vf_chromakey.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/intreadwrite.h"
#include "libavutil/pixdesc.h"
#include "avfilter.h"
#include "filters.h"
 
typedef struct ChromakeyContext {
    const AVClass *class;
 
    uint8_t chromakey_rgba[4];
    uint16_t chromakey_uv[2];
 
    float similarity;
    float blend;
 
    int is_yuv;
    int depth;
    int mid;
    int max;
 
    int hsub_log2;
    int vsub_log2;
 
    int (*do_slice)(AVFilterContext *ctx, void *arg,
                    int jobnr, int nb_jobs);
} ChromakeyContext;
 
static uint8_t do_chromakey_pixel(ChromakeyContext *ctx, uint8_t u[9], uint8_t v[9])
{
    double diff = 0.0;
    int du, dv, i;
 
    for (i = 0; i < 9; ++i) {
        du = (int)u[i] - ctx->chromakey_uv[0];
        dv = (int)v[i] - ctx->chromakey_uv[1];
 
        diff += sqrt((du * du + dv * dv) / (255.0 * 255.0 * 2));
    }
 
    diff /= 9.0;
 
    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 uint16_t do_chromakey_pixel16(ChromakeyContext *ctx, uint16_t u[9], uint16_t v[9])
{
    double max = ctx->max;
    double diff = 0.0;
    int du, dv, i;
 
    for (i = 0; i < 9; ++i) {
        du = (int)u[i] - ctx->chromakey_uv[0];
        dv = (int)v[i] - ctx->chromakey_uv[1];
 
        diff += sqrt((du * du + dv * dv) / (max * max * 2));
    }
 
    diff /= 9.0;
 
    if (ctx->blend > 0.0001) {
        return av_clipd((diff - ctx->similarity) / ctx->blend, 0.0, 1.0) * max;
    } else {
        return (diff > ctx->similarity) ? max : 0;
    }
}
 
static av_always_inline void get_pixel_uv(AVFrame *frame, int hsub_log2, int vsub_log2, int x, int y, uint8_t *u, uint8_t *v)
{
    if (x < 0 || x >= frame->width || y < 0 || y >= frame->height)
        return;
 
    x >>= hsub_log2;
    y >>= vsub_log2;
 
    *u = frame->data[1][frame->linesize[1] * y + x];
    *v = frame->data[2][frame->linesize[2] * y + x];
}
 
static av_always_inline void get_pixel16_uv(AVFrame *frame, int hsub_log2, int vsub_log2, int x, int y, uint16_t *u, uint16_t *v)
{
    if (x < 0 || x >= frame->width || y < 0 || y >= frame->height)
        return;
 
    x >>= hsub_log2;
    y >>= vsub_log2;
 
    *u = AV_RN16(&frame->data[1][frame->linesize[1] * y + 2 * x]);
    *v = AV_RN16(&frame->data[2][frame->linesize[2] * y + 2 * x]);
}
 
static int do_chromakey_slice(AVFilterContext *avctx, void *arg, int jobnr, int nb_jobs)
{
    AVFrame *frame = arg;
 
    const int slice_start = ff_slice_pos(frame->height, jobnr, nb_jobs);
    const int slice_end = ff_slice_pos(frame->height, jobnr + 1, nb_jobs);
 
    ChromakeyContext *ctx = avctx->priv;
 
    int x, y, xo, yo;
    uint8_t u[9], v[9];
 
    memset(u, ctx->chromakey_uv[0], sizeof(u));
    memset(v, ctx->chromakey_uv[1], sizeof(v));
 
    for (y = slice_start; y < slice_end; ++y) {
        for (x = 0; x < frame->width; ++x) {
            for (yo = 0; yo < 3; ++yo) {
                for (xo = 0; xo < 3; ++xo) {
                    get_pixel_uv(frame, ctx->hsub_log2, ctx->vsub_log2, x + xo - 1, y + yo - 1, &u[yo * 3 + xo], &v[yo * 3 + xo]);
                }
            }
 
            frame->data[3][frame->linesize[3] * y + x] = do_chromakey_pixel(ctx, u, v);
        }
    }
 
    return 0;
}
 
static int do_chromakey16_slice(AVFilterContext *avctx, void *arg, int jobnr, int nb_jobs)
{
    AVFrame *frame = arg;
 
    const int slice_start = ff_slice_pos(frame->height, jobnr, nb_jobs);
    const int slice_end = ff_slice_pos(frame->height, jobnr + 1, nb_jobs);
 
