This was written in answer to a question on the AppleSupport Communities FCPX forum from freejunkpete that can be found here.
There are a lot of questions here, many of which overlap, and I’ll start off by saying there is no right answer, except perhaps for one. You almost never need to optimize on import.
“My project is quite large (making a 20min film with my entire source media totaling about 750gb, on my external 2TB HD). I elected to optimize the media when importing (it is not all imported yet, i am making the film in sections), and also to copy the files over.”
First, you should use the Delete Generated Library Files function to get rid of optimized, proxy, and render files. Remove them all to start with. If you have optimized, this is will resurrect a huge amount of drive space. So who needs to optimize and when? With a recent computer, with a fast processor and fast graphics capabilities, you almost never need to optimize to start. Your computer is capable of playing back the media without problem.
One of the default preferences is to optimize multicam clips. You should switch this off. If your system has difficulty playing back multiple streams of video because of processor capabilities, or more likely because of drive capabilities, increasing the file size to giant ProRes files will certainly not improve drive performance. If you have difficulty with playback for multicam clips, it’s much more beneficial to create proxy files, and that’s what I would recommend. You might want to use FCP feedback from the Final Cut Pro menu to request the option to select proxy files for multicam clips.
“I have since decided to leave files in place because the .fcpbundle file was just getting too massive (800gb+ and i have barely started editing, which means my ext HD is already running out of space). I read in other threads that you suggested turning background rendering off. Does this mean at some point there will be a huge rendering process that will need to occur? but in the interim it will save me space?”
There are many different questions in here that aren’t really related. Let’s consider the leave in place option. I almost never recommend this option, primarily because, a) you can’t leave camera media in place and have to make a decision for that, and b) because you quickly end up with media scattered in various places on the system and perhaps on multiple drives, which makes backup and archive much more complex and more likely to create mistakes.
The only time I use the leave in place function is if I move a file, like still images, into the library location (more about that in a moment), inside FCP’s Original Media folder. Then I import from that location and leave in place.
In Import preferences, set importing to copy to library storage location. This can be inside the library or outside, but do not use the leave in place option. You can always select this if you need it in the import window. It also means if you drag and drop, files will not be left in place, but will go into the library location.
I rarely recommend using the In Library option for importing media. Except for small projects, maybe a commercial with a relatively small amount of media, that you’re working on yourself, it’s usually better I think to specify a library location for your media. Whenever you need to collaborate, either with other users or with other applications, it almost always better to use external media, not managed media, which is media that’s stored inside the library.
Because you have changed your import options midway through the production you now have media both inside and outside the library and in different locations.
For most productions, it’s better I think to use an external location for your media. When you make a new library, select it in the Browser and in library properties in the Inspector, change the default library location for Media by clicking the Modify Settings button. For Media select choose and make a new folder on your media drive to store the media. I usually just give it the same name as the library, and it usually sits next to the library. For Cache I choose the same folder so the cache bundle is saved inside the media folder. For Backups I use the default ~/Movies location as it’s on the system drive, separate from the media drive. Now whenever I import, I import into the set library location. When I want to add audio or stills or other graphics files, I simply save them into the media folder that FCP creates inside the assigned folder. Then when I import I use the leave in place function because the files are already where they need to be.
So what to do about the state where there is media all over the place, both inside and outside the library bundle? This is what the Consolidate function is for. At any time you can create a new location for the library media. As described above, in library properties use the Modify Settings button to create a new library location. Once that’s set, use the Consolidate function to put everything into that folder. Clips that are inside the library will be moved to this folder and replaced with symlinks; clips that are outside the library will be copied into the library folder. Obviously it’s better if you do this right to start with rather than part why through the production.
The question of rendering is entirely separate from this, and again whether and when you render depends on your system capabilities. In most cases computer systems and graphics card are sufficient for playback even if there is reduced quality during playback. This will be most apparent on still images. When stopped, the image will look great, but during playback it will look soft or pixelated. Most editors accept the limitations of playback of unrendered media and opt for better performance. Maintaining the continuity and fluidity of editing is much more important to me than seeing a pristine image during playback. If I have effects applying and the computer drops frames and stutters in playback, I will accept that as a small price to pay for continuing creative work without interruption. If it gets bothersome, at that point I will select the area that’s causing playback problems and use the keyboard shortcut to force the area of the timeline to render. Remember, when you render you’re not rendering an individual clip, but an area of the timeline, all the layers and all the effects and content in a timeline area is selected and collapsed into a single high resolution, high data rate file. And remember that after you’ve worked on a section and moved on to a completely different part of the timeline, you can always discard the no longer needed render files.
“in my situation, in terms of importing, do you think i should just check the box for proxy files, leave 'copy files' unchecked, and turn off background rendering? Will this affect my final project in the long term? And also is there a way to rectify what I have already imported, to reduce its size?”
“as a related question, if i choose not to optimize as i import (to save space as well), will this affect the quality of the final film, or will the quality ultimately be there, but just not as i am editing?”
Whether you use optimized media, proxy files, whether you render or don’t render has absolutely no affect on the quality of the output file. In most cases when you’re sharing, the application is working directly from the original media files to the output file. All the other files are largely irrelevant. So when do you use optimized and proxy? I mentioned already using proxy for multicam media. If you are working with large format files, RED media, 2K or 4K media, you will always certainly want to create proxy files. You should be aware for these large formats proxy files are often not in the ProRes Proxy codec but in ProRes 422, which is small in comparison to the gigantic files created by media such as RED RAW. Proxy files are also useful if you want to use FCPX as an offline system, take the project on the road with a laptop. There is no real system for creating offline media with proxy files in FCP, though it can be done with care, but that’s another discussion. An option for creating an offline library might be another opportunity to visit the FCP feedback form.
There are instances when you might want to optimize. Many people working with color correction in FCP, using either the built in color board, or third party tools like Color Finale or HyColor Pro or Hawaiki AutoGrade, will want to optimize their media. Most H.264 based formats do not hold up well when using extensive color correction, which seems to have become the norm these days. Often it seems this is done just because it’s possible without real benefit, and to considerable distraction from the storytelling process; but that’s a different discussion. For extensive grading ProRes 422 will handle image manipulation far better than a heavily compressed format. What’s really needed at this point is a way to select the clips in the timeline and to have the application generate optimized files for the selected clips; again it's time to use that feedback form. When doing extensive effects and color correction work you may well want to optimize your clips using the transcode media function.
This has probably raised more questions than I’ve answered. Ask, and I’ll add an answer, at least an opinion. All of this is my opinion. There is no right way. There is no single answer to how everyone wants to work, and I’m sure many would disagree with me, but you asked my opinion, so here it is, for whatever it’s worth.
