Hello, I am on Fedora core 2. Xine-ui still complains about missing libpng after I installed libpng.
What is the meaning of warning message.

[root@localhost root]# rpm -i libpng-1.2.8-1.fc2.src.rpm
warning: libpng-1.2.8-1.fc2.src.rpm: V3 DSA signature: NOKEY, key ID 4f2a6fd2
[root@localhost xine-ui-0.99.3]# ./configure
checking build system type... i686-redhat-linux-gnu
checking host system type... i686-redhat-linux-gnu
checking target system type... i686-redhat-linux-gnu
checking for a BSD-compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking for style of include used by make... GNU
checking for gcc... gcc
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... no
checking for suffix of executables...
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ANSI C... none needed
checking dependency style of gcc... gcc3
checking for strerror in -lcposix... no
checking for gcc... (cached) gcc
checking whether we are using the GNU C compiler... (cached) yes
checking whether gcc accepts -g... (cached) yes
checking for gcc option to accept ANSI C... (cached) none needed
checking dependency style of gcc... (cached) gcc3
checking how to run the C preprocessor... gcc -E
checking for egrep... grep -E
checking for ANSI C header files... yes
checking for sys/types.h... yes
checking for sys/stat.h... yes
checking for stdlib.h... yes
checking for string.h... yes
checking for memory.h... yes
checking for strings.h... yes
checking for inttypes.h... yes
checking for stdint.h... yes
checking for unistd.h... yes
checking minix/config.h usability... no
checking minix/config.h presence... no
checking for minix/config.h... no
checking for ANSI C header files... (cached) yes
checking whether make sets $(MAKE)... (cached) yes
checking for a BSD-compatible install... /usr/bin/install -c
checking whether ln -s works... yes
checking for a sed that does not truncate output... /bin/sed
checking for ld used by gcc... /usr/bin/ld
checking if the linker (/usr/bin/ld) is GNU ld... yes
checking for /usr/bin/ld option to reload object files... -r
checking for BSD-compatible nm... /usr/bin/nm -B
checking how to recognise dependent libraries... pass_all
checking dlfcn.h usability... yes
checking dlfcn.h presence... yes
checking for dlfcn.h... yes
checking for g++... g++
checking whether we are using the GNU C++ compiler... yes
checking whether g++ accepts -g... yes
checking dependency style of g++... gcc3
checking how to run the C++ preprocessor... g++ -E
checking for g77... g77
checking whether we are using the GNU Fortran 77 compiler... yes
checking whether g77 accepts -g... yes
checking the maximum length of command line arguments... 32768
checking command to parse /usr/bin/nm -B output from gcc object... ok
checking for objdir... .libs
checking for ar... ar
checking for ranlib... ranlib
checking for strip... strip
checking if gcc static flag works... yes
checking if gcc supports -fno-rtti -fno-exceptions... no
checking for gcc option to produce PIC... -fPIC
checking if gcc PIC flag -fPIC works... yes
checking if gcc supports -c -o file.o... yes
checking whether the gcc linker (/usr/bin/ld) supports shared libraries... yes
checking whether -lc should be explicitly linked in... no
checking dynamic linker characteristics... GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
checking for shl_load... no
checking for shl_load in -ldld... no
checking for dlopen... no
checking for dlopen in -ldl... yes
checking whether a program can dlopen itself... yes
checking whether a statically linked program can dlopen itself... yes
checking if libtool supports shared libraries... yes
checking whether to build shared libraries... yes
checking whether to build static libraries... no
configure: creating libtool
appending configuration tag "CXX" to libtool
checking for ld used by g++... /usr/bin/ld
checking if the linker (/usr/bin/ld) is GNU ld... yes
checking whether the g++ linker (/usr/bin/ld) supports shared libraries... yes
checking for g++ option to produce PIC... -fPIC
checking if g++ PIC flag -fPIC works... yes
checking if g++ supports -c -o file.o... yes
checking whether the g++ linker (/usr/bin/ld) supports shared libraries... yes
checking dynamic linker characteristics... GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
checking for shl_load... (cached) no
checking for shl_load in -ldld... (cached) no
checking for dlopen... (cached) no
checking for dlopen in -ldl... (cached) yes
checking whether a program can dlopen itself... (cached) yes
checking whether a statically linked program can dlopen itself... (cached) yes
appending configuration tag "F77" to libtool
checking if libtool supports shared libraries... yes
checking whether to build shared libraries... yes
checking whether to build static libraries... no
checking for g77 option to produce PIC... -fPIC
checking if g77 PIC flag -fPIC works... yes
checking if g77 supports -c -o file.o... yes
checking whether the g77 linker (/usr/bin/ld) supports shared libraries... yes
checking dynamic linker characteristics... GNU/Linux ld.so
checking how to hardcode library paths into programs... immediate
checking whether stripping libraries is possible... yes
checking for ranlib... (cached) ranlib
checking for an ANSI C-conforming const... yes