    ChromakeyContext *ctx = avctx->priv;
 
    int x, y, xo, yo;
    uint16_t u[9], v[9];
 
    for (int i = 0; i < 9; i++) {
        u[i] = ctx->chromakey_uv[0];
        v[i] = ctx->chromakey_uv[1];
    }
 
    for (y = slice_start; y < slice_end; ++y) {
        for (x = 0; x < frame->width; ++x) {
            uint16_t *dst = (uint16_t *)(frame->data[3] + frame->linesize[3] * y);
 
            for (yo = 0; yo < 3; ++yo) {
                for (xo = 0; xo < 3; ++xo) {
                    get_pixel16_uv(frame, ctx->hsub_log2, ctx->vsub_log2, x + xo - 1, y + yo - 1, &u[yo * 3 + xo], &v[yo * 3 + xo]);
                }
            }
 
            dst[x] = do_chromakey_pixel16(ctx, u, v);
        }
    }
 
    return 0;
}
 
static int do_chromahold_slice(AVFilterContext *avctx, void *arg, int jobnr, int nb_jobs)
{
    ChromakeyContext *ctx = avctx->priv;
    AVFrame *frame = arg;
    const int slice_start = ff_slice_pos(frame->height >> ctx->vsub_log2, jobnr, nb_jobs);
    const int slice_end = ff_slice_pos(frame->height >> ctx->vsub_log2, jobnr + 1, nb_jobs);
 
    int x, y, alpha;
 
    for (y = slice_start; y < slice_end; ++y) {
        for (x = 0; x < frame->width >> ctx->hsub_log2; ++x) {
            int u = frame->data[1][frame->linesize[1] * y + x];
            int v = frame->data[2][frame->linesize[2] * y + x];
            double diff;
            int du, dv;
 
            du = u - ctx->chromakey_uv[0];
            dv = v - ctx->chromakey_uv[1];
 
            diff = sqrt((du * du + dv * dv) / (255.0 * 255.0 * 2.0));
 
            alpha = diff > ctx->similarity;
            if (ctx->blend > 0.0001) {
                double f = 1. - av_clipd((diff - ctx->similarity) / ctx->blend, 0.0, 1.0);
 
                frame->data[1][frame->linesize[1] * y + x] = 128 + (u - 128) * f;
                frame->data[2][frame->linesize[2] * y + x] = 128 + (v - 128) * f;
            } else if (alpha) {
                frame->data[1][frame->linesize[1] * y + x] = 128;
                frame->data[2][frame->linesize[2] * y + x] = 128;
            }
        }
    }
 
    return 0;
}
 
static int do_chromahold16_slice(AVFilterContext *avctx, void *arg, int jobnr, int nb_jobs)
{
    ChromakeyContext *ctx = avctx->priv;
    AVFrame *frame = arg;
    const int slice_start = ff_slice_pos(frame->height >> ctx->vsub_log2, jobnr, nb_jobs);
    const int slice_end = ff_slice_pos(frame->height >> ctx->vsub_log2, jobnr + 1, nb_jobs);
    const int mid = ctx->mid;
    double max = ctx->max;
 
    int x, y, alpha;
 
    for (y = slice_start; y < slice_end; ++y) {
        for (x = 0; x < frame->width >> ctx->hsub_log2; ++x) {
            int u = AV_RN16(&frame->data[1][frame->linesize[1] * y + 2 * x]);
            int v = AV_RN16(&frame->data[2][frame->linesize[2] * y + 2 * x]);
            double diff;
            int du, dv;
 
            du = u - ctx->chromakey_uv[0];
            dv = v - ctx->chromakey_uv[1];
 
            diff = sqrt((du * du + dv * dv) / (max * max * 2.0));
 
            alpha = diff > ctx->similarity;
            if (ctx->blend > 0.0001) {
                double f = 1. - av_clipd((diff - ctx->similarity) / ctx->blend, 0.0, 1.0);
 
