Using avconv to Convert Videos for Low Bandwidth (3G)
In working further on a video project, I had to re-encode (reencode?) them to a lower bitrate for slower connections.
So far, this seems to work:
avconv -i in.mp4 -c:a copy -c:v libx264 -crf 28 -preset veryfast out.mp4
MP4Box -brand mp42 out.mp4
Further details here: