vf_colorkey.c

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/*
 * Copyright (c) 2015 Timo Rothenpieler <timo@rothenpieler.org>
 *
 * 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
 */
 
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
#include "avfilter.h"
#include "formats.h"
#include "internal.h"
#include "video.h"
 
typedef struct ColorkeyContext {
    const AVClass *class;
 
    /* color offsets rgba */
    int co[4];
 
    uint8_t colorkey_rgba[4];
    float similarity;
    float blend;
 
    int (*do_slice)(AVFilterContext *ctx, void *arg,
                    int jobnr, int nb_jobs);
} ColorkeyContext;
 
static uint8_t do_colorkey_pixel(ColorkeyContext *ctx, uint8_t r, uint8_t g, uint8_t b)
{
    int dr = (int)r - ctx->colorkey_rgba[0];
    int dg = (int)g - ctx->colorkey_rgba[1];
    int db = (int)b - ctx->colorkey_rgba[2];
 
    double diff = sqrt((dr * dr + dg * dg + db * db) / (255.0 * 255.0 * 3.0));
 
    if (ctx->blend > 0.0001) {
        return av_clipd((diff - ctx->similarity) / ctx->blend, 0.0, 1.0) * 255.0;
    } else {
        return (diff > ctx->similarity) ? 255 : 0;
    }
}
 
static int do_colorkey_slice(AVFilterContext *avctx, void *arg, int jobnr, int nb_jobs)
{
    AVFrame *frame = arg;
 
    const int slice_start = (frame->height * jobnr) / nb_jobs;
    const int slice_end = (frame->height * (jobnr + 1)) / nb_jobs;
 
    ColorkeyContext *ctx = avctx->priv;
 
    int o, x, y;
 
    for (y = slice_start; y < slice_end; ++y) {
        for (x = 0; x < frame->width; ++x) {
            o = frame->linesize[0] * y + x * 4;
 
            frame->data[0][o + ctx->co[3]] =
                do_colorkey_pixel(ctx,
                                  frame->data[0][o + ctx->co[0]],
                                  frame->data[0][o + ctx->co[1]],
                                  frame->data[0][o + ctx->co[2]]);
        }
    }
 
    return 0;
}
 
static int do_colorhold_slice(AVFilterContext *avctx, void *arg, int jobnr, int nb_jobs)
{
    AVFrame *frame = arg;
 
    const int slice_start = (frame->height * jobnr) / nb_jobs;
    const int slice_end = (frame->height * (jobnr + 1)) / nb_jobs;
 
    ColorkeyContext *ctx = avctx->priv;
 
    int x, y;
 
    for (y = slice_start; y < slice_end; ++y) {
        for (x = 0; x < frame->width; ++x) {
            int o, t, r, g, b;
 
            o = frame->linesize[0] * y + x * 4;
            r = frame->data[0][o + ctx->co[0]];
            g = frame->data[0][o + ctx->co[1]];
            b = frame->data[0][o + ctx->co[2]];
 
            t = do_colorkey_pixel(ctx, r, g, b);
 
            if (t > 0) {
                int a = (r + g + b) / 3;
                int rt = 255 - t;
 
                frame->data[0][o + ctx->co[0]] = (a * t + r * rt + 127) >> 8;
                frame->data[0][o + ctx->co[1]] = (a * t + g * rt + 127) >> 8;
                frame->data[0][o + ctx->co[2]] = (a * t + b * rt + 127) >> 8;
            }
        }
    }
 
    return 0;
}
 
static av_cold int init_filter(AVFilterContext *avctx)
{
    ColorkeyContext *ctx = avctx->priv;
 
    if (!strcmp(avctx->filter->name, "colorkey")) {
        ctx->do_slice = do_colorkey_slice;
    } else {
        ctx->do_slice = do_colorhold_slice;
    }
 
    return 0;
}
 
static int filter_frame(AVFilterLink *link, AVFrame *frame)
{
    AVFilterContext *avctx = link->dst;
    ColorkeyContext *ctx = avctx->priv;
    int res;
 
    if (res = ff_filter_execute(avctx, ctx->do_slice, frame, NULL,
                                FFMIN(frame->height, ff_filter_get_nb_threads(avctx))))
        return res;
 
