Background and testing
I’m trying to backup my iCloud Photo library. Previously I used the iCloud for Windows application, and it would let me download full years at a time. So each year I would download the previous year.
iCloud for Windows has since been updated and now no longer has the ability to download full years. Now it integrates into Windows Explorer, similar to OneDrive and Google Drive.
The application doesn’t allow you to choose where to store the files. It defaults to:
%userprofile%\Pictures\iCloud Photos\Photos\
If you’re like me with hundreds of gigabytes of photos and videos and not enough space on the C drive, you’ll need to create a folder link to solve this issue.
The “streaming” file structure idea is very convenient. I set my backup software (SyncBack) to back up this location. This would actually finally allow me to do incremental backups and be able to sync edits and deletions. So I thought…
As the sync task was running, the iCloud files went from being available online only, to downloaded to my local drive:
From “Available when online”: 
To “Available on this device”: 
This makes sense, and I was impressed that SyncBack was able to do this, I thought it might have just backed up the shortcut “stub files” but no, it triggers a full download while backing up. I was interested to know if later when I was running an incremental backup, and the file was only online, not downloaded to the local drive, whether it would re-download it locally when comparing the backup source and destination.
I was monitoring the downloads and I noticed that some video files couldn’t open! I realised that these “corrupt” files all had no data in the metadata field “length” so I could see in file explorer how many were affected, and there were lots.. Video files that were OK, had a value in the length field.
I checked on my phone and I was able to play one of these “corrupt” video files on the phone OK. So at least it’s not corrupt in iCloud.
I then tracked the same file down on https://www.icloud.com/photos/
This gets interesting:
Default download defaults to “Most Compatible”:
If you click on the little down arrow on the cloud icon or the 3 dots you get more options:
So here’s what you get:
01 - Copied from Windows Explorer iCloud folder. This file is corrupt and won’t open. No metadata.
02/03 - Default or “Most compatible” download from icloud.com. Highly compressed version of the video. 1280x720 resolution in h264. Incorrect metadata. Showing the wrong time for “media created”.
04 - “Unmodified Original” download from icloud.com The real original file. 3840x2160 in h265 and correct metadata.
Going back and investigating videos that haven’t corrupted they have been converted! The files that show up in iCloud Photos in Windows explorer open/download as h264. The originals are h265 (HEVC). So not only are heaps corrupt, but ALL are re-encoded, lower quality files if you use iCloud in File Explorer.
I went to compare one of the image files. Live photos are missing too. The file is the same from iCloud website
You can see how much extra space the re-encoding is taking up. Even if it doesn’t corrupt the file you don’t want double the file size and the loss of quality!
Here is an example of a non-corrupt video:
01 - Copied from Windows Explorer iCloud folder. Incorrect metadata. Wrong date and time for “media created”. 3840x2160 h264. Much larger file size than original. 292MB
02 - Default or “Most compatible” download from icloud.com. Highly compressed version of the video. 1280x720 resolution in h264. Incorrect metadata Showing the wrong time for “media created” (1 minute out).
03 - “Unmodified Original” download from icloud.com The real original file. 3840x2160 in h265 and correct metadata smaller file size of 152MB.
Final test was downloading image files:
01 - Copied from Windows Explorer iCloud folder. This is the original file. 4032x3024 .heic Great! However it’s missing the accompanying “live” video.
02 - Default or “Most compatible” download from icloud.com. Downloads a .zip with a re-compressed .jpg for the image and re-encoded .mov for the “live” video. The image is 2048x1536 .jpg. So it’s downscaled and converted. The .mov is scaled down and re-encoded 960x720 h264. I won’t compare the metadata because these sidecar .mov for live photos probably don’t have much of a standard. I did have a quick look in exiftool and it does have embedded metadata that shows when it was taken.
03 - “Unmodified Original” download from icloud.com. Downloads a .zip with a .heic for the image and a .mov for the “live” video. These are the real original files. The image is 4032x3024 .heic. The video is 1920x1440 in h265 at a larger file size of 3MB.
