yading@10: /*
yading@10:  * Copyright (c) 2012 Steven Robertson
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * simple channel-swapping filter to get at the alpha component
yading@10:  */
yading@10: 
yading@10: #include <string.h>
yading@10: 
yading@10: #include "libavutil/pixfmt.h"
yading@10: #include "avfilter.h"
yading@10: #include "drawutils.h"
yading@10: #include "internal.h"
yading@10: #include "formats.h"
yading@10: #include "video.h"
yading@10: 
yading@10: enum { Y, U, V, A };
yading@10: 
yading@10: typedef struct {
yading@10:     int is_packed_rgb;
yading@10:     uint8_t rgba_map[4];
yading@10: } AlphaExtractContext;
yading@10: 
yading@10: static int query_formats(AVFilterContext *ctx)
yading@10: {
yading@10:     static const enum AVPixelFormat in_fmts[] = {
yading@10:         AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,
yading@10:         AV_PIX_FMT_RGBA, AV_PIX_FMT_BGRA, AV_PIX_FMT_ARGB, AV_PIX_FMT_ABGR,
yading@10:         AV_PIX_FMT_NONE
yading@10:     };
yading@10:     static const enum AVPixelFormat out_fmts[] = { AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE };
yading@10:     ff_formats_ref(ff_make_format_list(in_fmts), &ctx->inputs[0]->out_formats);
yading@10:     ff_formats_ref(ff_make_format_list(out_fmts), &ctx->outputs[0]->in_formats);
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int config_input(AVFilterLink *inlink)
yading@10: {
yading@10:     AlphaExtractContext *extract = inlink->dst->priv;
yading@10:     extract->is_packed_rgb =
yading@10:         ff_fill_rgba_map(extract->rgba_map, inlink->format) >= 0;
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int filter_frame(AVFilterLink *inlink, AVFrame *cur_buf)
yading@10: {
yading@10:     AlphaExtractContext *extract = inlink->dst->priv;
yading@10:     AVFilterLink *outlink = inlink->dst->outputs[0];
yading@10:     AVFrame *out_buf = ff_get_video_buffer(outlink, outlink->w, outlink->h);
yading@10:     int ret;
yading@10: 
yading@10:     if (!out_buf) {
yading@10:         ret = AVERROR(ENOMEM);
yading@10:         goto end;
yading@10:     }
yading@10:     av_frame_copy_props(out_buf, cur_buf);
yading@10: 
yading@10:     if (extract->is_packed_rgb) {
yading@10:         int x, y;
yading@10:         uint8_t *pcur, *pout;
yading@10:         for (y = 0; y < outlink->h; y++) {
yading@10:             pcur = cur_buf->data[0] + y * cur_buf->linesize[0] + extract->rgba_map[A];
yading@10:             pout = out_buf->data[0] + y * out_buf->linesize[0];
yading@10:             for (x = 0; x < outlink->w; x++) {
yading@10:                 *pout = *pcur;
yading@10:                 pout += 1;
yading@10:                 pcur += 4;
yading@10:             }
yading@10:         }
yading@10:     } else {
yading@10:         const int linesize = abs(FFMIN(out_buf->linesize[Y], cur_buf->linesize[A]));
yading@10:         int y;
yading@10:         for (y = 0; y < outlink->h; y++) {
yading@10:             memcpy(out_buf->data[Y] + y * out_buf->linesize[Y],
yading@10:                    cur_buf->data[A] + y * cur_buf->linesize[A],
yading@10:                    linesize);
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     ret = ff_filter_frame(outlink, out_buf);
yading@10: 
yading@10: end:
yading@10:     av_frame_free(&cur_buf);
yading@10:     return ret;
yading@10: }
yading@10: 
yading@10: static const AVFilterPad alphaextract_inputs[] = {
yading@10:     {
yading@10:         .name         = "default",
yading@10:         .type         = AVMEDIA_TYPE_VIDEO,
yading@10:         .config_props = config_input,
yading@10:         .filter_frame = filter_frame,
yading@10:     },
yading@10:     { NULL }
yading@10: };
yading@10: 
yading@10: static const AVFilterPad alphaextract_outputs[] = {
yading@10:     {
yading@10:         .name = "default",
yading@10:         .type = AVMEDIA_TYPE_VIDEO,
yading@10:     },
yading@10:     { NULL }
yading@10: };
yading@10: 
yading@10: AVFilter avfilter_vf_alphaextract = {
yading@10:     .name           = "alphaextract",
yading@10:     .description    = NULL_IF_CONFIG_SMALL("Extract an alpha channel as a "
yading@10:                       "grayscale image component."),
yading@10:     .priv_size      = sizeof(AlphaExtractContext),
yading@10:     .query_formats  = query_formats,
yading@10:     .inputs         = alphaextract_inputs,
yading@10:     .outputs        = alphaextract_outputs,
yading@10: };