Watched Folders

A watched folder automatically compresses any image you drop into it, then exports it to a destination folder. It's the only JPGBoost automation that runs continuously, with nothing for you to launch.

How it works

Unlike other automations, which process a batch the moment you call them, a watched folder runs continuously as long as JPGBoost is open.

Setting up a watched folder

1. Open Settings (⌘,) then the Watched Folders tab.
2. Add a folder and choose the folder to watch.
3. Choose the destination folder, which must be different from the one above.
4. Set either a format and quality, or a named export profile.
5. Enable the folder. Watching starts right away.

Rules to know

• The watched folder's destination folder always wins over the profile's, if the profile has one.
• Format, quality, and destination are determined once per pass, not once per file. A missing profile is therefore flagged only once for the whole batch, and every file in a given pass shares the same settings.
• Editing a folder only restarts its own watching, without re-triggering catch-up on the others.
• Disabling or deleting a folder mid-batch interrupts files that haven't started yet. Ones already being compressed run to completion.

How detection works

A few useful details for understanding the behavior you'll see:

• Detection relies on event-driven watching of the folder, not regular polling: nothing loops in the background.
• A short delay lets a drop of several files settle before analysis, to avoid processing copies that are still in progress.
• JPGBoost checks that a file's size has stopped changing before processing it. This check only applies to files modified less than two seconds ago. Files that are already stable, for example present in the folder at first launch, are processed immediately.
• A file still being written is simply picked up again at the next event.
• Files in the same pass are compressed in parallel, up to the number of cores available.

What's already been processed

Each watched folder remembers the size and modification date of files it has already compressed. An unchanged file is therefore not reprocessed after the app restarts, or on a second event covering the same drop.

Only files actually compressed are recorded. In case of a temporary failure, for example if the destination folder is unavailable or the disk is full, the file is retried on the next pass instead of being considered processed. Entries corresponding to deleted files are automatically cleared out over successive passes.

Tracking activity

The Watched Folders tab provides three indicators, all viewable without opening the main window:

• a progress bar under each folder while a batch is processing, showing files processed out of the total;
• the Recent Activity section, listing the most recently processed files and any errors, with a button to clear it;
• the error log, which shows only failures, up to twenty, so you can spot them without scanning through successes.

Limitations

Example uses