avfilter: add find_rect filter

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -2644,6 +2644,7 @@ eq_filter_deps="gpl"
 fftfilt_filter_deps="avcodec"
 fftfilt_filter_select="rdft"
 flite_filter_deps="libflite"
+find_rect_filter_deps="gpl"
 frei0r_filter_deps="frei0r dlopen"
 frei0r_src_filter_deps="frei0r dlopen"
 fspp_filter_deps="gpl"

doc/filters.texi

@@ -5163,6 +5163,36 @@ framework.
 
 It does not take parameters.
 
+@section find_rect
+
+Find a rectangular object
+
+It accepts the following options:
+
+@table @option
+@item object
+Filepath of the object image, needs to be in gray8.
+
+@item threshold
+Detection threshold, default is 0.5.
+
+@item mipmaps
+Number of mipmaps, default is 3.
+
+@item xmin, ymin, xmax, ymax
+Specifies the rectangle in which to search.
+@end table
+
+@subsection Examples
+
+@itemize
+@item
+Generate a representative palette of a given video using @command{ffmpeg}:
+@example
+ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
+@end example
+@end itemize
+
 @anchor{format}
 @section format
 

libavfilter/Makefile

@@ -126,6 +126,7 @@ OBJS-$(CONFIG_FFTFILT_FILTER)                += vf_fftfilt.o
 OBJS-$(CONFIG_FIELD_FILTER)                  += vf_field.o
 OBJS-$(CONFIG_FIELDMATCH_FILTER)             += vf_fieldmatch.o
 OBJS-$(CONFIG_FIELDORDER_FILTER)             += vf_fieldorder.o
+OBJS-$(CONFIG_FIND_RECT_FILTER)              += vf_find_rect.o
 OBJS-$(CONFIG_FORMAT_FILTER)                 += vf_format.o
 OBJS-$(CONFIG_FRAMESTEP_FILTER)              += vf_framestep.o
 OBJS-$(CONFIG_FPS_FILTER)                    += vf_fps.o

libavfilter/allfilters.c

@@ -142,6 +142,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(FIELD,          field,          vf);
     REGISTER_FILTER(FIELDMATCH,     fieldmatch,     vf);
     REGISTER_FILTER(FIELDORDER,     fieldorder,     vf);
+    REGISTER_FILTER(FIND_RECT,      find_rect,      vf);
     REGISTER_FILTER(FORMAT,         format,         vf);
     REGISTER_FILTER(FPS,            fps,            vf);
     REGISTER_FILTER(FRAMEPACK,      framepack,      vf);

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  5
-#define LIBAVFILTER_VERSION_MINOR  14
+#define LIBAVFILTER_VERSION_MINOR  15
 #define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

