Windows: use ffmpeg from Rtools when available

.github/workflows/R-CMD-check.yaml

@@ -22,6 +22,7 @@ jobs:
           - {os: macos-14,        r: 'release'}
           - {os: windows-latest,  r: '4.1'}
           - {os: windows-latest,  r: '4.2'}
+          - {os: windows-latest,  r: '4.3'}
           - {os: windows-latest,  r: 'release'}
           - {os: ubuntu-latest,   r: 'devel', http-user-agent: 'release'}
           - {os: ubuntu-24.04,   r: 'release'}

NEWS

@@ -1,3 +1,6 @@
+0.9.4
+  - Windows: use ffmpeg from Rtools when available
+
 0.9.3
   - Fixes for ffmpeg 7.1
   - Cleanup configure script

src/Makevars.win

@@ -1,3 +1,11 @@
+PKG_CONFIG_NAME = libavfilter
+PKG_CONFIG ?= $(BINPREF)pkg-config
+PKG_LIBS := $(shell $(PKG_CONFIG) --libs $(PKG_CONFIG_NAME))
+
+ifneq ($(PKG_LIBS),)
+$(info using ffmpeg from Rtools)
+PKG_CPPFLAGS := $(shell $(PKG_CONFIG) --cflags $(PKG_CONFIG_NAME))
+else
 RWINLIB = ../windows/ffmpeg
 PKG_CPPFLAGS = -I$(RWINLIB)/include -D__USE_MINGW_ANSI_STDIO=1 -DR_NO_REMAP -DSTRICT_R_HEADERS
 PKG_LIBS = -L$(RWINLIB)/lib${subst gcc,,$(COMPILED_BY)}$(R_ARCH) \
@@ -6,11 +14,14 @@ PKG_LIBS = -L$(RWINLIB)/lib${subst gcc,,$(COMPILED_BY)}$(R_ARCH) \
 	-lvorbis -lvorbisenc -logg -lvpx \
 	-lbz2 -lsecur32 -lws2_32 -liconv -lz -lmp3lame -lx264 \
 	-lxvidcore -pthread -lole32 -lm -luser32 -lbcrypt -lmfplat -lmfuuid -lstrmiids
+endif
 
-all: winlibs clean
+all: $(SHLIB)
 
-clean:
-	rm -f $(SHLIB) $(OBJECTS)
+$(OBJECTS): $(RWINLIB)
 
-winlibs:
+$(RWINLIB):
 	"${R_HOME}/bin${R_ARCH_BIN}/Rscript.exe" "../tools/winlibs.R"
+
+clean:
+	rm -f $(SHLIB) $(OBJECTS)