| /* |
| * 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 "internal.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) |
| { |
| static const 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 |
| }; |
| static const 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 filter_frame(AVFilterLink *inlink, AVFilterBufferRef *cur_buf) |
| { |
| AlphaExtractContext *extract = inlink->dst->priv; |
| AVFilterLink *outlink = inlink->dst->outputs[0]; |
| AVFilterBufferRef *out_buf = |
| ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h); |
| int ret; |
| |
| if (!out_buf) { |
| ret = AVERROR(ENOMEM); |
| goto end; |
| } |
| avfilter_copy_buffer_ref_props(out_buf, cur_buf); |
| |
| if (extract->is_packed_rgb) { |
| int x, y; |
| uint8_t *pcur, *pout; |
| for (y = 0; y < outlink->h; y++) { |
| pcur = 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 < outlink->w; x++) { |
| *pout = *pcur; |
| pout += 1; |
| pcur += 4; |
| } |
| } |
| } else { |
| const int linesize = abs(FFMIN(out_buf->linesize[Y], cur_buf->linesize[A])); |
| int y; |
| for (y = 0; y < outlink->h; y++) { |
| memcpy(out_buf->data[Y] + y * out_buf->linesize[Y], |
| cur_buf->data[A] + y * cur_buf->linesize[A], |
| linesize); |
| } |
| } |
| |
| ret = ff_filter_frame(outlink, out_buf); |
| |
| end: |
| avfilter_unref_buffer(cur_buf); |
| return ret; |
| } |
| |
| static const AVFilterPad alphaextract_inputs[] = { |
| { |
| .name = "default", |
| .type = AVMEDIA_TYPE_VIDEO, |
| .config_props = config_input, |
| .filter_frame = filter_frame, |
| .min_perms = AV_PERM_READ, |
| }, |
| { NULL } |
| }; |
| |
| static const AVFilterPad alphaextract_outputs[] = { |
| { |
| .name = "default", |
| .type = AVMEDIA_TYPE_VIDEO, |
| }, |
| { NULL } |
| }; |
| |
| 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 = alphaextract_inputs, |
| .outputs = alphaextract_outputs, |
| }; |