libavfilter/vf_find_rect.c

+/*
+ * Copyright (c) 2014-2015 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU 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.
+ */
+
+/**
+ * @todo switch to dualinput
+ */
+
+#include "libavutil/avassert.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/opt.h"
+#include "internal.h"
+
+#include "lavfutils.h"
+
+#define MAX_MIPMAPS 5
+
+typedef struct FOCContext {
+    AVClass *class;
+    float threshold;
+    int mipmaps;
+    int xmin, ymin, xmax, ymax;
+    char *obj_filename;
+    int last_x, last_y;
+    AVFrame *obj_frame;
+    AVFrame *needle_frame[MAX_MIPMAPS];
+    AVFrame *haystack_frame[MAX_MIPMAPS];
+} FOCContext;
+
+#define OFFSET(x) offsetof(FOCContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+static const AVOption foc_options[] = {
+    { "object", "object bitmap filename", OFFSET(obj_filename), AV_OPT_TYPE_STRING, {.str = NULL}, .flags = FLAGS },
+    { "threshold", "set threshold", OFFSET(threshold), AV_OPT_TYPE_FLOAT, {.dbl = 0.5}, 0, 1.0, FLAGS },
+    { "mipmaps", "set mipmaps", OFFSET(mipmaps), AV_OPT_TYPE_INT, {.i64 = 3}, 1, MAX_MIPMAPS, FLAGS },
+    { "xmin", "", OFFSET(xmin), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, FLAGS },
+    { "ymin", "", OFFSET(ymin), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, FLAGS },
+    { "xmax", "", OFFSET(xmax), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, FLAGS },
+    { "ymax", "", OFFSET(ymax), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, FLAGS },
+    { NULL }
+};
+
+static const AVClass foc_class = {
+    .class_name       = "find_rect",
+    .item_name        = av_default_item_name,
+    .option           = foc_options,
+    .version          = LIBAVUTIL_VERSION_INT,
+    .category         = AV_CLASS_CATEGORY_FILTER,
+};
+
+static int query_formats(AVFilterContext *ctx)
+{
+    static const enum AVPixelFormat pix_fmts[] = {
+        AV_PIX_FMT_YUV420P,
+        AV_PIX_FMT_YUVJ420P,
+        AV_PIX_FMT_NONE
+    };
+
+    return ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+}
+
+static AVFrame *downscale(AVFrame *in)
+{
+    int x, y;
+    AVFrame *frame = av_frame_alloc();
+    uint8_t *src, *dst;
+    if (!frame)
+        return NULL;
+
+    frame->format = in->format;
+    frame->width  = (in->width + 1) / 2;
+    frame->height = (in->height+ 1) / 2;
+
+    if (av_frame_get_buffer(frame, 32) < 0) {
+        av_frame_free(&frame);
+        return NULL;
+    }
+    src = in   ->data[0];
+    dst = frame->data[0];
+
+    for(y = 0; y < frame->height; y++) {
+        for(x = 0; x < frame->width; x++) {
+            dst[x] = (  src[2*x+0]
+                      + src[2*x+1]
+                      + src[2*x+0 + in->linesize[0]]
+                      + src[2*x+1 + in->linesize[0]]
+                      + 2) >> 2;
+        }
+        src += 2*in->linesize[0];
+        dst += frame->linesize[0];
+    }
+    return frame;
+}
+
+static float compare(const AVFrame *haystack, const AVFrame *obj, int offx, int offy)
+{
+    int x,y;
+    int o_sum_v = 0;
+    int h_sum_v = 0;
+    int64_t oo_sum_v = 0;
+    int64_t hh_sum_v = 0;
+    int64_t oh_sum_v = 0;
+    float c;
+    int n = obj->height * obj->width;
+    const uint8_t *odat = obj     ->data[0];
+    const uint8_t *hdat = haystack->data[0] + offx + offy * haystack->linesize[0];
+    int64_t o_sigma, h_sigma;
+
+    for(y = 0; y < obj->height; y++) {
+        for(x = 0; x < obj->width; x++) {
+            int o_v = odat[x];
+            int h_v = hdat[x];
+            o_sum_v += o_v;
+            h_sum_v += h_v;
+            oo_sum_v += o_v * o_v;
+            hh_sum_v += h_v * h_v;
+            oh_sum_v += o_v * h_v;
+        }
+        odat += obj->linesize[0];
+        hdat += haystack->linesize[0];
+    }
+    o_sigma = n*oo_sum_v - o_sum_v*(int64_t)o_sum_v;
+    h_sigma = n*hh_sum_v - h_sum_v*(int64_t)h_sum_v;
+
+    if (o_sigma == 0 || h_sigma == 0)
+        return 1.0;
+
+    c = (n*oh_sum_v - o_sum_v*(int64_t)h_sum_v) / (sqrt(o_sigma)*sqrt(h_sigma));
+
+    return 1 - fabs(c);
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    FOCContext *foc = ctx->priv;
+
+    if (foc->xmax <= 0)
+        foc->xmax = inlink->w - foc->obj_frame->width;
+    if (foc->ymax <= 0)
+        foc->ymax = inlink->h - foc->obj_frame->height;
+
+    return 0;
+}
+
+static float search(FOCContext *foc, int pass, int maxpass, int xmin, int xmax, int ymin, int ymax, int *best_x, int *best_y, float best_score)
