1/*
2 * Copyright (c) 2003 Rich Felker
3 * Copyright (c) 2012 Stefano Sabatini
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22/**
23 * @file
24 * field filter, based on libmpcodecs/vf_field.c by Rich Felker
25 */
26
27#include "libavutil/opt.h"
28#include "libavutil/pixdesc.h"
29#include "avfilter.h"
30#include "internal.h"
31
32enum FieldType { FIELD_TYPE_TOP = 0, FIELD_TYPE_BOTTOM };
33
34typedef struct {
35    const AVClass *class;
36    enum FieldType type;
37    int nb_planes;              ///< number of planes of the current format
38} FieldContext;
39
40#define OFFSET(x) offsetof(FieldContext, x)
41#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
42
43static const AVOption field_options[] = {
44    {"type", "set field type (top or bottom)", OFFSET(type), AV_OPT_TYPE_INT, {.i64=FIELD_TYPE_TOP}, 0, 1, FLAGS, "field_type" },
45    {"top",    "select top field",    0, AV_OPT_TYPE_CONST, {.i64=FIELD_TYPE_TOP},    INT_MIN, INT_MAX, FLAGS, "field_type"},
46    {"bottom", "select bottom field", 0, AV_OPT_TYPE_CONST, {.i64=FIELD_TYPE_BOTTOM}, INT_MIN, INT_MAX, FLAGS, "field_type"},
47    {NULL}
48};
49
50AVFILTER_DEFINE_CLASS(field);
51
52static int config_props_output(AVFilterLink *outlink)
53{
54    AVFilterContext *ctx = outlink->src;
55    FieldContext *field = ctx->priv;
56    AVFilterLink *inlink = ctx->inputs[0];
57
58    field->nb_planes = av_pix_fmt_count_planes(outlink->format);
59
60    outlink->w = inlink->w;
61    outlink->h = (inlink->h + (field->type == FIELD_TYPE_TOP)) / 2;
62
63    av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d type:%s -> w:%d h:%d\n",
64           inlink->w, inlink->h, field->type == FIELD_TYPE_BOTTOM ? "bottom" : "top",
65           outlink->w, outlink->h);
66    return 0;
67}
68
69static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
70{
71    FieldContext *field = inlink->dst->priv;
72    AVFilterLink *outlink = inlink->dst->outputs[0];
73    int i;
74
75    inpicref->height = outlink->h;
76    inpicref->interlaced_frame = 0;
77
78    for (i = 0; i < field->nb_planes; i++) {
79        if (field->type == FIELD_TYPE_BOTTOM)
80            inpicref->data[i] = inpicref->data[i] + inpicref->linesize[i];
81        inpicref->linesize[i] = 2 * inpicref->linesize[i];
82    }
83    return ff_filter_frame(outlink, inpicref);
84}
85
86static const AVFilterPad field_inputs[] = {
87    {
88        .name         = "default",
89        .type         = AVMEDIA_TYPE_VIDEO,
90        .filter_frame = filter_frame,
91    },
92    { NULL }
93};
94
95static const AVFilterPad field_outputs[] = {
96    {
97        .name         = "default",
98        .type         = AVMEDIA_TYPE_VIDEO,
99        .config_props = config_props_output,
100    },
101    { NULL }
102};
103
104AVFilter ff_vf_field = {
105    .name        = "field",
106    .description = NULL_IF_CONFIG_SMALL("Extract a field from the input video."),
107    .priv_size   = sizeof(FieldContext),
108    .inputs      = field_inputs,
109    .outputs     = field_outputs,
110    .priv_class  = &field_class,
111};
112