@@ -4,6 +4,7 @@ releases are sorted from youngest to oldest.

 version <next>

 - aecho filter

+- perspective filter ported from libmpcodecs

 version 2.0:

@@ -39,6 +39,7 @@ Specifically, the GPL parts of FFmpeg are

     - vf_mp.c

     - vf_noise.c

     - vf_owdenoise.c

+    - vf_perspective.c

     - vf_pp.c

     - vf_sab.c

     - vf_smartblur.c

@@ -2175,6 +2175,7 @@ mpdecimate_filter_deps="gpl avcodec"

 mptestsrc_filter_deps="gpl"

 negate_filter_deps="lut_filter"

 noise_filter_deps="gpl"

+perspective_filter_deps="gpl"

 resample_filter_deps="avresample"

 ocv_filter_deps="libopencv"

 owdenoise_filter_deps="gpl"

@@ -5722,6 +5722,44 @@ pad="2*iw:2*ih:ow-iw:oh-ih"

 @end example

 @end itemize

+@section perspective

+

+Correct perspective of video not recorded perpendicular to the screen.

+

+A description of the accepted parameters follows.

+

+@table @option

+@item x0

+@item y0

+@item x1

+@item y1

+@item x2

+@item y2

+@item x3

+@item y3

+Set coordinates expression for top left, top right, bottom left and bottom right corners.

+Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.

+

+The expressions can use the following variables:

+

+@table @option

+@item W

+@item H

+the width and height of video frame.

+@end table

+

+@item interpolation

+Set interpolation for perspective correction.

+

+It accepts the following values:

+@table @samp

+@item linear

+@item cubic

+@end table

+

+Default value is @samp{linear}.

+@end table

+

 @section pixdesctest

 Pixel format descriptor test filter, mainly useful for internal

@@ -166,6 +166,7 @@ OBJS-$(CONFIG_OVERLAY_FILTER)                += vf_overlay.o dualinput.o

 OBJS-$(CONFIG_OWDENOISE_FILTER)              += vf_owdenoise.o

 OBJS-$(CONFIG_PAD_FILTER)                    += vf_pad.o

 OBJS-$(CONFIG_PERMS_FILTER)                  += f_perms.o

+OBJS-$(CONFIG_PERSPECTIVE_FILTER)            += vf_perspective.o

 OBJS-$(CONFIG_PIXDESCTEST_FILTER)            += vf_pixdesctest.o

 OBJS-$(CONFIG_PP_FILTER)                     += vf_pp.o

 OBJS-$(CONFIG_PSNR_FILTER)                   += vf_psnr.o dualinput.o

@@ -161,6 +161,7 @@ void avfilter_register_all(void)

     REGISTER_FILTER(OWDENOISE,      owdenoise,      vf);

     REGISTER_FILTER(PAD,            pad,            vf);

     REGISTER_FILTER(PERMS,          perms,          vf);

+    REGISTER_FILTER(PERSPECTIVE,    perspective,    vf);

     REGISTER_FILTER(PIXDESCTEST,    pixdesctest,    vf);

     REGISTER_FILTER(PP,             pp,             vf);

     REGISTER_FILTER(PSNR,           psnr,           vf);

@@ -30,8 +30,8 @@

 #include "libavutil/avutil.h"

 #define LIBAVFILTER_VERSION_MAJOR  3

-#define LIBAVFILTER_VERSION_MINOR  80

-#define LIBAVFILTER_VERSION_MICRO 101

+#define LIBAVFILTER_VERSION_MINOR  81

+#define LIBAVFILTER_VERSION_MICRO 100

 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

                                                LIBAVFILTER_VERSION_MINOR, \

new file mode 100644

@@ -0,0 +1,407 @@

+/*

+ * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>

+ * Copyright (c) 2013 Paul B Mahol

+ *

+ * 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

+ */

+

+#include "libavutil/eval.h"

+#include "libavutil/imgutils.h"

