4b78dca493808bc6905606a8ead413f1ed2a157c
[libav.git] / libavfilter / vf_slicify.c
1 /*
2 * Copyright (c) 2007 Bobby Bingham
3 *
4 * This file is part of Libav.
5 *
6 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * video slicing filter
24 */
25
26 #include "avfilter.h"
27 #include "internal.h"
28 #include "video.h"
29 #include "libavutil/pixdesc.h"
30
31 typedef struct {
32 int h; ///< output slice height
33 int vshift; ///< vertical chroma subsampling shift
34 uint32_t lcg_state; ///< LCG state used to compute random slice height
35 int use_random_h; ///< enable the use of random slice height values
36 } SliceContext;
37
38 static av_cold int init(AVFilterContext *ctx, const char *args)
39 {
40 SliceContext *slice = ctx->priv;
41
42 slice->h = 16;
43 if (args) {
44 if (!strcmp(args, "random")) {
45 slice->use_random_h = 1;
46 } else {
47 sscanf(args, "%d", &slice->h);
48 }
49 }
50 return 0;
51 }
52
53 static int config_props(AVFilterLink *link)
54 {
55 SliceContext *slice = link->dst->priv;
56
57 slice->vshift = av_pix_fmt_descriptors[link->format].log2_chroma_h;
58
59 return 0;
60 }
61
62 static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
63 {
64 SliceContext *slice = link->dst->priv;
65
66 if (slice->use_random_h) {
67 slice->lcg_state = slice->lcg_state * 1664525 + 1013904223;
68 slice->h = 8 + (uint64_t)slice->lcg_state * 25 / UINT32_MAX;
69 }
70
71 /* ensure that slices play nice with chroma subsampling, and enforce
72 * a reasonable minimum size for the slices */
73 slice->h = FFMAX(8, slice->h & (-1 << slice->vshift));
74
75 av_log(link->dst, AV_LOG_DEBUG, "h:%d\n", slice->h);
76 link->cur_buf = NULL;
77
78 ff_start_frame(link->dst->outputs[0], picref);
79 }
80
81 static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
82 {
83 SliceContext *slice = link->dst->priv;
84 int y2;
85
86 if (slice_dir == 1) {
87 for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h)
88 ff_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);
89
90 if (y2 < y + h)
91 ff_draw_slice(link->dst->outputs[0], y2, y + h - y2, slice_dir);
92 } else if (slice_dir == -1) {
93 for (y2 = y + h; y2 - slice->h >= y; y2 -= slice->h)
94 ff_draw_slice(link->dst->outputs[0], y2 - slice->h, slice->h, slice_dir);
95
96 if (y2 > y)
97 ff_draw_slice(link->dst->outputs[0], y, y2 - y, slice_dir);
98 }
99 }
100
101 AVFilter avfilter_vf_slicify = {
102 .name = "slicify",
103 .description = NULL_IF_CONFIG_SMALL("Pass the images of input video on to next video filter as multiple slices."),
104
105 .init = init,
106
107 .priv_size = sizeof(SliceContext),
108
109 .inputs = (const AVFilterPad[]) {{ .name = "default",
110 .type = AVMEDIA_TYPE_VIDEO,
111 .get_video_buffer = ff_null_get_video_buffer,
112 .start_frame = start_frame,
113 .draw_slice = draw_slice,
114 .config_props = config_props,
115 .end_frame = ff_null_end_frame, },
116 { .name = NULL}},
117 .outputs = (const AVFilterPad[]) {{ .name = "default",
118 .type = AVMEDIA_TYPE_VIDEO, },
119 { .name = NULL}},
120 };