aboutsummaryrefslogtreecommitdiffstats
path: root/libavfilter/vf_slicify.c
blob: f81ab0d0c19d2671ed490cf6d4f0167574194f08 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
/*
 * Copyright (c) 2007 Bobby Bingham
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * video slicing filter
 */

#include "avfilter.h"
#include "internal.h"
#include "video.h"
#include "libavutil/common.h"
#include "libavutil/pixdesc.h"

typedef struct {
    int h;          ///< output slice height
    int vshift;     ///< vertical chroma subsampling shift
    uint32_t lcg_state; ///< LCG state used to compute random slice height
    int use_random_h;   ///< enable the use of random slice height values
} SliceContext;

static av_cold int init(AVFilterContext *ctx, const char *args)
{
    SliceContext *slice = ctx->priv;

    slice->h = 16;
    if (args) {
        if (!strcmp(args, "random")) {
            slice->use_random_h = 1;
        } else {
            sscanf(args, "%d", &slice->h);
        }
    }
    return 0;
}

static int config_props(AVFilterLink *link)
{
    SliceContext *slice = link->dst->priv;
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);

    slice->vshift = desc->log2_chroma_h;

    return 0;
}

static int start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
{
    SliceContext *slice = link->dst->priv;

    if (slice->use_random_h) {
        slice->lcg_state = slice->lcg_state * 1664525 + 1013904223;
        slice->h = 8 + (uint64_t)slice->lcg_state * 25 / UINT32_MAX;
    }

    /* ensure that slices play nice with chroma subsampling, and enforce
     * a reasonable minimum size for the slices */
    slice->h = FFMAX(8, slice->h & (-1 << slice->vshift));

    av_log(link->dst, AV_LOG_DEBUG, "h:%d\n", slice->h);
    link->cur_buf = NULL;

    return ff_start_frame(link->dst->outputs[0], picref);
}

static int draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
{
    SliceContext *slice = link->dst->priv;
    int y2, ret = 0;

    if (slice_dir == 1) {
        for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h) {
            ret = ff_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);
            if (ret < 0)
                return ret;
        }

        if (y2 < y + h)
            return ff_draw_slice(link->dst->outputs[0], y2, y + h - y2, slice_dir);
    } else if (slice_dir == -1) {
        for (y2 = y + h; y2 - slice->h >= y; y2 -= slice->h) {
            ret = ff_draw_slice(link->dst->outputs[0], y2 - slice->h, slice->h, slice_dir);
            if (ret < 0)
                return ret;
        }

        if (y2 > y)
            return ff_draw_slice(link->dst->outputs[0], y, y2 - y, slice_dir);
    }
    return 0;
}

static const AVFilterPad avfilter_vf_slicify_inputs[] = {
    {
        .name             = "default",
        .type             = AVMEDIA_TYPE_VIDEO,
        .get_video_buffer = ff_null_get_video_buffer,
        .start_frame      = start_frame,
        .draw_slice       = draw_slice,
        .config_props     = config_props,
        .end_frame        = ff_null_end_frame,
    },
    { NULL }
};

static const AVFilterPad avfilter_vf_slicify_outputs[] = {
    {
        .name = "default",
        .type = AVMEDIA_TYPE_VIDEO,
    },
    { NULL }
};

AVFilter avfilter_vf_slicify = {
    .name      = "slicify",
    .description = NULL_IF_CONFIG_SMALL("Pass the images of input video on to next video filter as multiple slices."),

    .init      = init,

    .priv_size = sizeof(SliceContext),

    .inputs    = avfilter_vf_slicify_inputs,
    .outputs   = avfilter_vf_slicify_outputs,
};