If we have a a line graph, we need to make sure the data values are sorted by x.
but we still want to sort the categories, so we explicitly pull out the possible categories
to make sure they are sorted.
There is also a minor fix to use the FFMPEG_BIN environment variable if its defined.
If we have a a line graph, we need to make sure the data values are sorted by x. but we still want to sort the categories, so we explicitly pull out the possible categories to make sure they are sorted.
There is also a minor fix to use the FFMPEG_BIN environment variable if its defined.