Easy 4K Workflow

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In the last post I questioned the visual value of 4K. However, it’s inevitable that more and more distributors will be asking for 4K deliverables, so you might as well start planning how you are going to achieve that. There are certainly plenty of demos showing how easy it is to edit 4K content and they use iPhone video for the demo material. The reality is that such footage is crap and should only be used when it’s the only camera available. At the low end, there are plenty of cameras to choose from that work with highly-compressed 4K images and yet, yield great results. The Blackmagic Design URSA Mini, Sony FS7 and Canon C300 Mark II come to mind. Bump up to something in a more cinema-style package and you are looking at a Sony F55, RED, ARRI or even the AJA CION.

df1816_easy_4k_1While many cameras record to various proprietary compressed codecs, having a common media codec is the most ideal. Typically this means Apple ProRes or Avid DNxHD/HR. Some cameras and standalone monitor/recorders can natively generate media in these formats. In other circumstances, it requires an interim transcode before editing. This is where system throughput becomes a big issue. For example, if you want to work with native 4K material as ProRes 4444, you are going to need fast drives. On my home Mac Pro tower, I have two internal 7200RPM spinning drives for media striped as RAID-0. In addition to these and the boot drive, I also have another internal SSD media drive. When I checked their relative performance with the AJA System Test utility, these clocked at 161 write /168 read for the RAID-0 stripe and 257/266 for the single SSD. That’s good enough for approximately 27fps and 43fps respectively, if the media were large 3840 x 2160 (2160p) ProRes 4444 files. In other words, both drive units are adequate for a single stream of 2160p/23.98 as ProRes 4444, but would have a tougher time with two streams or more.

Unfortunately the story doesn’t end with drive performance alone, because some NLEs handle real-time playback of 4K media better than do others. I’ve performed a number of tests with 4K files in Apple Final Cut Pro X, Adobe Premiere Pro CC, Avid Media Composer and Blackmagic Design DaVinci Resolve. This has been on a number of different units, including a couple of Mac Pro towers, as well as a newer “trash can” Mac Pro. Plus, I’ve run tests with local drives, attached media RAIDs, and network-attached storage systems. What I’ve found is that as long as you have fast drive performance, then the bottleneck is the NLE.

Pretty much all of these choices can handle a single stream of 4K media without too much of an issue. However, when you stack up a second layer or track for a simple 2D PIP composite, generally the system struggles. In some cases, FCPX has performed better than the others, but not consistently.  The others all choked to varying degrees. When you limit it to a single stream of 4K video with associated audio, then FCPX performs more fluidly at a higher quality level than Media Composer or Premiere Pro, although Media Composer also performed well in some of the tests. My conclusion, for now, is that if you want to work with native 4K media in a client-involved session, and with the least amount of rendering, then FCPX is the clear winner – at least on the Mac platform. For many editors it will be the most viable choice.

Native workflow

The first big plus for Final Cut Pro X is how easily it works with native media that it’s compatible with. That’s one thing I don’t generally advocate on a large project like a show or feature film – opting instead to create “optimized” media first, either externally or within FCPX. Nevertheless, a lot of native codecs can be quite easy on the system. For example, one client cut an indie feature, using all native camera files from his Sony FS7. His Final Cut system was a tricked out iMac that was a couple of years old and a Promise Pegasus RAID array. Initially he cut the film from native 4K FS7 files to an FCPX 1080p timeline. I was doing the grading in Resolve, so I had him export a single, flattened movie file from the timeline as 1080p ProRes 4444. I brought this into Resolve, “bladed” the cuts to create edit points and applied my color correction. I exported a single ProRes 4444 master file, which he could import back into FCPX and marry with the post-production mix.

df1816_easy_4k_2Fast forward a year and the film distributor was inquiring whether they could easily produce a 4K master instead of a 1080 master. This turned out to be relatively simple. All my client had to do was change his FCPX project (timeline) settings to 4K, double-check the scaling for his clips and export a new 4K ProRes 4444 file of the timeline. In Resolve, I also changed the timeline setting to 4K and then relinked to the new 4K file. Voila! – all the cuts lined up and the previous grades all looked fine. Then I simply exported the graded 4K file to send back to the client.

In this example, even with a roundtrip to Resolve and a change from 1080p to 2160p, FCPX performed perfectly without much fuss. However, for many, you wouldn’t even need to go this far. Depending on how much you like to play and tweak during the color grade, there are plenty of ways to do this and stay totally inside FCPX. You could use tools like the Color Board, Hawaiki Color, Color Finale, or even some home-brew Motion effects, and achieve excellent results without ever leaving Final Cut Pro X.

As a reminder, Media Composer, Premiere Pro CC and Resolve are all capable of working with native media, including 4K.

Proxy workflow

df1816_easy_4k_4In addition to native 4K post, Apple engineers built an ingenious internal proxy workflow into Final Cut. Transcode the camera files in the background, flip a toggle, and work with the proxy files until you are ready to export a master. When you opt to transcode proxies, FCPX generates half-resolution, ProRes Proxy media corresponding to your original files. As an example, if your media consists of 2160p XAVC camera files, FCPX creates corresponding 1080p ProRes Proxy files. Even though the proxy media’s frame is 1/4th the size of the 4K original, FCPX takes care of handling the scaling math in the timeline between original and proxy media. The viewer display will also appear very close in quality, regardless of whether you have switched to original/optimized or proxy media. The majority of legacy A/V output cards, like a Blackmagic Design Decklink, are only capable of displaying SD and HD content to an external monitor. FCPX can send it the proper data so that a 4K timeline is displayed as a scaled 1080 output to your external video monitor.

Although proxies are small for a 4K project, these are still rather large to be moving around among multiple editors. It’s not an official part of the Final Cut operation, but you can replace these generated proxies with your own versions, with some caveats. Let’s say you have 3840 x 2160, log-gamma-encoded, 4K camera files. You would first need to have FCPX generate proxies. However, using an external application such as EditReady, Compressor, etc, you could transcode these camera files into small 960×540 ProRes Proxy media, complete with a LUT applied and timecode/clip name burnt in. Then find your Proxy Media folder, trash the FCPX-generated files and replace them with your own files. FCPX should properly relink to these and understand the correct relationship between the original and the proxy files. (This post explains the process in more detail.) There are several caveats. Clip name, frame rate, clip length, aspect ratio, and audio channel configurations must match. Otherwise you are good to go.df1816_easy_4k_3

The benefit to this solution is that you can freely edit with the proxies on a lightweight system, such as a MacBook Pro with a portable drive. When ready, move back to a beefier unit and storage, flip to original/optimized media, double-check all effects and color-correction on a good monitor, and then export the master files. It’s worth noting that this workflow is also potentially possible with Premiere Pro CC, because the new version to be introduced later this year will include a proxy editing workflow.

Naturally there is no single solution, but Final Cut Pro X makes this process far easier than any other tool that I use. If 4K is increasingly looming on the horizon for you, then FCPX is certainly worth a test run.

©2016 Oliver Peters