avfilter: add zscale filter

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

Changelog

@@ -21,6 +21,7 @@ version <next>:
 - extensive native AAC encoder improvements
 - ADPCM PSX decoder
 - genh, vag, ads & svag demuxer
+- zscale filter
 
 
 version 2.8:

configure

@@ -269,6 +269,7 @@ External library support:
   --enable-libxcb-shape    enable X11 grabbing shape rendering [autodetect]
   --enable-libxvid         enable Xvid encoding via xvidcore,
                            native MPEG-4/Xvid encoder exists [no]
+  --enable-libzimg         enable z.lib, needed for zscale filter [no]
   --enable-libzmq          enable message passing via libzmq [no]
   --enable-libzvbi         enable teletext support via libzvbi [no]
   --disable-lzma           disable lzma [autodetect]
@@ -1456,6 +1457,7 @@ EXTERNAL_LIBRARY_LIST="
     libxcb_shape
     libxcb_xfixes
     libxvid
+    libzimg
     libzmq
     libzvbi
     lzma
@@ -2843,6 +2845,7 @@ tinterlace_pad_test_deps="tinterlace_filter"
 uspp_filter_deps="gpl avcodec"
 zmq_filter_deps="libzmq"
 zoompan_filter_deps="swscale"
+zscale_filter_deps="libzimg"
 
 # examples
 avio_reading="avformat avcodec avutil"
@@ -5423,6 +5426,7 @@ enabled libx265           && require_pkg_config x265 x265.h x265_api_get &&
                                die "ERROR: libx265 version must be >= 57."; }
 enabled libxavs           && require libxavs xavs.h xavs_encoder_encode -lxavs
 enabled libxvid           && require libxvid xvid.h xvid_global -lxvidcore
+enabled libzimg           && require_pkg_config zimg zimg.h zimg_get_api_version
 enabled libzmq            && require_pkg_config libzmq zmq.h zmq_ctx_new
 enabled libzvbi           && require libzvbi libzvbi.h vbi_decoder_new -lzvbi
 enabled mmal              && { check_lib interface/mmal/mmal.h mmal_port_connect -lmmal_core -lmmal_util -lmmal_vc_client -lbcm_host ||

doc/filters.texi

@@ -11856,6 +11856,177 @@ zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
 @end example
 @end itemize
 
+@section zscale
+Scale (resize) the input video, using the z.lib library:
+https://github.com/sekrit-twc/zimg.
+
+The zscale filter forces the output display aspect ratio to be the same
+as the input, by changing the output sample aspect ratio.
+
+If the input image format is different from the format requested by
+the next filter, the zscale filter will convert the input to the
+requested format.
+
+@subsection Options
+The filter accepts the following options.
+
+@table @option
+@item width, w
+@item height, h
+Set the output video dimension expression. Default value is the input
+dimension.
+
+If the @var{width} or @var{w} is 0, the input width is used for the output.
+If the @var{height} or @var{h} is 0, the input height is used for the output.
+
+If one of the values is -1, the zscale filter will use a value that
+maintains the aspect ratio of the input image, calculated from the
+other specified dimension. If both of them are -1, the input size is
+used
+
+If one of the values is -n with n > 1, the zscale filter will also use a value
+that maintains the aspect ratio of the input image, calculated from the other
+specified dimension. After that it will, however, make sure that the calculated
+dimension is divisible by n and adjust the value if necessary.
+
+See below for the list of accepted constants for use in the dimension
+expression.
+
+@item size, s
+Set the video size. For the syntax of this option, check the
+@ref{video size syntax,,"Video size" section in the ffmpeg-utils manual,ffmpeg-utils}.
+
+@item dither, d
+Set the dither type.
+
+Possible values are:
+@table @var
+@item none
+@item ordered
+@item random
+@item error_diffusion
+@end table
+
+Default is none.
+
+@item filter, f
+Set the resize filter type.
+
+Possible values are:
+@table @var
+@item point
+@item bilinear
+@item bicubic
+@item spline16
+@item spline36
+@item lanczos
+@end table
+
+Default is bilinear.
+
+@item range, r
+Set the color range.
+
+Possible values are:
+@table @var
+@item input
+@item limited
+@item full
+@end table
+
+Default is same as input.
+
+@item primaries, p
+Set the color primaries.
+
+Possible values are:
+@table @var
+@item input
+@item 709
+@item unspecified
+@item 170m
+@item 240m
+@item 2020
+@end table
+
+Default is same as input.
+
+@item transfer, t
+Set the transfer characteristics.
+
+Possible values are:
+@table @var
+@item input
+@item 709
+@item unspecified
+@item 601
+@item linear
+@item 2020_10
+@item 2020_12
+@end table
+
+Default is same as input.
+
+@item matrix, m
+Set the colorspace matrix.
+
+Possible value are:
+@table @var
+@item input
+@item 709
+@item unspecified
+@item 470bg
+@item 170m
+@item 2020_ncl
+@item 2020_cl
+@end table
+
+Default is same as input.
+@end table
+
+The values of the @option{w} and @option{h} options are expressions
+containing the following constants:
+
+@table @var
+@item in_w
+@item in_h
+The input width and height
+
+@item iw
+@item ih
+These are the same as @var{in_w} and @var{in_h}.
+
+@item out_w
+@item out_h
+The output (scaled) width and height
+
+@item ow
+@item oh
+These are the same as @var{out_w} and @var{out_h}
+
+@item a
+The same as @var{iw} / @var{ih}
+
+@item sar
+input sample aspect ratio
+
+@item dar
+The input display aspect ratio. Calculated from @code{(iw / ih) * sar}.
+
+@item hsub
+@item vsub
+horizontal and vertical input chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+
+@item ohsub
+@item ovsub
+horizontal and vertical output chroma subsample values. For example for the
+pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
+@end table
+
+@table @option
+@end table
+
 @c man end VIDEO FILTERS
 
 @chapter Video Sources

libavfilter/Makefile

@@ -246,6 +246,7 @@ OBJS-$(CONFIG_XBR_FILTER)                    += vf_xbr.o
 OBJS-$(CONFIG_YADIF_FILTER)                  += vf_yadif.o
 OBJS-$(CONFIG_ZMQ_FILTER)                    += f_zmq.o
 OBJS-$(CONFIG_ZOOMPAN_FILTER)                += vf_zoompan.o
+OBJS-$(CONFIG_ZSCALE_FILTER)                 += vf_zscale.o
 
 OBJS-$(CONFIG_ALLRGB_FILTER)                 += vsrc_testsrc.o
 OBJS-$(CONFIG_ALLYUV_FILTER)                 += vsrc_testsrc.o

libavfilter/allfilters.c

@@ -267,6 +267,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(YADIF,          yadif,          vf);
     REGISTER_FILTER(ZMQ,            zmq,            vf);
     REGISTER_FILTER(ZOOMPAN,        zoompan,        vf);
+    REGISTER_FILTER(ZSCALE,         zscale,         vf);
 
     REGISTER_FILTER(ALLRGB,         allrgb,         vsrc);
     REGISTER_FILTER(ALLYUV,         allyuv,         vsrc);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR   6
-#define LIBAVFILTER_VERSION_MINOR  11
+#define LIBAVFILTER_VERSION_MINOR  12
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \