Fix -j argument

src/emulsion/main.py

@@ -53,9 +53,16 @@ def parse_args(config):
 	# Time settings
 	parser.add_argument('--base-date', default=None, help='Base date or date/time (e.g. 2023-04-10 or 2023-04-10 12:00:00).')
 	parser.add_argument('--time-increment', type=int, default=None, help='Time increment in seconds between images.')
-	parser.add_argument('--sidecar', action='store_true', help='Write to sidecar XMP files (e.g. image.jpg.xmp) instead of embedding.')
+	parser.add_argument('--embed', action='store_true', help='Embed EXIF data directly into the image file instead of a sidecar.')
 	parser.add_argument('--dry-run', action='store_true', help='Show what would be changed without modifying files.')
-	parser.add_argument('-j', '--workers', type=int, default=os.cpu_count() or 1, help='Number of parallel workers to run exiftool; defaults to number of CPUs.')
+	parser.add_argument(
+		'-j', '--workers',
+		type=int,
+		nargs='?',
+		const=os.cpu_count() or 1,
+		default=os.cpu_count() or 1,
+		help='Number of parallel workers to run exiftool; defaults to number of CPUs.'
+	)
 	parser.add_argument('--init-config', action='store_true', help='Create a default config file (if none exists) and exit.')
 
 	args = parser.parse_args()
@@ -257,7 +264,7 @@ def main():
 				timestamp_str = ts_dt.strftime("%Y:%m:%d %H:%M:%S")
 
 				sidecar_source = None
-				if args.sidecar:
+				if not args.embed:
 					target_file_path = f"{f}.xmp"
 					# If sidecar doesn't exist, we must tell ExifTool to create it from the source image
 					if not os.path.exists(target_file_path):