Originally committed as revision 25795 to svn://svn.ffmpeg.org/ffmpeg/trunk
per-(p)rogram. All metadata specifiers other than global must be followed by the
stream/chapter/program number. If metadata specifier is omitted, it defaults to
global.
+
+By default, global metadata is copied from the first input file to all output files,
+per-stream and per-chapter metadata is copied along with streams/chapters. These
+default mappings are disabled by creating any mapping of the relevant type. A negative
+file index can be used to create a dummy mapping that just disables automatic copying.
+
For example to copy metadata from the first stream of the input file to global metadata
of the output file:
@example