avfilter: add afftfilter

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

Changelog

@@ -56,6 +56,7 @@ version <next>:
 - ahistogram filter
 - only seek with the right mouse button in ffplay
 - toggle full screen when double-clicking with the left mouse button in ffplay
+- afftfilt filter
 
 
 version 2.8:

configure

@@ -2841,6 +2841,8 @@ unix_protocol_deps="sys_un_h"
 unix_protocol_select="network"
 
 # filters
+afftfilt_filter_deps="avcodec"
+afftfilt_filter_select="fft"
 amovie_filter_deps="avcodec avformat"
 aresample_filter_deps="swresample"
 ass_filter_deps="libass"
@@ -6065,6 +6067,7 @@ done
 enabled zlib && add_cppflags -DZLIB_CONST
 
 # conditional library dependencies, in linking order
+enabled afftfilt_filter     && prepend avfilter_deps "avcodec"
 enabled amovie_filter       && prepend avfilter_deps "avformat avcodec"
 enabled aresample_filter    && prepend avfilter_deps "swresample"
 enabled asyncts_filter      && prepend avfilter_deps "avresample"

doc/filters.texi

@@ -733,6 +733,83 @@ afade=t=out:st=875:d=25
 @end example
 @end itemize
 
+@section afftfilt
+Apply arbitrary expressions to samples in frequency domain.
+
+@table @option
+@item real
+Set frequency domain real expression for each separate channel separated
+by '|'. Default is "1".
+If the number of input channels is greater than the number of
+expressions, the last specified expression is used for the remaining
+output channels.
+
+@item imag
+Set frequency domain imaginary expression for each separate channel
+separated by '|'. If not set, @var{real} option is used.
+
+Each expression in @var{real} and @var{imag} can contain the following
+constants:
+
+@table @option
+@item sr
+sample rate
+
+@item b
+current frequency bin number
+
+@item nb
+number of available bins
+
+@item ch
+channel number of the current expression
+
+@item chs
+number of channels
+
+@item pts
+current frame pts
+@end table
+
+@item win_size
+Set window size.
+
+It accepts the following values:
+@table @samp
+@item w16
+@item w32
+@item w64
+@item w128
+@item w256
+@item w512
+@item w1024
+@item w2048
+@item w4096
+@item w8192
+@item w16384
+@item w32768
+@item w65536
+@end table
+Default is @code{w4096}
+
+@item win_func
+Set window function. Default is @code{hann}.
+
+@item overlap
+Set window overlap. If set to 1, the recommended overlap for selected
+window function will be picked. Default is @code{0.75}.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Increase first 50 bins by 0.1 and lower all other frequencies by factor of 10:
+@example
+afftfilt="1.1*between(b\,0\,49)+0.1*between(b\,50\,f)"
+@end example
+@end itemize
+
 @anchor{aformat}
 @section aformat
 

libavfilter/Makefile

@@ -29,6 +29,7 @@ OBJS-$(CONFIG_ACROSSFADE_FILTER)             += af_afade.o
 OBJS-$(CONFIG_ADELAY_FILTER)                 += af_adelay.o
 OBJS-$(CONFIG_AECHO_FILTER)                  += af_aecho.o
 OBJS-$(CONFIG_AEMPHASIS_FILTER)              += af_aemphasis.o
+OBJS-$(CONFIG_AFFTFILT_FILTER)               += af_afftfilt.o window_func.o
 OBJS-$(CONFIG_ANEQUALIZER_FILTER)            += af_anequalizer.o
 OBJS-$(CONFIG_AEVAL_FILTER)                  += aeval.o
 OBJS-$(CONFIG_AFADE_FILTER)                  += af_afade.o

libavfilter/allfilters.c

@@ -52,6 +52,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(AEMPHASIS,      aemphasis,      af);
     REGISTER_FILTER(AEVAL,          aeval,          af);
     REGISTER_FILTER(AFADE,          afade,          af);
+    REGISTER_FILTER(AFFTFILT,       afftfilt,       af);
     REGISTER_FILTER(AFORMAT,        aformat,        af);
     REGISTER_FILTER(AGATE,          agate,          af);
     REGISTER_FILTER(AINTERLEAVE,    ainterleave,    af);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   6
-#define LIBAVFILTER_VERSION_MINOR  25
+#define LIBAVFILTER_VERSION_MINOR  26
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \