2 * Copyright (c) 2007 Bobby Bingham
4 * This file is part of Libav.
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.
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.
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
23 * video slicing filter
29 #include "libavutil/common.h"
30 #include "libavutil/pixdesc.h"
33 int h; ///< output slice height
34 int vshift; ///< vertical chroma subsampling shift
35 uint32_t lcg_state; ///< LCG state used to compute random slice height
36 int use_random_h; ///< enable the use of random slice height values
39 static av_cold int init(AVFilterContext *ctx, const char *args)
41 SliceContext *slice = ctx->priv;
45 if (!strcmp(args, "random")) {
46 slice->use_random_h = 1;
48 sscanf(args, "%d", &slice->h);
54 static int config_props(AVFilterLink *link)
56 SliceContext *slice = link->dst->priv;
58 slice->vshift = av_pix_fmt_descriptors[link->format].log2_chroma_h;
63 static int start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
65 SliceContext *slice = link->dst->priv;
67 if (slice->use_random_h) {
68 slice->lcg_state = slice->lcg_state * 1664525 + 1013904223;
69 slice->h = 8 + (uint64_t)slice->lcg_state * 25 / UINT32_MAX;
72 /* ensure that slices play nice with chroma subsampling, and enforce
73 * a reasonable minimum size for the slices */
74 slice->h = FFMAX(8, slice->h & (-1 << slice->vshift));
76 av_log(link->dst, AV_LOG_DEBUG, "h:%d\n", slice->h);
79 return ff_start_frame(link->dst->outputs[0], picref);
82 static int draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
84 SliceContext *slice = link->dst->priv;
88 for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h) {
89 ret = ff_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);
95 return ff_draw_slice(link->dst->outputs[0], y2, y + h - y2, slice_dir);
96 } else if (slice_dir == -1) {
97 for (y2 = y + h; y2 - slice->h >= y; y2 -= slice->h) {
98 ret = ff_draw_slice(link->dst->outputs[0], y2 - slice->h, slice->h, slice_dir);
104 return ff_draw_slice(link->dst->outputs[0], y, y2 - y, slice_dir);
109 AVFilter avfilter_vf_slicify = {
111 .description = NULL_IF_CONFIG_SMALL("Pass the images of input video on to next video filter as multiple slices."),
115 .priv_size = sizeof(SliceContext),
117 .inputs = (const AVFilterPad[]) {{ .name = "default",
118 .type = AVMEDIA_TYPE_VIDEO,
119 .get_video_buffer = ff_null_get_video_buffer,
120 .start_frame = start_frame,
121 .draw_slice = draw_slice,
122 .config_props = config_props,
123 .end_frame = ff_null_end_frame, },
125 .outputs = (const AVFilterPad[]) {{ .name = "default",
126 .type = AVMEDIA_TYPE_VIDEO, },