Now, I know not everyone has a Linux machine just lying around, but I do, and maybe in the future it might be enough to convince you to build your own file-server for your home (for media perhaps?).

Before starting, you need to make sure you have the ffmpeg binary installed on your Linux box. As of this posting, I have ffmpeg-0.4.9-0.3.20051207.2.el4.rf installed on my CentOS4 machine. I will leave it as an exercise to you to figure out how to install it if you don’t have it.

ash@galactica:[/tmp]> ffmpeg -vcodec xvid -b 500 -qmin 1 -qmax 7 -bufsize 4096 -g 300 -acodec aac -ab 96 -i doctor.who.102.the.end.of.the.world.avi -s 320×240 -aspect 16:9 doctor.who.102.the.end.of.the.world.mp4

Here is a run down of what the switches mean and how they affect your converted video:

-vcodec — this is the video codec you want the converted video to use. For iPod use, I suggest xvid. It is basically the same codec as mpeg4 (except open source) and you don’t run into buffer-underflow problems as often.

-b — this is the video bitrate in kbit/s (higher bitrate means higher quality).

-qmin & -qmax — this controls the quality when dealing with VBR (variable bit rate). Basically a range to keep the quality between.

-acodec — the audio codec to use. When converting to iPod video, this must be aac since that is the only format the iPod supports.

-ab — this is the audio bitrate in kbit/s. 96 kbit/s offers decent audio quality for iPod use.

-i — input file (obviously?).

-s — size of the output video. The iPod supports 320×240, 480×480 and with the newest firmware, now supports 640×480. If you want to retain the source aspect ratio, make sure you calculate the new size to follow the sources aspect ratio.

-aspect — aspect ratio for the converted video. This is especially important if your input video is 16:9 and you want to keep the ratio and replace the extra space with black bars. The aspect ratio is usually 4:3 or 16:9.

Now,after you have run this command, your video should begin to be converted. The time it takes to convert depends greatly on the hardware being used. I often offload this task to a P-III 800 machine, and it seems to be able to encode a video in the same time it would take to watch it. Again, the nice thing about offloading this task is that you can now use your main system for other fun tasks.

Might I suggest maybe using your main machine to whip up a quick script to encode a list of videos, perhaps at night when spare cpu cycles are pleniful? The nice thing about batching up video conversions like this, is that it is also compatible with mac’s running OSX. Sure, you could use the mac-GUI program to do it, but that is going to require a whole lot more human interaction to convert 10 shows.

For mor information of supported codecs, see the FFMPEG Documentation