lavfi: port tinterlace filter from MPlayer

Port MPlayer tinterlace filter from MPlayer, with some ideas taken
from the FFmbc/libavfilter port, with the following main differences:

* added support for full-scale YUVJ formats
* added support for YUVA420P
* request_frame() on the filter is forced to return a frame
* some code factorization (related to the copy_picture_fields() function)
* fixed black padding values for mode 3

Changelog

@@ -11,6 +11,7 @@ version next:
 - thumbnail video filter
 - XML output in ffprobe
 - asplit audio filter
+- tinterlace video filter
 
 
 version 0.9:

configure

@@ -1652,6 +1652,7 @@ mptestsrc_filter_deps="gpl"
 negate_filter_deps="lut_filter"
 ocv_filter_deps="libopencv"
 scale_filter_deps="swscale"
+tinterlace_filter_deps="gpl"
 yadif_filter_deps="gpl"
 
 # libraries

doc/filters.texi

@@ -2433,6 +2433,40 @@ Complete example of a thumbnail creation with @command{ffmpeg}:
 ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
 @end example
 
+@section tinterlace
+
+Perform various types of temporal field interlacing.
+
+Frames are counted starting from 1, so the first input frame is
+considered odd.
+
+This filter accepts a single parameter specifying the mode. Available
+modes are:
+
+@table @samp
+@item 0
+Move odd frames into the upper field, even into the lower field,
+generating a double height frame at half framerate.
+
+@item 1
+Only output even frames, odd frames are dropped, generating a frame with
+unchanged height at half framerate.
+
+@item 2
+Only output odd frames, even frames are dropped, generating a frame with
+unchanged height at half framerate.
+
+@item 3
+Expand each frame to full height, but pad alternate lines with black,
+generating a frame with double height at the same input framerate.
+
+@item 4
+Interleave the upper field from odd frames with the lower field from
+even frames, generating a frame with unchanged height at half framerate.
+@end table
+
+Default mode is 0.
+
 @section transpose
 
 Transpose rows with columns in the input video and optionally flip it.

libavfilter/Makefile

@@ -81,6 +81,7 @@ OBJS-$(CONFIG_SHOWINFO_FILTER)               += vf_showinfo.o
 OBJS-$(CONFIG_SLICIFY_FILTER)                += vf_slicify.o
 OBJS-$(CONFIG_SPLIT_FILTER)                  += vf_split.o
 OBJS-$(CONFIG_THUMBNAIL_FILTER)              += vf_thumbnail.o
+OBJS-$(CONFIG_TINTERLACE_FILTER)             += vf_tinterlace.o
 OBJS-$(CONFIG_TRANSPOSE_FILTER)              += vf_transpose.o
 OBJS-$(CONFIG_UNSHARP_FILTER)                += vf_unsharp.o
 OBJS-$(CONFIG_VFLIP_FILTER)                  += vf_vflip.o

libavfilter/allfilters.c

@@ -91,6 +91,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (SLICIFY,     slicify,     vf);
     REGISTER_FILTER (SPLIT,       split,       vf);
     REGISTER_FILTER (THUMBNAIL,   thumbnail,   vf);
+    REGISTER_FILTER (TINTERLACE,  tinterlace,  vf);
     REGISTER_FILTER (TRANSPOSE,   transpose,   vf);
     REGISTER_FILTER (UNSHARP,     unsharp,     vf);
     REGISTER_FILTER (VFLIP,       vflip,       vf);

libavfilter/avfilter.h

@@ -30,8 +30,8 @@
 #include "libavcodec/avcodec.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  2
-#define LIBAVFILTER_VERSION_MINOR 55
-#define LIBAVFILTER_VERSION_MICRO 101
+#define LIBAVFILTER_VERSION_MINOR 56
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \