doc/filters: clarify use of graph2dot

The GRAPH_DESCRIPTION string supplied to graph2dot must include explicitly
defined inputs and outputs which are not normally part of the command line
used in a real invocation.

This clarifies that requirement, and provides an example.

Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
This commit is contained in:
Tim Nicholson 2012-09-19 09:02:01 +01:00 committed by Stefano Sabatini
parent f398617b19
commit b90210e9c5
1 changed files with 12 additions and 1 deletions

View File

@ -79,7 +79,18 @@ display graph.png
@end example
can be used to create and display an image representing the graph
described by the @var{GRAPH_DESCRIPTION} string.
described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be
a complete self-contained graph, with its inputs and outputs explicitly defined.
For example if your command line is of the form:
@example
ffmpeg -i infile -vf scale=640:360 outfile
@end example
your @var{GRAPH_DESCRIPTION} string will need to be of the form:
@example
nullsrc,scale=640:360,nullsink
@end example
you may also need to set the @var{nullsrc} parameters and add a @var{format}
filter in order to simulate a specific input file.
@c man end GRAPH2DOT