X-Git-Url: https://git.videolan.org/?p=ffmpeg.git;a=blobdiff_plain;f=doc%2Ffilters.texi;h=92f86124cdfca7d61ad2389b6e1505c326ff1839;hp=33436ad267c288ddab3e2277023b870857705cbc;hb=884c890535c5fa1b7e1c4456a42fec174051b7bb;hpb=4977e467a50a690a46af5988d568eaab2e5933c7 diff --git a/doc/filters.texi b/doc/filters.texi index 33436ad267..92f86124cd 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -347,6 +347,66 @@ aconvert=u8:auto @end example @end itemize +@section aecho + +Apply echoing to the input audio. + +Echoes are reflected sound and can occur naturally amongst mountains +(and sometimes large buildings) when talking or shouting; digital echo +effects emulate this behaviour and are often used to help fill out the +sound of a single instrument or vocal. The time difference between the +original signal and the reflection is the @code{delay}, and the +loudness of the reflected signal is the @code{decay}. +Multiple echoes can have different delays and decays. + +A description of the accepted parameters follows. + +@table @option +@item in_gain +Set input gain of reflected signal. Default is @code{0.6}. + +@item out_gain +Set output gain of reflected signal. Default is @code{0.3}. + +@item delays +Set list of time intervals in milliseconds between original signal and reflections +separated by '|'. Allowed range for each @code{delay} is @code{(0 - 90000.0]}. +Default is @code{1000}. + +@item decays +Set list of loudnesses of reflected signals separated by '|'. +Allowed range for each @code{decay} is @code{(0 - 1.0]}. +Default is @code{0.5}. +@end table + +@subsection Examples + +@itemize +@item +Make it sound as if there are twice as many instruments as are actually playing: +@example +aecho=0.8:0.88:60:0.4 +@end example + +@item +If delay is very short, then it sound like a (metallic) robot playing music: +@example +aecho=0.8:0.88:6:0.4 +@end example + +@item +A longer delay will sound like an open air concert in the mountains: +@example +aecho=0.8:0.9:1000:0.3 +@end example + +@item +Same as above but with one more mountain: +@example +aecho=0.8:0.9:1000|1800:0.3|0.25 +@end example +@end itemize + @section afade Apply fade-in/out effect to input audio.