How to convert Canon PowerShot movies to MPEG 4 (DivX) format on Linux

DivX format is somewhat more widely supported and much more efficient than the
Canon's native MJPEG format.  Also, the Canon records audio with a weird
sampling rate (11024 Hz) which results in high-frequency noise when played
with typical player applications; resampling the audio track solves this
problem.

Some video quality is lost during the conversion process, so you may want to
archive the original MJPEG format files.

* Install mplayer RPM from www.mplayerhq.hu, plus dependent RPMs, including
  lame.

* To convert an MJPEG movie file:

  mencoder -o OUTPUTFILE -oac mp3lame -ovc lavc -srate 11025 \
    -channels 1 -af-adv force=1 -lameopts preset=medium \
    -lavcopts vcodec=msmpeg4v2:vbitrate=400 -mc 0 INPUTFILE

  The resulting AVI file should be about 20% of the original size.  These
  settings are optimized for 320x240 at 15 frames/sec.  You may need to
  increase the bit rate for higher-bandwidth video, and you may get better
  results using the multi-pass (vpass) feature of the lavc encoder.

* To rotate the movie 90 degrees clockwise, append:

  -vop rotate=1

  to the mencoder command line.  To rotate the movie 90 degrees
  counterclockwise, append:

  -vop rotate=2

* To combine multiple input files into a single output file, just add more
  filenames to the mencoder command line.