This is the one part of the Compressor that catches people out, so it is worth two minutes.
Never put the output on the SD card
The app writes the shrunk photos to an output folder, and that folder must be on your computer’s drive — not back onto the SD card the photos came from.
The card is already nearly full of the originals, so there is rarely room for the output as well.
The app suggests a folder named after your source, like 200TLCPR_FeedbunkAI_Ready. If your photos are on an SD card or USB stick that is nearly full, it suggests a folder in Pictures on this computer. If the card has plenty of room, it suggests a folder right next to your photos — on the card.
Check the Output folder box before you start. If it points at the card, click Choose… and pick a folder on your computer, for example under Pictures.
Working space versus output size
The app tells you two numbers before it starts:
- Disk space needed during processing
- Free disk on output drive
The first is usually larger than the finished output, and for video jobs it can be very much larger. Extracting frames from a video writes large temporary files first and shrinks them afterwards, so a job that produces about 1 GB of finished photos can need many times that while it runs. That temporary space is released when the job finishes.
If the space it needs is more than the space that is free, the app warns you before you start:
The output drive doesn’t have enough free space: processing needs about X, but only Y is free. Choose an output folder on a drive with more space — for example this computer’s main drive. Part of this is temporary scratch space for video frame extraction and is freed when the job finishes.
If you click Start compression anyway, the job does not start. The app tells you how much space it needs and how much is free. Pick a drive with more room, or clear some space, then click Start compression again.
How much space will I actually need
For a straightforward folder of stills, the finished output is a small fraction of the originals — a card holding tens of gigabytes typically produces a couple of gigabytes.
For video, plan on much more headroom while the job runs. If you are tight on space, do the job in pieces: point the app at one video or one subfolder at a time, upload it, then delete the output folder before starting the next.
After you have uploaded
Once your project shows up on the website and the upload has finished, the output folder has done its job. You can delete it.
Keep the originals on the SD card or a backup drive until you have seen your report and you are happy with it. If something needs re-running, having the originals saves you a repeat trip to the barn.