Sony 4K XAVC-S Multicam not able to play smoothly!!!

Hi, I'm currently involved in a really huge project which contains many many interviews shot with Sonys A7S & FS7 & A7R - all in 4K! Now I wanted to cut the interviews inside of FCPX 10.3.1 and I am not able to play back the Multicam clip smoothly while editing it.
We made some more tests (Multicam clip just 1080p resolution) and tested the whole setup in Premiere and DaVinci. Premiere ran it perfectly smooth without dropped frames but I don't like the program and the project is currently in the middle so switching to Premiere would be a mess.

My question: Isn't FCPX able to run a 4K-3-CAM-1-AUDIO-MULTICAM setup without problems???

I do this literally every day without an issue. I generally have 3-9 cameras. If the drive is fast enough and there are no effects applied, I can do three cameras without proxies. With proxies, I haven't found a limit yet. I'm a little confused. You say it is 4k, but you say the multicam clip is 1080p. That may be your problem. You didn't really give much to go on. Computer stats, hard drive, are you working in a project that has different settings than the source (frame rate, ratio, etc)?

I am on a maxed out 2015 MBP. I generally work off bus powered USB-3 G-Tech drives, but I get better results with more robust drives and over thunderbolt. I always do my multicam cut in proxy with no effects. I haven't used Resolve in over a year, but I remember testing it and finding that it had playback issues that didn't work with my workflow. I have never heard of Premiere running better on a Mac than FCPX, usually the opposite is true.

I was also totally astonished! FCPX slower than Premiere in Multicam????

So here are my specs:
Mac Pro (2013) 12-Core 64 GB RAM 2xD700 1 TB harddrive

Footage:
1x SONY A7S
1x SONY A7R
1x SONY FS7

All shot in 4k 29,97

Multicam is like source material (4K 3840x2160 29,97).

We have a fibre connected Tiger RAID which gives us 600W-500R performance when everybody is working on. We tested the RAID in normal circumstances and played all 3 4K files directly from the hard drive - no problems. Even in a project at 4k and all 4k files stocked on another and scaled side by side - no problem. Just when watching them inside the multicam viewer and editing them - very worse performance.

DFPete wrote: ...many many interviews shot with Sonys A7S & FS7 & A7R - all in 4K! Now I wanted to cut the interviews inside of FCPX 10.3.1 and I am not able to play back the Multicam clip smoothly while editing it....tested the whole setup in Premiere and DaVinci. Premiere ran it perfectly smooth without dropped frames...Isn't FCPX able to run a 4K-3-CAM-1-AUDIO-MULTICAM setup without problems???

I regularly edit two-camera 4K multicam interviews, some of it shot on the Sony A7RII. Multicam H.264 4K can be challenging on any hardware or software. In general FCPX is much faster than Premiere CC 2017 when tested on the same Mac hardware. I have run back-to-back tests many times. Premiere keyboard lag is terrible when issuing JKL commands while doing FF/REV on an H264 4K timeline. It is so slow it feels like the keyboard is broken. When FF on a H264 4k timeline (not multicam) the program monitor update rate can be like a slide show -- once every 2 sec. This is on a top-spec 2015 iMac 27 with the media on a Thunderbolt 2 SSD RAID-0 array, and with Mercury Playback set for GPU acceleration using the Metal API.

That said, even FCPX is not fast enough on that hardware to be really smooth on multicam H264 4K. I usually transcode to proxy for this. I would expect a 12-core nMP with D700s would be faster and give more headroom before using proxy, but I haven't tested that. OTOH the Xeon CPU does not have Quick Sync which really expedites H264 encode/decode.

Fortunately for Premiere users, Adobe recently added proxy support. IMO it was virtually unusable without that on multicam H264 4K. Using proxy, Premiere is very fast. However it takes about 2x as long to create proxy files as FCPX but that's usually an unattended operation, so no big deal.

I can't explain your observed difference between Premiere and FCPX, as it is contrary to tests I have done many times. However Premiere does not support Quick Sync whereas FCPX does, so on an iMac that could be one reason FCPX is so much faster. On a nMP maybe there is less difference between Premiere and FCPX, since neither one can use Quick Sync due to the Xeon CPU not having it.

There are several things you can do to improve performance in FCPX:

(1) Change viewer from Better Quality to Better Performance

(2) Edit your 4k content in a 1080p timeline. This uses 1080p render files instead of 4k so it speeds up some tings. This does not preclude cropping or zooming into the 4k frame. When you export the project it uses the full original 4k resolution for this.

If you need to export in 4k you can copy/paste the edited 1080p timeline to a blank 4k project and do that. All 4k resolution will be retained.

(3) Use proxy mode. FCPX has superb proxy support and it's very easy to use. It need not be all the material. As a documentary editor I often deal with 50:1 or 100:1 shooting ratios, and FCPX can generally skim 4k content in the Event Browser OK. I skim it, mark favorites, rejects and keywords, then transcode to proxy only the clips I'll be using.

Thanks for all the suggestions. I made all that but it's not going to be better.
I think the most missing thing in the trashcan Mac Pros is QuickSync.

It just occurred to me, have you checked that you have all the codecs installed. After you install FCPX there are additional materials that need to be installed. Also ProApps updates through the app store provide new codecs periodically. Check and see if you have this installed:

support.apple.com/kb/dl1396?locale=en_US

Did you try proxies?

Yes of course! Much better performance. But it takes A LOT of time to transcode hours and hours of material.