iPhone 17 pro res video help.

[Apleeseed84]

I got the 17 pro last week, took it on a weekend trip the following day and tried experimenting on it. I didn’t know that the only way to record 4k hdr 120hz is by using an external storage device. I didn’t have an ssd drive but I did have an usb c/sd card reader handy with a 1tb sd card with v30 recording speeds.

I used it a few times, but since I was recording in a hurry, I never realized that the iPhone prompted me that my usb c sd card reader(apple branded) had slow recording speeds.

The videos were recorded all right, but the frame rate is slow and jumpy. Is there a way to salvage the recordings using IMovie like seeing if I can reduce the frame rates? I’m new to all this. I tried exporting them to my iPhone it’s 240gb of video and currently my iPhone doesn’t have enough space and iMovie won’t recognize my external sd card reader.

Another apple customer service rep told me to talk to an apple support technician under the support app. Funnily enough i did my Apple personal session after the trip which helped me understand the camera, after the trip. I’m prepared for my next trip, I found some fast portable ssd portable hard drives for my next trip but i thought I was being a genius by using the portable sd card reader. Anyone else had an experience with this?

 

[Kottu]

1. Recording requirement: iPhone 15 Pro/Pro Max can only do 4K 120 fps ProRes if it’s writing directly to fast external storage. Apple’s card reader + V30 SD card is way too slow (V30 = ~30 MB/s minimum sustained speed; 120 fps ProRes can need ~400–800 MB/s). That’s why the footage came out stuttery.
2. Resulting video files: The iPhone still wrote files, but because the storage couldn’t keep up, frames got dropped → you see that “jumpy” playback.
3. Editing situation:
   • iMovie on iOS doesn’t read directly from external drives/card readers. You’d need to copy footage into the iPhone/iPad first, which isn’t practical with 240 GB if you don’t have the space.
   • Even if you could import, iMovie won’t “fix” dropped frames; the missing frames are gone. At best, you can re-interpret the footage at a lower frame rate so it plays more smoothly (e.g., 30 fps instead of broken 120 fps).

What you can do

• On Mac (best option):
  • Copy the SD card footage to a Mac with enough storage.
  • Use Final Cut Pro, DaVinci Resolve (free), or Premiere Pro.
  • Re-interpret footage: tell the software to play it back at 24/30/60 fps. This can make it appear smoother because it isn’t trying to hold to 120 fps when frames are missing.
• 
  
• On iPad/iPhone (limited):
  • Without enough free storage, iMovie won’t help.
  • If you have an iPad with USB-C and more space, you could try importing there.
  • Alternatively, use LumaFusion (paid app, but way more flexible than iMovie). It can sometimes read from external drives and also lets you change project frame rates.
• Practical salvage tip:
  The videos aren’t ruined; they just can’t play at the frame rate you intended. If you downconvert them to 30 fps or 24 fps in editing, they’ll look more watchable (though not true slow-motion).

Courtesy: ChatGPT