[FFmpeg-devel] [PATCH 1/2] avfilter/vf_colorkey: Add colorkey video filter

Timo Rothenpieler timo at rothenpieler.org
Tue Apr 28 19:31:32 CEST 2015


---
 Changelog                 |   1 +
 MAINTAINERS               |   1 +
 doc/filters.texi          |  39 +++++++
 libavfilter/Makefile      |   1 +
 libavfilter/allfilters.c  |   1 +
 libavfilter/vf_colorkey.c | 264 ++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 307 insertions(+)
 create mode 100644 libavfilter/vf_colorkey.c

diff --git a/Changelog b/Changelog
index 02dd77b..21ea398 100644
--- a/Changelog
+++ b/Changelog
@@ -18,6 +18,7 @@ version <next>:
 - nvenc level and tier options
 - chorus filter
 - Canopus HQ/HQA decoder
+- colorkey video filter
 
 
 version 2.6:
diff --git a/MAINTAINERS b/MAINTAINERS
index 598c0b3..18f6ba3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -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 at linux-fr.org>)
   vf_drawbox.c/drawgrid                 Andrey Utkin
diff --git a/doc/filters.texi b/doc/filters.texi
index b7a9c9b..29aaa1a 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -3026,6 +3026,45 @@ colorbalance=rs=.3
 @end example
 @end itemize
 
+ at section colorkey
+RGB colorspace color keying.
+
+The filter accepts the following options:
+
+ at table @option
+ at item color
+The color which will be replaced with transparency.
+
+ at item similarity
+Similarity percentage with the key color.
+
+0.01 matches only the exact key color, while 1.0 matches everything.
+
+ at 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.
+ at end table
+
+ at subsection Examples
+
+ at itemize
+ at item
+Make every green pixel in the input image transparent:
+ at example
+ffmpeg -i input.png -vf colorkey=green out.png
+ at end example
+
+ at item
+Overlay a greenscreen-video on top of a static background image.
+ at 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
+ at end example
+ at end itemize
+
 @section colorlevels
 
 Adjust video input frames using levels.
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 48cee50..60e6b52 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -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
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 7961dca..2eeec7f 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -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);
diff --git a/libavfilter/vf_colorkey.c b/libavfilter/vf_colorkey.c
new file mode 100644
index 0000000..6c76991
--- /dev/null
+++ b/libavfilter/vf_colorkey.c
@@ -0,0 +1,264 @@
+/*
+ * Copyright (c) 2015 Timo Rothenpieler <timo at 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 "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 int convert_format(int fmt)
+{
+    switch(fmt) {
+    case AV_PIX_FMT_0RGB:
+        return AV_PIX_FMT_ARGB;
+    case AV_PIX_FMT_0BGR:
+        return AV_PIX_FMT_ABGR;
+    case AV_PIX_FMT_BGR0:
+        return AV_PIX_FMT_BGRA;
+    case AV_PIX_FMT_RGB0:
+        return AV_PIX_FMT_RGBA;
+    default:
+        return fmt;
+    }
+}
+
+static int offset_r(int fmt)
+{
+    switch(fmt) {
+    case AV_PIX_FMT_ARGB:
+        return 1;
+    case AV_PIX_FMT_ABGR:
+        return 3;
+    case AV_PIX_FMT_BGRA:
+        return 2;
+    case AV_PIX_FMT_RGBA:
+    default:
+        return 0;
+    }
+}
+
+static int offset_g(int fmt)
+{
+    switch(fmt) {
+    case AV_PIX_FMT_ARGB:
+    case AV_PIX_FMT_ABGR:
+        return 2;
+    case AV_PIX_FMT_BGRA:
+    case AV_PIX_FMT_RGBA:
+    default:
+        return 1;
+    }
+}
+
+static int offset_b(int fmt)
+{
+    switch(fmt) {
+    case AV_PIX_FMT_ARGB:
+        return 3;
+    case AV_PIX_FMT_ABGR:
+        return 1;
+    case AV_PIX_FMT_BGRA:
+        return 0;
+    case AV_PIX_FMT_RGBA:
+    default:
+        return 2;
+    }
+}
+
+static int offset_a(int fmt)
+{
+    switch(fmt) {
+    case AV_PIX_FMT_ARGB:
+    case AV_PIX_FMT_ABGR:
+        return 0;
+    case AV_PIX_FMT_BGRA:
+    case AV_PIX_FMT_RGBA:
+    default:
+        return 3;
+    }
+}
+
+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(FFMAX(diff - ctx->similarity, 0.0) / ctx->blend, 0.0, 1.0) * 255.0;
+    } else {
+        return ((diff - ctx->similarity) > 0.0) ? 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;
+
+    frame->format = convert_format(frame->format);
+
+    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 int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *avctx = outlink->src;
+    ColorkeyContext *ctx = avctx->priv;
+
+    outlink->w = avctx->inputs[0]->w;
+    outlink->h = avctx->inputs[0]->h;
+    outlink->time_base = avctx->inputs[0]->time_base;
+
+    outlink->format = convert_format(avctx->inputs[0]->format);
+
+    ctx->co[0] = offset_r(outlink->format);
+    ctx->co[1] = offset_g(outlink->format);
+    ctx->co[2] = offset_b(outlink->format);
+    ctx->co[3] = offset_a(outlink->format);
+
+    return 0;
+}
+
+static int query_formats(AVFilterContext *avctx)
+{
+    static const enum AVPixelFormat pixel_fmts_in[] = {
+        AV_PIX_FMT_0RGB,
+        AV_PIX_FMT_ARGB,
+        AV_PIX_FMT_RGB0,
+        AV_PIX_FMT_RGBA,
+        AV_PIX_FMT_0BGR,
+        AV_PIX_FMT_ABGR,
+        AV_PIX_FMT_BGR0,
+        AV_PIX_FMT_BGRA,
+        AV_PIX_FMT_NONE
+    };
+
+    static const enum AVPixelFormat pixel_fmts_out[] = {
+        AV_PIX_FMT_ARGB,
+        AV_PIX_FMT_RGBA,
+        AV_PIX_FMT_ABGR,
+        AV_PIX_FMT_BGRA,
+        AV_PIX_FMT_NONE
+    };
+
+    AVFilterFormats *input_formats;
+    AVFilterFormats *output_formats;
+
+    input_formats = ff_make_format_list(pixel_fmts_in);
+    if (!input_formats)
+        return AVERROR(ENOMEM);
+
+    output_formats = ff_make_format_list(pixel_fmts_out);
+    if (!output_formats)
+        return AVERROR(ENOMEM);
+
+    ff_formats_ref(input_formats, &avctx->inputs[0]->out_formats);
+    ff_formats_ref(output_formats, &avctx->outputs[0]->in_formats);
+
+    return 0;
+}
+
+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,
+};
-- 
2.3.6



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