avfilter: add showspectrumpic filter

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

Changelog

@@ -50,6 +50,7 @@ version <next>:
 - VAAPI VP9 hwaccel
 - audio high-order multiband parametric equalizer
 - automatic bitstream filtering
+- showspectrumpic filter
 
 
 version 2.8:

doc/filters.texi

@@ -14704,6 +14704,112 @@ ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
 @end example
 @end itemize
 
+@section showspectrumpic
+
+Convert input audio to a single video frame, representing the audio frequency
+spectrum.
+
+The filter accepts the following options:
+
+@table @option
+@item size, s
+Specify the video size for the output. For the syntax of this option, check the
+@ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
+Default value is @code{4096x2048}.
+
+@item mode
+Specify display mode.
+
+It accepts the following values:
+@table @samp
+@item combined
+all channels are displayed in the same row
+@item separate
+all channels are displayed in separate rows
+@end table
+Default value is @samp{combined}.
+
+@item color
+Specify display color mode.
+
+It accepts the following values:
+@table @samp
+@item channel
+each channel is displayed in a separate color
+@item intensity
+each channel is displayed using the same color scheme
+@item rainbow
+each channel is displayed using the rainbow color scheme
+@item moreland
+each channel is displayed using the moreland color scheme
+@item nebulae
+each channel is displayed using the nebulae color scheme
+@item fire
+each channel is displayed using the fire color scheme
+@end table
+Default value is @samp{intensity}.
+
+@item scale
+Specify scale used for calculating intensity color values.
+
+It accepts the following values:
+@table @samp
+@item lin
+linear
+@item sqrt
+square root, default
+@item cbrt
+cubic root
+@item log
+logarithmic
+@end table
+Default value is @samp{log}.
+
+@item saturation
+Set saturation modifier for displayed colors. Negative values provide
+alternative color scheme. @code{0} is no saturation at all.
+Saturation must be in [-10.0, 10.0] range.
+Default value is @code{1}.
+
+@item win_func
+Set window function.
+
+It accepts the following values:
+@table @samp
+@item rect
+@item bartlett
+@item hann
+@item hanning
+@item hamming
+@item blackman
+@item welch
+@item flattop
+@item bharris
+@item bnuttall
+@item bhann
+@item sine
+@item nuttall
+@item lanczos
+@item gauss
+@end table
+Default value is @code{hann}.
+
+@item orientation
+Set orientation of time vs frequency axis. Can be @code{vertical} or
+@code{horizontal}. Default is @code{vertical}.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Extract an audio spectrogram of a whole audio track
+in a 1024x1024 picture using @command{ffmpeg}:
+@example
+ffmpeg -i audio.flac -lavfi showspectrumpic=s=1024x1024 spectrogram.png
+@end example
+@end itemize
+
 @section showvolume
 
 Convert input audio volume to a video output.

libavfilter/Makefile

@@ -286,6 +286,7 @@ OBJS-$(CONFIG_CONCAT_FILTER)                 += avf_concat.o
 OBJS-$(CONFIG_SHOWCQT_FILTER)                += avf_showcqt.o lswsutils.o lavfutils.o
 OBJS-$(CONFIG_SHOWFREQS_FILTER)              += avf_showfreqs.o window_func.o
 OBJS-$(CONFIG_SHOWSPECTRUM_FILTER)           += avf_showspectrum.o window_func.o
+OBJS-$(CONFIG_SHOWSPECTRUMPIC_FILTER)        += avf_showspectrum.o window_func.o
 OBJS-$(CONFIG_SHOWVOLUME_FILTER)             += avf_showvolume.o
 OBJS-$(CONFIG_SHOWWAVES_FILTER)              += avf_showwaves.o
 OBJS-$(CONFIG_SHOWWAVESPIC_FILTER)           += avf_showwaves.o

libavfilter/allfilters.c

@@ -306,6 +306,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(SHOWCQT,        showcqt,        avf);
     REGISTER_FILTER(SHOWFREQS,      showfreqs,      avf);
     REGISTER_FILTER(SHOWSPECTRUM,   showspectrum,   avf);
+    REGISTER_FILTER(SHOWSPECTRUMPIC, showspectrumpic, avf);
     REGISTER_FILTER(SHOWVOLUME,     showvolume,     avf);
     REGISTER_FILTER(SHOWWAVES,      showwaves,      avf);
     REGISTER_FILTER(SHOWWAVESPIC,   showwavespic,   avf);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   6
-#define LIBAVFILTER_VERSION_MINOR  22
+#define LIBAVFILTER_VERSION_MINOR  23
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \