lavfi: port perspective filter from libmpcodecs

Signed-off-by: Paul B Mahol <onemda@gmail.com>

8 files changed, 452 insertions, 2 deletions

diff --git a/Changelog b/Changelog
index ecbb39d84a..48149a39b1 100644
--- a/Changelog
+++ b/Changelog
@@ -4,6 +4,7 @@ releases are sorted from youngest to oldest.
 version <next>
 
 - aecho filter
+- perspective filter ported from libmpcodecs
 
 
 version 2.0:
diff --git a/LICENSE b/LICENSE
index 99f6478c7d..575824e19c 100644
--- a/LICENSE
+++ b/LICENSE
@@ -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
diff --git a/configure b/configure
index 1ec803285a..ab3ac2704f 100755
--- a/configure
+++ b/configure
@@ -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"
diff --git a/doc/filters.texi b/doc/filters.texi
index 6f3994a204..7d4eeea26e 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -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
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 306b24cb65..7f10409f0e 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -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
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 26472f8dc7..bda6e3cc7f 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -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);
diff --git a/libavfilter/version.h b/libavfilter/version.h
index 1a41f92acc..b706fe2c9b 100644
--- a/libavfilter/version.h
+++ b/libavfilter/version.h
@@ -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, \
diff --git a/libavfilter/vf_perspective.c b/libavfilter/vf_perspective.c
new file mode 100644
index 0000000000..35b4ea8c12
--- /dev/null
+++ b/libavfilter/vf_perspective.c
@@ -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,
+};