@@ -47,6 +47,7 @@ version next:

 - hue filter

 - ICO muxer

 - SubRip encoder and decoder without embedded timing

+- edge detection filter

 version 0.11:

@@ -1929,6 +1929,33 @@ For more information about libfreetype, check:

 For more information about fontconfig, check:

 @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}.

+@section edgedetect

+

+Detect and draw edges. The filter uses the Canny Edge Detection algorithm.

+

+This filter accepts the following optional named parameters:

+

+@table @option

+@item low, high

+Set low and high threshold values used by the Canny thresholding

+algorithm.

+

+The high threshold selects the "strong" edge pixels, which are then

+connected through 8-connectivity with the "weak" edge pixels selected

+by the low threshold.

+

+@var{low} and @var{high} threshold values must be choosen in the range

+[0,1], and @var{low} should be lesser or equal to @var{high}.

+

+Default value for @var{low} is @code{20/255}, and default value for @var{high}

+is @code{50/255}.

+@end table

+

+Example:

+@example

+edgedetect=low=0.1:high=0.4

+@end example

+

 @section fade

 Apply fade-in/out effect to input video.

@@ -90,6 +90,7 @@ OBJS-$(CONFIG_DELOGO_FILTER)                 += vf_delogo.o

 OBJS-$(CONFIG_DESHAKE_FILTER)                += vf_deshake.o

 OBJS-$(CONFIG_DRAWBOX_FILTER)                += vf_drawbox.o

 OBJS-$(CONFIG_DRAWTEXT_FILTER)               += vf_drawtext.o

+OBJS-$(CONFIG_EDGEDETECT_FILTER)             += vf_edgedetect.o

 OBJS-$(CONFIG_FADE_FILTER)                   += vf_fade.o

 OBJS-$(CONFIG_FIELDORDER_FILTER)             += vf_fieldorder.o

 OBJS-$(CONFIG_FIFO_FILTER)                   += fifo.o

@@ -81,6 +81,7 @@ void avfilter_register_all(void)

     REGISTER_FILTER (DESHAKE,     deshake,     vf);

     REGISTER_FILTER (DRAWBOX,     drawbox,     vf);

     REGISTER_FILTER (DRAWTEXT,    drawtext,    vf);

+    REGISTER_FILTER (EDGEDETECT,  edgedetect,  vf);

     REGISTER_FILTER (FADE,        fade,        vf);

     REGISTER_FILTER (FIELDORDER,  fieldorder,  vf);

     REGISTER_FILTER (FIFO,        fifo,        vf);

@@ -29,8 +29,8 @@

 #include "libavutil/avutil.h"

 #define LIBAVFILTER_VERSION_MAJOR  3

-#define LIBAVFILTER_VERSION_MINOR  9

-#define LIBAVFILTER_VERSION_MICRO 102

+#define LIBAVFILTER_VERSION_MINOR  10

+#define LIBAVFILTER_VERSION_MICRO 100

 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

                                                LIBAVFILTER_VERSION_MINOR, \

new file mode 100644

@@ -0,0 +1,323 @@

+/*

+ * Copyright (c) 2012 Clément Bœsch

+ *

+ * 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

+ * Edge detection filter

+ *

+ * @url https://en.wikipedia.org/wiki/Canny_edge_detector

+ */

+

+#include "libavutil/opt.h"

+#include "avfilter.h"

+#include "formats.h"

+#include "internal.h"

+#include "video.h"

+

+typedef struct {

+    const AVClass *class;

+    uint8_t  *tmpbuf;

+    uint16_t *gradients;

+    char     *directions;

+    double   low, high;

+    uint8_t  low_u8, high_u8;

+} EdgeDetectContext;

+

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

+static const AVOption edgedetect_options[] = {

+    { "high", "set high threshold", OFFSET(high), AV_OPT_TYPE_DOUBLE, {.dbl=50/255.}, 0, 1 },

+    { "low",  "set low threshold",  OFFSET(low),  AV_OPT_TYPE_DOUBLE, {.dbl=20/255.}, 0, 1 },

+    { NULL },

+};

+

+AVFILTER_DEFINE_CLASS(edgedetect);

+

+static av_cold int init(AVFilterContext *ctx, const char *args)

+{

+    int ret;

