diff options
Diffstat (limited to 'libavfilter/vf_alphaextract.c')
| -rw-r--r-- | libavfilter/vf_alphaextract.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/libavfilter/vf_alphaextract.c b/libavfilter/vf_alphaextract.c new file mode 100644 index 0000000000..45d3dd46d7 --- /dev/null +++ b/libavfilter/vf_alphaextract.c @@ -0,0 +1,133 @@ +/* + * 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, +}; |