Compress Videos on an SSD or SD Card from Your iPhone, iPad or Mac

Published October 19, 2026.

You come back from a trip with a card full of drone or camera footage. Importing it all into Photos would fill your iPhone, and copying it to a laptop first means carrying one. What you want is smaller files on the card itself, so the footage fits wherever it ends up.

HEVCut's External drive tool does that. You pick a folder on an SD card, SSD, or USB drive, and HEVCut compresses the videos and photos inside it right there, on your iPhone, iPad, or Mac. This guide covers the steps, which files it reads, exactly what it writes, and why deleting originals on a drive needs more care than in Photos.

For cables, readers, and transfer speeds, see SD cards, readers, and cables for DJI to iPhone transfers and Import video footage to iPhone via USB-C. This guide starts once the drive is connected.

Quick answer

Connect the card or drive, open HEVCut, and tap External drive on Home.
Pick the card or a folder on it.
Tap Process. Each file gets a compressed copy next to it, named after the original with _compressed added.
Check a few results, then delete originals only once you're sure, because deleting on a drive is permanent.

Before you start

Check the drive format. Apple says an external drive used with iPhone must have a single data partition and be formatted as APFS, APFS (encrypted), macOS Extended (HFS+), exFAT, FAT32, or FAT. Most camera and drone cards use exFAT or FAT32.

Make sure the card can be written to. HEVCut writes the compressed file to the drive, so the drive needs free space and write access. Many SD cards have a small lock switch on the side. Apple's support article for the Mac SD card slot says a "cannot be modified" message can mean the slider is in the locked position.

Power big drives. The same Apple page on external storage notes that external hard drives often need their own power source when connected to an iPhone, for example through a powered USB hub.

Compress files on a drive

Compress videos on an SD card or SSD with HEVCut

01
Connect the card or drive. On iPhone or iPad, use a USB-C drive or card reader, or Apple's camera adapter on a Lightning model. On a Mac, use the SD card slot if it has one.
02
Open HEVCut and tap External drive on Home. The file picker opens.
03
Choose the card or a folder on it, such as DCIM. HEVCut includes every subfolder. On the External Storage screen, Select Folder and Change Folder open the same picker.
04
Wait for the scan. File names and sizes appear first, then duration, resolution, and frame rate fill in.
05
Check your settings with the gear (Settings) in the toolbar, and use the sort menu to put Largest Files or Most Savings first.
06
Tap Process to compress every file that can shrink, or tap single files to queue just those. Keep the drive connected until the queue finishes.
07
Review the results. Open a file and choose Keep Compressed or Revert, or use Commit or Undo in the toolbar for every compressed file at once.

Which files HEVCut reads

HEVCut looks through the folder you pick and all of its subfolders, and skips hidden files.

Kind	Extensions
Video	`.mp4`, `.mov`, `.m4v`, `.hevc`
Photo	`.heic`, `.heif`, `.jpg`, `.jpeg`, `.png`, `.avif`

Other video containers, such as .mkv, .avi, .mts, or .webm, can show up in the list, but Apple's video frameworks may not be able to read them. If a file can't be read, HEVCut reports an error and leaves the file alone. Other files on the card, such as low-resolution proxy files or thumbnails with their own extensions, are ignored.

You can sort the grid by Largest Files, Longest Duration, Most Savings, Newest First, or Oldest First. A file that HEVCut estimates won't shrink by at least 5% is marked as optimized and isn't queued.

What HEVCut writes to the drive

HEVCut never changes the original file. It writes a new file into the same folder:

Original	Compressed copy
`DJI_0042.MP4`	`DJI_0042.MP4_compressed.mov`
`IMG_0042.JPG`	`IMG_0042_compressed.heic` (or `.avif`)

Video copies keep the original file name and extension before _compressed, so two clips that differ only by extension never collide. Photo copies use HEIC or AVIF, whichever you picked in Photo Compression settings.

