I used mencoder utility to convert my video files. But it was compiled without libfaac. So if you specify AAC encoding, an error occurs. Details and solutions can be found here. I just added the Medibuntu repository as described:
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# sudo wget --output-document=/etc/apt/sources.list.d/medibuntu.list http://www.medibuntu.org/sources.list.d/$(lsb_release -cs).list # sudo apt-get --quiet update # sudo apt-get --yes --quiet --allow-unauthenticated install medibuntu-keyring # sudo apt-get --quiet update |
NOTE: ffmpeg utility in Lucid release does not support *.rm/*.rmvb yet.
Then install mencoder and codecs:
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# sudo apt-get install mencoder libavcodec-extra-52 libavformat-extra-52 |
Now you can convert videos. Here’s a sample to convert a *.rmvb(848×480) to a *.mp4(320×240):
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# mencoder -oac lavc -ovc lavc -lavcopts acodec=libfaac:abitrate=96:aglobal=1:vcodec=mpeg4:vbitrate=500:vglobal=1 -vf scale=320:180,harddup -vf-add expand=:240 -ofps 24000/1001 -of lavf source.rmvb -o target.mp4 |
Modify fps/codec/bitrate values as you wish. The aglobal & vglobal options seem to be essential for iPod.
In order to keep video aspect after scaling, the output file should be 360×204. we use the -vf-add filter to add black band to the top and bottom of it. Other command line options, please refer to its manpage.
Lastly, install gtkpod to import your *.mp4 files.
Updated Mar 27, 2012: The above command line is for iPod Nano. For high quality H264 encoding used in iPod Touch or iPhone, run:
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# mencoder -oac faac -faacopts raw:object=2:mpeg=4:br=96 -ovc x264 -x264encopts nocabac:global_header:bframes=0:level_idc=30:bitrate=600:threads=auto -vf scale=960:-2,harddup -ofps 24000/1001 -of lavf -lavfopts format=mp4 source.rmvb -o target.mp4 |