checking for inline... inline
checking for off_t... yes
checking for size_t... yes
checking for working alloca.h... yes
checking for alloca... yes
checking for stdlib.h... (cached) yes
checking for unistd.h... (cached) yes
checking for getpagesize... yes
checking for working mmap... yes
checking whether we are using the GNU C Library 2.1 or newer... yes
checking argz.h usability... yes
checking argz.h presence... yes
checking for argz.h... yes
checking limits.h usability... yes
checking limits.h presence... yes
checking for limits.h... yes
checking locale.h usability... yes
checking locale.h presence... yes
checking for locale.h... yes
checking nl_types.h usability... yes
checking nl_types.h presence... yes
checking for nl_types.h... yes
checking malloc.h usability... yes
checking malloc.h presence... yes
checking for malloc.h... yes
checking stddef.h usability... yes
checking stddef.h presence... yes
checking for stddef.h... yes
checking for stdlib.h... (cached) yes
checking for string.h... (cached) yes
checking for unistd.h... (cached) yes
checking sys/param.h usability... yes
checking sys/param.h presence... yes
checking for sys/param.h... yes
checking for feof_unlocked... yes
checking for fgets_unlocked... yes
checking for getcwd... yes
checking for getegid... yes
checking for geteuid... yes
checking for getgid... yes
checking for getuid... yes
checking for mempcpy... yes
checking for munmap... yes
checking for putenv... yes
checking for setenv... yes
checking for setlocale... yes
checking for stpcpy... yes
checking for strchr... yes
checking for strcasecmp... yes
checking for strdup... yes
checking for strtoul... yes
checking for tsearch... yes
checking for __argz_count... yes
checking for __argz_stringify... yes
checking for __argz_next... yes
checking for iconv... yes
checking for iconv declaration...
extern size_t iconv (iconv_t cd, char * *inbuf, size_t *inbytesleft, char * *outbuf, size_t *outbytesleft);
checking for nl_langinfo and CODESET... yes
checking for LC_MESSAGES... yes
checking whether NLS is requested... yes
checking whether included gettext is requested... no
checking libintl.h usability... yes
checking libintl.h presence... yes
checking for libintl.h... yes
checking for GNU gettext in libc... yes
checking for dcgettext... yes
checking for msgfmt... /usr/bin/msgfmt
checking for gmsgfmt... /usr/bin/msgfmt
checking for xgettext... /usr/bin/xgettext
checking for bison... bison
checking version of bison... 1.875, ok
checking for catalogs to be installed... fr es pt_BR de sk pl uk cs it ja
checking for plural forms in GNU msgfmt... yes
checking for an ANSI C-conforming const... (cached) yes
checking for inline... (cached) inline
checking for off_t... (cached) yes
checking for size_t... (cached) yes
checking for xine-config... /usr/local/bin/xine-config
checking for XINE-LIB version >= 1.0.0... yes
checking for strsep... yes
checking for strpbrk... yes
checking for setenv... (cached) yes
checking whether XINE_PARAM_AUDIO_AMP_MUTE is declared... yes
checking for pthread_create in -lpthread... yes
checking for dlopen in -lc... no
checking for dlopen in -ldl... (cached) yes
checking for X... libraries /usr/X11R6/lib, headers /usr/X11R6/include
checking for gethostbyname... yes
checking for connect... yes
checking for remove... yes
checking for shmat... yes
checking for IceConnectionNumber in -lICE... yes
checking for XvQueryExtension in -lXv... yes
checking for XShmAttach in -lXext... yes
checking sys/ipc.h usability... yes
checking sys/ipc.h presence... yes
checking for sys/ipc.h... yes
checking sys/shm.h usability... yes
checking sys/shm.h presence... yes
checking for sys/shm.h... yes
checking whether shmctl IPC_RMID allowes subsequent attaches... yes
checking for X11/extensions/XShm.h... yes
checking for XineramaQueryExtension in -lXinerama... yes
checking for XF86VidModeQueryExtension in -lXxf86vm... yes
checking for XTestFakeKeyEvent in -lXtst... yes
checking for readline.h... /usr/include/readline/readline.h
checking curses.h usability... yes
checking curses.h presence... yes
checking for curses.h... yes
checking for cbreak in -lncurses... yes
checking for curl-config... /usr/bin/curl-config
checking for CURL-LIB version >= 7.10.2... yes
checking for socket in -lsocket... no
checking for gethostbyname in -lnsl... yes
checking for aalib-config... no
checking for aainfo... no
checking for AALIB version >= 1.2.0... no
*** The aalib-config|aainfo program installed by AALIB could not be found
*** If AALIB was installed in PREFIX, make sure PREFIX/bin is in
*** your path, or use --with-aalib-prefix to set the prefix
*** where AALIB is installed.
checking for caca-config... no
no
*** The caca-config program installed by CACA could not be found
*** If CACA was installed in PREFIX, make sure PREFIX/bin is in
*** your path, or use --with-caca-prefix to set the prefix
*** where CACA is installed.
*** All CACA-dependent parts will be disabled ***
checking for pkg-config... /usr/bin/pkg-config
checking whether to have Xft support... yes
checking Xft UTF-8 support... yes
checking for png_read_info in -lpng... no
configure: error: *** libpng is needed (PNG library not found) - try to use --with-png-prefix option ***
[root@localhost xine-ui-0.99.3]#

