Where Does Delta Patcher Save the Patched File?

What happens, step by step

This is how current versions of Delta Patcher handle output, based on the program’s source code:

1. It builds the output name

   It takes the original file’s folder, name and extension, and inserts PATCHED directly before the extension, with no space: Game (USA).iso → Game (USA)PATCHED.iso.

2. xdelta3 writes the patched file

   The new file is written under that name in the original’s folder. If a file with that name already exists, it’s overwritten. At this point, the original and the new file both exist.

3. If the patch fails, it stops here

   Your original is never touched when patching fails.

4. If it succeeds and backup is off, the original is replaced

   Delta Patcher deletes the original file and renames …PATCHED to the original name. The deleted file doesn’t go to the Recycle Bin or Trash.

5. If it succeeds and backup is on, both files stay

   Nothing else happens. You keep the untouched original and the new …PATCHED file side by side.

Output naming examples

Why this matters

• You can’t send output to another drive. The folder containing the original needs enough free space and write permission. Otherwise the patch fails with file open failed or write failed. Fixing permission problems.
• Re-applying the same patch fails. With backup off, the file with the original’s name is now the patched version, so applying the patch again gives a checksum error. Fixing already-patched files.
• Other programs may not recognize the new name. A …PATCHED file may need renaming before a program or emulator will use it.

Disc images with .cue sheets

A .cue file lists the .bin files that make up a disc image by name. If you patch Game.bin with backup on, the result is GamePATCHED.bin, but Game.cue still points to Game.bin, so your emulator loads the unpatched data. Fix it one of two ways:

1. Move the patched .bin and a copy of the .cue into a new folder and rename the .bin to the name in the cue sheet, or
2. open the .cue in a text editor and change the file name on the FILE line to the patched file’s name.

A safe workflow: keep originals and patched files separate

Because output always lands next to the input, the easiest way to control where it goes is to control where the input is. This folder layout works well:

Patching/
├── originals/     untouched, verified source files (never patch here)
├── work/          copies of the original + the .xdelta patch
└── patched/       finished files, renamed and ready to use

1. Store verified originals separately

   Keep untouched source files in originals. On Windows you can set them read-only (right-click → Properties → Read-only) so nothing modifies them by accident.

2. Copy the original into a working folder

   Copy (don’t move) the original and the patch into work.

3. Patch the copy

   Select the copy in Delta Patcher. With backup off, the copy is replaced by the patched file, which is fine because the real original is safe elsewhere.

4. Move and rename the result

   Move the patched file into patched and give it a descriptive name, such as Game (USA) [Translation v1.2].iso.

“My original file is gone”

If you applied a patch with Backup original file off, the file that now has the original’s name is the patched version, and the original was deleted, not moved to the Recycle Bin or Trash. To confirm, compare its checksum with the original checksum in the patch’s readme. How to check a checksum. To get the original back, restore it from your own backup or make a fresh copy from the source you originally used. Next time, tick Backup original file or use the workflow above.

If you need to choose the output name

For full control over the output path, as in scripts or batch jobs, use the xdelta3 command line, which takes the output file as an argument:

xdelta3 -d -s "originals/Game (USA).iso" translation.xdelta "patched/Game (USA) [Translation].iso"