> ffmpeg -i %d.png video.ogv
ffmpeg version 0.7.3-4:0.7.3-2ubuntu1, Copyright (c) 2000-2011 the Libav developers
  built on Dec 26 2011 11:13:24 with gcc 4.6.2
  configuration: --extra-version='4:0.7.3-2ubuntu1' --arch=amd64 --prefix=/usr --libdir=/usr/lib/x86_64-linux-gnu --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --enable-runtime-cpudetect --enable-libfreetype --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/x86_64-linux-gnu --enable-shared --disable-static
  libavutil    51.  7. 0 / 51.  7. 0
  libavcodec   53.  6. 0 / 53.  6. 0
  libavformat  53.  3. 0 / 53.  3. 0
  libavdevice  53.  0. 0 / 53.  0. 0
  libavfilter   2.  4. 0 /  2.  4. 0
  libswscale    2.  0. 0 /  2.  0. 0
  libpostproc  52.  0. 0 / 52.  0. 0
%d.png: No such file or directory