+#include "libavutil/pixdesc.h"

+#include "libavutil/opt.h"

+#include "avfilter.h"

+#include "formats.h"

+#include "internal.h"

+#include "video.h"

+

+#define SUB_PIXEL_BITS  8

+#define SUB_PIXELS      (1 << SUB_PIXEL_BITS)

+#define COEFF_BITS      11

+

+#define LINEAR 0

+#define CUBIC  1

+

+typedef struct PerspectiveContext {

+    const AVClass *class;

+    char *expr_str[4][2];

+    double ref[4][2];

+    int32_t (*pv)[2];

+    int32_t coeff[SUB_PIXELS][4];

+    int interpolation;

+    int linesize[4];

+    int height[4];

+    int hsub, vsub;

+    int nb_planes;

+

+    void (*perspective)(struct PerspectiveContext *s,

+                        uint8_t *dst, int dst_linesize,

+                        uint8_t *src, int src_linesize,

+                        int w, int h, int hsub, int vsub);

+} PerspectiveContext;

+

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

+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM

+

+static const AVOption perspective_options[] = {

+    { "x0", "set top left x coordinate",     OFFSET(expr_str[0][0]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },

+    { "y0", "set top left y coordinate",     OFFSET(expr_str[0][1]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },

+    { "x1", "set top right x coordinate",    OFFSET(expr_str[1][0]), AV_OPT_TYPE_STRING, {.str="W"}, 0, 0, FLAGS },

+    { "y1", "set top right y coordinate",    OFFSET(expr_str[1][1]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },

+    { "x2", "set bottom left x coordinate",  OFFSET(expr_str[2][0]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },

+    { "y2", "set bottom left y coordinate",  OFFSET(expr_str[2][1]), AV_OPT_TYPE_STRING, {.str="H"}, 0, 0, FLAGS },

+    { "x3", "set bottom right x coordinate", OFFSET(expr_str[3][0]), AV_OPT_TYPE_STRING, {.str="W"}, 0, 0, FLAGS },

+    { "y3", "set bottom right y coordinate", OFFSET(expr_str[3][1]), AV_OPT_TYPE_STRING, {.str="H"}, 0, 0, FLAGS },

+    { "interpolation", "set interpolation", OFFSET(interpolation), AV_OPT_TYPE_INT, {.i64=LINEAR}, 0, 1, FLAGS, "interpolation" },

+    {      "linear", "", 0, AV_OPT_TYPE_CONST, {.i64=LINEAR}, 0, 0, FLAGS, "interpolation" },

+    {       "cubic", "", 0, AV_OPT_TYPE_CONST, {.i64=CUBIC},  0, 0, FLAGS, "interpolation" },

+    { NULL }

+};

+

+AVFILTER_DEFINE_CLASS(perspective);

+

+static int query_formats(AVFilterContext *ctx)

+{

+    static const enum AVPixelFormat pix_fmts[] = {

+        AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVA422P, AV_PIX_FMT_YUVA420P,

+        AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P, AV_PIX_FMT_YUVJ422P,AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ411P,

+        AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV411P, AV_PIX_FMT_YUV410P,

+        AV_PIX_FMT_GBRP, AV_PIX_FMT_GBRAP, AV_PIX_FMT_GRAY8, AV_PIX_FMT_NONE

+    };

+

+    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));

+    return 0;

+}

+

+static inline double get_coeff(double d)

+{

+    double coeff, A = -0.60;

+

+    d = fabs(d);

+

+    if (d < 1.0)

+        coeff = (1.0 - (A + 3.0) * d * d + (A + 2.0) * d * d * d);

+    else if (d < 2.0)

+        coeff = (-4.0 * A + 8.0 * A * d - 5.0 * A * d * d + A * d * d * d);

+    else

+        coeff = 0.0;

+

+    return coeff;

+}

+

+static const char *const var_names[] = {   "W",   "H", NULL };

+enum                                   { VAR_W, VAR_H, VAR_VARS_NB };

