yes, PNG can be simpler :-)

Originally committed as revision 1545 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/Makefile

@@ -20,7 +20,7 @@ OBJS+= asf.o
 endif
 
 # image formats
-OBJS+= pnm.o yuv.o png.o libpng/png.o libpng/pngread.o libpng/pngrutil.o libpng/pngwrite.o libpng/pngwutil.o jpeg.o gifdec.o
+OBJS+= pnm.o yuv.o png.o jpeg.o gifdec.o
 # file I/O
 OBJS+= avio.o aviobuf.o file.o 
 OBJS+= framehook.o