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/*
* Copyright (c) 2012 Steven Robertson
*
* 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
* simple channel-swapping filter to get at the alpha component
*/
#include <string.h>
#include "libavutil/pixfmt.h"
#include "avfilter.h"
#include "drawutils.h"
#include "formats.h"
#include "video.h"
enum { Y, U, V, A };
typedef struct {
int is_packed_rgb;
uint8_t rgba_map[4];
} AlphaExtractContext;
static int query_formats(AVFilterContext *ctx)
{
enum AVPixelFormat in_fmts[] = {
AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
AV_PIX_FMT_RGBA, AV_PIX_FMT_BGRA, AV_PIX_FMT_ARGB, AV_PIX_FMT_ABGR,
AV_PIX_FMT_NONE
};
enum AVPixelFormat out_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
ff_formats_ref(ff_make_format_list(in_fmts), &ctx->inputs[0]->out_formats);
ff_formats_ref(ff_make_format_list(out_fmts), &ctx->outputs[0]->in_formats);
return 0;
}
static int config_input(AVFilterLink *inlink)
{
AlphaExtractContext *extract = inlink->dst->priv;
extract->is_packed_rgb =
ff_fill_rgba_map(extract->rgba_map, inlink->format) >= 0;
return 0;
}
static int draw_slice(AVFilterLink *inlink, int y0, int h, int slice_dir)
{
AlphaExtractContext *extract = inlink->dst->priv;
AVFilterBufferRef *cur_buf = inlink->cur_buf;
AVFilterBufferRef *out_buf = inlink->dst->outputs[0]->out_buf;
if (extract->is_packed_rgb) {
int x, y;
uint8_t *pin, *pout;
for (y = y0; y < (y0 + h); y++) {
pin = cur_buf->data[0] + y * cur_buf->linesize[0] + extract->rgba_map[A];
pout = out_buf->data[0] + y * out_buf->linesize[0];
for (x = 0; x < out_buf->video->w; x++) {
*pout = *pin;
pout += 1;
pin += 4;
}
}
} else if (cur_buf->linesize[A] == out_buf->linesize[Y]) {
const int linesize = cur_buf->linesize[A];
memcpy(out_buf->data[Y] + y0 * linesize,
cur_buf->data[A] + y0 * linesize,
linesize * h);
} else {
const int linesize = FFMIN(out_buf->linesize[Y], cur_buf->linesize[A]);
int y;
for (y = y0; y < (y0 + h); y++) {
memcpy(out_buf->data[Y] + y * out_buf->linesize[Y],
cur_buf->data[A] + y * cur_buf->linesize[A],
linesize);
}
}
return ff_draw_slice(inlink->dst->outputs[0], y0, h, slice_dir);
}
AVFilter avfilter_vf_alphaextract = {
.name = "alphaextract",
.description = NULL_IF_CONFIG_SMALL("Extract an alpha channel as a "
"grayscale image component."),
.priv_size = sizeof(AlphaExtractContext),
.query_formats = query_formats,
.inputs = (const AVFilterPad[]) {
{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO,
.config_props = config_input,
.draw_slice = draw_slice,
.min_perms = AV_PERM_READ },
{ .name = NULL }
},
.outputs = (const AVFilterPad[]) {
{ .name = "default",
.type = AVMEDIA_TYPE_VIDEO, },
{ .name = NULL }
},
};
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