+

+static int config_input(AVFilterLink *inlink)

+{

+    double x0, x1, x2, x3, x4, x5, x6, x7, q;

+    AVFilterContext *ctx = inlink->dst;

+    PerspectiveContext *s = ctx->priv;

+    double (*ref)[2] = s->ref;

+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);

+    double values[VAR_VARS_NB] = { [VAR_W] = inlink->w, [VAR_H] = inlink->h };

+    int h = inlink->h;

+    int w = inlink->w;

+    int x, y, i, j, ret;

+

+    for (i = 0; i < 4; i++) {

+        for (j = 0; j < 2; j++) {

+            if (!s->expr_str[i][j])

+                return AVERROR(EINVAL);

+            ret = av_expr_parse_and_eval(&s->ref[i][j], s->expr_str[i][j],

+                                         var_names, &values[0],

+                                         NULL, NULL, NULL, NULL,

+                                         0, 0, ctx);

+            if (ret < 0)

+                return ret;

+        }

+    }

+

+    s->hsub = desc->log2_chroma_w;

+    s->vsub = desc->log2_chroma_h;

+    s->nb_planes = av_pix_fmt_count_planes(inlink->format);

+    if ((ret = av_image_fill_linesizes(s->linesize, inlink->format, inlink->w)) < 0)

+        return ret;

+

+    s->height[1] = s->height[2] = FF_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);

+    s->height[0] = s->height[3] = inlink->h;

+

+    s->pv = av_realloc_f(s->pv, w * h, 2 * sizeof(*s->pv));

+    if (!s->pv)

+        return AVERROR(ENOMEM);

+

+    x6 = ((ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *

+          (ref[2][1] - ref[3][1]) -

+         ( ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *

+          (ref[2][0] - ref[3][0])) * h;

+    x7 = ((ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *

+          (ref[1][0] - ref[3][0]) -

+         ( ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *

+          (ref[1][1] - ref[3][1])) * w;

+    q =  ( ref[1][0] - ref[3][0]) * (ref[2][1] - ref[3][1]) -

+         ( ref[2][0] - ref[3][0]) * (ref[1][1] - ref[3][1]);

+

+    x0 = q * (ref[1][0] - ref[0][0]) * h + x6 * ref[1][0];

+    x1 = q * (ref[2][0] - ref[0][0]) * w + x7 * ref[2][0];

+    x2 = q *  ref[0][0] * w * h;

+    x3 = q * (ref[1][1] - ref[0][1]) * h + x6 * ref[1][1];

+    x4 = q * (ref[2][1] - ref[0][1]) * w + x7 * ref[2][1];

+    x5 = q *  ref[0][1] * w * h;

+

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

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

+            int u, v;

+

+            u = (int)floor(SUB_PIXELS * (x0 * x + x1 * y + x2) /

+                                        (x6 * x + x7 * y + q * w * h) + 0.5);

+            v = (int)floor(SUB_PIXELS * (x3 * x + x4 * y + x5) /

+                                        (x6 * x + x7 * y + q * w * h) + 0.5);

+

+            s->pv[x + y * w][0] = u;

+            s->pv[x + y * w][1] = v;

+        }

+    }

+

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

+        double d = i / (double)SUB_PIXELS;

+        double temp[4];

+        double sum = 0;

+

+        for (j = 0; j < 4; j++)

+            temp[j] = get_coeff(j - d - 1);

+

+        for (j = 0; j < 4; j++)

+            sum += temp[j];

+

+        for (j = 0; j < 4; j++)

+            s->coeff[i][j] = (int)floor((1 << COEFF_BITS) * temp[j] / sum + 0.5);

+    }

+

+    return 0;

+}

+

+static void resample_cubic(PerspectiveContext *s,

+                           uint8_t *dst, int dst_linesize,

+                           uint8_t *src, int src_linesize,

+                           int w, int h, int hsub, int vsub)

