-ddump-signatures \
-danti-alias-factor=$(ANTI_ALIAS_FACTOR)
+ifdef QUIET_BUILD
+LILYPOND_BOOK_VERBOSE =
+else
LILYPOND_BOOK_VERBOSE = --verbose
+endif
+
LILYPOND_BOOK_INFO_IMAGES_DIR = $(if $(INFO_IMAGES_DIR),--info-images-dir=$(INFO_IMAGES_DIR),)
LILYPOND_BOOK_FLAGS = $(LILYPOND_BOOK_VERBOSE) $(LILYPOND_BOOK_INFO_IMAGES_DIR)