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Editing 4K video with a Mac Pro (late 2013)

by | Apr 10, 2014 | Blog, MAARTECH | 0 comments

Apple Canada graciously loaned me a well-equipped Mac Pro (late 2013) to use while editing the review of the Sony 4K FDR-AX1


After the first few days of shooting with the AX1, it was obvious to me that although my iMac (late 2009) could handle the 4K video – it was with lots of dropped frames and lots of waiting. Mostly frustrating, somewhat tedious. So the loan was very much appreciated.

What you cannot appreciate until you see it is how sleek and well designed this computer is. 

It is however, hard to review a computer with video. So my apologies for a video presentation that’s a little less visual than average.

 I contacted Sharp’s media relations team, but was not able to borrow a 4K monitor. I was able to connect my 27” iMac (2560×1440) as a monitor using target display mode and a mini-display port to mini-display port cable (hard to find, but it’s available from and canada computers in Toronto). After connecting, command-F2 to switch the display between the two systems on the iMac monitor. Neat! The 1440 resolution is nearly enough to enjoy the 2180 footage.

 Sony’s 4K TVs can display 4K through HDMI, but not from a file on USB. I took the MacPro to the Sony store to see the footage at full resolution. The TV and MacPro synced resolutions automatically – although the desktop is very small at 4K, even on a 65” set. The footage is brilliant. Worth noting that the MacPro does have some limitations for 4K output – only two of three outputs can be 60p. 

 We compared the original files from the camera with the edited footage and I did notice some colour degradation – and Sony’s Karol Warminiec explained that the extended x.v colour space (also called triluminous) wasn’t preserved in any software editor. He thought that the next release of Sony Vegas would support it. As a result some reds and greens are a little less vibrant in the edited footage. I expect that other NLEs including FCP will also include support by enhancements to their import and export filters.

 As I mention, the MacPro is quiet. I did watch power consumption using a Wemo insight switch. The average consumption during editing is about 120 watts – that’s less than my iMac, but of course, it doesn’t include a monitor. Interestingly, it cycles down much further than the iMac – less than 2watts in standby mode, which is about the same as off.

While rendering the youtube 4K output , it peaked up to about 240 watts for the two or so hours it took. I could feel the warm air rising out of the top of the unit, but still did not hear the fan.

 Watching memory usage, I noted that FCP doesn’t really use up 32GB until rendering starts. While editing, the memory footprint was in the 16GB range. So there’s clearly room to spare to run more apps, or further optimize the performance of FCP.

 And all that said, this is not the ultimate solution. Transitions don’t always play in realtime until they’re rendered, and I did experience an occasional beach ball moment while working. Editing HD on my iMac still flows a little more nicely than 4K on the MacPro. But I expect these (like so many things about 4K) are growing pains. Of course, I was editing at full res (using Apple ProRes files, which are automatically created on input by the XAVC-S filter) and using proxy files would eliminate all of those issues.

 The video is shot with my NEX VG20 video camera, and my westcott green screen kit. Pretty happy with the way those scenes turned out. Screens were recorded using QuickTime screen capture at 2560×1440. Edited in FCP 10.1 mostly on the iMac, final output at 1080. Interestingly (as you seen in the activity monitor in the video), even doing both full screen video capture and rendering a video file still doesn’t really stress the processor. 

 If you are editing video, I highly recommend a dedicated video editing keyboard (I used a standard bluetooth keyboard with the MacPro). The keycaps to provide shortcuts, colour coding and the numeric keys make it much simpler. I used a trackpad with the MacPro, and realize I prefer a mouse.

 Finally, I do wish that FCP wasn’t so rigid about some things. For example, I’d love to see the youtube file, or even just create the youtube version without uploading it automatically at the end of the render process. In the past it was a file that you could find, but even by opening the new FCP package file, it’s only there temporarily and gets deleted after its uploaded. (sigh).

 I welcome your comments and suggestions.

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