+    EdgeDetectContext *edgedetect = ctx->priv;

+

+    edgedetect->class = &edgedetect_class;

+    av_opt_set_defaults(edgedetect);

+

+    if ((ret = av_set_options_string(edgedetect, args, "=", ":")) < 0)

+        return ret;

+

+    edgedetect->low_u8  = edgedetect->low  * 255.;

+    edgedetect->high_u8 = edgedetect->high * 255.;

+    return 0;

+}

+

+static int query_formats(AVFilterContext *ctx)

+{

+    static const enum PixelFormat pix_fmts[] = {PIX_FMT_GRAY8, PIX_FMT_NONE};

+    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));

+    return 0;

+}

+

+static int config_props(AVFilterLink *inlink)

+{

+    AVFilterContext *ctx = inlink->dst;

+    EdgeDetectContext *edgedetect = ctx->priv;

+

+    edgedetect->tmpbuf     = av_malloc(inlink->w * inlink->h);

+    edgedetect->gradients  = av_calloc(inlink->w * inlink->h, sizeof(*edgedetect->gradients));

+    edgedetect->directions = av_malloc(inlink->w * inlink->h);

+    if (!edgedetect->tmpbuf || !edgedetect->gradients || !edgedetect->directions)

+        return AVERROR(ENOMEM);

+    return 0;

+}

+

+static void gaussian_blur(AVFilterContext *ctx, int w, int h,

+                                uint8_t *dst, int dst_linesize,

+                          const uint8_t *src, int src_linesize)

+{

+    int i, j;

+

+    memcpy(dst, src, w); dst += dst_linesize; src += src_linesize;

+    memcpy(dst, src, w); dst += dst_linesize; src += src_linesize;

+    for (j = 2; j < h - 2; j++) {

+        dst[0] = src[0];

+        dst[1] = src[1];

+        for (i = 2; i < w - 2; i++) {

+            /* Gaussian mask of size 5x5 with sigma = 1.4 */

+            dst[i] = ((src[-2*src_linesize + i-2] + src[2*src_linesize + i-2]) * 2

+                    + (src[-2*src_linesize + i-1] + src[2*src_linesize + i-1]) * 4

+                    + (src[-2*src_linesize + i  ] + src[2*src_linesize + i  ]) * 5

+                    + (src[-2*src_linesize + i+1] + src[2*src_linesize + i+1]) * 4

+                    + (src[-2*src_linesize + i+2] + src[2*src_linesize + i+2]) * 2

+

+                    + (src[  -src_linesize + i-2] + src[  src_linesize + i-2]) *  4

+                    + (src[  -src_linesize + i-1] + src[  src_linesize + i-1]) *  9

+                    + (src[  -src_linesize + i  ] + src[  src_linesize + i  ]) * 12

+                    + (src[  -src_linesize + i+1] + src[  src_linesize + i+1]) *  9

+                    + (src[  -src_linesize + i+2] + src[  src_linesize + i+2]) *  4

+

+                    + src[i-2] *  5

+                    + src[i-1] * 12

+                    + src[i  ] * 15

+                    + src[i+1] * 12

+                    + src[i+2] *  5) / 159;

+        }

+        dst[i    ] = src[i    ];

+        dst[i + 1] = src[i + 1];

+

+        dst += dst_linesize;

+        src += src_linesize;

+    }

+    memcpy(dst, src, w); dst += dst_linesize; src += src_linesize;

+    memcpy(dst, src, w);

+}

+

+enum {

+    DIRECTION_45UP,

+    DIRECTION_45DOWN,

+    DIRECTION_HORIZONTAL,

+    DIRECTION_VERTICAL,

+};

+

+static int get_rounded_direction(int gx, int gy)

+{

+    /* reference angles:

+     *   tan( pi/8) = sqrt(2)-1

+     *   tan(3pi/8) = sqrt(2)+1

+     * Gy/Gx is the tangent of the angle (theta), so Gy/Gx is compared against

+     * <ref-angle>, or more simply Gy against <ref-angle>*Gx

+     *

+     * Gx and Gy bounds = [1020;1020], using 16-bit arithmetic:

+     *   round((sqrt(2)-1) * (1<<16)) =  27146

+     *   round((sqrt(2)+1) * (1<<16)) = 158218

+     */

+    if (gx) {

+        int tanpi8gx, tan3pi8gx;

