@@ -2,6 +2,7 @@ Entries are sorted chronologically from oldest to youngest within each release,

 releases are sorted from youngest to oldest.

 version <next>:

+- colorkey video filter

 version 2.7:

@@ -352,6 +352,7 @@ Filters:

   avf_showcqt.c                         Muhammad Faiz

   vf_blend.c                            Paul B Mahol

   vf_colorbalance.c                     Paul B Mahol

+  vf_colorkey.c                         Timo Rothenpieler

   vf_dejudder.c                         Nicholas Robbins

   vf_delogo.c                           Jean Delvare (CC <khali@linux-fr.org>)

   vf_drawbox.c/drawgrid                 Andrey Utkin

@@ -3029,6 +3029,45 @@ colorbalance=rs=.3

 @end example

 @end itemize

+@section colorkey

+RGB colorspace color keying.

+

+The filter accepts the following options:

+

+@table @option

+@item color

+The color which will be replaced with transparency.

+

+@item similarity

+Similarity percentage with the key color.

+

+0.01 matches only the exact key color, while 1.0 matches everything.

+

+@item blend

+Blend percentage.

+

+0.0 makes pixels either fully transparent, or not transparent at all.

+

+Higher values result in semi-transparent pixels, with a higher transparency

+the more similar the pixels color is to the key color.

+@end table

+

+@subsection Examples

+

+@itemize

+@item

+Make every green pixel in the input image transparent:

+@example

+ffmpeg -i input.png -vf colorkey=green out.png

+@end example

+

+@item

+Overlay a greenscreen-video on top of a static background image.

+@example

+ffmpeg -i background.png -i video.mp4 -filter_complex "[1:v]colorkey=0x3BBD1E:0.3:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.flv

+@end example

+@end itemize

+

 @section colorlevels

 Adjust video input frames using levels.

@@ -102,6 +102,7 @@ OBJS-$(CONFIG_BOXBLUR_FILTER)                += vf_boxblur.o

 OBJS-$(CONFIG_CODECVIEW_FILTER)              += vf_codecview.o

 OBJS-$(CONFIG_COLORBALANCE_FILTER)           += vf_colorbalance.o

 OBJS-$(CONFIG_COLORCHANNELMIXER_FILTER)      += vf_colorchannelmixer.o

+OBJS-$(CONFIG_COLORKEY_FILTER)               += vf_colorkey.o

 OBJS-$(CONFIG_COLORLEVELS_FILTER)            += vf_colorlevels.o

 OBJS-$(CONFIG_COLORMATRIX_FILTER)            += vf_colormatrix.o

 OBJS-$(CONFIG_COPY_FILTER)                   += vf_copy.o

@@ -118,6 +118,7 @@ void avfilter_register_all(void)

     REGISTER_FILTER(CODECVIEW,      codecview,      vf);

     REGISTER_FILTER(COLORBALANCE,   colorbalance,   vf);

     REGISTER_FILTER(COLORCHANNELMIXER, colorchannelmixer, vf);

+    REGISTER_FILTER(COLORKEY,       colorkey,       vf);

     REGISTER_FILTER(COLORLEVELS,    colorlevels,    vf);

     REGISTER_FILTER(COLORMATRIX,    colormatrix,    vf);

     REGISTER_FILTER(COPY,           copy,           vf);

new file mode 100644

@@ -0,0 +1,169 @@

+/*

+ * 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;

+} 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));

+

+    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 filter_frame(AVFilterLink *link, AVFrame *frame)

+{

+    AVFilterContext *avctx = link->dst;

+    int res;

+

+    if (res = av_frame_make_writable(frame))

+        return res;

+

+    if (res = avctx->internal->execute(avctx, do_colorkey_slice, frame, NULL, FFMIN(frame->height, avctx->graph->nb_threads)))

+        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_plus1 - 1;

+

+    return 0;

+}

+

+static av_cold int query_formats(AVFilterContext *avctx)

+{

+    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

+    };

+

+    AVFilterFormats *formats = NULL;

+

+    formats = ff_make_format_list(pixel_fmts);

+    if (!formats)

+        return AVERROR(ENOMEM);

+

+    return ff_set_common_formats(avctx, formats);

+}

+

+static const AVFilterPad colorkey_inputs[] = {

+    {

+        .name = "default",

+        .type = AVMEDIA_TYPE_VIDEO,

+        .filter_frame = filter_frame,

+    },

+    { NULL }

+};

+

+static const AVFilterPad colorkey_outputs[] = {

+    {

+        .name = "default",

+        .type = AVMEDIA_TYPE_VIDEO,

+        .config_props  = config_output,

+    },

+    { NULL }

+};

+

+#define OFFSET(x) offsetof(ColorkeyContext, x)

+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

+

+static const AVOption colorkey_options[] = {

+    { "color", "set the colorkey key color", OFFSET(colorkey_rgba), AV_OPT_TYPE_COLOR, { .str = "black" }, CHAR_MIN, CHAR_MAX, 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);

+

+AVFilter ff_vf_colorkey = {

+    .name          = "colorkey",

+    .description   = NULL_IF_CONFIG_SMALL("colorkey filter"),

+    .priv_size     = sizeof(ColorkeyContext),

+    .priv_class    = &colorkey_class,

+    .query_formats = query_formats,

+    .inputs        = colorkey_inputs,

+    .outputs       = colorkey_outputs,

+    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,

+};