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authorTim Nicholson <Tim.Nicholson@bbc.co.uk>2012-09-19 09:02:01 +0100
committerStefano Sabatini <stefasab@gmail.com>2012-09-19 11:50:09 +0200
commitb90210e9c5ea365befef61b10b9a34ce37f9e679 (patch)
tree1fb6afabc89de8fe42bc0e02fe7cb21e5d12d5a1
parentf398617b197d9a44b27d3313df8cd6c72b6a168a (diff)
downloadffmpeg-b90210e9c5ea365befef61b10b9a34ce37f9e679.tar.gz
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>
-rw-r--r--doc/filters.texi13
1 files changed, 12 insertions, 1 deletions
diff --git a/doc/filters.texi b/doc/filters.texi
index 60b240d5d4..e202d383d9 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:
+@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