+

+        if (gx < 0)

+            gx = -gx, gy = -gy;

+        gy <<= 16;

+        tanpi8gx  =  27146 * gx;

+        tan3pi8gx = 158218 * gx;

+        if (gy > -tan3pi8gx && gy < -tanpi8gx)  return DIRECTION_45UP;

+        if (gy > -tanpi8gx  && gy <  tanpi8gx)  return DIRECTION_HORIZONTAL;

+        if (gy >  tanpi8gx  && gy <  tan3pi8gx) return DIRECTION_45DOWN;

+    }

+    return DIRECTION_VERTICAL;

+}

+

+static void sobel(AVFilterContext *ctx, int w, int h,

+                        uint16_t *dst, int dst_linesize,

+                  const uint8_t  *src, int src_linesize)

+{

+    int i, j;

+    EdgeDetectContext *edgedetect = ctx->priv;

+

+    for (j = 1; j < h - 1; j++) {

+        dst += dst_linesize;

+        src += src_linesize;

+        for (i = 1; i < w - 1; i++) {

+            const int gx =

+                -1*src[-src_linesize + i-1] + 1*src[-src_linesize + i+1]

+                -2*src[                i-1] + 2*src[                i+1]

+                -1*src[ src_linesize + i-1] + 1*src[ src_linesize + i+1];

+            const int gy =

+                -1*src[-src_linesize + i-1] + 1*src[ src_linesize + i-1]

+                -2*src[-src_linesize + i  ] + 2*src[ src_linesize + i  ]

+                -1*src[-src_linesize + i+1] + 1*src[ src_linesize + i+1];

+

+            dst[i] = FFABS(gx) + FFABS(gy);

+            edgedetect->directions[j*w + i] = get_rounded_direction(gx, gy);

+        }

+    }

+}

+

+static void non_maximum_suppression(AVFilterContext *ctx, int w, int h,

+                                          uint8_t  *dst, int dst_linesize,

+                                    const uint16_t *src, int src_linesize)

+{

+    int i, j;

+    EdgeDetectContext *edgedetect = ctx->priv;

+

+#define COPY_MAXIMA(ay, ax, by, bx) do {                \

+    if (src[i] > src[(ay)*src_linesize + i+(ax)] &&     \

+        src[i] > src[(by)*src_linesize + i+(bx)])       \

+        dst[i] = av_clip_uint8(src[i]);                 \

+} while (0)

+

+    for (j = 1; j < h - 1; j++) {

+        dst += dst_linesize;

+        src += src_linesize;

+        for (i = 1; i < w - 1; i++) {

+            switch (edgedetect->directions[j*w + i]) {

+            case DIRECTION_45UP:        COPY_MAXIMA( 1, -1, -1,  1); break;

+            case DIRECTION_45DOWN:      COPY_MAXIMA(-1, -1,  1,  1); break;

+            case DIRECTION_HORIZONTAL:  COPY_MAXIMA( 0, -1,  0,  1); break;

+            case DIRECTION_VERTICAL:    COPY_MAXIMA(-1,  0,  1,  0); break;

+            }

+        }

+    }

+}

+

+static void double_threshold(AVFilterContext *ctx, int w, int h,

+                                   uint8_t *dst, int dst_linesize,

+                             const uint8_t *src, int src_linesize)

+{

+    int i, j;

+    EdgeDetectContext *edgedetect = ctx->priv;

+    const int low  = edgedetect->low_u8;

+    const int high = edgedetect->high_u8;

+

+    for (j = 0; j < h; j++) {

+        for (i = 0; i < w; i++) {

+            if (src[i] > high) {

+                dst[i] = src[i];

+                continue;

+            }

+

+            if ((!i || i == w - 1 || !j || j == h - 1) &&

+                src[i] > low &&

+                (src[-src_linesize + i-1] > high ||

+                 src[-src_linesize + i  ] > high ||

+                 src[-src_linesize + i+1] > high ||

+                 src[                i-1] > high ||

+                 src[                i+1] > high ||

+                 src[ src_linesize + i-1] > high ||

+                 src[ src_linesize + i  ] > high ||

+                 src[ src_linesize + i+1] > high))