                AV_WN16(&frame->data[1][frame->linesize[1] * y + 2 * x], mid + (u - mid) * f);
                AV_WN16(&frame->data[2][frame->linesize[2] * y + 2 * x], mid + (v - mid) * f);
            } else if (alpha) {
                AV_WN16(&frame->data[1][frame->linesize[1] * y + 2 * x], mid);
                AV_WN16(&frame->data[2][frame->linesize[2] * y + 2 * x], mid);
            }
        }
    }
 
    return 0;
}
 
static int filter_frame(AVFilterLink *link, AVFrame *frame)
{
    AVFilterContext *avctx = link->dst;
    ChromakeyContext *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;
 
    if (!strcmp(avctx->filter->name, "chromakey"))
        frame->alpha_mode = avctx->outputs[0]->alpha_mode;
    return ff_filter_frame(avctx->outputs[0], frame);
}
 
#define FIXNUM(x) lrint((x) * (1 << 10))
#define RGB_TO_U(rgb) (((- FIXNUM(0.16874) * rgb[0] - FIXNUM(0.33126) * rgb[1] + FIXNUM(0.50000) * rgb[2] + (1 << 9) - 1) >> 10) + 128)
#define RGB_TO_V(rgb) (((  FIXNUM(0.50000) * rgb[0] - FIXNUM(0.41869) * rgb[1] - FIXNUM(0.08131) * rgb[2] + (1 << 9) - 1) >> 10) + 128)
 
static av_cold int config_output(AVFilterLink *outlink)
{
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(outlink->format);
    AVFilterContext *avctx = outlink->src;
    ChromakeyContext *ctx = avctx->priv;
    int factor;
 
    ctx->depth = desc->comp[0].depth;
    ctx->mid = 1 << (ctx->depth - 1);
    ctx->max = (1 << ctx->depth) - 1;
 
    factor = 1 << (ctx->depth - 8);
 
    if (ctx->is_yuv) {
        ctx->chromakey_uv[0] = ctx->chromakey_rgba[1] * factor;
        ctx->chromakey_uv[1] = ctx->chromakey_rgba[2] * factor;
    } else {
        ctx->chromakey_uv[0] = RGB_TO_U(ctx->chromakey_rgba) * factor;
        ctx->chromakey_uv[1] = RGB_TO_V(ctx->chromakey_rgba) * factor;
    }
 
    if (!strcmp(avctx->filter->name, "chromakey")) {
        outlink->alpha_mode = AVALPHA_MODE_STRAIGHT;
        ctx->do_slice = ctx->depth <= 8 ? do_chromakey_slice : do_chromakey16_slice;
    } else {
        ctx->do_slice = ctx->depth <= 8 ? do_chromahold_slice: do_chromahold16_slice;
    }
 
    return 0;
}
 
static av_cold int config_input(AVFilterLink *inlink)
{
    AVFilterContext *avctx = inlink->dst;
    ChromakeyContext *ctx = avctx->priv;
    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
 
    ctx->hsub_log2 = desc->log2_chroma_w;
    ctx->vsub_log2 = desc->log2_chroma_h;
 
    return 0;
}
 
static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
                           char *res, int res_len, int flags)
{
    int ret;
 
    ret = ff_filter_process_command(ctx, cmd, args, res, res_len, flags);
    if (ret < 0)
        return ret;
 
    return config_output(ctx->outputs[0]);
}
 
static const AVFilterPad inputs[] = {
    {
        .name           = "default",
        .type           = AVMEDIA_TYPE_VIDEO,
        .flags          = AVFILTERPAD_FLAG_NEEDS_WRITABLE,
        .filter_frame   = filter_frame,
        .config_props   = config_input,
    },
};
 
static const AVFilterPad outputs[] = {
    {
        .name           = "default",
        .type           = AVMEDIA_TYPE_VIDEO,
        .config_props   = config_output,
    },
};
 
#define OFFSET(x) offsetof(ChromakeyContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
 
static const AVOption chromakey_options[] = {
    { "color", "set the chromakey key color", OFFSET(chromakey_rgba), AV_OPT_TYPE_COLOR, { .str = "black" }, 0, 0, FLAGS },
    { "similarity", "set the chromakey similarity value", OFFSET(similarity), AV_OPT_TYPE_FLOAT, { .dbl = 0.01 }, 0.00001, 1.0, FLAGS },
    { "blend", "set the chromakey key blend value", OFFSET(blend), AV_OPT_TYPE_FLOAT, { .dbl = 0.0 }, 0.0, 1.0, FLAGS },
    { "yuv", "color parameter is in yuv instead of rgb", OFFSET(is_yuv), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
    { NULL }
};
 
