Final Cut Pro - How do I make my file size smaller?

There’s nothing wrong; you’re not using the application correctly.

1. You might be creating proxy files or optimized files or render files, some of which might be very large and also very unnecessary. If your system drive is limited you should work on an external SSD.
2. FCP has many export formats. You’re probably exporting a high resolution master file. Use an H.264 setting or an Apple Devices setting or one of the others.

Having 100GB available is not much to begin with.

There are a number of things that can trip a new user.

You should start by doing this:

1) In Preferences->Playback, UNcheck "background render"

2) In Preferences->Import, UNcheck all the transcoding options

3) Select your library, and from the File menu choose "Delete Generated Library Files". Check all the boxes, including All Render Files, and confirm.

4) Close the library and reopen it (or quit and restart FCP).

You have now recovered several GB and won't as easily generate a lot of huge and unnecessary files.

Ian

I agree that Compressor or HandBrake allow you to make much smaller videos, and for most people they are still plenty good enough. I am grateful for having that option, and I do use it on occasion.

However, it may be useful to know this: if you try to export a "talking head" video directly, using FCP, "Export File", "Video and Audio", H264, you will see that the end result is much much much smaller than the initial estimate.

The nature of the video allows it to be much compressed, and it ends up with a smaller bit rate, and hence a smaller size.

I have done hundreds of those in the last two years, teaching remotely during the pandemic.

A one hour class in 1080p or slight greater (I edited in whatever frame size Zoom output) is only a few hundred MB, not several GB.

You can go even further to reduce the file size of your final movie.

FCP X can be overkill when it comes to exporting your video as a typical 1080p project will be encoded with a bit rate of around 20Mbps.

This is erring on the side of safety but in many cases the bit rate can be reduced dramatically resulting in very much smaller files with virtually identical quality.

iMovie allows you to use a custom bit rate by dragging a slider . . . even as low as 3.33Mbps for a 1080p project. This would make your file only one sixth the usual size.

FCP X has no such features so you would have to make a custom preset with Compressor.

If you don't have Compressor, you can use the free app HandBrake.

In addition, there is a great thing you can do to smooth the learning curve.

Take some time to follow the excellent - and free - introductory course at izzyvideo.

You will, amongst many other things, understand what happened to you, and learn many more things that will avoid many headaches in the future.

The alternative settings under "Computer" simply reduce the frame size from 1080p to 720p, 480p etc. with a corresponding reduction in bit rate but that rate is still unnecessarily high for many purposes.

The Apple Devices and Web options appear to use a lower bit rate but it still seems to be around 15Mbps which is often 2 or 3 times higher than is absolutely necessary. If you check the bit rate of many 1080p YouTube videos you will find that they are often below 3Mbps . . . I am of course referring to the "talking heads" type and not the adrenalin-fuelled action-packed ones.

You are of course correct, Ian.

But it may be useful to the OP to note that FCP also has several other options for export, that may produce smaller files

There are different options for "Apple Devices"; "Computer" allows for changing the export size too.

And for the ultimate "post stamp" experience (I am old enough to remember when Quicktime first appeared in 1991 😎)

there is an "e-mail" export setting... not useful for distribution, but if you want to show the gist of what you are doing and can only send by e-mail, or you are nostalgic for thes old days...

That sounded exciting but I can't replicate the smaller file sizes you mention.

I exported a 34 second 1080p talking head clip using Computer and the result was a video bit rate of 20Mbps.

I then tried the Video and Audio setting with H.264 and that video bit rate ended up even higher at 25.1Mbps producing a file of 105MB for the 34 second clip.

Incidentally the original talking head clip (not mine) was only 2.775Mbps and beautifully sharp and smooth.

A few years ago I tested FCP bitrates with H.264 1080p output (I have now switched to H.265):

Apple Devices Better Quality: 10.15 Mbit/s.

Computer Better Quality: 19.76 Mbit/s.

Web Hosting: 14.95 Mbit/s.

Apple ProRes 422 120.77 Mbit/s.

Compressor is IMHO a quite cheap FCP add-on that enables more tweaking.

And then there is ffmpeg which is just as good or maybe even better with some learning curve. For example .mov ProRes PCM to .mp4 H.265 AAC (edit -crf for quality and -preset for encoding speed etc):

ffmpeg -i input.mov -c:v libx265 -pix_fmt yuv420p -crf 18 -preset slow -timecode 00:00:00:00 -tag:v hvc1 -c:a aac -b:a 128k output.mp4

or the same as a batch:

for i in *.mov; do ffmpeg -i "$i" -c:v libx265 -pix_fmt yuv420p -crf 18 -preset slow -timecode 00:00:00:00 -tag:v hvc1 -c:a aac -b:a 128k "${i%.*}_converted.mp4"; done

I have installed ffmpeg with MacPorts, Homebrew might be more user friendly but not so kosher.