As part of the last post I initially used a bash script to generate the commands to output the individual videos. As per usual, when I finally got fed up of the limitations and syntax issues in bash I switched to a proper programming language, perl. However this time I learnt a neat trick to doing multi-line commands in bash with comments embedded using the array feature of bash. A multi-line command typically looks like:
melt \ color:black \ out=$audiolen \ ...
However what if you want to add comments into the command? You can’t.
To solve this create an array:
cmd=( # Take black background track for same number of seconds as the MP3, then add 10 seconds of another image melt color:black out=$audiolen ... )
and then use the following magic to execute it:
Using this you can also conditionally add in extra statements if you’re using a pipeline-type program such as imagemagick (
cmd+=( # Output to the file -consumer avformat target="$target" mlt_profile="hdv_720_25p" f=mpeg acodec=mp2 ab=96k vcodec=mpeg2video vb=1000k )