Three ways to speed up a screen recording on Mac and Windows — and why the 8GB file you started with is the real problem, not the speed.
You recorded a two hour session. The file is 8GB, and playing it back at 1x is unwatchable. So now you're looking for the setting that makes it go faster.
There are a few ways to do it, and I'll go through all of them. But I want to be upfront about something first: speeding up a recording after the fact fixes the watching problem and none of the others. You still recorded every frame, you still filled the disk, and you still have to sit through an export. If that's the part bothering you, skip to the last section.
Speed it up in QuickTime (macOS)
QuickTime can't do it. That's the short answer and it surprises people.
QuickTime Player will play a file back faster with the arrow keys, but there's no way to export at that speed. What you're changing is playback, not the file. Close it and reopen and you're back to 1x.
If you're on a Mac with iMovie installed, that's the free path: drop the clip on the timeline, click it, open the speed controls, and set it to the fastest option. iMovie caps out at 20x, which sounds like a lot until you do the maths on a two hour recording — 20x turns 120 minutes into 6 minutes. Still long.
Speed it up with ffmpeg
If you're comfortable in a terminal this is the fastest and most flexible option:
ffmpeg -i input.mov -filter:v "setpts=0.05*PTS" -an output.mp4
setpts multiplies each frame's timestamp. 0.05 is 20x faster (1 divided by 20). For 60x, use 0.0167. The -an drops the audio, which you almost certainly want — sped-up audio is unusable and dropping it saves you a re-encode of a track nobody will hear.
One thing worth knowing: this throws frames away at playback time but still has to decode every single one of them first. On a long recording it's slow, and it will heat your machine up.
Speed it up in your editor
Premiere, Final Cut, DaVinci Resolve and CapCut all do this properly. Right-click the clip, find speed/duration, type a percentage. 2000% is 20x. Resolve and Premiere will happily go far beyond that.
The advantage over ffmpeg is that you can see what you're doing and trim first. The disadvantage is that you've now opened a full video editor to perform one operation, and you're still working with the enormous source file.
Why the file is so big
Here's the part that took me a while to internalise.
A screen recorder captures at a fixed frame rate — usually 30 or 60 frames per second. Two hours at 30fps is 216,000 frames. Every one of those gets encoded and written to disk, whether or not anything on screen changed.
When you speed that up 20x afterwards, you throw away 19 of every 20 frames. You did all the work of capturing them, storing them, and decoding them, and then you discarded them. The 8GB was spent to produce a file you were always going to shrink.
That's the actual inefficiency. Not the speed — the capture.
Record at an interval instead
The alternative is interval capture, which is what a timelapse actually is. Instead of recording 30 frames a second and discarding most of them, you capture one frame every N seconds and keep all of them.
Set an interval of 2 seconds on that same two hour session and you get 3,600 frames instead of 216,000. At 30fps that plays back as a 2 minute video. The file is a couple hundred megabytes rather than 8GB, there's no speed-up step, and there's no export that takes longer than the thing you're exporting.
The trade-off is real and worth stating: you have to decide the interval before you record, not after. If you pick 10 seconds and it turns out you wanted 2, you can't get those frames back — they were never captured. My rule of thumb is to go finer than you think you need, because a 2 second interval can always be thinned out later, and 10 seconds can't be filled in.
If you want to work out the right number before you hit record, I built a frame interval calculator that takes your session length and target video length and gives you the interval.
Which one should you use
Genuinely depends on what you have:
- You already have the recording and just need it shorter — ffmpeg if you're comfortable with it, your editor if you're not. Nothing else to think about.
- You do this occasionally — same answer. Not worth changing your workflow for something you do once a month.
- You do this every week — record at an interval. The time you save on exports alone will pay for the change in a couple of sessions, and you stop losing a chunk of your drive to source files you delete afterwards.
I fell into the third category, which is most of why Tau exists. I was recording coding sessions to keep myself focused, and the part that eventually annoyed me enough to do something about it wasn't the speeding up — it was watching a progress bar crawl through an export of footage I'd already decided to throw away.