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/*
* copyright (c) 2007 Bobby Bingham
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file libavfilter/vf_slicify.c
* video slicing filter
*/
#include "avfilter.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, void *opaque)
{
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;
slice->vshift = av_pix_fmt_descriptors[link->format].log2_chroma_h;
return 0;
}
static void start_frame(AVFilterLink *link, AVFilterPicRef *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);
avfilter_start_frame(link->dst->outputs[0], picref);
}
static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
{
SliceContext *slice = link->dst->priv;
int y2;
if (slice_dir == 1) {
for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h)
avfilter_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);
if (y2 < y + h)
avfilter_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)
avfilter_draw_slice(link->dst->outputs[0], y2 - slice->h, slice->h, slice_dir);
if (y2 > y)
avfilter_draw_slice(link->dst->outputs[0], y, y2 - y, slice_dir);
}
}
AVFilter avfilter_vf_slicify = {
.name = "slicify",
.description = "Pass the images of input video on to next video filter as multiple slices.",
.init = init,
.priv_size = sizeof(SliceContext),
.inputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.get_video_buffer = avfilter_null_get_video_buffer,
.start_frame = start_frame,
.draw_slice = draw_slice,
.config_props = config_props,
.end_frame = avfilter_null_end_frame, },
{ .name = NULL}},
.outputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO, },
{ .name = NULL}},
};
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