avfilter: add audio pulsator filter

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

1 files changed, 57 insertions, 0 deletions

diff --git a/doc/filters.texi b/doc/filters.texi
index b3ab84a35e..9f722376b8 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -1030,6 +1030,63 @@ It accepts the following values:
 @end table
 @end table
 
+@section apulsator
+
+Audio pulsator is something between an autopanner and a tremolo.
+But it can produce funny stereo effects as well. Pulsator changes the volume
+of the left and right channel based on a LFO (low frequency oscillator) with
+different waveforms and shifted phases.
+This filter have the ability to define an offset between left and right
+channel. An offset of 0 means that both LFO shapes match each other.
+The left and right channel are altered equally - a conventional tremolo.
+An offset of 50% means that the shape of the right channel is exactly shifted
+in phase (or moved backwards about half of the frequency) - pulsator acts as
+an autopanner. At 1 both curves match again. Every setting in between moves the
+phase shift gapless between all stages and produces some "bypassing" sounds with
+sine and triangle waveforms. The more you set the offset near 1 (starting from
+the 0.5) the faster the signal passes from the left to the right speaker.
+
+The filter accepts the following options:
+
+@table @option
+@item level_in
+Set input gain. By default it is 1. Range is [0.015625 - 64].
+
+@item level_out
+Set output gain. By default it is 1. Range is [0.015625 - 64].
+
+@item mode
+Set waveform shape the LFO will use. Can be one of: sine, triangle, square,
+sawup or sawdown. Default is sine.
+
+@item amount
+Set modulation. Define how much of original signal is affected by the LFO.
+
+@item offset_l
+Set left channel offset. Default is 0. Allowed range is [0 - 1].
+
+@item offset_r
+Set right channel offset. Default is 0.5. Allowed range is [0 - 1].
+
+@item width
+Set pulse width. Default is 1. Allowed range is [0 - 2].
+
+@item timing
+Set possible timing mode. Can be one of: bpm, ms or hz. Default is hz.
+
+@item bpm
+Set bpm. Default is 120. Allowed range is [30 - 300]. Only used if timing
+is set to bpm.
+
+@item ms
+Set ms. Default is 500. Allowed range is [10 - 2000]. Only used if timing
+is set to ms.
+
+@item hz
+Set frequency in Hz. Default is 2. Allowed range is [0.01 - 100]. Only used
+if timing is set to hz.
+@end table
+
 @anchor{aresample}
 @section aresample