2 * Copyright (c) 2012 Steven Robertson
4 * This file is part of FFmpeg.
6 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 * simple channel-swapping filter to get at the alpha component
28 #include "libavutil/pixfmt.h"
30 #include "drawutils.h"
40 } AlphaExtractContext;
42 static int query_formats(AVFilterContext *ctx)
44 static const enum AVPixelFormat in_fmts[] = {
45 AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
46 AV_PIX_FMT_RGBA, AV_PIX_FMT_BGRA, AV_PIX_FMT_ARGB, AV_PIX_FMT_ABGR,
49 static const enum AVPixelFormat out_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
50 ff_formats_ref(ff_make_format_list(in_fmts), &ctx->inputs[0]->out_formats);
51 ff_formats_ref(ff_make_format_list(out_fmts), &ctx->outputs[0]->in_formats);
55 static int config_input(AVFilterLink *inlink)
57 AlphaExtractContext *extract = inlink->dst->priv;
58 extract->is_packed_rgb =
59 ff_fill_rgba_map(extract->rgba_map, inlink->format) >= 0;
63 static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *cur_buf)
65 AlphaExtractContext *extract = inlink->dst->priv;
66 AVFilterLink *outlink = inlink->dst->outputs[0];
67 AVFilterBufferRef *out_buf =
68 ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
72 ret = AVERROR(ENOMEM);
75 avfilter_copy_buffer_ref_props(out_buf, cur_buf);
77 if (extract->is_packed_rgb) {
80 for (y = 0; y < outlink->h; y++) {
81 pcur = cur_buf->data[0] + y * cur_buf->linesize[0] + extract->rgba_map[A];
82 pout = out_buf->data[0] + y * out_buf->linesize[0];
83 for (x = 0; x < outlink->w; x++) {
90 const int linesize = abs(FFMIN(out_buf->linesize[Y], cur_buf->linesize[A]));
92 for (y = 0; y < outlink->h; y++) {
93 memcpy(out_buf->data[Y] + y * out_buf->linesize[Y],
94 cur_buf->data[A] + y * cur_buf->linesize[A],
99 ret = ff_filter_frame(outlink, out_buf);
102 avfilter_unref_buffer(cur_buf);
106 static const AVFilterPad alphaextract_inputs[] = {
109 .type = AVMEDIA_TYPE_VIDEO,
110 .config_props = config_input,
111 .filter_frame = filter_frame,
112 .min_perms = AV_PERM_READ,
117 static const AVFilterPad alphaextract_outputs[] = {
120 .type = AVMEDIA_TYPE_VIDEO,
125 AVFilter avfilter_vf_alphaextract = {
126 .name = "alphaextract",
127 .description = NULL_IF_CONFIG_SMALL("Extract an alpha channel as a "
128 "grayscale image component."),
129 .priv_size = sizeof(AlphaExtractContext),
130 .query_formats = query_formats,
131 .inputs = alphaextract_inputs,
132 .outputs = alphaextract_outputs,