configure and ffmpeg issue

[samuelv@xxxxxxxxxxx (Samuel Vinson)]

Hello,

Sometimes the configure script doesn't find the presence of libraries.
For libavcodec, libavformat and libswscale, I submit the following lines 
for aconfigure.ac

     AC_CHECK_LIB(avcodec,
            avcodec_init,
            [ac_ffmpeg_cflags="$ac_ffmpeg_cflags -DPJMEDIA_HAS_LIBAVCODEC=1"
             ac_ffmpeg_ldflags="$ac_ffmpeg_ldflags -lavcodec"
            ],
            [],
            [-lavutil]
            )
         AC_CHECK_LIB(avformat,
                  av_register_all,
                  [ac_ffmpeg_cflags="$ac_ffmpeg_cflags 
-DPJMEDIA_HAS_LIBAVFORMAT=1"
                   ac_ffmpeg_ldflags="$ac_ffmpeg_ldflags -lavformat"
                  ],
                  [],
            [-lavcodec -lavutil]
                  )
         AC_CHECK_LIB(swscale,
                  sws_scale,
                  [ac_ffmpeg_cflags="$ac_ffmpeg_cflags 
-DPJMEDIA_HAS_LIBSWSCALE=1"
                   ac_ffmpeg_ldflags="$ac_ffmpeg_ldflags -lswscale"
                  ],
                  [],
                  [-lavutil]
                  )

Regards

Samuel