Advice on how to configure new iMac Pro for my needs

[Joe Marler]

[Cherin Bower] “I am purchasing a new iMac pro…I shoot around 10 TB of 4k and slo mo footage each year…
I had an imac, but I don’t use it because my laptops performed better. Here are its specs:
iMac Retina 5k, 27-inch, Late 2015…3.2 GHz Intel core i5….AMD Radeon R9 M380 2048 MB….1 TB?

…I have over 100 TB of footage I’m dealing with on external drives and about 30 TB of that is 4k to edit. I run final cut pro x with some 3d graphics while compressing/converting footage in compressor or edit ready and copying/transferring large video files or libraries at any given time. I also render and convert in Apple ProRes 422 where I can….

Cherin, using FCPX, a top-spec 2017 iMac 27 could handle this if you used proxy files. I know this because I’m editing a 20 TB documentary on one and have about 300 TB of on-line storage, mostly 4k H264.

The 2017 iMac is about 2x faster than a top-spec 2015 iMac at H264. It generates ProRes proxies from 4k H264 about 2x faster than a 12-core D700 Mac Pro. It might be 3x faster than your 3.2Ghz i5 with R9 M380.

That said, documentaries shot on H264 with a high shooting ratio are technically very challenging. A top-spec 2017 iMac could do this (using proxy) but it can be a struggle and the proxy workflow for external proxies (ie outside the library) is complicated and tricky.

For this class of endeavor, an iMac Pro would definitely give more performance headroom and the possibility of editing native 4k XAVC-L MXF files without transcoding to proxy. I have not tested this, only mentioning the possibility. The limited early reviews indicate that Apple has somehow added hardware acceleration for H264 encode/decode to the Xeon-based iMac Pro. Nobody yet knows how this was done, whether a custom Xeon design or using the special transcode logic on the Vega GPU.

You will often hear people say “just transcode to ProRes”. That may be OK for scripted narratives but for large-scale documentaries with many cameras it doesn’t work. E.g, we can’t put HDMI recorders on our fleet of drones, our 12 GoPros or our motion control cameras. We have several HDMI recorders but IMO they don’t work well in the rough-and-tumble field documentary environment.

This is where an iMac Pro could make a huge difference. If it can smoothly and rapidly edit all your camera-native content, then suddenly you have eliminated all transcoding, and all the associated time and space. It would be a gigantic improvement and simplification of your post production workflow. I don’t know for certain it will do that for your 4k XAVC-L MXF content, but my 2017 iMac is on the borderline of being able to smoothly edit camera native 4k H264 XAVC-S without proxy (single cam, not multicam).

Likewise the 4k H264 video from GoPros and DJI drones is highly compressed and can be difficult to edit. However I suspect an iMac Pro can smoothly edit that without proxies or optimized media — because my 2017 iMac nearly can. So there is a performance threshold, that if obtained, is absolutely transformative when dealing with large amounts of this type of material.

That said, if you edit collaboratively with anyone not having an iMac Pro or want to edit on a laptop, you’ll need to generate proxies for that.

Another issue is compute-intensive effects. E.g, Digital Anarchy Flicker Free can miraculously de-flicker a time lapse or banding caused by fluorescent lights but it’s extremely CPU-intensive and slow to run. Likewise Neat Video. Running plugins like these on 4k material is agonizing but sometimes necessary. This is another area an iMac Pro would help.

I don’t know the optimal iMac Pro config for your case but even a base model would be much faster than anything you have. I’d personally get an 8 or 10-core model with Vega 64 GPU and at least 32GB. For FCPX 32GB is probably enough and according to the latest info Apple and 3rd party service providers can upgrade the iMac Pro memory. That said 64GB and 2TB SSD would give plenty of “elbow room”.

In general I would not suggest transcoding to the 4k video sharing presets of Compressor for later editing. By default that uses only 19 megabit/sec for 4k. Even if using a higher bitrate, you are transcoding one H264 format to another for editing. By contrast if using proxy you are editing a ProRes version of the original camera files — there is no generation loss or lower quality from diminished bit rate.

I know there’s a tendency to browse the camera files using Finder, and some codecs make that very difficult. However another solution is just ingest everything to FCPX and browse it there. If using “leave files in place” this is very fast and takes no additional disk space — provided the machine is fast enough without proxies. The iMac Pro might be that machine.

[Steve Connor]

Hi Cherin, I checked out your YouTube channel, what fascinating work you do! Please let us know how the iMac Pro works for you. I imagine it’s going to be quite a leap in performance, but until we start seeing some real world use of them in January we can only really guess.

\”Traditional NLEs have timelines. FCPX has storylines\” W.Soyka

[Cherin Bower]

Thank you Joe, and thanks for reading my long post. I’m looking forward to how much better the iMac pro will perform to my current setup. I think I will go with the specs I mentioned and maybe the 10-core and change my work flow to at least “leave files in place”. If I need to generate some proxies, like from drone footage or anything else that is not playing back I’ll do that instead of transcoding clips in compressor. I will have a big job going back and replacing all the mxf files that are compressed to 4k sharing services, but it sounds like that is not good to have those compressed clips in such a high end project. If I can’t edit them natively, I’ll go for proxies first. I’ve heard this a lot, so I know it must be worth changing. Plus the large fcp libraries were hard to deal with and back up.

Thanks again!

Videographer/Ecologist
MPG Ranch Montana