A common question I get these days is: “I’m editing 30-60 minute video projects. How powerful a computer do I need?”
The answer is easy: Video editing software doesn’t care about duration. What affects the amount of computing power you need are:
This answer is true for Final Cut, Premiere, Express, Resolve, or any other NLE. Let me explain why.
Let’s pretend I’m editing a ten-minute travelog on my recent trip to New Zealand. I have footage that I shot on scene and animated maps that show where I traveled around the two islands. These two media folders total 431.11 GB of media.
However, I only have 32 GB of RAM available. Hmm… clearly it is impossible to load 431 GB of media into 32 GB of memory! And, in fact, no NLE does.
Here, I’ve edited these clips into a breath-taking sequence of visual perfection. (Smile… since I don’t plan to show you this edit, we can easily assume it’s perfect.)
Yet, when we look at the memory allocation displayed during playback in Activity Monitor, Final Cut is using less than 700 MB of RAM! Looking at the distribution chart at the bottom, the total of all apps open at this instant on the computer are using about 17 GB of RAM, with another 7 GB used for cacheing.
Surprisingly 6 GB of RAM isn’t even used!
NOTE: Free (unused) memory is calculated as (Physical Memory – Memory Used – Cached Files). Swap is when the application you are running requires more memory than is available. At that point, macOS moves (swaps) files stored in RAM to the hard disk temporally to clear room for the currently active application. System performance slows when the operating starts swapping files so, in general, you want this number to be zero.
However, to be truthful, macOS is so good at managing memory that I never worry about it. I illustrate it here simply to explain why the duration of a video project is not important from a system hardware point-of-view.
NOTE: You’ll find Activity Monitor in Applications > Utilities.
Let’s switch over to Premiere. Premiere caches media more aggressively than Final Cut. Importing the same clips and building a similar project, we see that Premiere is only using 4 GB of RAM during playback, while the computer is using about 20 GB for all applications, along with 11 GB of cached files.
NOTE: Cached files are files which are stored in RAM because they will be needed by an application, but are not yet in use. Since RAM is faster than any hard disk, this is a way to boost performance.
What’s happening with FCP, Premiere and other NLEs, is that they only load a few frames to a few seconds of all the media under or near the playhead. That way, when you press Play, the system responds instantly. As the playhead scrolls, the operating system loads the next few seconds coming up for playback. When playback stops, the system waits to see what you do next, then, as you move the playhead, it loads more media accordingly.
NOTE: If you have less RAM, less of each file is cached.
To provide dynamic preview, thumbnails of the entire project are cached so that as you skim, the system can display thumbnails in the timeline.
While memory management is more complicated than this, the key point is that media files are never fully loaded into RAM. Only those portions of media closest to the playhead are loaded, then flushed from memory as the playhead moves on.
SUMMARY
These statistics explain why we don’t need massive amounts of RAM for video editing. The software itself is designed to run comfortably in less memory than you have installed. Where extra RAM does help is in cacheing files, which speeds scrolling, rendering and multicam playback.
In general, based upon conversations with Apple:
Now you know.