    return ff_filter_frame(avctx->outputs[0], frame);
}
 
static av_cold int config_output(AVFilterLink *outlink)
{
    AVFilterContext *avctx = outlink->src;
    ColorkeyContext *ctx = avctx->priv;
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(outlink->format);
    int i;
 
    outlink->w = avctx->inputs[0]->w;
    outlink->h = avctx->inputs[0]->h;
    outlink->time_base = avctx->inputs[0]->time_base;
 
    for (i = 0; i < 4; ++i)
        ctx->co[i] = desc->comp[i].offset;
 
    return 0;
}
 
static const enum AVPixelFormat pixel_fmts[] = {
    AV_PIX_FMT_ARGB,
    AV_PIX_FMT_RGBA,
    AV_PIX_FMT_ABGR,
    AV_PIX_FMT_BGRA,
    AV_PIX_FMT_NONE
};
 
static const AVFilterPad colorkey_inputs[] = {
    {
        .name = "default",
        .type = AVMEDIA_TYPE_VIDEO,
        .flags        = AVFILTERPAD_FLAG_NEEDS_WRITABLE,
        .filter_frame = filter_frame,
    },
};
 
static const AVFilterPad colorkey_outputs[] = {
    {
        .name = "default",
        .type = AVMEDIA_TYPE_VIDEO,
        .config_props  = config_output,
    },
};
 
#define OFFSET(x) offsetof(ColorkeyContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
 
#if CONFIG_COLORKEY_FILTER
 
static const AVOption colorkey_options[] = {
    { "color", "set the colorkey key color", OFFSET(colorkey_rgba), AV_OPT_TYPE_COLOR, { .str = "black" }, 0, 0, FLAGS },
    { "similarity", "set the colorkey similarity value", OFFSET(similarity), AV_OPT_TYPE_FLOAT, { .dbl = 0.01 }, 0.01, 1.0, FLAGS },
    { "blend", "set the colorkey key blend value", OFFSET(blend), AV_OPT_TYPE_FLOAT, { .dbl = 0.0 }, 0.0, 1.0, FLAGS },
    { NULL }
};
 
AVFILTER_DEFINE_CLASS(colorkey);
 
const AVFilter ff_vf_colorkey = {
    .name          = "colorkey",
    .description   = NULL_IF_CONFIG_SMALL("Turns a certain color into transparency. Operates on RGB colors."),
    .priv_size     = sizeof(ColorkeyContext),
    .priv_class    = &colorkey_class,
    .init          = init_filter,
    FILTER_INPUTS(colorkey_inputs),
    FILTER_OUTPUTS(colorkey_outputs),
    FILTER_PIXFMTS_ARRAY(pixel_fmts),
    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
    .process_command = ff_filter_process_command,
};
 
#endif /* CONFIG_COLORKEY_FILTER */
#if CONFIG_COLORHOLD_FILTER
 
static const AVOption colorhold_options[] = {
    { "color", "set the colorhold key color", OFFSET(colorkey_rgba), AV_OPT_TYPE_COLOR, { .str = "black" }, 0, 0, FLAGS },
    { "similarity", "set the colorhold similarity value", OFFSET(similarity), AV_OPT_TYPE_FLOAT, { .dbl = 0.01 }, 0.01, 1.0, FLAGS },
    { "blend", "set the colorhold blend value", OFFSET(blend), AV_OPT_TYPE_FLOAT, { .dbl = 0.0 }, 0.0, 1.0, FLAGS },
    { NULL }
};
 
AVFILTER_DEFINE_CLASS(colorhold);
 
const AVFilter ff_vf_colorhold = {
    .name          = "colorhold",
    .description   = NULL_IF_CONFIG_SMALL("Turns a certain color range into gray. Operates on RGB colors."),
    .priv_size     = sizeof(ColorkeyContext),
    .priv_class    = &colorhold_class,
    .init          = init_filter,
    FILTER_INPUTS(colorkey_inputs),
    FILTER_OUTPUTS(colorkey_outputs),
    FILTER_PIXFMTS_ARRAY(pixel_fmts),
    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
    .process_command = ff_filter_process_command,
};
 
#endif /* CONFIG_COLORHOLD_FILTER */