lavdev: add libavfilter virtual input device

This input device is to be considered still experimental, only video
output is supported.

1 files changed, 54 insertions, 0 deletions

diff --git a/doc/indevs.texi b/doc/indevs.texi
index af9b1a680f..d443a6a079 100644
--- a/doc/indevs.texi
+++ b/doc/indevs.texi
@@ -133,6 +133,60 @@ $ jack_connect metro:120_bpm ffmpeg:input_1
 For more information read:
 @url{http://jackaudio.org/}
 
+@section lavfi
+
+Libavfilter input virtual device.
+
+This input device reads data from the open output pads of a libavfilter
+filtergraph.
+
+For each filtergraph open output, the input device will create a
+corresponding stream which is mapped to the generated output. Currently
+only video data is supported. The filtergraph is specified through the
+option @option{graph}.
+
+To enable this input device, you need to configure your builf with
+@code{--enable-libavfilter}.
+
+@subsection Options
+
+@table @option
+
+@item graph
+Specify the filtergraph to use as input. Each video open output must be
+labelled by a unique string of the form "out@var{N}", where @var{N} is a
+number starting from 0 corresponding to the mapped input stream
+generated by the device.
+The first unlabelled output is automatically assigned to the "out0"
+label, but all the others need to be specified explicitely.
+
+If not specified defaults to the filename specified for the input
+device.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Create a color video stream and play it back with @file{ffplay}:
+@example
+ffplay -f lavfi -graph "color=pink [out0]" dummy
+@end example
+
+@item
+As the previous example, but use filename for specifying the graph
+description, and omit the "out0" label:
+@example
+ffplay -f lavfi color=pink
+@end example
+
+@item
+Create three different video test filtered sources and play them:
+@example
+ffplay -f lavfi -graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
+@end example
+@end itemize
+
 @section libdc1394
 
 IIDC1394 input device, based on libdc1394 and libraw1394.