Path to a file to read; special characters and spaces must be escaped with
backslash or single quotes.
+All subsequent directives apply to that file.
+
@item @code{ffconcat version 1.0}
Identify the script type and version. It also sets the @option{safe} option
to 1 if it was to its default -1.
appears exactly as is (no extra space or byte-order-mark) on the very first
line of the script.
+@item @code{duration @var{dur}}
+Duration of the file. This information can be specified from the file;
+specifying it here may be more efficient or help if the information from the
+file is not available or accurate.
+
@end table
@subsection Options