82ecae8a70
These filters are designed for storing and transmitting video sequences with alpha using higher-efficiency codecs such as x264 which don't natively support an alpha channel. 'alphaextract' takes an input stream with an alpha channel and returns a video containing just the alpha component as a grayscale value; 'alphamerge' takes an RGB or YUV stream and adds an alpha channel recovered from a second grayscale stream. Signed-off-by: Steven Robertson <steven@strobe.cc> Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
118 lines
3.8 KiB
C
118 lines
3.8 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 "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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enum PixelFormat in_fmts[] = {
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PIX_FMT_YUVA444P, PIX_FMT_YUVA422P, PIX_FMT_YUVA420P,
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PIX_FMT_RGBA, PIX_FMT_BGRA, PIX_FMT_ARGB, PIX_FMT_ABGR,
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PIX_FMT_NONE
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};
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enum PixelFormat out_fmts[] = { PIX_FMT_GRAY8, 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 void draw_slice(AVFilterLink *inlink, int y0, int h, int slice_dir)
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{
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AlphaExtractContext *extract = inlink->dst->priv;
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AVFilterBufferRef *cur_buf = inlink->cur_buf;
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AVFilterBufferRef *out_buf = inlink->dst->outputs[0]->out_buf;
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if (extract->is_packed_rgb) {
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int x, y;
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uint8_t *pin, *pout;
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for (y = y0; y < (y0 + h); y++) {
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pin = 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 < out_buf->video->w; x++) {
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*pout = *pin;
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pout += 1;
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pin += 4;
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}
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}
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} else if (cur_buf->linesize[A] == out_buf->linesize[Y]) {
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const int linesize = cur_buf->linesize[A];
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memcpy(out_buf->data[Y] + y0 * linesize,
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cur_buf->data[A] + y0 * linesize,
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linesize * h);
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} else {
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const int linesize = FFMIN(out_buf->linesize[Y], cur_buf->linesize[A]);
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int y;
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for (y = y0; y < (y0 + 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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ff_draw_slice(inlink->dst->outputs[0], y0, h, slice_dir);
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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 = (const AVFilterPad[]) {
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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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.draw_slice = draw_slice,
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.min_perms = AV_PERM_READ },
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{ .name = NULL }
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},
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.outputs = (const AVFilterPad[]) {
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{ .name = "default",
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.type = AVMEDIA_TYPE_VIDEO, },
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{ .name = NULL }
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},
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};
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