+{
+    int x, y;
+
+    if (pass + 1 <= maxpass) {
+        int sub_x, sub_y;
+        search(foc, pass+1, maxpass, xmin>>1, (xmax+1)>>1, ymin>>1, (ymax+1)>>1, &sub_x, &sub_y, 1.0);
+        xmin = FFMAX(xmin, 2*sub_x - 4);
+        xmax = FFMIN(xmax, 2*sub_x + 4);
+        ymin = FFMAX(ymin, 2*sub_y - 4);
+        ymax = FFMIN(ymax, 2*sub_y + 4);
+    }
+
+    for (y = ymin; y <= ymax; y++) {
+        for (x = xmin; x <= xmax; x++) {
+            float score = compare(foc->haystack_frame[pass], foc->needle_frame[pass], x, y);
+            av_assert0(score != 0);
+            if (score < best_score) {
+                best_score = score;
+                *best_x = x;
+                *best_y = y;
+            }
+        }
+    }
+    return best_score;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFrame *in)
+{
+    AVFilterContext *ctx = inlink->dst;
+    FOCContext *foc = ctx->priv;
+    float best_score;
+    int best_x, best_y;
+    int i;
+
+    foc->haystack_frame[0] = av_frame_clone(in);
+    for (i=1; i<foc->mipmaps; i++) {
+        foc->haystack_frame[i] = downscale(foc->haystack_frame[i-1]);
+    }
+
+    best_score = search(foc, 0, 0,
+                        FFMAX(foc->xmin, foc->last_x - 8),
+                        FFMIN(foc->xmax, foc->last_x + 8),
+                        FFMAX(foc->ymin, foc->last_y - 8),
+                        FFMIN(foc->ymax, foc->last_y + 8),
+                        &best_x, &best_y, 1.0);
+
+    best_score = search(foc, 0, foc->mipmaps - 1, foc->xmin, foc->xmax, foc->ymin, foc->ymax,
+                        &best_x, &best_y, best_score);
+
+    for (i=0; i<MAX_MIPMAPS; i++) {
+        av_frame_free(&foc->haystack_frame[i]);
+    }
+
+    if (best_score > foc->threshold) {
+        return ff_filter_frame(ctx->outputs[0], in);
+    }
+
+    av_log(ctx, AV_LOG_DEBUG, "Found at %d %d score %f\n", best_x, best_y, best_score);
+    foc->last_x = best_x;
+    foc->last_y = best_y;
+
+    av_frame_make_writable(in);
+
+    av_dict_set_int(&in->metadata, "lavfi.rect.w", foc->obj_frame->width, 0);
+    av_dict_set_int(&in->metadata, "lavfi.rect.h", foc->obj_frame->height, 0);
+    av_dict_set_int(&in->metadata, "lavfi.rect.x", best_x, 0);
+    av_dict_set_int(&in->metadata, "lavfi.rect.y", best_y, 0);
+
+    return ff_filter_frame(ctx->outputs[0], in);
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    FOCContext *foc = ctx->priv;
+    int i;
+
+    for (i = 0; i < MAX_MIPMAPS; i++) {
+        av_frame_free(&foc->needle_frame[i]);
+        av_frame_free(&foc->haystack_frame[i]);
+    }
+
+    if (foc->obj_frame)
+        av_freep(&foc->obj_frame->data[0]);
+    av_frame_free(&foc->obj_frame);
+}
+
+static av_cold int init(AVFilterContext *ctx)
+{
+    FOCContext *foc = ctx->priv;
+    int ret, i;
+
+    if (!foc->obj_filename) {
+        av_log(ctx, AV_LOG_ERROR, "object filename not set\n");
+        return AVERROR(EINVAL);
+    }
+
+    foc->obj_frame = av_frame_alloc();
+    if (!foc->obj_frame)
+        return AVERROR(ENOMEM);
+
+    if ((ret = ff_load_image(foc->obj_frame->data, foc->obj_frame->linesize,
+                             &foc->obj_frame->width, &foc->obj_frame->height,
+                             &foc->obj_frame->format, foc->obj_filename, ctx)) < 0)
+        return ret;
+
+    if (foc->obj_frame->format != AV_PIX_FMT_GRAY8) {
+        av_log(ctx, AV_LOG_ERROR, "object image is not a grayscale image\n");
+        return AVERROR(EINVAL);
+    }
+
+    foc->needle_frame[0] = av_frame_clone(foc->obj_frame);
+    for (i = 1; i < foc->mipmaps; i++) {
+        foc->needle_frame[i] = downscale(foc->needle_frame[i-1]);
+        if (!foc->needle_frame[i])
+            return AVERROR(ENOMEM);
+    }
+
+    return 0;
+}
+
+static const AVFilterPad foc_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_input,
+        .filter_frame = filter_frame,
+    },
+    { NULL }
+};
+
+static const AVFilterPad foc_outputs[] = {
+    {
+        .name = "default",
+        .type = AVMEDIA_TYPE_VIDEO,
+    },
+    { NULL }
+};
+
+AVFilter ff_vf_find_rect = {
+    .name            = "find_rect",
+    .description     = NULL_IF_CONFIG_SMALL("Find a user specified object"),
+    .priv_size       = sizeof(FOCContext),
+    .init            = init,
+    .uninit          = uninit,
+    .query_formats   = query_formats,
+    .inputs          = foc_inputs,
+    .outputs         = foc_outputs,
+    .priv_class      = &foc_class,
+};