+{

+    const int linesize = s->linesize[0];

+    int x, y;

+

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

+        int sy = y << vsub;

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

+            int u, v, subU, subV, sum, sx;

+

+            sx   = x << hsub;

+            u    = s->pv[sx + sy * linesize][0] >> hsub;

+            v    = s->pv[sx + sy * linesize][1] >> vsub;

+            subU = u & (SUB_PIXELS - 1);

+            subV = v & (SUB_PIXELS - 1);

+            u  >>= SUB_PIXEL_BITS;

+            v  >>= SUB_PIXEL_BITS;

+

+            if (u > 0 && v > 0 && u < w - 2 && v < h - 2){

+                const int index = u + v*src_linesize;

+                const int a = s->coeff[subU][0];

+                const int b = s->coeff[subU][1];

+                const int c = s->coeff[subU][2];

+                const int d = s->coeff[subU][3];

+

+                sum = s->coeff[subV][0] * (a * src[index - 1 -     src_linesize] + b * src[index - 0 -     src_linesize]  +

+                                      c *      src[index + 1 -     src_linesize] + d * src[index + 2 -     src_linesize]) +

+                      s->coeff[subV][1] * (a * src[index - 1                   ] + b * src[index - 0                   ]  +

+                                      c *      src[index + 1                   ] + d * src[index + 2                   ]) +

+                      s->coeff[subV][2] * (a * src[index - 1 +     src_linesize] + b * src[index - 0 +     src_linesize]  +

+                                      c *      src[index + 1 +     src_linesize] + d * src[index + 2 +     src_linesize]) +

+                      s->coeff[subV][3] * (a * src[index - 1 + 2 * src_linesize] + b * src[index - 0 + 2 * src_linesize]  +

+                                      c *      src[index + 1 + 2 * src_linesize] + d * src[index + 2 + 2 * src_linesize]);

+            } else {

+                int dx, dy;

+

+                sum = 0;

+

+                for (dy = 0; dy < 4; dy++) {

+                    int iy = v + dy - 1;

+

+                    if (iy < 0)

+                        iy = 0;

+                    else if (iy >= h)

+                        iy = h-1;

+                    for (dx = 0; dx < 4; dx++) {

+                        int ix = u + dx - 1;

+

+                        if (ix < 0)

+                            ix = 0;

+                        else if (ix >= w)

+                            ix = w - 1;

+

+                        sum += s->coeff[subU][dx] * s->coeff[subV][dy] * src[ ix + iy * src_linesize];

+                    }

+                }

+            }

+

+            sum = (sum + (1<<(COEFF_BITS * 2 - 1))) >> (COEFF_BITS * 2);

+            sum = av_clip(sum, 0, 255);

+            dst[x + y * dst_linesize] = sum;

+        }

+    }

+}

+

+static void resample_linear(PerspectiveContext *s,

+                            uint8_t *dst, int dst_linesize,

+                            uint8_t *src, int src_linesize,

+                            int w, int h, int hsub, int vsub)

+{

+    const int linesize = s->linesize[0];

+    int x, y;

+

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

+        int sy = y << vsub;

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

+            int u, v, subU, subV, sum, sx, index, subUI, subVI;

+

+            sx   = x << hsub;

+            u    = s->pv[sx + sy * linesize][0] >> hsub;

+            v    = s->pv[sx + sy * linesize][1] >> vsub;

+            subU = u & (SUB_PIXELS - 1);

+            subV = v & (SUB_PIXELS - 1);

+            u  >>= SUB_PIXEL_BITS;

+            v  >>= SUB_PIXEL_BITS;

+

+            index = u + v * src_linesize;

+            subUI = SUB_PIXELS - subU;

+            subVI = SUB_PIXELS - subV;

+

+            if ((unsigned)u < (unsigned)(w - 1)){

+                if((unsigned)v < (unsigned)(h - 1)){

+                    sum = subVI * (subUI * src[index] + subU * src[index + 1]) +

