The only reason to use optimized or proxy is if your Mac is not powerful enough to playback the multicam well enough to edit with. Build the multicam, try it out, see if your system can handle it. If so, great. If not, then optimize or use proxies.
The Apple support recommends optimization for a clean and a smooth workflow if heavy FX applied incl multicam clips.
On the other hand, my iMac handles pretty well 1080p projects, but I'm concerned about more about quality, clean output than speed.
Just to confirm, do I need to optimize the files to ProRes for multicam if I plan to do VFX or keep using avc1 codec(Canon 7d mk2) in multicam loaded 1080p project?
Much appreciated for the support.
FCPX can make use of Intel's Quick Sync. Intel's Quick Sync helps playback H.264 video files but it will not help playback all forms of H.264. I say use the H.264 files and see what happens. It might work.
So, have you tested output yet? What FX exactly are you using?
I use a lot stabilize FX, optical flow, compositing, motion FX plugins and audio FX. Had some degraded, noticeable choppiness or lack of smooth results, particularly on the section of the clips where stabilize FX, optical flow, speed ramp FX applied.
In contrast to above where no FX applied, the avc1 clips behaved fairly fine when used in the multicam or even in complex compound clips.
Is it to do with smooth frame based edit where optimised ProRes make it possible for clean output or render better results when transcode the master projects in compressor?
FYI, I'd no issues before when offloading the footage direct from CF cards with optimized option ticked. I wish all high end DSLR cameras had a ProRes recording option like RAW recording as in some pro cameras.
Choppy playback is only playback, it won't output that, it'll output smoothly. So this is only dealing with playback for editing. Render the section your working on should help. AVC1 will take some effort for a computer to playback smoothly. What Mac (year model specs) do you have? Are you editing on the system drive or on a very fast external drive? Does your camera have an H.264 option to record in?
iMac 27 5K (mid 2015) and MBPr mid 2012 on the go, Mojave 10.14.6 running on external portable SSD runs both machine, as for the project library and media they're on Promise Pegasus R4
the footages imported from CF, the camera Canon 7Dmk2 avc1 is in .mov container.
In the past, I'd always optimised the media imported from the camera above in the past and edited the 1080p projects with ProRes 422 codec blissfully and deliver the finals in 720p very clean and efficiently. But lately, due to constraints of space on the R4 and high volume of work, had to change the workflow started editing on avc1 clips straight without optimising. Although the hardware set up as it is overly sufficient, I keep having above issues reflected not just on playback but in master files and final delivery. It sounds a bit bizarre, found no solution yet.