my suggestion is to download the latest rpm build of xine. that will tell you what you need to install then download the relevant rpms it tells you to and type

rpm -Uvh whatever.rpm

Otherwise, if you know where you installed aalib, caca and libpng, try setting the prefix directory for it like the configure script asks (ie ./configure --with-png-prefix /directory-where-it-is

EDIT: I just noticed - you installed the libpng uncompiled source package!!!! you need the binary package! (i.e. one without .src. in the title).

Further trouble installing libpng
How to go around this:
[root@localhost downloads]# rpm -i libpng-1.2.8-1.fc2.i386.rpm
warning: libpng-1.2.8-1.fc2.i386.rpm: V3 DSA signature: NOKEY, key ID 4f2a6fd2
file /usr/lib/libpng.so.3 from install of libpng-1.2.8-1.fc2 conflicts with file from package libpng-1.2.2-22
file /usr/lib/libpng12.so.0 from install of libpng-1.2.8-1.fc2 conflicts with file from package libpng-1.2.2-22
file /usr/share/man/man5/png.5.gz from install of libpng-1.2.8-1.fc2 conflicts with file from package libpng-1.2.2-22
[root@localhost downloads]#
By the way, I have dowloaded the source of libpng, and went through the install instructions a couple of times, but I am still unable to install it by.