lavfi: avectorscope filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index fe38b7f561..17c54c5e6c 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -7324,6 +7324,68 @@ tools.
 
 Below is a description of the currently available multimedia filters.
 
+@section avectorscope
+
+Convert input audio to a video output, representing the audio vector
+scope.
+
+The filter is used to measure the difference between channels of stereo
+audio stream. A monoaural signal, consisting of identical left and right
+signal, results in straight vertical line. Any stereo separation is visible
+as a deviation from this line, creating a Lissajous figure.
+If the straight (or deviation from it) but horizontal line appears this
+indicates that the left and right channels are out of phase.
+
+The filter accepts the following options:
+
+@table @option
+@item mode, m
+Set the vectorscope mode.
+
+Available values are:
+@table @samp
+@item lissajous
+Lissajous rotated by 45 degrees.
+
+@item lissajous_xy
+Same as above but not rotated.
+@end table
+
+Default value is @samp{lissajous}.
+
+@item size, s
+Set the video size for the output. Default value is @code{400x400}.
+
+@item rate, r
+Set the output frame rate. Default value is @code{25}.
+
+@item rc
+@item gc
+@item bc
+Specify the red, green and blue contrast. Default values are @code{40}, @code{160} and @code{80}.
+Allowed range is @code{[0, 255]}.
+
+@item rf
+@item gf
+@item bf
+Specify the red, green and blue fade. Default values are @code{15}, @code{10} and @code{5}.
+Allowed range is @code{[0, 255]}.
+
+@item zoom
+Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Complete example using @command{ffplay}:
+@example
+ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
+             [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
+@end example
+@end itemize
+
 @section concat
 
 Concatenate audio and video streams, joining them together one after the