1/*
2 * Copyright (c) 2013 Paul B Mahol
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21#include "libavutil/pixdesc.h"
22#include "avfilter.h"
23#include "internal.h"
24
25typedef struct {
26    int nb_planes;
27    AVFrame *second;
28} SeparateFieldsContext;
29
30static int config_props_output(AVFilterLink *outlink)
31{
32    AVFilterContext *ctx = outlink->src;
33    SeparateFieldsContext *sf = ctx->priv;
34    AVFilterLink *inlink = ctx->inputs[0];
35
36    sf->nb_planes = av_pix_fmt_count_planes(inlink->format);
37
38    if (inlink->h & 1) {
39        av_log(ctx, AV_LOG_ERROR, "height must be even\n");
40        return AVERROR_INVALIDDATA;
41    }
42
43    outlink->time_base.num = inlink->time_base.num;
44    outlink->time_base.den = inlink->time_base.den * 2;
45    outlink->frame_rate.num = inlink->frame_rate.num * 2;
46    outlink->frame_rate.den = inlink->frame_rate.den;
47    outlink->w = inlink->w;
48    outlink->h = inlink->h / 2;
49
50    return 0;
51}
52
53static void extract_field(AVFrame *frame, int nb_planes, int type)
54{
55    int i;
56
57    for (i = 0; i < nb_planes; i++) {
58        if (type)
59            frame->data[i] = frame->data[i] + frame->linesize[i];
60        frame->linesize[i] *= 2;
61    }
62}
63
64static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
65{
66    AVFilterContext *ctx = inlink->dst;
67    SeparateFieldsContext *sf = ctx->priv;
68    AVFilterLink *outlink = ctx->outputs[0];
69    int ret;
70
71    inpicref->height = outlink->h;
72    inpicref->interlaced_frame = 0;
73
74    if (!sf->second) {
75        goto clone;
76    } else {
77        AVFrame *second = sf->second;
78
79        extract_field(second, sf->nb_planes, second->top_field_first);
80
81        if (second->pts != AV_NOPTS_VALUE &&
82            inpicref->pts != AV_NOPTS_VALUE)
83            second->pts += inpicref->pts;
84        else
85            second->pts = AV_NOPTS_VALUE;
86
87        ret = ff_filter_frame(outlink, second);
88        if (ret < 0)
89            return ret;
90clone:
91        sf->second = av_frame_clone(inpicref);
92        if (!sf->second)
93            return AVERROR(ENOMEM);
94    }
95
96    extract_field(inpicref, sf->nb_planes, !inpicref->top_field_first);
97
98    if (inpicref->pts != AV_NOPTS_VALUE)
99        inpicref->pts *= 2;
100
101    return ff_filter_frame(outlink, inpicref);
102}
103
104static int request_frame(AVFilterLink *outlink)
105{
106    AVFilterContext *ctx = outlink->src;
107    SeparateFieldsContext *sf = ctx->priv;
108    int ret;
109
110    ret = ff_request_frame(ctx->inputs[0]);
111    if (ret == AVERROR_EOF && sf->second) {
112        sf->second->pts *= 2;
113        extract_field(sf->second, sf->nb_planes, sf->second->top_field_first);
114        ret = ff_filter_frame(outlink, sf->second);
115        sf->second = 0;
116    }
117
118    return ret;
119}
120
121static const AVFilterPad separatefields_inputs[] = {
122    {
123        .name         = "default",
124        .type         = AVMEDIA_TYPE_VIDEO,
125        .filter_frame = filter_frame,
126    },
127    { NULL }
128};
129
130static const AVFilterPad separatefields_outputs[] = {
131    {
132        .name          = "default",
133        .type          = AVMEDIA_TYPE_VIDEO,
134        .config_props  = config_props_output,
135        .request_frame = request_frame,
136    },
137    { NULL }
138};
139
140AVFilter ff_vf_separatefields = {
141    .name        = "separatefields",
142    .description = NULL_IF_CONFIG_SMALL("Split input video frames into fields."),
143    .priv_size   = sizeof(SeparateFieldsContext),
144    .inputs      = separatefields_inputs,
145    .outputs     = separatefields_outputs,
146};
147