A few details matter once you move these files elsewhere:

Dates are kept. The compressed file gets the original's creation and modification dates, so it sorts next to the original in Files and Finder. A compressed video also carries the clip's capture date inside the file, taken from the clip's own metadata or, failing that, from the file date.
The encode is written on the drive. HEVCut writes to a temporary folder next to the original and renames the result only when it's finished, so a _compressed file appears only once it's complete. The drive needs enough free space for the new file.
No bigger files. If the result isn't smaller than the original, HEVCut keeps only the original and tells you: "Compression did not produce a smaller file. Your original was kept."
Already compressed is skipped. A file that already has a _compressed copy next to it isn't compressed again. A _compressed file whose original is gone shows up as its own item, so you can compress it harder if you want.

Settings: the same presets as your library

The drive uses the same settings as library compression, from the gear in the toolbar. Video presets (Gentle, Standard, High, Maximum) cap output at 1080p, and Maximum at 720p, unless you turn on Keep original resolution, which is free. Drone footage you plan to edit later is a good case for keeping 4K. Keep 4K or drop to 1080p? has the numbers for each preset.

Video output is HEVC in a .mov file. HDR footage stays HDR (HLG or HDR10) in 10-bit HEVC. Photo presets cap the long side at 3840, 2560, or 1080 pixels.

HEVCut compresses footage on an SD card or SSD in place, on your iPhone, iPad, or Mac, with nothing uploaded.

Try free

Deleting originals on a drive is permanent

In your Photos library, deleted originals sit in Recently Deleted for 30 days. A drive has no such safety net: when HEVCut deletes a file there, it's gone.

One file: open it and tap Keep Compressed. This deletes the original right away, without a second prompt.
All compressed files: tap Commit (the checkmark) in the toolbar. HEVCut asks first: "This will permanently delete the original files. This action cannot be undone."
Changed your mind: Revert on one file, or Undo in the toolbar for all, deletes the compressed copies and keeps every original.

Files that are queued or being compressed are locked, so you can't delete them mid-run.

Keep a backup until you've checked

Play a few compressed clips, especially fast pans, low light, and HDR shots, before you delete originals. If the footage matters, keep the originals on a second drive or computer until you're happy with the results.

Running alongside library compression

HEVCut encodes one video at a time, and its library queue and drive queue never run together. If your Photos library is compressing, tapping Process shows Already Compressing with "Your photo library is still compressing. Wait for it to finish, or stop it, before compressing files on a drive." The same happens the other way around. Picking a different folder also stops a drive run in progress.

On iPhone and iPad with iOS 26, a drive run keeps going after you leave the app, with the same system progress bar as library compression. See How to compress iPhone videos in the background. Keep the drive plugged in while it works. On a Mac, the run continues while you use other apps; see How to compress your Photos library on a Mac.

Pro tip

On a trip, compress the card each evening, check a few clips, delete the originals you're sure about, then import the smaller files into Photos. For a full trip routine, see Travel-proof DJI to iPhone workflow and Batch compress a DJI vacation on iPhone.

Frequently asked questions

Does HEVCut copy my footage to the iPhone before compressing it?

No. It reads each file from the drive and writes the compressed file into the same folder, next to the original. Your Photos library isn't touched, and nothing is uploaded.

Which video formats can HEVCut compress from a drive?

MP4, MOV, M4V, and HEVC video files, plus HEIC, HEIF, JPG, PNG, and AVIF photos. Files in other containers, such as MKV, AVI, or WebM, can appear in the list, but your device may not be able to read them. If a file can't be read, HEVCut reports an error and leaves it as it is.

Can I get my original back after deleting it from the drive?

No. A drive or SD card has no Recently Deleted album, so deleting an original there is permanent. HEVCut warns you before a batch delete. Back up anything you can't replace before you delete originals.

Why is a file marked as already optimized?

HEVCut only compresses files it estimates will shrink by at least 5% with your current settings. Tapping such a file opens its details instead of queueing it. A stronger preset may make it eligible.

Can I compress my Photos library and a drive at the same time?

No. HEVCut runs one queue at a time. If one is running, starting the other shows Already Compressing with the name of the running queue. Wait for it to finish, or stop it first.

Does it work with the free version?

Yes. Drive compression uses the same presets and the same free compression allowance as your library. Keep original resolution is free; Fine-tune needs Pro.