lavfi: EBU R.128 scanner.

1 files changed, 47 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index 916aa6f8b9..d9e73b38cc 100644
--- a/doc/filters.texi
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@@ -4480,6 +4480,53 @@ setpts=PTS+10/TB
 @end example
 @end itemize
 
+@section ebur128
+
+EBU R128 scanner filter. This filter takes an audio stream as input and outputs
+it unchanged. By default, it logs a message at a frequency of 10Hz with the
+Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}),
+Integrated loudness (@code{I}) and Loudness Range (@code{LRA}).
+
+The filter also has a video output (see the @var{video} option) with a real
+time graph to observe the loudness evolution. The graphic contains the logged
+message mentioned above, so it is not printed anymore when this option is set,
+unless the verbose logging is set. The main graphing area contains the
+short-term loudness (3 seconds of analysis), and the gauge on the right is for
+the momentary loudness (400 milliseconds).
+
+More information about the Loudness Recommendation EBU R128 on
+@url{http://tech.ebu.ch/loudness}.
+
+The filter accepts the following named parameters:
+
+@table @option
+
+@item video
+Activate the video output. The audio stream is passed unchanged whether this
+option is set or no. The video stream will be the first output stream if
+activated. Default is @code{0}.
+
+@item size
+Set the video size. This option is for video only. Default and minimum
+resolution is @code{640x480}.
+
+@item meter
+Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and
+@code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any
+other integer value between this range is allowed.
+
+@end table
+
+Example of real-time graph using @command{ffplay}, with a EBU scale meter +18:
+@example
+ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
+@end example
+
+Run an analysis with @command{ffmpeg}:
+@example
+ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
+@end example
+
 @section settb, asettb
 
 Set the timebase to use for the output frames timestamps.