For posterity:
I have a Canon HF200 HD video camera, which records to AVCHD format. AVCHD is H.264 encoded video and AC-3 encoded audio in a MPEG-2 Transport Stream (m2ts, mts) container. This format is not supported by Aperture 3, which I use to store my video.
With Blizzard’s help, I figured out an ffmpeg command-line to convert to H.264 encoded video and AAC encoded audio in an MPEG-4 (mp4) container. This is supported by Aperture 3 and other Quicktime apps.
$ ffmpeg -sameq -ab 256k -i input-file.m2ts -s hd1080 output-file.mp4 -acodec aac
Command-line order is important, which is infuriating. If you move
the -s or -ab arguments, they may not work. Add -deinterlace if
the source videos are interlaced, which mine were originally until I
turned it off. The only downside to this is that it generates huge
output files, on the order of 4-5x greater than the input file.
Update, 28 April 2010: Alexander Wauck emailed me to say that re-encoding the video isn’t necessary, and that the existing H.264 video could be moved from the m2ts container to the mp4 container with a command-line like this:
$ ffmpeg -i input-file.m2ts -ab 256k -vcodec copy -acodec aac output-file.mp4
And he’s right… as long as you don’t need to deinterlace the video.
With the whatever-random-ffmpeg-trunk checkout I have, adding
-deinterlace to the command-line segfaults. I actually had tried
-vcodec copy early in my experiments but abandoned it after I found
that it didn’t deinterlace. I had forgotten to try it again after I
moved past my older interlaced videos. Thanks Alex!