vf_slicify.c
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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 
26 #include "avfilter.h"
27 #include "libavutil/pixdesc.h"
28 
29 typedef struct {
30  int h;
31  int vshift;
32  uint32_t lcg_state;
34 } SliceContext;
35 
36 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
37 {
38  SliceContext *slice = ctx->priv;
39 
40  slice->h = 16;
41  if (args) {
42  if (!strcmp(args, "random")) {
43  slice->use_random_h = 1;
44  } else {
45  sscanf(args, "%d", &slice->h);
46  }
47  }
48  return 0;
49 }
50 
51 static int config_props(AVFilterLink *link)
52 {
53  SliceContext *slice = link->dst->priv;
54 
56 
57  return 0;
58 }
59 
60 static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
61 {
62  SliceContext *slice = link->dst->priv;
63 
64  if (slice->use_random_h) {
65  slice->lcg_state = slice->lcg_state * 1664525 + 1013904223;
66  slice->h = 8 + (uint64_t)slice->lcg_state * 25 / UINT32_MAX;
67  }
68 
69  /* ensure that slices play nice with chroma subsampling, and enforce
70  * a reasonable minimum size for the slices */
71  slice->h = FFMAX(8, slice->h & (-1 << slice->vshift));
72 
73  av_log(link->dst, AV_LOG_DEBUG, "h:%d\n", slice->h);
74 
75  avfilter_start_frame(link->dst->outputs[0], picref);
76 }
77 
78 static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
79 {
80  SliceContext *slice = link->dst->priv;
81  int y2;
82 
83  if (slice_dir == 1) {
84  for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h)
85  avfilter_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);
86 
87  if (y2 < y + h)
88  avfilter_draw_slice(link->dst->outputs[0], y2, y + h - y2, slice_dir);
89  } else if (slice_dir == -1) {
90  for (y2 = y + h; y2 - slice->h >= y; y2 -= slice->h)
91  avfilter_draw_slice(link->dst->outputs[0], y2 - slice->h, slice->h, slice_dir);
92 
93  if (y2 > y)
94  avfilter_draw_slice(link->dst->outputs[0], y, y2 - y, slice_dir);
95  }
96 }
97 
99  .name = "slicify",
100  .description = NULL_IF_CONFIG_SMALL("Pass the images of input video on to next video filter as multiple slices."),
101 
102  .init = init,
103 
104  .priv_size = sizeof(SliceContext),
105 
106  .inputs = (AVFilterPad[]) {{ .name = "default",
107  .type = AVMEDIA_TYPE_VIDEO,
108  .get_video_buffer = avfilter_null_get_video_buffer,
109  .start_frame = start_frame,
110  .draw_slice = draw_slice,
111  .config_props = config_props,
112  .end_frame = avfilter_null_end_frame, },
113  { .name = NULL}},
114  .outputs = (AVFilterPad[]) {{ .name = "default",
115  .type = AVMEDIA_TYPE_VIDEO, },
116  { .name = NULL}},
117 };