Manatee
How to shrink an hour-long meeting recording on a Mac
A one-hour video call recording that weighs 2 to 5 GB is mostly wasted space: the picture is a shared slide or a grid of faces that barely changes, recorded at a rate meant for fast motion. Somewhere between 300 MB and 1 GB holds an hour of video comfortably, and if nobody needs to see it, the audio alone is usually under 60 MB. Trim the dead time, decide whether anyone needs the picture, then shrink to a size you name.
Why an hour of talking takes up gigabytes
Three things usually combine.
- A generous, steady bitrate. Many recorders, whether a video call app’s own local recording or a general screen recorder, encode at a high rate chosen so that fast motion stays clean, and some hold it there regardless of what is on screen. They spend nearly the same bits on a slide that sits still for six minutes as on a scrolling spreadsheet. An hour of almost nothing changing still costs full price.
- The whole screen. If you recorded the call with the Mac’s own recorder (Shift-Command-5) and chose Record Entire Screen, it captured the whole Retina display, menu bar and all, at far more pixels than the call’s video ever had. A screen recording that turned into a 4 GB file explains how much that multiplies the size.
- Detail that was never there. The other participants’ video reached you already compressed for the internet. Recording it at a high bitrate preserves the call’s blur and blockiness in great detail, but it cannot add sharpness the call never carried. That is good news: shrinking a meeting recording costs far less visible quality than shrinking camera footage.
You can see the rate your file was recorded at. Select it in Finder and press Command-I for the size, then work it out: every 1 Mbps of bitrate costs about 450 MB per hour. A one-hour file of 3.6 GB was recorded at roughly 8 Mbps, several times what its content needs. QuickTime Player shows the figure directly: choose Window > Show Movie Inspector and read the Data Rate line.
First, decide who needs to see it
The right size depends on what the recording is for, so answer that before touching any settings.
- It is a record of what was said. Minutes, a transcript, a colleague who missed it and will listen on a walk, a note of who agreed to what. Nobody needs the picture. Keep the audio and skip the rest of the video advice.
- Someone needs the shared screen. A product demo, a training session, a walkthrough of a document or a dashboard. Keep the video, and keep it big enough that small text stays readable.
- Only part of it matters. If the useful material is the twelve minutes in the middle, trim to those first. Length is the one saving that costs nothing in quality.
What size is reasonable for an hour
Rough starting points for an hour of H.264 video, based on what the screen holds. They are not rules; a call that shared a playing video or a lot of animation needs more.
| What people need from it | Rough bitrate | One hour |
|---|---|---|
| Small text on a shared screen, 1080p | about 2 Mbps | about 900 MB |
| Slides and faces, 720p | about 1 Mbps | about 450 MB |
| Faces only, watched in a small window | about 0.6 Mbps | about 270 MB |
| Audio only, speech | 64 to 128 kbps | about 30 to 60 MB |
To scale for length, multiply the bitrate in Mbps by 7.5 to get roughly the megabytes per minute. A 40-minute call at 1 Mbps is about 300 MB.
Check where the file is going, too. A shared folder has no hard limit, but a 4 GB upload over home internet can take most of an hour, and everyone who opens it has to download the lot. An email attachment, capped at around 20 to 25 MB by most providers, only takes the audio of a short call, or a link.
Keep the picture: trim, then shrink to a number
- Trim the dead time. Open the recording in QuickTime Player, choose Edit > Trim, and drag the yellow handles past the waiting-for-people minutes at the start and the goodbyes at the end. Then choose File > Export As and pick 1080p (or the largest size listed, if the recording is smaller). That writes the trimmed copy as a new file, and a full-screen Retina recording comes down to 1080p on the way. If QuickTime will not open the file (browser-based call tools often save WebM), skip this step or convert the file to MP4 first.
- Open Manatee and choose Shrink. Type the size you want in MB: say 450 for an hour of slides and faces, or 900 if a shared screen full of small text has to stay legible.
- Drop the recording in. Drag it onto the window or the menu bar icon, or right-click it in Finder and choose Services > Fix with Manatee. The job list shows progress; an hour of video takes a while.
- Check the result. Manatee writes a new file next to the original and never modifies the original. Open the new copy, jump to a moment where someone shared their screen, and look at it full size. If the text is soft, shrink the original again with a larger number rather than shrinking the shrunk copy.
Manatee finds the quality that fits the size you typed, so you do not have to work out bitrates. It is not an editor: it will not cut a section out of the middle, blur someone’s face or remove a participant’s audio. And it runs entirely on the Mac, with no upload and no account, which suits a recording full of colleagues’ faces, client names and things said in confidence. Every feature is free for the first 24 hours, then $9 once.
When the audio is all anyone needs
If the picture is not needed, an audio file is the biggest saving available: an hour of speech is tens of megabytes rather than gigabytes. Before converting anything, look in the folder where the recording was saved, because some video call apps write a separate audio file alongside the video.
Otherwise, export it yourself:
- QuickTime Player. Open the recording and choose File > Export As > Audio Only. You get an M4A file holding the recording’s soundtrack, which plays on any Mac, iPhone and most other devices.
- WebM and MKV files, which QuickTime refuses. Convert the recording to MP4 with Manatee’s Convert mode first, then export the audio from that copy in QuickTime.
- MP3. If the destination asks for MP3 by name, drop the M4A into Manatee’s Convert mode and pick MP3. Otherwise M4A is the better default.
If the audio of a three-hour workshop is still too big for an email, how to make an audio file smaller to email from a Mac covers the bitrate arithmetic and the tools that let you set it.
Questions
Will shrinking make the shared screen unreadable?
Not at a sensible size. Static slides and documents compress very well, because most of each frame is the same as the last. Problems start when an hour of 1080p screen sharing is pushed well under 500 MB. Check a frame with the smallest text before you delete anything.
A colleague’s copy of the same meeting is a tenth the size of mine. Why?
Most likely theirs was processed by the call service before download, at a modest bitrate, while yours was recorded locally at a high one, or theirs shows only the active speaker rather than a gallery or a full screen. The content is the same; the encoding is not.
By the end of the recording, the voices are out of step with the faces. Will shrinking fix that?
No. That is clock drift between the audio and video, common in long recordings, and re-encoding carries it over. A two-hour recording that drifts out of sync by the end explains how to measure and correct it.
Should I keep the original?
Until you have watched the shrunk copy at a few points and scrubbed to the very end, yes. After that, the original is usually several gigabytes of the same meeting, and deleting it is a reasonable choice.