[FFmpeg-cvslog] doc/filters: clarify use of graph2dot

[Tim Nicholson]

ffmpeg | branch: master | Tim Nicholson <Tim.Nicholson at bbc.co.uk> | Wed Sep 19 09:02:01 2012 +0100| [b90210e9c5ea365befef61b10b9a34ce37f9e679] | committer: Stefano Sabatini

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 at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b90210e9c5ea365befef61b10b9a34ce37f9e679
---

 doc/filters.texi |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index 60b240d..e202d38 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -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:
+ at example
+ffmpeg -i infile -vf scale=640:360 outfile
+ at end example
+your @var{GRAPH_DESCRIPTION} string will need to be of the form:
+ at example
+nullsrc,scale=640:360,nullsink
+ at 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