+                          subV  * (subUI * src[index + src_linesize] + subU * src[index + src_linesize + 1]);

+                    sum = (sum + (1 << (SUB_PIXEL_BITS * 2 - 1)))>> (SUB_PIXEL_BITS * 2);

+                } else {

+                    if (v < 0)

+                        v = 0;

+                    else

+                        v = h - 1;

+                    index = u + v * src_linesize;

+                    sum   = subUI * src[index] + subU * src[index + 1];

+                    sum   = (sum + (1 << (SUB_PIXEL_BITS - 1))) >> SUB_PIXEL_BITS;

+                }

+            } else {

+                if ((unsigned)v < (unsigned)(h - 1)){

+                    if (u < 0)

+                        u = 0;

+                    else

+                        u = w - 1;

+                    index = u + v * src_linesize;

+                    sum   = subVI * src[index] + subV * src[index + src_linesize];

+                    sum   = (sum + (1 << (SUB_PIXEL_BITS - 1))) >> SUB_PIXEL_BITS;

+                } else {

+                    if (u < 0)

+                        u = 0;

+                    else

+                        u = w - 1;

+                    if (v < 0)

+                        v = 0;

+                    else

+                        v = h - 1;

+                    index = u + v * src_linesize;

+                    sum   = src[index];

+                }

+            }

+

+            sum = av_clip(sum, 0, 255);

+            dst[x + y * dst_linesize] = sum;

+        }

+    }

+}

+

+static av_cold int init(AVFilterContext *ctx)

+{

+    PerspectiveContext *s = ctx->priv;

+

+    switch (s->interpolation) {

+    case LINEAR: s->perspective = resample_linear; break;

+    case CUBIC:  s->perspective = resample_cubic;  break;

+    }

+

+    return 0;

+}

+

+static int filter_frame(AVFilterLink *inlink, AVFrame *frame)

+{

+    AVFilterContext *ctx = inlink->dst;

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

+    PerspectiveContext *s = ctx->priv;

+    AVFrame *out;

+    int plane;

+

+    out = ff_get_video_buffer(outlink, outlink->w, outlink->h);

+    if (!out) {

+        av_frame_free(&frame);

+        return AVERROR(ENOMEM);

+    }

+    av_frame_copy_props(out, frame);

+

+    for (plane = 0; plane < s->nb_planes; plane++) {

+        int hsub = plane == 1 || plane == 2 ? s->hsub : 0;

+        int vsub = plane == 1 || plane == 2 ? s->vsub : 0;

+        s->perspective(s, out->data[plane], out->linesize[plane],

+                       frame->data[plane], frame->linesize[plane],

+                       s->linesize[plane], s->height[plane], hsub, vsub);

+    }

+

+    av_frame_free(&frame);

+    return ff_filter_frame(outlink, out);

+}

+

+static av_cold void uninit(AVFilterContext *ctx)

+{

+    PerspectiveContext *s = ctx->priv;

+

+    av_freep(&s->pv);

+}

+

+static const AVFilterPad perspective_inputs[] = {

+    {

+        .name             = "default",

+        .type             = AVMEDIA_TYPE_VIDEO,

+        .filter_frame     = filter_frame,

+        .config_props     = config_input,

+    },

+    { NULL }

+};

+

+static const AVFilterPad perspective_outputs[] = {

+    {

+        .name          = "default",

+        .type          = AVMEDIA_TYPE_VIDEO,

+    },

+    { NULL }

+};

+

+AVFilter avfilter_vf_perspective = {

+    .name          = "perspective",

+    .description   = NULL_IF_CONFIG_SMALL("Correct the perspective of video."),

+    .priv_size     = sizeof(PerspectiveContext),

+    .init          = init,

+    .uninit        = uninit,

+    .query_formats = query_formats,

+    .inputs        = perspective_inputs,

+    .outputs       = perspective_outputs,

+    .priv_class    = &perspective_class,

+    .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,

+};