static const enum AVPixelFormat chromakey_fmts[] = {
    AV_PIX_FMT_YUVA420P,
    AV_PIX_FMT_YUVA422P,
    AV_PIX_FMT_YUVA444P,
    AV_PIX_FMT_YUVA420P9,  AV_PIX_FMT_YUVA422P9,  AV_PIX_FMT_YUVA444P9,
    AV_PIX_FMT_YUVA420P10, AV_PIX_FMT_YUVA422P10, AV_PIX_FMT_YUVA444P10,
    AV_PIX_FMT_YUVA422P12, AV_PIX_FMT_YUVA444P12,
    AV_PIX_FMT_YUVA420P16, AV_PIX_FMT_YUVA422P16, AV_PIX_FMT_YUVA444P16,
    AV_PIX_FMT_NONE
};
 
AVFILTER_DEFINE_CLASS(chromakey);
 
const FFFilter ff_vf_chromakey = {
    .p.name        = "chromakey",
    .p.description = NULL_IF_CONFIG_SMALL("Turns a certain color into transparency. Operates on YUV colors."),
    .p.priv_class  = &chromakey_class,
    .p.flags       = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
    .priv_size     = sizeof(ChromakeyContext),
    FILTER_INPUTS(inputs),
    FILTER_OUTPUTS(outputs),
    FILTER_PIXFMTS_ARRAY(chromakey_fmts),
    .process_command = process_command,
};
 
static const AVOption chromahold_options[] = {
    { "color", "set the chromahold key color", OFFSET(chromakey_rgba), AV_OPT_TYPE_COLOR, { .str = "black" }, 0, 0, FLAGS },
    { "similarity", "set the chromahold similarity value", OFFSET(similarity), AV_OPT_TYPE_FLOAT, { .dbl = 0.01 }, 0.00001, 1.0, FLAGS },
    { "blend", "set the chromahold blend value", OFFSET(blend), AV_OPT_TYPE_FLOAT, { .dbl = 0.0 }, 0.0, 1.0, FLAGS },
    { "yuv", "color parameter is in yuv instead of rgb", OFFSET(is_yuv), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
    { NULL }
};
 
static const enum AVPixelFormat hold_pixel_fmts[] = {
    AV_PIX_FMT_YUV420P,
    AV_PIX_FMT_YUV422P,
    AV_PIX_FMT_YUV444P,
    AV_PIX_FMT_YUVA420P,
    AV_PIX_FMT_YUVA422P,
    AV_PIX_FMT_YUVA444P,
    AV_PIX_FMT_YUV420P9,   AV_PIX_FMT_YUV422P9,   AV_PIX_FMT_YUV444P9,
    AV_PIX_FMT_YUV420P10,  AV_PIX_FMT_YUV422P10,  AV_PIX_FMT_YUV444P10,
    AV_PIX_FMT_YUV444P12,  AV_PIX_FMT_YUV422P12,  AV_PIX_FMT_YUV420P12,
    AV_PIX_FMT_YUV444P14,  AV_PIX_FMT_YUV422P14,  AV_PIX_FMT_YUV420P14,
    AV_PIX_FMT_YUV420P16,  AV_PIX_FMT_YUV422P16,  AV_PIX_FMT_YUV444P16,
    AV_PIX_FMT_YUVA420P9,  AV_PIX_FMT_YUVA422P9,  AV_PIX_FMT_YUVA444P9,
    AV_PIX_FMT_YUVA420P10, AV_PIX_FMT_YUVA422P10, AV_PIX_FMT_YUVA444P10,
    AV_PIX_FMT_YUVA422P12, AV_PIX_FMT_YUVA444P12,
    AV_PIX_FMT_YUVA420P16, AV_PIX_FMT_YUVA422P16, AV_PIX_FMT_YUVA444P16,
    AV_PIX_FMT_NONE
};
 
AVFILTER_DEFINE_CLASS(chromahold);
 
const FFFilter ff_vf_chromahold = {
    .p.name        = "chromahold",
    .p.description = NULL_IF_CONFIG_SMALL("Turns a certain color range into gray."),
    .p.priv_class  = &chromahold_class,
    .p.flags       = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
    .priv_size     = sizeof(ChromakeyContext),
    FILTER_INPUTS(inputs),
    FILTER_OUTPUTS(outputs),
    FILTER_PIXFMTS_ARRAY(hold_pixel_fmts),
    .process_command = process_command,
};