+                dst[i] = src[i];

+            else

+                dst[i] = 0;

+        }

+        dst += dst_linesize;

+        src += src_linesize;

+    }

+}

+

+static int end_frame(AVFilterLink *inlink)

+{

+    AVFilterContext *ctx = inlink->dst;

+    EdgeDetectContext *edgedetect = ctx->priv;

+    AVFilterLink *outlink = inlink->dst->outputs[0];

+    AVFilterBufferRef  *inpicref = inlink->cur_buf;

+    AVFilterBufferRef *outpicref = outlink->out_buf;

+    uint8_t  *tmpbuf    = edgedetect->tmpbuf;

+    uint16_t *gradients = edgedetect->gradients;

+

+    /* gaussian filter to reduce noise  */

+    gaussian_blur(ctx, inlink->w, inlink->h,

+                  tmpbuf,            inlink->w,

+                  inpicref->data[0], inpicref->linesize[0]);

+

+    /* compute the 16-bits gradients and directions for the next step */

+    sobel(ctx, inlink->w, inlink->h,

+          gradients, inlink->w,

+          tmpbuf,    inlink->w);

+

+    /* non_maximum_suppression() will actually keep & clip what's necessary and

+     * ignore the rest, so we need a clean output buffer */

+    memset(tmpbuf, 0, inlink->w * inlink->h);

+    non_maximum_suppression(ctx, inlink->w, inlink->h,

+                            tmpbuf,    inlink->w,

+                            gradients, inlink->w);

+

+    /* keep high values, or low values surrounded by high values */

+    double_threshold(ctx, inlink->w, inlink->h,

+                     outpicref->data[0], outpicref->linesize[0],

+                     tmpbuf,             inlink->w);

+

+    ff_draw_slice(outlink, 0, outlink->h, 1);

+    return ff_end_frame(outlink);

+}

+

+static av_cold void uninit(AVFilterContext *ctx)

+{

+    EdgeDetectContext *edgedetect = ctx->priv;

+    av_freep(&edgedetect->tmpbuf);

+    av_freep(&edgedetect->gradients);

+    av_freep(&edgedetect->directions);

+}

+

+static int null_draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir) { return 0; }

+

+AVFilter avfilter_vf_edgedetect = {

+    .name          = "edgedetect",

+    .description   = NULL_IF_CONFIG_SMALL("Detect and draw edge."),

+    .priv_size     = sizeof(EdgeDetectContext),

+    .init          = init,

+    .uninit        = uninit,

+    .query_formats = query_formats,

+

+    .inputs    = (const AVFilterPad[]) {

+       {

+           .name             = "default",

+           .type             = AVMEDIA_TYPE_VIDEO,

+           .draw_slice       = null_draw_slice,

+           .config_props     = config_props,

+           .end_frame        = end_frame,

+           .min_perms        = AV_PERM_READ

+        },

+        { .name = NULL }

+    },

+    .outputs   = (const AVFilterPad[]) {

+        {

+            .name            = "default",

+            .type            = AVMEDIA_TYPE_VIDEO,

+        },

+        { .name = NULL }

+    },

+};

@@ -42,6 +42,7 @@ do_lavfi "crop_scale"         "crop=iw-100:ih-100:100:100,scale=400:-1"

 do_lavfi "crop_scale_vflip"   "null,null,crop=iw-200:ih-200:200:200,crop=iw-20:ih-20:20:20,scale=200:200,scale=250:250,vflip,vflip,null,scale=200:200,crop=iw-100:ih-100:100:100,vflip,scale=200:200,null,vflip,crop=iw-100:ih-100:100:100,null"

 do_lavfi "crop_vflip"         "crop=iw-100:ih-100:100:100,vflip"

 do_lavfi "drawbox"            "drawbox=224:24:88:72:#FF8010@0.5"

+do_lavfi "edgedetect"         "edgedetect"

 do_lavfi "fade"               "fade=in:5:15,fade=out:30:15"

 do_lavfi "null"               "null"

 do_lavfi "overlay"            "split[m],scale=88:72,pad=96:80:4:4[o2];[m]fifo[o1],[o1][o2]overlay=240:16"

new file mode 100644

@@ -0,0 +1 @@

+edgedetect          16bce636eef1a82e18837d176f4187c1