line. As you say, at least it works and it’s only the render out time that is really slow.

The 4k BRAW from the Pocket 4k is actually ok on my machine, it’s just the 6k that is slow. I guess I’ll have to decide between a Pocket 4k with speed booster or shooting mainly 4k ProRes or the Pocket 6k. To be honest either option would be a step up in image quality from what I’m using now.