Command to repackage a MP4 video from a FLV container to a MP4 container.

flv-to-mp4.sh

#!/usr/bin/env sh
# Stored at: https://gist.github.com/4452136
# Assumes the given path points to a FLV file with MP4 video.

# Use ffmpeg to repackage the file.
ffmpeg -i "$1" -acodec copy -vcodec copy "$1".mp4


# old version:
# Not used anymore as VLC seems to have a bug that creates broken
# MP4 files which do not play back correctly.
#
# Call VLC to repackage the video/audio to a MP4 container.

# Path to VLC executable
#VLCPATH=/Applications/Vision/VLC.app/Contents/MacOS/VLC

# Call VLC:
# * -I dummy: without a graphical interface
# * $1: input file name
# * conversion specification
# ** mp4 container, no change to the streams
# ** write to original file name with ».mp4« appended
# * vlc://quit: exit vlc when done
#$VLCPATH -I dummy "$1" ":sout=#standard{mux=mp4,dst=$1.mp4,access=file}" vlc://quit

Free method: Handbrake, Freemake Video Converter, Formatfactory
Paid yet professional and easy method: iDealshare VideoGo https://www.idealshare.net/video-converter/convert-flv-to-mp4-on-mac-windows.html