separatefields filter

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

Changelog

@@ -16,6 +16,7 @@ version <next>:
   filtergraph description to be read from a file
 - OpenCL support
 - audio phaser filter
+- separatefields filter
 
 
 version 1.2:

doc/filters.texi

@@ -4896,6 +4896,16 @@ scale='min(500\, iw*3/2):-1'
 @end example
 @end itemize
 
+@section separatefields
+
+The @code{separatefields} takes a frame-based video input and splits
+each frame into its components fields, producing a new half height clip
+with twice the frame rate and twice the frame count.
+
+This filter use field-dominance information in frame to decide which
+of each pair of fields to place first in the output.
+If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter.
+
 @section setdar, setsar
 
 The @code{setdar} filter sets the Display Aspect Ratio for the filter
@@ -4970,6 +4980,7 @@ To set a display aspect ratio of 16:9, and specify a maximum integer value of
 setdar=ratio='16:9':max=1000
 @end example
 
+@anchor{setfield}
 @section setfield
 
 Force field for the output video frame.

libavfilter/Makefile

@@ -148,6 +148,7 @@ OBJS-$(CONFIG_PERMS_FILTER)                  += f_perms.o
 OBJS-$(CONFIG_PIXDESCTEST_FILTER)            += vf_pixdesctest.o
 OBJS-$(CONFIG_PP_FILTER)                     += vf_pp.o
 OBJS-$(CONFIG_REMOVELOGO_FILTER)             += bbox.o lswsutils.o lavfutils.o vf_removelogo.o
+OBJS-$(CONFIG_SEPARATEFIELDS_FILTER)         += vf_separatefields.o
 OBJS-$(CONFIG_SCALE_FILTER)                  += vf_scale.o
 OBJS-$(CONFIG_SELECT_FILTER)                 += f_select.o
 OBJS-$(CONFIG_SENDCMD_FILTER)                += f_sendcmd.o

libavfilter/allfilters.c

@@ -146,6 +146,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(SCALE,          scale,          vf);
     REGISTER_FILTER(SELECT,         select,         vf);
     REGISTER_FILTER(SENDCMD,        sendcmd,        vf);
+    REGISTER_FILTER(SEPARATEFIELDS, separatefields, vf);
     REGISTER_FILTER(SETDAR,         setdar,         vf);
     REGISTER_FILTER(SETFIELD,       setfield,       vf);
     REGISTER_FILTER(SETPTS,         setpts,         vf);

libavfilter/version.h

@@ -29,8 +29,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  49
+#define LIBAVFILTER_VERSION_MINOR  50
-#define LIBAVFILTER_VERSION_MICRO 101
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \

libavfilter/vf_separatefields.c

@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2013 Paul B Mahol
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/pixdesc.h"
+#include "avfilter.h"
+#include "internal.h"
+
+typedef struct {
+    int nb_planes;
+    int64_t frame_count;
+    double ts_unit;
+} SeparateFieldsContext;
+
+static int config_props_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    SeparateFieldsContext *sf = ctx->priv;
+    AVFilterLink *inlink = ctx->inputs[0];
+
+    sf->nb_planes = av_pix_fmt_count_planes(inlink->format);;
+
+    if (inlink->h & 1) {
+        av_log(ctx, AV_LOG_ERROR, "height must be even\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    outlink->frame_rate.num = inlink->frame_rate.num * 2;
+    outlink->frame_rate.den = inlink->frame_rate.den;
+    outlink->w = inlink->w;
+    outlink->h = inlink->h / 2;
+    sf->ts_unit = av_q2d(av_inv_q(av_mul_q(outlink->frame_rate, inlink->time_base)));
+
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
+{
+    AVFilterContext *ctx = inlink->dst;
+    SeparateFieldsContext *sf = ctx->priv;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AVFrame *second;
+    int i, ret;
+
+    inpicref->height = outlink->h;
+    inpicref->interlaced_frame = 0;
+
+    second = av_frame_clone(inpicref);
+    if (!second)
+        return AVERROR(ENOMEM);
+
+    for (i = 0; i < sf->nb_planes; i++) {
+        if (!inpicref->top_field_first)
+            inpicref->data[i] = inpicref->data[i] + inpicref->linesize[i];
+        else
+            second->data[i] = second->data[i] + second->linesize[i];
+        inpicref->linesize[i] *= 2;
+        second->linesize[i]   *= 2;
+    }
+
+    inpicref->pts = sf->frame_count++ * sf->ts_unit;
+    second->pts   = sf->frame_count++ * sf->ts_unit;
+
+    ret = ff_filter_frame(outlink, inpicref);
+    if (ret < 0)
+        return ret;
+    return ff_filter_frame(outlink, second);
+}
+
+static const AVFilterPad separatefields_inputs[] = {
+    {
+        .name             = "default",
+        .type             = AVMEDIA_TYPE_VIDEO,
+        .filter_frame     = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad separatefields_outputs[] = {
+    {
+        .name          = "default",
+        .type          = AVMEDIA_TYPE_VIDEO,
+        .config_props  = config_props_output,
+    },
+    { NULL }
+};
+
+AVFilter avfilter_vf_separatefields = {
+    .name          = "separatefields",
+    .description   = NULL_IF_CONFIG_SMALL("Split input video frames into fields."),
+    .priv_size     = sizeof(SeparateFieldsContext),
+    .inputs        = separatefields_inputs,
+    .outputs       = separatefields_outputs,
+};