134 lines
3.9 KiB
C
134 lines
3.9 KiB
C
/*
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* Copyright (c) 2012 Steven Robertson
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg 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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* FFmpeg 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 FFmpeg; 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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* simple channel-swapping filter to get at the alpha component
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*/
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#include <string.h>
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#include "libavutil/pixfmt.h"
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#include "avfilter.h"
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#include "drawutils.h"
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#include "internal.h"
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#include "formats.h"
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#include "video.h"
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enum { Y, U, V, A };
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typedef struct {
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int is_packed_rgb;
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uint8_t rgba_map[4];
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} AlphaExtractContext;
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static int query_formats(AVFilterContext *ctx)
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{
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static const enum AVPixelFormat in_fmts[] = {
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AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
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AV_PIX_FMT_RGBA, AV_PIX_FMT_BGRA, AV_PIX_FMT_ARGB, AV_PIX_FMT_ABGR,
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AV_PIX_FMT_NONE
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};
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static const enum AVPixelFormat out_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
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ff_formats_ref(ff_make_format_list(in_fmts), &ctx->inputs[0]->out_formats);
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ff_formats_ref(ff_make_format_list(out_fmts), &ctx->outputs[0]->in_formats);
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return 0;
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}
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static int config_input(AVFilterLink *inlink)
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{
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AlphaExtractContext *extract = inlink->dst->priv;
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extract->is_packed_rgb =
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ff_fill_rgba_map(extract->rgba_map, inlink->format) >= 0;
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return 0;
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}
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static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *cur_buf)
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{
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AlphaExtractContext *extract = inlink->dst->priv;
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AVFilterLink *outlink = inlink->dst->outputs[0];
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AVFilterBufferRef *out_buf =
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ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
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int ret;
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if (!out_buf) {
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ret = AVERROR(ENOMEM);
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goto end;
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}
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avfilter_copy_buffer_ref_props(out_buf, cur_buf);
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if (extract->is_packed_rgb) {
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int x, y;
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uint8_t *pcur, *pout;
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for (y = 0; y < outlink->h; y++) {
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pcur = cur_buf->data[0] + y * cur_buf->linesize[0] + extract->rgba_map[A];
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pout = out_buf->data[0] + y * out_buf->linesize[0];
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for (x = 0; x < outlink->w; x++) {
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*pout = *pcur;
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pout += 1;
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pcur += 4;
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}
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}
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} else {
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const int linesize = abs(FFMIN(out_buf->linesize[Y], cur_buf->linesize[A]));
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int y;
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for (y = 0; y < outlink->h; y++) {
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memcpy(out_buf->data[Y] + y * out_buf->linesize[Y],
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cur_buf->data[A] + y * cur_buf->linesize[A],
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linesize);
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}
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}
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ret = ff_filter_frame(outlink, out_buf);
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end:
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avfilter_unref_buffer(cur_buf);
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return ret;
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}
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static const AVFilterPad alphaextract_inputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_VIDEO,
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.config_props = config_input,
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.filter_frame = filter_frame,
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.min_perms = AV_PERM_READ,
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},
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{ NULL }
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};
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static const AVFilterPad alphaextract_outputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_VIDEO,
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},
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{ NULL }
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};
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AVFilter avfilter_vf_alphaextract = {
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.name = "alphaextract",
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.description = NULL_IF_CONFIG_SMALL("Extract an alpha channel as a "
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"grayscale image component."),
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.priv_size = sizeof(AlphaExtractContext),
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.query_formats = query_formats,
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.inputs = alphaextract_inputs,
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.outputs = alphaextract_outputs,
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};
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