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128 lines
4.2 KiB
C
128 lines
4.2 KiB
C
/*
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* Copyright (c) 2007 Bobby Bingham
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* video slicing filter
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*/
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#include "avfilter.h"
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#include "internal.h"
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#include "video.h"
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#include "libavutil/pixdesc.h"
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typedef struct {
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int h; ///< output slice height
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int vshift; ///< vertical chroma subsampling shift
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uint32_t lcg_state; ///< LCG state used to compute random slice height
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int use_random_h; ///< enable the use of random slice height values
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} SliceContext;
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static av_cold int init(AVFilterContext *ctx, const char *args)
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{
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SliceContext *slice = ctx->priv;
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slice->h = 16;
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if (args) {
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if (!strcmp(args, "random")) {
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slice->use_random_h = 1;
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} else {
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sscanf(args, "%d", &slice->h);
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}
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}
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return 0;
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}
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static int config_props(AVFilterLink *link)
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{
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SliceContext *slice = link->dst->priv;
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slice->vshift = av_pix_fmt_descriptors[link->format].log2_chroma_h;
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return 0;
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}
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static int start_frame(AVFilterLink *link, AVFilterBufferRef *picref)
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{
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SliceContext *slice = link->dst->priv;
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if (slice->use_random_h) {
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slice->lcg_state = slice->lcg_state * 1664525 + 1013904223;
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slice->h = 8 + (uint64_t)slice->lcg_state * 25 / UINT32_MAX;
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}
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/* ensure that slices play nice with chroma subsampling, and enforce
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* a reasonable minimum size for the slices */
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slice->h = FFMAX(8, slice->h & (-1 << slice->vshift));
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av_log(link->dst, AV_LOG_DEBUG, "h:%d\n", slice->h);
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link->cur_buf = NULL;
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return ff_start_frame(link->dst->outputs[0], picref);
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}
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static int draw_slice(AVFilterLink *link, int y, int h, int slice_dir)
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{
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SliceContext *slice = link->dst->priv;
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int y2, ret = 0;
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if (slice_dir == 1) {
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for (y2 = y; y2 + slice->h <= y + h; y2 += slice->h) {
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ret = ff_draw_slice(link->dst->outputs[0], y2, slice->h, slice_dir);
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if (ret < 0)
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return ret;
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}
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if (y2 < y + h)
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return ff_draw_slice(link->dst->outputs[0], y2, y + h - y2, slice_dir);
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} else if (slice_dir == -1) {
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for (y2 = y + h; y2 - slice->h >= y; y2 -= slice->h) {
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ret = ff_draw_slice(link->dst->outputs[0], y2 - slice->h, slice->h, slice_dir);
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if (ret < 0)
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return ret;
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}
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if (y2 > y)
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return ff_draw_slice(link->dst->outputs[0], y, y2 - y, slice_dir);
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}
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return 0;
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}
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AVFilter avfilter_vf_slicify = {
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.name = "slicify",
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.description = NULL_IF_CONFIG_SMALL("Pass the images of input video on to next video filter as multiple slices."),
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.init = init,
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.priv_size = sizeof(SliceContext),
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.inputs = (const AVFilterPad[]) {{ .name = "default",
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.type = AVMEDIA_TYPE_VIDEO,
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.get_video_buffer = ff_null_get_video_buffer,
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.start_frame = start_frame,
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.draw_slice = draw_slice,
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.config_props = config_props,
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.end_frame = ff_null_end_frame, },
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{ .name = NULL}},
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.outputs = (const AVFilterPad[]) {{ .name = "default",
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.type = AVMEDIA_TYPE_VIDEO, },
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{ .name = NULL}},
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};
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