convert multiple images to a movie file

You can use mencoder for this, the powerful video converter that comes with mplayer.

• Make sure your image files are properly numbered, for example:
  frame0001.png
  frame0002.png
  frame0003.png
  ...
  frame0600.png
  JPEG and TARGA files are also supported
• Converting these 600 frames into a movie at 30 frames/second would result in a 20 second video. Put your accompanying audio (if you have it) in a 20 second .wav file, called audio.wav (for example)
• Now run:
  mencoder "mf://*.png" -mf fps=30 -ovc lavc -lavcopts vhq:vbitrate=1500 -audiofile audio.wav -oac mp3lame -lameopts preset=medium -o mymovie.avi
• An explanation of some of the options:
  -mf fps=30: set the frame rate to 30 frames/second
  vbitrate=1500: set the average bitrate to use for video encoding. The optimal value for your video depends a lot on the frame size. For small frames, say 320x240, you can try lower values, e.g. 750
  -oac mp3lame: compress the audio to the MP3 format
  -lameopts preset=medium: a relatively high quality preset that does variable bitrate encoding at 150-180 kbps